The spots on cucurbit leaves produced by the Phoma blight are usually more irregular in shape and most often are on the margin of the leaves. The spots are light brown on cantaloupe and cucumber and dark brown on watermelon. Fewer lesions are produced on stems but symptoms also tend to spread from the crown of the plant, giving the plant a blighted appearance. Fruit are generally not affected.

Signs of damage

Crop rotations with nonhost plants such as small grain, corn, of two or more years are effective in reducing the incidence if disease-free seed are used. Currently no varieties are resistant.

How to prevent

A fungicide such as benomyl (Benlate), chlorothalonil (Bravo), copper, maneb (Manzate D or Dithane M-22 Special), mancozeb (Dithane M-45 or Manzate 200) or Dikar (Polyram) may be used to control the disease in the field. It is important to start the spray schedule as soon as the plants emerge and spray at 7-10 day intervals, covering all plant surfaces. High pressure (400 psi), high volume (100 gal/acre for a mature crop) spray equipment provides most effective coverage.

Treat

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Phoma blights

Leaves Go Yellow and Fall Off. Dropping Old and New Leaves Alike.  Wilting, Limp Leaves. Leaves Turning Splotchy Black or Dark Brown.  Mushy Roots Mean Overwatering.  An Overwatered Succulent Will Rot and Turn Mushy.

Soaking the ground for a longer period of time less often, and not watering by hand but using a sprinkler or soaker hose, is the way to handle that situation. Mulch around the plant will also help keep a more even level of moisture.

Move your plant to a shady area even if it is a full-sun plant. Remove any dead or dying leaves. These should be easily recognizable. Check your pot for proper drainage and, if possible, create additional air space around the roots. This will allow oxygen to reach the root zone. Remove any dead or dying roots and keep only the roots that are healthy. Water only when the soil is dry to the touch, but do not let it get too dry. You should also seize all fertilization at this point until the plant is healthy again. Treat with a fungicide.

Water excess and/or uneven watering

When late blight infects stems, everything above the infection site dies. Infected tomato fruits develop rough, leathery spots or dark, water-soaked areas that rot rapidly. Potato tubers bear dark, irregular spots on the surface and reddish-brown spots that extend down into the flesh. Decay continues after harvest.

Fungicides for the control of potato blight are normally only used in a preventative manner, optionally in conjunction with disease forecasting. In susceptible varieties, sometimes fungicide applications may be needed weekly. An early spray is most effective. The choice of fungicide can depend on the nature of local strains of P. infestans. Metalaxyl is a fungicide that was marketed for use against P. infestans, but suffered serious resistance issues when used on its own. In some regions of the world during the 1980s and 1990s, most strains of P. infestans became resistant to metalaxyl, but in subsequent years many populations shifted back to sensitivity. To reduce the occurrence of resistance, it is strongly advised to use single-target fungicides such as metalaxyl along with carbamate compounds. A combination of other compounds are recommended for managing metalaxyl-resistant strains. These include mandipropamid, chlorothalonil, fluazinam, triphenyltin, mancozeb, and others. In the United States, the Environmental Protection Agency has approved oxathiapiprolin for use against late blight.

Ridging is often used to reduce tuber contamination by blight. This normally involves piling soil or mulch around the stems of the potato blight meaning the pathogen has farther to travel to get to the tuber. Another approach is to destroy the canopy around five weeks before harvest, using a contact herbicide or sulfuric acid to burn off the foliage. Eliminating infected foliage reduces the likelihood of tuber infection.

Late blight

Plants with severe rust infection may appear stunted, chlorotic (yellowed), or may display signs of infection such as rust fruiting bodies. Rust fungi grow intracellularly, and make spore-producing fruiting bodies within or, more often, on the surfaces of affected plant parts.

Planting resistant crops is the ideal form of disease prevention, however, mutations can give rise to new strains of fungi that can overcome plant resistance. Although the disease cannot be stopped by removal of the alternate host, the life cycle is disrupted and the rate of mutation is decreased because of reduced genetic recombination. This allows resistance bred crops to remain effective for a longer period of time.

Macrocyclic Disease: Developing a management plan for this type of disease depends largely on whether the repeating stage (urediniospores) occur on the economically important host plant or the alternate host. For example, the repeating stage in white pine blister rust disease does not occur on white pines but on the alternate host, Ribes spp. During August and September Ribes spp. give rise to teliospores which infect white pines. Removal of the alternate host disrupts the life cycle of the rust fungi Cronartium ribicola, preventing the formation of basidiospores which infect the primary host. Although spores from white pines cannot infect other white pines, survival spores may overwinter on infected pines and reinfect Ribes spp. the following season. Infected tissue is removed from white pines and strict quarantines of Ribes spp. are maintained in high risk areas.

Pucciniales

Loss of chlorophyll, with the resulting yellowing of the leaves is the most obvious sign of senescence and in some cases, as seen in Figure 1a and c, the additional synthesis of anthocyanins during senescence results in dramatic orange, red and even purple coloration.

Leaf senescence occurs when the leaf is no longer of use to the plant. It is a normal aging process.

Senescence

Uneven swelling and maturation of the drupe, as well as premature staining without enlargement.

Neem oil as a preventative or light-infection treatment. Copper fungicides or phosphorus acid fungicides can treat larger scale infections. Prevention is the best cure.

Planting resistant cultivars. Treating with hot water on Roses cuttings can be effective, the water must be 44 degrees and treated for 15 minutes.

Peronosporaceae

A range of lesions can occur including concentric oblong light oval-shaped rings (early sign), light green diamond-shaped areas, concentric green and tan oval-shaped rings, tan necrotic spots, and green islands within tan necrotic spots. Damage can reduce harvest yield and grade of onions.

Reduced bulb size and quality of symptoms develop while bulbs are still growing. Control thrips. Control weeds and volunteer onion plants. Remove and destroy infected plants.

Monitor thrips populations with sticky traps starting in June. Damage is often first noticed at field edges, in areas of stressed plants, or in locations with thin plant stands. Infected plants may not show symptoms for several weeks. Sometimes symptoms may never appear. Reduced bulb size and quality of symptoms develop while bulbs are still growing. Control thrips. Control weeds and volunteer onion plants. Remove and destroy infected plants. Rotate crops.

Iris yellow spot virus

Wilting, stunting, uneven plant growth, crown rot, plant death. Roots are discolored, the cortex may slough off, leaving the vascular cylinder.

Fertilize carefully with a slow-release formula in summer months. Water long and sparingly (no more than once a week), early in the day. This way, grass blades have a chance to dry out before nightfall. Aerate the soil to prevent thatch buildup and to loosen compacted, poorly draining soil.

For warm-season Pythium diseases, time fungicide applications preventively or at the very first onset of disease symptoms.

Pythium diseases

If your plant is not getting enough light, the most common sign is the yellowing and dropping of leaves, stunted leaf growth, elongated stems, and a dull-green color. If your plant is getting too much light, then its leaves will have singed tips, burned patches, or will be falling off (yikes!).

You can prevent this from happening by turning the plant once a week or every time you water. This ensure all leaves are exposed to roughly the same amount of light. All plants will bend towards their light source, and we recommend turning all your houseplants at least once a week to prevent “one-sided” growth.

Most plants will survive illuminance ten times lower than listed below but will not grow as well or bloom. Most plants grown as houseplants are selected because they are already adapted to growing at typical house temperatures, between 15° and 25°C. Exceptions do occur, and some plants require chilling periods at lower temperatures (down to 5° or 10°) in winter when less light is available. Houseplants are generally grown in specialized soils called potting compost or potting soil, not in local natural soil. A good potting compost mixture includes soil conditioners to provide the plant with nutrients, support, adequate drainage, and proper aeration. Most potting composts contain a combination of peat and vermiculite or perlite. Concern over environmental damage to peat bogs, however, is leading to the replacement of peat by coir (coconut fibre), which is a sustainable resource. Sterilised soil can also be used.

Lack of light

Symptoms begin as oval to elongate lesions that are generally reddish-brown in color. In the late stages of the disease, erumpent pustules produce numerous black sooty spores. Severe infestations with many stem lesions may weaken plant stems and result in lodging.

Since the fungus overwinters on other plant material, clean up dead plants at the end of the season. Rotate your allium crops to areas that were not previously hosting plants in the family. Remove wild forms of allium, which can also host the fungal spores.

The rust species Puccinia obtegens has shown some promise for controlling Canada thistle, but it must be used in conjunction with other control measures to be effective.

Puccinia

The first symptom is usually the appearance of minute yellow stippling on the upper surface of leaves that have mites on the undersides. Infested leaves generally become yellow and may drop off from plants. Red spider mites on the back of a leaf (left) and mite damage on a cucurbit leaf (right).

Host plant resistance can be a valuable component of an IPM system that is compatible with other control measures such as chemical control, and it makes beneficial natural enemies more effective. In many cases, even partially resistant cultivars are useful to enhance the efficacy of biocontrol agents.

Insecticidal soap or botanical insecticides can be used to spot treat heavily infested areas. On fruit trees, horticultural oil should be applied early in the season or late in the fall to destroy overwintering eggs. Dust on leaves, branches and fruit encourages mites.

Tetranychidae

Primary symptoms of infection include wilting leaves, blight of young shoots, sunken and darkened areas of stems with possible sap or resin flow, cankering on larger stems and branches, browning of the vascular tissue when bark is scraped away, and canopy dieback.

Avoid planting sites prone to spring frosts and use fertilization, irrigation, and weed control practices that discourage late-season growth and promote early hardening off. Sprays for mummy berry and botrytis may help, particularly during flowering.

Prune and discard all blighted stems and cankered branches from the canopy. For trees with thin bark and dense canopies (e.g. Japanese maple and kousa dogwood), annual sanitation pruning of dead stems, especially on interior canopy branches, can help to avoid disease outbreaks in the future.

Phomopsis cankers and blights

The chlorophyll content of the plant leaves is reduced which results in pale yellow color (chlorosis). Older leaves turn completely yellow. Flowering, fruitings, protein and starch contents are reduced. Reduction in protein results in stunted growth and dormant lateral buds.

Nitrogen deficiency can be prevented in the short term by using grass mowings as a mulch, or foliar feeding with manure, and in the longer term by building up levels of organic matter in the soil.

Fertilizers like ammonium phosphate, calcium ammonium nitrate, urea can be supplied. Foliar spray of urea can be a quick method.

Nitrogen deficiency

Rust symptoms first appear on the upper and/or lower surfaces of leaves as small yellow or white slightly raised spots.

Remove all infected parts and destroy them. For bramble fruits, remove and destroy all the infected plants and replant the area with resistant varieties. Clean away all debris in between plants to prevent rust from spreading. Avoid splashing water onto the leaves, as this can help spread rust.

Use a mild bleach solution, and rinse and dry them thoroughly before putting them away. Rake up and remove fallen or dead leaves and other plant debris. Some gardeners compost vegetation that show signs of rust, expecting the compost pile to heat up enough to kill the spores.

Rust

Mealybugs damage crops in a variety of ways. Pupae and females drink the sap of the plant, slowing growth and causing deformation and yellowing of the leaves, sometimes with subsequent leaf fall. The overall effect is a weakening of photosynthesis and hence a decrease in yield.

To keep mealybugs at bay, spray your plants once a week with a solution of neem oil in water. If you coat all plant surfaces, the neem oil will slow or stop feeding on your plants by a wide variety of pests. In addition, the oil coats any eggs or crawlers and will smother them.

Pyrethroids such as permethrin, bifenthrin or cyfluthrin can be used to control mealybugs. Some gardeners use Green Lacewing (Chrysopidae) larvae to control mealybug infestations, as the larval Lacewings are voracious predators of aphids and other small insects.

Pseudococcidae

Death can occur with a sudden browning of the leaves, as with the red oaks, or over time with gradual leaf loss. P. ramorum infection in twigs can lead to shoot tip dieback and wilting. Shoot tip wilting, or flagging, can be useful in identifying trees that are infected but not showing bleeding symptoms.

Truly, the best defenses against Sudden Oak Death include avoiding moving the host plant material long distances, knowing exactly where the disease is, and avoiding traveling in infected areas.

There is no treatment for sudden oak death. A fungicide can be used to allay some of the symptoms but it cannot be cured. Preventative actions are the most successful, by creating barriers between infected and non-infected areas and removing infected plants after they've been diagnosed.

Sudden oak death

Symptoms of infected plants are premature yellowing, dieback, wilting of older leaves, and stunting of plants, followed by death of all foliage and sometimes root rot. Unlike Botrytis species, S. cepivorum does not produce spores to spread and establish disease.

The hyperparasite Coniothyrium minitans may provide biological control, and a commercialized product ‘Contans’ is based on this.

Certain crops such as lettuce, beans and chicory can contribute to inoculum build-up significantly. Soil infestations can also be reduced by metam sodium and biological soil disinfestation.

Sclerotiniaceae

A diagnostic feature of this disease is the presence of many dark-brown, pimple-like structures called pycnidia (fruiting bodies of the fungus) that are readily visible in the tan centers of the spots. When spots are numerous, affected leaves turn yellow and eventually shrivel up, brown, and drop off.

Use disease-free seed. There's no evidence that this fungus is carried by seeds, but err on the safe side and don't save seed from infected plants. Thoroughly processing the tomato seeds you are saving will also help rid the seeds of lingering diseases.
Start with a clean garden. Dispose of all affected plants. The fungus can over-winter on the debris of diseased plants. It's important to dispose of all the affected plants far away from the garden and the compost pile. Keep in mind that it may have spread to your potatoes and eggplants, too.
Avoid overhead watering. Water aids the spread of Septoria leaf spot. Keep it off the leaves as much as possible by watering at the base of the plant only. Of course, it's impossible to keep the rain off your plants, but every little bit helps.
Provide room for air circulation. Leave some space between your tomato plants so there is good airflow. Stake them so that they are not touching the ground and not all bunched together. Good air circulation is especially important during damp and rainy periods.
Mulch below the plants. A layer of mulch will help prevent spores on the ground from splashing up onto the lower leaves.
Plant next year's tomatoes in a different section of your garden. In small gardens, it's not always practical to rotate your crops, so good clean up and sanitation become even more important.

Removing infected leaves. Remove infected leaves immediately, and be sure to wash your hands and pruners thoroughly before working with uninfected plants.
Consider organic fungicide options. Fungicides containing either copper or potassium bicarbonate will help prevent the spreading of the disease. Begin spraying as soon as the first symptoms appear and follow the label directions for continued management.
Consider chemical fungicides. While chemical options are not ideal, they may be the only option for controlling advanced infections. One of the least toxic and most effective is chlorothalonil (sold under the names Fungonil and Daconil).

Septoria leaf spot

General symptoms on the solanaceous crops and cucurbits include seed rot and seedling blight which discolors the roots and causes seedlings to topple over. Preemergence and postemergence damping-off are also possible symptoms that may occur.

Avoid overhead watering that can produce surface runoff, and consider slow drip irrigation instead. Hardy Phytophthora blight pathogens will survive in both hot summer and cold winter compost piles. Remove infected plants immediately, bag and dispose of infected debris, and always keep your garden clean.

Crop rotation may reduce the number of pathogens in the soil and, "a minimum of a 3 years crop rotation which alternates with non-host species is recommended to avoid build-up of P. capsici spores." Crops should also avoid conditions that would be conducive to the pathogen by using well drained soils and raised beds. As stated above, "Excess moisture is the single most important component to the initial infection and subsequent spreading of Phytophthora capsici. Overall, a study by K.H. Lamour and M.K. Hausbeck found that "crop rotation and mefenoxam are not likely to provide economic control". Mefenoxem is the active enantiomer contained in the racemic fungicide metalaxyl used to defend against Phytophthora capsici. Sexual recombination provides the genetic diversity to promote resistance towards fungicides in P. capsici. The failure of crop rotation as a means to control P. capsici may also be due to weeds playing the role of an alternative host in the absence of common hosts. According to a study done by the University of Florida, "In Florida, and perhaps elsewhere, weeds may contribute to pathogen survival in the absence of a host crop or when propagules may not readily survive in soil or plant debris." To avoid fruit rot of vegetable crops in the Cucurbitaceae, trellising cucurbit fruits and other ways to keep the fruit off the ground is a way to control secondary inoculants (zoospores) from physically being splashed from the soil onto the fruit. Control of Phytophthora capsici is easier in drier climates with less rainfall such as California. In these areas, it is important to practice placing drip irrigation emitters away from the stems of pepper plants in order to reduce the incidence of crown rot in peppers.

Phytophthora blight

Yellowing between the leaf veins, sometimes with reddish brown tints and early leaf fall. Magnesium deficiency is common in tomatoes, apples, grape vines, raspberries, roses and rhododendrons.

Reducing or avoiding calcium-rich foods two hours before or after eating magnesium-rich foods. avoiding high-dose zinc supplements. treating vitamin D deficiency. eating raw vegetables instead of cooking them. quitting smoking.

Epsom salts dissolved in water and sprayed onto foliage and applied around the roots will cure magnesium deficiency. In future, feed plants in spring with balanced plant food that contains magnesium. For rhododendrons and azaleas, feed with a plant food specifically formulated for lime-hating or ericaceous plants.

Magnesium deficiency

Spider mites damage foliage by sucking juices from the leaves. This shows up as stippling on the leaves and more severe damage can result in leaf bronzing that may lead to leaf drop. Leaf drop increases incidence of sun/light burn and negatively affects both vegetative and flowering stages. 
Additional signs of spider mites are curled and/or burned leaf edges as well as leaves that have taken on a leathery texture. Webbing will be produced when mite populations grow in size and can be found on foliage, twigs and fruit/buds.

Look before you buy:
Inspect indoor and outdoor plants before purchasing to make sure they aren’t infested.
Keep plants healthy:
Make sure plants are well-watered and fertilized. Healthy plants are more able to withstand pests and diseases, while weakened or stressed plants are more susceptible to problems.
Keep the area clean:
Clear weeds and debris out of garden areas where pests can more easily hide.
Bump up moisture levels:
Since spider mites thrive in dry conditions, keep air humidity levels higher around plants.
Use high-quality soil:
Use a high-quality, sterile potting soil to avoid possible soil-borne pests.

Chemical pesticide use actually encourages the spread of spider mites by killing the beneficial insects that prey on them. Mites are also known to develop quick resistance to various pesticides. For these reasons, it’s important to control mites with effective natural and organic methods.
1 Prune leaves, stems and other infested parts of plants well past any webbing and discard in trash (and not in compost piles). Don’t be hesitant to pull entire plants to prevent the mites spreading to its neighbors.
2 Wash plants with a strong stream of water and reduce pest numbers.
3 Commercially available beneficial insects, such as ladybugs, lacewing and predatory mites are important natural enemies. For best results, make releases when pest levels are low to medium.
4 Nuke Em, a relatively new organic insecticide containing food-grade ingredients, works fast and kills most indoor gardening pests at the egg, larvae or adult stage. Best of all, it does this without leaving a residue on the leaves that can impact flavor.
5 BotaniGard ES is a highly effective biological insecticide containing Beauveria bassiana, an entomopathogenic fungus that attacks a long-list of troublesome crop pests – even resistant strains! Weekly applications can prevent insect population explosions and provide protection equal to or better than conventional chemical pesticides.
6 Mix Pure Neem Oil with Coco-Wet and apply every 3-5 days to kill pest eggs indoors and interrupt the reproductive cycle. Make sure to spray all plant parts, including the undersides of leaves. Do NOT apply when temperatures exceed 90˚F and wait at last six hours before turning lights on.
7 If populations are high, use a least-toxic, short-lived pesticide (Take Down Spray, Doktor Doom Foggers) to reduce infestations, then release predatory mites to maintain control.
8 Insecticidal soap or botanical insecticides can be used to spot treat heavily infested areas.
9 On fruit trees, horticultural oil should be applied early in the season or late in the fall to destroy overwintering eggs.
10 Dust on leaves, branches and fruit encourages mites. A mid-season hosing (or two!) to remove dust from trees is a worthwhile preventative.
11 Water stress makes both trees and garden plants more susceptible to mite infestations. Make sure your plants are properly watered.

Spider Mites

Some of the most common symptoms of nutrient deficiencies are chlorosis, foliage color changes, overall plant stunting and sometimes necrosis. All can be caused by one or more deficiencies.

Monitor pH Levels – There are lots of things that can cause a hydroponic nutrient solution to drift outside of the ideal range of about 5.6. Usually, if a nutrient solution is left unmonitored for too long, it can start drifting outside of this range because it gets too dense in raw, use nutrients. Other times, it might start becoming too acid or too alkaline when you add new hydroponic nutrients or transfer your plants to a new medium. Since pH levels can change very rapidly, it is important to check your pH level daily. The longer your nutrient solution spends outside of this ideal range, the greater the chance that your flowers or vegetables will suffer a plant deficiency. Use a pharmaceutical grade pH adjustment product designed specifically for hydroponics to make the necessary adjustments. This way you have less of a chance of accidentally over compensating your pH adjustments.  Keep Temperature Levels Stable – Your nutrient solution should be fairly cool to temperate, somewhere in the range of sixty six to seventy one degrees Fahrenheit. You should be particularly aware of this if you happen to live in an unusually warm or cold part of the world. If you feel it is necessary to prevent plant deficiency, take extra steps insulate your grow room against outside elements. You should also avoid placing your reservoir directly on the ground in your grow room, as the floor can be very cool, which can transfer to the reservoir and cause a plant deficiency.

When the temperature of your indoor garden or the nutrient solution falls below 55 degrees Fahrenheit, plants take up less phosphorus than they need. If you've determined that the temperature is not the problem, treat your plants to bone meal, a supplement that's rich in phosphorus.

Nutrient deficiency

Plant stunting and severe curling of leaves occur when the leafhopper Empoasca fabae punctures the undersurfaces of leaves and veins of bush beans and inhibits growth. This leafhopper also feeds on alfalfa and causes leaves to turn yellow and drop off.

Try to avoid moisture or humidity relationships as they affect the habitats of homopterans.

When controlling thrips, you can prune and get rid of any injured areas on the plant. Regular pruning helps get rid of thrips. Thrips on flowers can be eliminated as soon as you see signs of damage by using a mild insecticide like insecticidal soap or neem oil, or by pruning the flowers.

Homoptera

Typical leaf symptoms of viral diseases include mosaic patterns, chlorotic or necrotic lesions (Figure 13), yellowing, stripes or streaks, vein clearing, vein banding, and leaf rolling and curling.

Remove all infected plants and destroy them. Do NOT put them in the compost pile, as the virus may persist in infected plant matter. Burn infected plants or throw them out with the garbage. Monitor the rest of your plants closely, especially those that were located near infected plants. Disinfect gardening tools after every use. Keep a bottle of a weak bleach solution or other antiviral disinfectant to wipe your tools down with.

1. Remove all infected plants and destroy them. Do NOT put them in the compost pile, as the virus may persist in infected plant matter.
2. Monitor the rest of your plants closely, especially those that were located near infected plants.
3. Disinfect gardening tools after every use.

Viruses

Scales attack hundreds of ornamental varieties, and are found everywhere ornamental plants are grown. While some scales infest a wide variety of plants, others are host-specific. Many ornamentals are attacked by a single scale species, while others are attacked by numerous species.
Scales damage plants by sucking the juices from the plants. Heavily-infested plants appear unhealthy and produce little new growth. Scales that feed on leaves can cause leaf spotting; spots progressively increase in size as the scales continue to feed. With serious infestations, leaves drop prematurely, and twigs and branches may be killed. The sooty mold that develops on the honeydew produced by soft scales inhibits the plant’s ability to harvest light energy, reducing photosynthesis and further weakening the host plant. Scales that feed on twigs or bark generally do not produce leaf discoloration, but long-term feeding weakens the host plant. A chronic infestation can kill the host.

Periodically inspect host plants, particularly plants that have been previously infested. Since scale insects may occur on all plant parts, check the trunk and branches, as well as the twigs and leaves. The midvein of the underside of the leaf is common site for leaf-feeding scales to inhabit. Stems should be checked around buds, leaf petioles and lenticles or other depressions which may offer a place for the scales to hide and feed. The color contrast between the bark and the scale can be increased by wetting the bark with water before inspecting. Crawlers, the immature mobile life stage, may be monitored for by placing double-stick tape on some branches of the plant.
Stressed plants are more susceptible to scale attack. Maintaining healthy plants will minimize the likelihood of a plant being attacked.
Keep susceptible host plants healthy and well watered; scales nearly always attack stressed plants. Inspect plants periodically for presence of scales. If an infestation is detected, treat before the infestation becomes too severe, and monitor the progress of the treatment in the weeks and months after application. Be aware of the most commonly occurring scale problems in your area. Annual applications of soil-systemic insecticides to susceptible ornamentals are a good idea, particularly if plants are under stress.

Armored scale insects would be a breeze to eliminate if not for their thick outer coatings. The insects themselves are quite vulnerable, so you don’t need to go in with a huge arsenal. Horticultural oil is the very best way to destroy armored scale while preserving the predators that will readily feed on their young during the mobile “crawler” stage. Ideally, timing your application with the emergence of crawlers from their mothers’ covers will eliminate an entire generation all at once. Repeat sprays at five to six week intervals will knock the colony back, and persistence will destroy them entirely. Before applying horticultural oil, ensure that your plant is well hydrated and not heat stressed. Most plants won’t have a problem with horticultural oil mixed appropriately, but the odd bush or tree might experience phytotoxicity, so try a small spot first a few days ahead of when you plan to spray the whole plant.
It also is important to remember that it may take weeks or even months before complete control is observed. Control is delayed if the host plant is under stress, as uptake of the systemic insecticide is slowed. Judging efficacy is complicated by the fact that the scale shells often remain on the plant long after the insecticide has killed the insect underneath. After application, test for efficacy by scraping the shell off the plant and looking for the soft, pulpy insect underneath. If only dry shells are scraped off, then the treatment probably was effective.

Armored and Soft Scales

Symptoms of Cercospora leaf spot first appear as individual, circular spots that are tan to light brown with reddish purple borders. As the disease progresses, individual spots coalesce. Heavily infected leaves first become yellow and eventually turn brown and necrotic.

Avoid overwatering or watering in the late evening to reduce free moisture. Avoid overhead watering where the water can dislodge and disperse spores to uninfected plants. Space plants to encourage air movement and reduce high humidity levels.

For the most part, treating Cercospora leaf spot means preventing the fungi from infecting your plants in the first place.

Cercospora leaf spot

A sign of plant disease is physical evidence of the pathogen. For example, fungal fruiting bodies are a sign of disease. When you look at powdery mildew on a lilac leaf, you’re actually looking at the parasitic fungal disease organism itself (Microsphaera alni). Bacterial canker of stone fruits causes gummosis, a bacterial exudate emerging from the cankers. The thick, liquid exudate is primarily composed of bacteria and is a sign of the disease, although the canker itself is composed of plant tissue and is a symptom.

Good gardening habits and effective treatment help prevent, stop and control fungal disease
1. Start by planting healthy stock. 
2. Choose planting sites based on plant needs. 
3. Avoid overhead watering. 
4. Water early in the day. 
5. Don't crowd plants. 
6. Don't work a wet garden. 
7. Treat with a trusted, proven fungicide.

Baking soda, soap, and water is one of the safer ways to treat plant fungus issues, especially if the affected plants are inside your home. You really don't want to be spraying fungicide all over the inside of your home if you can avoid it!

Fungi

On the apple tree, the infections occur on leaves, fruit and young twigs. The brightly colored spots produced on the leaves make it easy to identify. Small, pale yellow spots appear on the upper surfaces of the leaves, usually during late April or May on the eastern seaboard of the United States. These spots gradually enlarge and turn orange or red and may show concentric rings of color. Drops of orange liquid may be visible on the spots. Later in the season, black dots appear on the orange spots on the upper leaf surface. In late summer, tube-like structures develop on the undersurface of the apple leaf. Infected leaves sometimes drop prematurely, particularly during drought conditions or when the tree is under additional stress. Infections on fruit are usually near the blossom end and are somewhat similar to the leaf lesions. On the eastern red cedar host, the fungus produces reddish-brown galls from 1⁄4–1 inch (6.4–25.4 mm) in diameter. These galls can be mistaken for cone structures by the uninitiated. After reaching a diameter of about 1⁄2 inch (13 mm), they show many small circular depressions. In the center of each depression is a small, pimple-like structure. In the spring these structures elongate into orange gelatinous protrusions or horns. The spore-bearing horns swell during rainy periods in April and May. The wind carries the microscopic spores to infect apple leaves, fruit and young twigs on trees within a radius of several miles of the infected tree. On other species of juniper more common in landscaping and bonsai, the sizes of the infections are reduced. Early in the infection, the galls are small bumps on the woody portions of the plant. They maintain the orange gelatinous form after the first warm rains of spring but generally on a greatly reduced scale.

Fungicide sprays applied in a timely manner are highly effective against the rust diseases during the apple cycle. Most sprays are applied four times at 7- to 10-day intervals, starting with pink bud on crabapples. These applications are to protect the apples from spores being released from the cedar host in mid-spring. If cedar apple rust disease is diagnosed on apple fruits and leaves it is far too late to spray. Systemic fungicides are available. Fungicides listed for use on apples can be used in July and August on the cedars to reduce infection. Application of fungicides to the junipers before and while they are in the infectious orange gelatinous state seems to reduce the severity of the outbreak.

Because apples are an economically important crop, control is usually focused there. Interruption of the disease cycle is the only effective method for control of the cedar apple rust. The recommended method of control is to “remove cedars located within a 1 mile (1.6 km) radius” of the apples to interrupt the disease cycle, though this method is seldom practical. For those doing bonsai, it is common to have the trees within feet of each other and on the central eastern seaboard of the United States, Eastern Red Cedar is a common first-growth conifer along roadsides.

Cedar-apple rust

Calcium deficiency symptoms appear initially as localized tissue necrosis leading to stunted plant growth, necrotic leaf margins on young leaves or curling of the leaves, and eventual death of terminal buds and root tips. Generally, the new growth and rapidly growing tissues of the plant are affected first. The mature leaves are rarely if ever affected because calcium accumulates to high concentrations in older leaves. Calcium deficiencies in plants are associated with reduced height, fewer nodes, and less leaf area.

Preventative measures, such as irrigating prior to especially high temperatures and stable irrigation will minimize the occurrence.

Calcium deficiency can sometimes be rectified by adding agricultural lime to acid soils, aiming at a pH of 6.5, unless the subject plants specifically prefer acidic soil. Organic matter should be added to the soil to improve its moisture-retaining capacity. However, because of the nature of the disorder (i.e. poor transport of calcium to low transpiring tissues), the problem cannot generally be cured by the addition of calcium to the roots. In some species, the problem can be reduced by prophylactic spraying with calcium chloride of tissues at risk. Plant damage is difficult to reverse, so corrective action should be taken immediately, supplemental applications of calcium nitrate at 200 ppm nitrogen, for example. Soil pH should be tested, and corrected if needed, because calcium deficiency is often associated with low pH.

Blossom end rot

Initially spots of limited size, slightly concave, appear at the peduncular scar of some fruits, or near growth cracks or various wounds. They gradually spread with a fairly typical dark brown to black colour. The lesions decay further while their perimeter is clearly identified. They eventually cover a large proportion of ripe or unripe fruits if the environmental conditions are favourable. Whatever their development stage, the fruits undergo internal rot extending to the seeds. Brown to black globular structures, pycnidia, can be observed in the damaged tissues. They are spherical and irregularly shaped, ostiolate, and contain many hyaline and unicellular conidia, containing two lipid droplets.

To control fungal outbreaks, as with bacteria, remove all infected plant parts, or plants. You may also choose to apply a fungicide. There are many products available for treatment, organically (copper, sulfur, and baking soda are common) or synthetically.

Dothideomycetes

Tissues affected by the symptoms of Erwinia amylovora include blossoms, fruits, shoots, and branches of apple (Pomoideae), pear, and many other rosaceous plants. All symptoms are above ground and are typically easy to recognize. Symptoms on blossoms include water soaking of the floral receptacle, ovary, and peduncles. This results in a dull, gray-green appearance at 1–2 weeks after petal fall, and eventually tissues will shrivel and turn black. The base of the blossom and young fruit show similar symptoms as infection spreads. Opaque white- or amber-colored droplets of bacterial ooze can be seen on the infected tissue when the environment is high in humidity. Shoots show similar symptoms but develop much more rapidly. A “Shepherd's Crook” can be seen when the tip of the shoot wilts, and diseased shoot leaves typically have blackening along the mid-vein and then die. In number, diseased shoots give the tree a blighted appearance. Initial infection of blossoms and shoots can spread to larger tree limbs. Branches will darken and become water soaked. Advanced infection develops cracks in bark and a sunken surface. Wood under the bark will become streaked with black discoloration. Immature fruit forms water-soaked lesions and later turned black. Bacterial ooze can be found on these lesions. Severe infections result in fruit turning entirely black and shriveling.

Phytosanitary measures have been employed as the best sanitary measures against E. amylovora dispersal. High risk countries are encouraged not to import plants susceptible to the pathogen into their territory because, once the bacteria become established in an area it is nearly impossible to eradicate the disease. Nurseries and orchards in such regions are placed on strict phytosanitary surveillance measures and well-monitored. Imported and infected crops are destroyed as soon as they are noticed since the bacteria spreads very rapidly and eradication methods are usually costly and inefficient.

The only effective treatment for plants already infected is to prune off the affected branches and remove them from the area. Plants or trees should be inspected routinely for the appearance of new infections. The rest of the plant can be saved if the blighted wood is removed before the infection spreads to the roots. There is no known cure; prevention is the key.

Fire blight

Black mold is characterized by obvious lesions that appear on the surface of ripe fruit. Lesions are light to dark brown and vary from small flecks affecting only epidermal tissue to large, more or less circular, sunken lesions with decay extending into the carpel wall and often into the seed locule. During warm, humid weather the fungus may sporulate to form a black, velvetlike layer on the surface of the sunken lesions.

Select resistant varieties of plants/crops that are less susceptible to important pathogens. Pathogens reproduce at higher rates on susceptible varieties compared with resistant or partially resistant varieties. Cultural practices grapeCapitalize on cultural practices to reduce the pathogen population or create conditions less favorable for the pathogen to develop. When fewer non-chemical control methods (such as sanitation) are used, resistance is more likely to develop, or will develop more rapidly. Monitor and maintain agronomic factors such as soil moisture and crop nutrition, and manage other pests, to avoid crop stress throughout the season.Inadequate or excessive fertilization with nitrogen may increase disease incidence in some crops.  For example, early blight of potato and tomato and dollar spot of turfgrass are favored by nitrogen deficiency.  Alternatively, the severity of spring dead spot of bermudagrass and some foliar diseases of wheat is increased with intensive nitrogen fertilization. Excessive irrigation or frequent irrigation with small amounts of water increases the incidence of many diseases by promoting spread of the pathogen and extending periods of leaf wetness, and high soil moisture. Rotate crops to allow greater flexibility in choosing different tillage practices and/or the use of fungicides with different MOAs. Be aware that applying a fungicide unnecessarily to a crop in one year in the absence of fungus could result in undesirable effects on pathogens of rotational crops. NOTE: It is possible to rotate different crops between years and, yet, still use the same fungicide MOA to control the same disease. When one crop can serve as a source of inoculum for a subsequent crop, the alternation scheme among at-risk fungicides should be continued between successive crops such that the first at-risk fungicide applied to a crop belongs to a different group than the last at-risk fungicide applied to the previous crop.Be aware that resistant plant pathogens can spread from nearby fields, highways, railroads, or utility rights-of-way areas near your farm or treated site. Local and regional cooperation in resistance management is essential. Participate in Extension programs that conduct area-wide monitoring for the presence of disease pathogens and potential resistance development. Submit reports of fungicide control failures so that the possibility of resistance can be monitored and evaluated.

Fungicides are pesticides that kill or prevent the growth of fungi and their spores. They can be used to control fungi that damage plants, including rusts, mildews and blights. They might also be used to control mold and mildew in other settings.

Alternaria black molds and stem cankers

Alternaria symptoms once infection begins include small, dark, circular spots that regularly reach ½ inch (1 cm.) in diameter.

Avoid overhead watering to limit leaf wetness, and allow enough space at planting time for good air circulation and ample sun penetration. Keep your garden free of fallen leaves all season, and especially thorough at fall cleanup time.

Treatment for Alternaria requires fungicide to be sprayed directly on infected plants, as well as improvements in sanitation and crop rotation to prevent future outbreaks. Organic gardeners are limited to sprays of captan or copper fungicides, making control much more challenging. Conventional gardeners can use chlorothanil, fludioxinil, imazalil, iprodine, maneb, mancozeb, or thiram on plants listed on the label of their chemical of choice, but should still strive for prevention in areas with known Alternaria pathogens.

Alternaria

Nymphs and adults feed on plant juices, attacking leaves, stems, buds, flowers, fruit, and/or roots, depending on the species. Most aphids especially like succulent new growth. Some, such as the green peach aphid, feed on a variety of plants, while others, such as the rosy apple aphid, focus on one or just a few plant hosts.
- Look for misshapen, curling, stunted, or yellowing leaves. Be sure to check the undersides of leaves; aphids love to hide there.
- If the leaves or stems are covered with a sticky substance, that is a sign that aphids may have been sipping sap. This “honeydew,” a sugary liquid produced by the insects as waste, can attract other insects, such as ants, which gather the substance for food. When aphids feed on trees, their honeydew can drop onto cars, outdoor furniture, driveways, and so on.
- The honeydew can sometimes encourage a fungal growth called sooty mold, causing branches and leaves to appear black.
- Flowers or fruit can become distorted or deformed due to feeding aphids.
- Some aphid species cause galls to form on roots or leaves.
- Aphids may transmit viruses between plants, and also attract other insects that prey on them, such as ladybugs.

- For fruit or shade trees, spray dormant horticultural oil to kill overwintering aphid eggs.
- Beneficial insects, such as ladybugs, lacewings, and parasitic wasps, will feed on aphids. Supplemental populations of these insects can be ordered online and should help keep the aphid populations controlled from the start.
- Companion planting can be very helpful to keep aphids away from your plants in the first place. For example:
1 Aphids are repelled by catnip.
2 Aphids are especially attracted to mustard and nasturtium. Plant these near more valuable plants as traps for the aphids. (Check your trap plants regularly to keep aphid populations from jumping to your valued plants.)
3 Nasturtiums spoil the taste of fruit tree sap for aphids and will help keep aphids off of broccoli.
4 Garlic and chives repel aphids when planted near lettuce, peas, and rose bushes.

- Try spraying cold water on the leaves; sometimes all aphids need is a cool blast to dislodge them. Typically they are unable to find their way back to the same plant.
- If you have a large aphid invasion, dust plants with flour. It constipates the pests. 
- Neem oil, insecticidal soaps, and horticultural oils are effective against aphids. Be sure to follow the application instructions provided on the packaging.
- You can often get rid of aphids by wiping or spraying the leaves of the plant with a mild solution of water and a few drops of dish soap. Soapy water should be reapplied every 2-3 days for 2 weeks.
- One variation of this soap-water mix includes cayenne pepper: Stir together 1 quart water, 1 tsp liquid dish soap, and a pinch of cayenne pepper. Do not dilute before spraying on plants.
- Diatomaceous earth (DE) is a non-toxic, organic material that will kill aphids. Do not apply DE when plants are in bloom; it is harmful to pollinators, too.

Aphids

The typical signs are brown or black feeding punctures visible on the affected plant tissues. Another conspicuous sign is honey dew, a sweet excretion that is released by the sucking insect. Often ants are attracted to feed on the honey dew.

Most true bugs do not cause serious harm to established plants. Provide proper cultural care so plants are vigorous. Provide adequate irrigation. Avoid growing shade-adapted species in full sunlight.

Effective ways to get rid of these stink bugs include sealing the house, dusting treatment, spraying with nicotine water, and using insect repellents. Stink bugs, also referred to as shield bugs, are a group of flying insects that belong to the Pentatomidae family of the order Hemiptera.

Hemiptera

Hosta virus X does not kill the plants infected, but Hostas that have been infected do show a variety of other symptoms, such as: Ink-bleed, which makes the plant look discolored in certain spots, and this effect is generally centered on a vein. An example of this is shown in the photo in this article. Desiccation or Collapsed tissue, which can be signs of heavier infection, makes the plant look as if it is dried out. Mottling, which makes the plant appear blotchy. This is not always a symptom of HVX, and could be from another virus, but it should always be treated as an infected plant regardless. A Hosta may no longer express symptoms of the virus when it grows back in the Spring, even though it may have shown symptoms in a previous year. Nonetheless, the plant should still be considered infected with HVX.

The only way to eliminate the disease is to destroy infected plants (and any associated plant debris) by burning (where allowed by local ordinance) or landfilling. DO NOT compost hostas with HVX.

Once a Hosta plant is infected, it will be infected for the rest of its life. Any plant suspected of being infected should be burned if it is legal to do so. If it is not, then it should be tossed in the garbage, but infected Hosta plants should never be composted. If any plant in a batch shows symptoms, the entire batch should be considered infected and be destroyed. Once a plant has been removed, the spot occupied by the Hosta should be left empty for a long time to prevent the spread of the virus to a plant that replaces it. The virus primarily spreads through infected sap, so cutting multiple plants with the same tool can spread the virus. Animals that eat the plants may also spread the virus through sap by eating from an infected plant and then eating from an uninfected plant.

Hosta virus x

- Black or dark brown, superficial fungal growth on the aerial parts of plants, particularly the upper leaf surfaces
- The amount of growth can vary from a fine soot-like or powdery deposit, to a thick sheet of growth that may crack or peel away from the leaf surface during dry conditions
- The growth can sometimes be washed away, leaving a healthy-looking leaf surface beneath
- Sap-sucking pests such as aphids, scale insects, mealybugs or whiteflies can often be found on the plant, above the point where the sooty mould is growing
- In some cases these insects may occur on plants that overhang those affected with sooty mould
- Ants may also be seen in association with the sap-sucking pests
- Leaves, stems, fruit, etc. where the sooty moulds are growing are contaminated with sticky honeydew

It isn’t really possible to preventively treat against sooty mold, and when it appears it is immediately recognizable.
There are a few things to do that can reduce the likeliness that this disease would appear.
- Ensure your plant has sufficient nutrients and is well watered. A plant weakened by poor soil or lack of water is a vulnerable plant.
- Increase the diversity of plants and flowers in your garden, it is the best way to protect them naturally from their predators.

Sooty mold grows on the honeydew dropped by many sap-feeding insects (most commonly aphids, scale and whiteflies). The honeydew is a sugary liquid that the insects excrete as waste. Sooty mold in itself does not feed on plant tissues or cause damage, but it can block enough sunlight to affect photosynthesis which can weaken the plant over time. It is also very ugly and difficult remove (more on that in a bit).
The first step is to identify and treat the insect causing the problem:
- Soft or armored scale (look like small turtle shells affixed to the stems and/or leaves, sometimes very well-camouflaged in color or texture. Egg sacs are often wispy and white),
- Aphids (small green, yellow or tan insects with thin legs & antennae, wooly aphids look a bit like tiny sheep)
- Whitefly (tiny, white-winged flies).
A population of insects large enough to cause a sooty mold problem is usually pretty easy to spot and identify. Controlling the insects will stop the rain of sugar water that feeds the sooty mold.
The mold itself is difficult to remove, but you can hasten the rate at which it naturally weathers off. Spraying the leaves with insecticidal soap can help soften the sooty coating. Spray late in the day so the soap remains moist for as long as possible. If you can spray a few hours before a heavy rain is forecast the rain will be better able to remove the sooty mold.
If the plant has a rugged leaf, like holly or gardenia, you can follow the soap application with a strong jet of water from your garden hose after you’ve given the soap a little time to soften the mold. Be careful with softer-leafed plants and new growth, as a strong water stream can tear or bruise leaves. You’ll probably have to repeat the process a few times to wear the coating of sooty mold off over time.
If your insect eradication was successful, you’ll see that new growth on the sooty mold affected plants will remain fresh and clean. The mold does not spread without the honeydew to grow on, so new sooty mold indicates a continuing insect problem.

Sooty Mold

In the fruits, black or brown lesions (e.g., on pods, scab, and pitting) are common. Infection on the inflorescence produces blight, necrosis, and lesions with flecks and streaks. Infected leaves produce abnormal colors and patterns with dark, necrotic, angular, or irregular areas.

Plant resistant plants, or buy healthy transplants. Plant your plants in well-drained soil.  Water your plants with a drip sprinkler, as opposed to an overhead sprinkler.. Keep ripening fruits from touching the soil. Remember to rotate your plants every 2 to 3 years.

The best control products were Daconil Ultrex (chlorothalonil), Pageant (pyraclostrobin and boscalid) and Spectro 90WDG (chlorothalonil and thiophanate methyl). In addition, mancozeb (i.e., Dithane and Pentathlon) or copper were also very effective when used preventively.

Colletotrichum

Symptoms vary across plant organs and tissues. B. cinerea is a soft rot that will have a collapsed and water soaked appearance on soft fruit and leaves. Brown lesions may develop slowly on undeveloped fruit. Twigs infected with gray mold will die back. Blossoms will cause fruit drop and injury, such as ridging on developing and mature fruit. Symptoms are visible at wound sites where the fungus begins to rot the plant. Gray masses with a velvety appearance are conidia on the plant tissues are a sign of plant pathogen. These conidia are asexual spores that will continue to infect the plant and surrounding hosts throughout the growing season making this a polycyclic disease. Plants can produce localized lesions when a pathogen attacks. An oxidative burst causes hypersensitive cell death called a hypersensitive response (HR). This soft rot can trigger HR to assist in colonization. Botrytis cinerea, as a necrotrophic pathogen, exploits the dead tissue for its pathogenicity or its ability to cause disease. Susceptible plants cannot use the HR to protect against Botrytis cinerea.

The best way to prevent gray mold is to space out plants so they have room to dry out after rain or watering. Remove infected flowers, leaves and stems. Infected plant parts should be buried or composted. Many flowering plants can recover from gray mold when warm, dry conditions return.

Prune or stake plants to improve air circulation between plants. · If growing indoors use a small clip-on fan to improve air flow.

Gray mold

Initial symptoms include large, angular or blocky, yellow areas visible on the upper surface. As lesions mature, they expand rapidly and turn brown. The under surface of infected leaves appears watersoaked. Upon closer inspection, a purple-brown mold (see arrow) becomes apparent. Small spores shaped like footballs can be observed among the mold with a 10x hand lens. In disease-favorable conditions (cool nights with long dew periods), downy mildew will spread rapidly, destroying leaf tissue without affecting stems or petioles.

As downy mildew like moist conditions, avoid dense planting and control weeds, to provide good air circulation around the plants. Water plants early in the morning, like watering plants in the evening, leads to high humidity that persists throughout the night.

Because the downy mildew pathogen does not overwinter in midwestern fields, crop rotations and tillage practices do not affect disease development. The pathogen tends to become established in late summer. Therefore, planting early season varieties may further reduce the already minor threat posed by downy mildew. Fungicides applied specifically for downy mildew control may be unnecessary. Broad spectrum protectant fungicides such as chlorothalonil, mancozeb, and fixed copper are at least somewhat effective in protecting against downy mildew infection. Systemic fungicides are labeled for use against cucurbit downy mildew, but are recommended only after diagnosis of this disease has been confirmed. One way to control downy mildew is to eliminate moisture and humidity around the impacted plants. Watering from below, such as with a drip system, and improve air circulation through selective pruning. In enclosed environments, like in the house or in a greenhouse, reducing the humidity will help as well.

Downy mildew

Wilted, downward-hanging foliage is often the first obvious symptom of Armillaria root rot. Other symptoms include foliage yellowing, leaf drop, and dieback of upper limbs. During the rainy fall and winter, groups of short-lived mushrooms often grow around the base of Armillaria-infected trees.

Cultural practices can also be effective for preventing the spread of Armillaria. High temperatures interfere with the progression of this disease; if soil temperatures reach 79 °F (26 °C), then the growth of Armillaria in the soil will be limited. Using collar excavation to expose primary roots directly below the crown to the continuous cycle of solar heating and air may reduce the colonization from Armillaria in trees that are already infected. This is called root collar excavation (RCE), and while it has been applied to citrus orchards and grapevines, this method has high labor costs and involvement due to the difficulty of carefully exposing these primary roots.

Sadly, there is no absolute treatment for Armillaria root rot. The disease can be managed by the consistent removal of dead trees and infected stumps. Armillaria requires consistent moisture to survive, and in citrus groves, excavation around the root crown has been an effective deterrent but not an ultimate cure.

Armillaria root rot

Scales or shell-like bumps on plant stems and the underside of leaves. These are the outer coverings of scale insect. Large populations may result in poor growth. Some species of scale insect excrete honeydew, which accumulates on the upper leaf surfaces. This can be colonised by a black non-parasitic fungus known as sooty mould. Some scale insects deposit their eggs under a covering of white waxy fibres in early summer.

Check susceptible plants frequently from spring onwards so action can be taken before a damaging population has developed. When choosing control options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section. If this is not sufficient to reduce the damage to acceptable levels then you may choose to use pesticides. Within this group the shorter persistence pesticides (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife than those with longer persistence and/or systemic action. Light infestations are of little consequence and can be tolerated. The best time to treat heavy attacks is when the more vulnerable nymphs are present, for many scales out of doors this is during mid-late summer. Scale insects on indoor plants can breed all year round and so there is no best time of year to treat. Note that dead scales can remain firmly attached to the plants. The success of any treatment can be gauged by the extent to which new growth remains free of scale insects.

To get rid of scale insects prune and dispose of infested branches, twigs and leaves. When scale numbers are low they may be rubbed or picked off of plants by hand. Dabbing individual pests with an alcohol-soaked cotton swab or neem-based leaf shine will also work when infestations are light.

Coccoidea

Fungus gnat damage will appear similar to that of any other root-related issue, such as root rot. Lower leaves may turn yellow and drop, and the plant’s growth may slow down or stop completely. In particularly bad cases, wilting of the entire plant could occur, followed by the death of the plant if roots are extremely damaged. 
In small numbers, fungus gnats are more of an annoyance than anything. In fact, the adult gnats don’t actively harm plants nor people. If their population gets out of hand, however, the larvae may start feeding on plant roots, causing notable damage. This is especially bad for young plants, such as seedlings, which have only a few delicate roots. Fungus gnats are also capable of spreading the plant pathogen that causes damping off and the eventual death of seedlings.

1. Keep soil dry: Fungus gnats seek out moist soil, so allowing your houseplants to dry out a bit between waterings can slow down or stop an infestation. Let the top inch or two of soil dry out before watering again, and try to go as long as possible between waterings. Gnats may be deterred from laying their eggs if the soil is dry on the surface.
2. Mosquito dunks (with beneficial bacteria): Mosquito dunks are used to keep mosquito larvae from populating fountains, animal troughs, fish ponds, and other small bodies of water. The product consists of a dry pellet containing a type of bacteria called Bacillus thuringiensis subspecies isrealensis. This beneficial bacteria infects and kills the larvae of flying insects, including mosquitoes, fruit flies, and fungus gnats.
To use mosquito dunks: Fill up a gallon jug (or watering can) with clean water and toss in a mosquito dunk. It’s a good idea to break up the dunk a bit before placing it in the water, or you can wait for it to soften before breaking it apart. Let the dunk soak in the water for as long as possible (at least overnight), then remove it from the water (the dunk can be reused) and use this water for fungus gnat–infested plants. The bacteria will have leeched into the water and will now infect and kill any larvae that come into contact with it in the soil. Repeat this process every time you water your plants for at least a few months.
3. Cover drainage holes: Though gnats typically remain near the tops of pots, they may find their way to the drainage holes on the underside of a pot and start laying eggs there, too. If this happens, cover the drainage holes with a piece of synthetic fabric to prevent the gnats from getting in or out of the hole, but to also let water pass through freely. Attach with tape or rubber bands.

Getting rid of fungus gnats is all about consistency. Catching the adults is fairly easy, but because the adult population comes in cycles, you need to make sure that your traps are refreshed regularly. For the best results, use a combination of the traps :
1. Sticky cards traps: These traps consist of a yellow note card covered in a sticky adhesive. They are most effective when cut into small squares and placed directly on top of the soil or attached to skewers just above the soil. Adult gnats will fly or crawl onto the card and become trapped. Fungus gnats are attracted to the color yellow, so use the yellow sticky cards rather than the blue ones. 
2. Cider-vinegar traps: Simple and effective, cider-vinegar traps consist of a shallow container with a small amount of apple cider vinegar, water, and liquid dish soap.
To make a cider-vinegar trap: Find a shallow container—a tuna can is perfect—and fill it with equal parts water and apple cider vinegar. (The liquid should be at least ¼-inch deep.) Put a few drops of liquid dish soap into the mixture and stir gently. Place the trap near the base of the affected plant or, ideally, inside the pot on top of the soil. Check it every few days to refresh with new vinegar and water.
3.Flypaper: Flypaper ribbons, such as those hung in horse barns to catch outdoor flies, can also be used to catch fungus gnats. However, these traps are usually overkill for gnats and can easily get stuck to things you don’t want them to stick to, such as furniture, hair, plants, and so on.

Fungus Gnats

Mealybugs have needle-like sucking mouthparts. Feeding activity can cause a yellowing of host leaves, distorted growth, premature leaf drop, and, with heavy populations, plant death. Mealybugs also produce large amounts of a sweet, sticky liquid waste product called honeydew. A black fungus called sooty mold may grow on the honeydew.

This pest is usually brought into the interiorscape on an infested plant. Therefore, one of the best ways to manage mealybugs on houseplants is to carefully check plants being considered for purchase and reject any infested plants. Quarantine new plants for 7-10 days in an isolated spot, and check for signs of mealybugs or other household pests before adding the plants to your interiorscape.
Provide proper cultural control so that the plants are vigorous and can tolerate moderate mealybug feeding without suffering too much damage. Do not over-water or over-fertilise — mealybugs are attracted to plants with high nitrogen levels and soft growth. Removing overwintering sites, such as loose bark, can help to reduce mealybug numbers. Predatory insects, such as lacewings, syrphid flies, ladybirds, and several small parasitic wasps, prey on outdoor mealybugs and can often keep their numbers down. An introduced beetle, Cryptolaemus montrouzieri, the mealybug destroyer, is available commercially for release in greenhouses. Avoid the unnecessary use of insecticide to minimise any adverse effect on these beneficial insects. Manage ants, which are attracted to honeydew produced by the mealybugs and will inhibit the activities of natural enemies.

1 Wash them away: Mealybugs can be dislodged with a steady stream of water. Repeat the treatment as necessary. This is best for light infestations.
2 Insecticidal soap: Insecticidal soaps are available on the market, or you can make your own by using a dish detergent such as Ivory Liquid. Try to find a product free of perfumes and additives that might harm plants. Mix the soap in a weak concentration with water (starting a 1 teaspoon per gallon and increasing as necessary). Spray on plants.
3 Neem oil: Neem oil is derived from the neem tree. Use according to label instructions. In addition to its insecticidal properties, neem is also a fungicide and has systemic benefits (meaning the plant absorbs it so it can control insects it doesn't directly contact). According to the Environmental Protection Association, neem is safe for use on vegetables and food plants as well as ornamentals.
4 Kitchen insect spray: This all-purpose insect spray. To make a batch, combine 1 garlic bulb, 1 small onion, and 1 teaspoon of cayenne pepper in a food processor or blender and process into a paste. Mix into 1 quart of water and steep for 1 hour. Strain through a cheesecloth and add 1 tablespoon of liquid dish soap. Mix well. The mixture can be stored for up to 1 week in the refrigerator.

Mealybug Pests

If the stem is mushy or brittle, check the roots for the same conditions. The roots, too, should be pliable but firm. If both the stems and roots are brittle or mushy, the plant is dead and you will simply need to start over.

Repot your plant. Use a high-quality indoor plant potting mix to revitalise your plant, and choose a pot that's wider than the last one. ... Trim your plant. If there's damage to the roots, trim back the leaves. Move your plant.  Water your plant.  Feed your plant.  Wipe your plant.

Gently remove the plant from its container. If you see more roots than soil, or roots coiling around the inside of the pot, it is time for a bigger container. Over time, most plants outgrow their pots. Sometimes, all it takes to revive a dying plant is a little repotting.

Dead plant

Usually the first sign of thrip damage is faded or dirty looking leaves. The leaves will start by turning white or grayish in color, then eventually brown as the damaged areas start to die.
Though it’s possible for thrips to kill a houseplant, it’s rare. Mature, healthy houseplants can handle a pretty heavy infestation. The biggest threat is to small or weak houseplants.
However, not only is a thrip infestation gross, they make your indoor plants look terrible, and heavy damage can stunt their growth. Other common symptoms include:
- Brown stripes on the leaves
- Faded, splotchy, pale-colored leaves
- Parts of the leaves are dying
- Flower buds are malformed, dropping, or won’t open
- Leaves start dropping unexpectedly
- New growth is deformed

Thrips can be difficult to get rid of. So, once you finally win the battle, you want to prevent them from ever coming back!
The good news is that there are a few easy ways to prevent thrips from infesting your houseplants…
- Monitor them on a regular basis for the first signs of an infestation
- Debug all of your plants before bringing them back inside for the winter
- Keep anything that you bring in from your garden (cut flowers, veggies…etc) far away from your houseplants
- Inspect all new houseplants before bringing them home, then quarantine them for a few weeks afterward

The first thing you should do as soon as you spot thrips on a houseplant is to quarantine the infested plant immediately. Then check all of the surrounding houseplants for signs of thrips, and isolate any others you may find.Make sure that you begin treating the infestation right away. Also, to help prevent thrips from spreading, always wash your hands after handling an infested houseplant.
RINSE THE LEAVES
If you can, take your houseplant outside, and rinse the leaves with the hose. That will remove many of the bugs, and quickly knock down their population.You could rinse the leaves in the sink or shower instead, and that will work too. Be sure to use tepid water, and take care not to overwater your houseplant in the process.
INSECTICIDAL SOAP
Soap kills thrips on contact, and will help to give you the upper hand. You can use a pre-mixed organic insecticidal soap, or make your own using 1 tsp mild liquid soap to 1 liter of water.Be sure to spray it directly on the infested leaves to kill the bugs. Insecticidal soap doesn’t have any kind of residual effect, so it’s important to treat them often in order to completely get rid of thrips.
WASH YOUR HOUSEPLANT
You could also try washing the leaves with diluted mild liquid soap, and rinse it off with water. This will kill thrips as well, and help to quickly get the population under control.Make sure you wash the undersides of leaves too, that’s where thrips like to hide. But before washing all of the leaves, it’s best to test the soap on a few first, to make sure it doesn’t damage your houseplant.
NEEM OIL 
It’s a naturally occurring insecticide, and also has a residual effect that will help to deter future infestations.Spray a neem oil solution directly on the leaves and stems. This will kill some of the bugs on contact, and others will die when they feed on the neem oil covered leaves. Either a pre-mixed horticultural oil or a hot pepper wax spray can also be very effective to get rid of thrips on houseplants.
STICKY TRAPS 
Since adult thrips are able to fly, sticky traps can work very well to capture them. Place either yellow or blue sticky traps near the infested houseplant to attract them.

Houseplant Thrips

All the visible and otherwise detectable changes in the infected plants make up the symptoms of the disease. Symptoms may change continuously from the moment of their appearance until the entire plant dies or they may develop up to a point and then remain more or less unchanged for the rest of the growing season. Symptoms may appear as soon as 2 to 4 days after inoculation, as happens in some localized viral diseases of herbaceous plants, or as late as 2 to 3 years after inoculation, as in the case of some viral, mollicute, and other diseases of trees. In most plant diseases, however, symptoms appear from a few days to a few weeks after inoculation.

Put weather stripping around your windows and doors, and replace any stripping that is worn; Keep any outdoor lights off, and turn off as many lights inside your home as possible, as stink bugs are attracted to light; Pull down window shades and blinds to keep the light from spilling outside at night.

You can either use silicone based caulk to cover the cracks or screens for windows and doors, or you can also spray the exterior of your home in the fall, for a plus of protection. You can use natural pesticides against these insects, if you prefer not to fill your home with chemical pesticides.

Pentatomidae

Cucurbits infected with tospovirus exhibit a variety of symptoms. Leaves can show bronzing to severe systemic chlorotic spotting. Other symptoms include leaf deformation, mosaic, die-back and overall plant stunting. Fruit symptoms can range from chlorotic ring spots on young fruit to necrotic lesions on older fruit.

Keep the greenhouse free of weeds inside and around the outside, since both thrips and tospoviruses are easily harbored in greenhouse weeds. When new cuttings or plugs arrive, check them for thrips or virus symptoms immediately. You can also employ virus indicator plants in the greenhouse.

Infected plants cannot be cured. Control measures aim to prevent or reduce the levels of disease in crops by removing or avoiding sources of virus infection and minimising spread by thrips.

Tospovirus

Sunscald symptoms will appear as yellow or white lesions on foliage and/or fruits. The lesions eventually may turn brown and/or shrivel. Foliage that is commonly affected includes impatiens, hosta, rhododendron, garden beans, peas, peppers and tomatoes.

When it comes to protecting your fruit plants and vines, common sense care is the best medicine for fruit sunscald prevention. Place the plants where they get enough shade in the afternoon. Give them the right amount of water and fertilizer, and be careful when you prune the branches and vines.

For plants already suffering, use a sunshade to restrict their exposure to UV light. Slowly give them more time each day with the sunshade removed until they are toughened up. This process can take about two weeks, at which time your plant should be ready for the sun.

Albino-berry

(Aphloia Theiformis)

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