Changes in leaf color or texture can signal an insect problem. Leaves may become spotted, speckled or yellowed when insects are present. Leaves might also become distorted or misshapen, often looking cupped or pinched. You may spot webbing draped along leaf undersides or where leaves attach to stems.

Signs of damage

Remove any sources of food, water or shelter. Store items in safe and enclosed containers. Dispose of garbage regularly with a tightly closed lid. Reduce clutter or areas where pests can hide. Seal and close off any cracks or holes to eliminate outside entry.

How to prevent

Wash plants with a strong spray of water to dislodge aphids, or remove and destroy affected plant parts. Organic solutions include spraying with horticultural oil (petroleum- or vegetable-based oil used to smother insects), insecticidal soap or neem (insecticide made from a tropical tree by the same name).

Treat

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Insecta

Whiteflies tend to prefer to feed on new growth, so check around any newly unfurled leaves first.
Check the undersides of leaves—especially around the veins—for white insects, even if they aren’t immediately visible, and feel leaf surfaces for sticky honeydew. If the whiteflies are feeding, they’ll suddenly all fly off the leaves in a swarm, so it’s very obvious.
You may also find eggs laid on the undersides of leaves. This is the beginning of a new generation! When the eggs hatch, the larvae will look like teeny white ovals without legs; they don’t move but they immediately start sucking the plant juice. This is why gardeners often miss whiteflies until it’s too late. Adult females can produce up to 400 eggs, which hatch in about one week to a month after laying. They are usually laid in a circular pattern. Eggs are pale yellow when newly laid and brown when about to hatch.

1 Your first line of defense should be inspecting all plants for pests before you bring them home, as well as keeping any new additions away from the rest of your plants for a period of time. This will allow you to identify and curtail any pest or disease issues that appear.
2 Keeping natural predators around will prevent whiteflies from ever exploding in population. For this reason, avoid using insecticides. Ladybugs, spiders, green lacewing larvae, and dragonflies are a few of many beneficial insects that can control a whitefly population. Hummingbirds are another natural predator. Try creating a habitat that will attract dragonflies and damselflies (which also helpfully eat mosquitoes) or beautiful hummingbirds.
3 When it comes to whiteflies, avoid chemical insecticides; they’re usually resistant and all you end up doing is killing the beneficial insects—their natural predators—and the insects that pollinate the garden for a better harvest!
4 Mulch early in the season with aluminum reflective mulch, especially around tomatoes and peppers. The reflective mulch makes it challenging for whiteflies to find their preferred host plants. 
5 Set out yellow index cards coated with petroleum jelly to monitor whiteflies, especially when it comes to tomatoes, peppers, sweet potatoes, or cabbage crops. A half-and-half mixture of petroleum jelly and dish soap, spread over small boards painted bright yellow, is sticky enough to catch little whiteflies, too. To whiteflies, the color yellow looks like a mass of new foliage. The bugs are attracted to the cards, get stuck in the jelly, and die.

To control whiteflies, there are various solutions and traps that you can use. The biggest tip is: start early! In the mornings and evenings, as you wander the garden or tend to your houseplants, check the back of the leaves for eggs or notice when little bugs “fly away” as you approach your plants.
- Always start with blasting whiteflies (as with aphids and many other insect pests) with your watering hose or a spray bottle. This will cause them to scatter and will dislodge nymphs and eggs to some extent.
- Consider spraying your plants’ leaves with an insecticidal soap, following the directions on the packaging. Be sure to spray the undersides of leaves, too. Follow up 2 or 3 times, as necessary. 
Spray plants in the evening when temperatures are cooler, as mid-day heat may cause an adverse reaction in your plant. Plus, spraying in the evening allows you to avoid accidentally spraying any pollinators or beneficial insects.
- According to the National Gardening Association, the following simple homemade mixture should be helpful to control and deter whiteflies: Use a mix of dish soap and water. A good squirt of soap to a gallon of water should work. As mentioned above, only spray in cooler temperatures; late in the day is best. The NGA mixture is a pretty benign combination, and whiteflies are nearly impossible to get rid of, so it’s best to try more preventative tactics first, as mentioned below.
- If all else fails and your whitefly population is persistent, you can (carefully) use a handheld vacuum every few days to remove them from your plants. This gets rid of both nymphs and adults. Just be sure NOT to empty your vacuum into a trash can inside your home afterward

Whiteflies

The first sign of powdery mildew is pale yellow leaf spots. White powdery spots can form on both upper and lower leaf surfaces, and quickly expand into large blotches. The large blotches can cover entire leaf, petiole and stem surfaces. When powdery mildew infects the majority of the foliage, the plant weakens and the fruit ripens prematurely.

Control is possible with triadimefon and propiconazole. It is also possible with hexaconazole, myclobutanil, and penconazole.

Standard fungicides are an effective way to manage powdery mildew disease on plants. Spray programs of conventional fungicides are advised to begin when powdery mildew symptoms and signs are first noticed. Conventional fungicides should be applied on a regular basis for best results against the disease.

Powdery mildew

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

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

- 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

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

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

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

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

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

Galls are most commonly found near ground level on the roots and lower branches of the plants. As the galls enlarge, they become woody and hard. The outer layer turns brown and corky. The plant may be weakened and stunted with some branch or tip dieback. Symptoms may not develop immediately after infection. Galls grow most rapidly during the warm months of the year.

Limit wounding of plant material. Avoid planting too deep. Avoid mounding soil up on newly planted trees. Keep crown of tree as dry as possible; Agrobacterium is favored by wet environments.

1. Prune out infected material. Crown gall cannot be eliminated from a shrub even though the infected plant may live for many years. To improve the appearance of the plant, prune out and destroy infected stems below the galled area. Sterilize the pruning shears after each cut with a mixture of one part bleach to nine parts water. 2. Destroy infected plants. Destroy the infected plant. The bacterium will remain in the soil so it is important to plant a resistant plant species. If the same species needs to be planted in the area, remove and replace the soil or consider soil sterilization. 3. Sterilize the soil. Soils known to be infected with crown gall bacteria can be sterilized using chemicals, heat, or antibiotics. This is not practical for most home gardeners. A biological control has been introduced using a bacterium, Agrobacterium radiobactor strain 84. This bacterium was discovered to be antagonistic to crown gall bacterium. It is available for use as a preplant treatment by dipping nursery stock in a suspension of the live bacteria in water. 4. Exclude the problem. When purchasing forsythia and euonymus plants, inspect them carefully for signs of galls. Do not purchase plants that show gall-forming symptoms. 5. Replant with a more resistant plant species. The following plants recommended by the University of Illinois show greater resistance to bacterial crown gall: barberry, hornbeam, true cedars, ginkgo, golden raintree, tulip tree, mahonia, spruce, linden, boxwood, catalpa, beech, holly, larch, magnolia, black gum, pine, Douglas fir, bald cypress, hemlock, birch, firethorn, redbud, smoke tree, sweet gum, deutzia, serviceberry, yellowwood, yew, and zelkova.

Crown gall

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

Rust diseases come in different varieties and can affect a wide range of plants. People often struggle with rust on their roses. It is easy to remember the defining characteristics of this fungus, as they match its name. Rust plant disease will look similar to the rust that appears on that old bicycle in the shed.
- Look for yellow or white spots forming on the upper leaves of a plant.
- Look for reddish to orange blister-like swellings called pustules on the undersides of leaves.
- Orange or yellow spots or streaks appear on the undersides of the leaves.
- Within these spots that form are spores.
- Usually leaf distortion and defoliation occur.

- Dust your plants with sulfur early in the season to prevent infection or to keep mild infections from spreading.
- Space your plants properly to encourage good air circulation.
- Avoid wetting the leaves when watering plants.
- There are many effective rust fungicides you can try.

1 Select rust-resistant plant varieties when available.
2 Pick off and destroy infected leaves and frequently rake under plants to remove all fallen debris.
3 Water in the early morning hours — avoiding overhead sprinklers — to give plants time to dry out during the day. Drip irrigation and soaker hoses can be used to help keep leaves dry.
4 Use a slow-release, organic fertilizer on crops and avoid excess nitrogen. Soft, leafy, new growth is most susceptible.
5 Apply copper sprays or sulfur powders to prevent infection of susceptible plants. For best results, apply early or at first sign of disease. Spray all plant parts thoroughly and repeat every 7-10 days up to the day of harvest.
6 Effectively treat fungal diseases with SERENADE Garden. This broad spectrum bio-fungicide uses a patented strain of Bacillus subtilis and is approved for organic gardening. Best of all, it’s safe to use — you can treat and pick crops the same day!
7 Containing sulfur and pyrethrins, Bonide® Orchard Spray is a safe, one-hit concentrate for insect attacks and fungal problems. For best results, apply as a protective spray (2.5 oz/ gallon) early in the season. If disease, insects or wet weather are present, mix 5 oz in one gallon of water. Thoroughly spray all parts of the plant, especially new shoots.
8 Prune or stake plants and remove weeds to improve air circulation. Make sure to disinfect your pruning tools (one part bleach to 4 parts water) after each cut.
9 Use a thick layer of mulch or organic compost to cover the soil after you have raked and cleaned it well. Mulch will prevent the disease spores from splashing back up onto the leaves. Burn or bag infected plants after the growing season . Do NOT compost.

Leaf Rust

Symptoms first appear as a slight yellowing of foliage and wilting of upper leaves. As wilting progresses, leaves may turn dull-green to brown and remain attached to the plant. When the stem and roots are cut diagonally, reddish-brown streaks are visible in the vascular tissues.
Signs and symptoms:
- Initially, plants wilt during the hottest part of the day and recover at night.
- Leaflets turn yellow on one side of the plant, or even just leaflets on one half of a compound leaf.
- The entire plant soon turns yellow and wilts. Browning of leaves occurs rarely.
- Peel the epidermis off the lower stem to see dark red and brown discolored vascular tissue.

Fusarium is most prevalent in warm soils. It is harbored in old plant debris and soil. The best way to prevent infection in your crops or plants is rotation and sterilization. 
Never plant the same crop in the same place annually. 
Pots should be sterilized with a bleach solution and new soil used when reusing them. You can also solarize beds, by spreading black plastic over an area in full sun for a month to kill the fungus. This causes extreme high temperatures that will “cook” the fungus and provide good control of Fusarium. 
Wash off tillage equipment, shoes and other tools that might have encountered infected soil. Remove all old plant debris annually and if you think it might be contaminated, burn it. Do not compost contaminated material as this provides an ideal incubation condition for propagating the fungus.

1 Plant resistant varieties when available.
2 Remove stricken growth from the garden and sterilize pruning clippers (one part bleach to 4 parts water) between cuts.
3 Use fumigants to control many garden insects, like cucumber beetles, which are known to spread the disease.
4 High nitrogen fertilizers may increase susceptibility to the disease. Test your soil and use a slow-release, organic fertilizer in the vegetable garden.
5 Hand pull or spot treat weeds using a weed flamer or natural herbicide — many weed species host the disease pathogen.
6 Mycostop is a biological fungicide that will safely protect crops against wilt caused by Fusarium. Approved for use in organic crop production, it can be applied as a soil spray or drench (1-2 gm/ 100 sq ft) to seedlings, ornamentals and vegetables. Apply sufficient water during application to move Mycostop into the root zone.
7 If the disease persists, it is best to remove the entire plant and solarize the soil before planting again.
To solarize the soil, you must leave a clear plastic tarp on the soil surface for 4-6 weeks during the hottest part of the year. Soil solarization will reduce or eliminate many soil inhabiting pests including nematodes, fungi, insects, weeds and weed seeds.

Fusarium Wilt

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

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

Young seedlings develop a rot at the crown. Later, the tissue becomes soft and constricted, and the plants wilt and fall over.

Tool Sterilization. Prune Damaged Foliage. Plant Resistant Vareities. Crop Rotation. Keep The Soil From Being Soggy. But Don't Let It Get Too Dry. Sow Seeds The Right Way. Airflow Helps.

Once fusarium wilt infects a plant, there is no effective treatment. Remove and dispose of affected plants immediately; don't compost this garden refuse. Whenever possible, remove and replace fusarium-infected garden soil.

Fusarium wilts, blights, rots and damping-off

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

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

Symptoms of bacterial infection in plants are much like the symptoms in fungal plant disease. They include leaf spots, blights, wilts, scabs, cankers and soft rots of roots, storage organs and fruit, and overgrowth. Bacterial spots: the most common symptom of bacterial disease is leaf spots.

The best way to prevent fungi from attacking your plants is to buy disease resistant varieties whenever possible. Other ways include minimizing the amount of water contacting foliage. Water at the soil level and early in the day. This allows foliage to dry out quickly, should it become wet.

Antibiotics: streptomycin and/or oxytetracycline may also help kill or suppress plant pathogenic bacteria prior to infection and reduce spread of the disease, but they will not cure plants that are already diseased. Antibiotics are also used to treat diseases caused by fastidious vascular bacteria.

Bacteria

Bacterial leaf spots show as necrotic, circular or angular lesions and may have a yellowish outline or halo. Early symptoms of bacterial leaf spots show on older leaves and lesions appear water-soaked. Bacterial spots affecting dicytyledounous plants that have net-like leaf veins sometimes take a more angular shape as they are restricted by the large leaf veins. Bacterial spots on monocotyledonous plants with parallel leaf veins have a streak or striped appearance. The most obvious symptom of bacterial leaf spots are the blackening of the spots after infection. Eventually older lesions dry out and become papery in texture. Bacterial spots can also produce white, yellow, light cream or silver bacterial exudate depending on the type of bacteria, which may ooze from splitting lesions and/or from the underside of the spots. Bacterial leaf spots caused by Pseudomonas show red-brown spots which can distort the infected leaves, whilst those caused by Xanthomonas are angular or circular in shape outlined with a yellow halo.

Prevention of leaf spot disease includes variety selection, crop rotations, plant hygiene and fungicide use for seeds and foliage. To stop the spread of pathogens good sanitation is key as well as the avoidance of handling plants when wet, planting pathogen-free and resistant cultivars and moving out infected plants. Reducing the humidity around plants and in greenhouses by good plant spacing for air circulation, and watering early in the day can also help prevent leaf spot disease. Disinfection of tools and washing of hands is important when handling infected plants. Susceptibility to leaf spot disease can occur due to insufficient or excessive fertilising of plants. Checking plants periodically for any signs and symptoms of disease is also good practice. Avoiding overhead watering and increasing air circulation by pruning plants should be done to prevent humid conditions. Collecting and removing fallen leaves is important in reducing the amount of pathogenic agents on the ground to prevent dispersal of disease.

Certain chemicals are used to treat leaf spot disease, such as the Bordeaux mixture, the first fungicide to have been developed, which treats many fungal and bacterial leaf spots. Other fungicides such as zineb, chlorothalonil and Captan, also treat leaf spot disease and Benomyl specifically treats Cercospora leaf spots, cherry leaf spot and black spot of roses. Thiabendazole is used to treat leaf spot diseases of turf and ornamentals. Both fenarimol and nuarimol are pyrimidines that also treats leaf spot disease. More chemicals include Triazoles an organosphosphate fungicide, Imazalil, Procholora and Fentin hydroxide. Registered fungicides in use are thiophanate methyl, chlorothalonil, ferban and mancozeb.

Bacterial leaf spot

All members of the class produce basidiocarps which range in size from tiny cups a few millimeters across to a giant polypore (Phellinus ellipsoideus) greater than several meters across and weigh up to 500 kilograms (1,100 lb). Agaricomycetes produce mushrooms, and are therefore the most familiar and conspicuous of all Fungi. Other Fungi produce macroscopic fruiting bodies as well, but the diversity of forms in the Agaricomycetes is unmatched.

A proven fungicide that prevents disease from becoming active and treats it quickly is a crucial part of your protection plan. GardenTech® Daconil® Fungicide, with the active ingredient chlorothalonil, provides protection against a broad spectrum of fungal pathogens and simplifies controlling fungal disease from your garden.

Used as a preventive and an active treatment, Daconil® Fungicide can prevent, control or stop more than 65 types of fungal disease on flowers, vegetables, shrubs, fruit and shade trees.

Agaricomycetes

Leaf curl and distortion. Leaf yellowing or stippling. Necrotic leaf spots. White sporulation of the pathogen on lower leaf surface. Defoliation.

Use hygiene measures. Start clean, remove crop residues and prevent splashing water.

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.

Peronosporea

Phyllosticta causes circular leaf spots with brown/reddish borders. The spots can be really large covering a large area of the leaf. Initial symptoms include small watersoaked regions on the leaves. lesions become more apparent with a ring-like pattern at alter stages.

Repeated applications of fungicides such as Dithane M45, Captan, Ferbam, Mancozeb or thiophanate-methylbased treatments will help control infection levels and can prevent new infections in healthy plants, but it is difficult if not impossible to completely eradicate the fungus in an infected host plant.

Remove and dispose of affected leaves from infected plants to keep the fungal spores from spreading into the growing environment. Some growers have reported covering the mature lesions with clear nail polish to prevent the dissemination of spores.

Phyllosticta leaf spots

Symptoms usually involve necrotic, often water-soaked leaf spots, typically most severe on lower leaves. The spots may be very small at first but develop an angular shape as the movement of the bacteria is limited by leaf veins. Eventually several spots may enlarge, coalesce and cause death of mature leaves.

Reduce humidity to encourage dry foliage and avoid dripping within the greenhouse. Avoid splashing water from plant to plant.  Avoid excess moisture and late day irrigation.

Chemical treatments work best as a preventive measure. Copper-based plant protection products have bactericidal activity (kill bacteria) and can be effective. Disinfection products that contain hydrogen peroxide or quaternary ammonia are also available.

Gammaproteobacteria

The most common sign of anthracnose is the spots that appear on new leaves. These spots are irregularly shaped and are tan, brown, or black in color. In some trees, these spots appear all over the leaves and on others they may appear along the leaf veins.

Plant resistant plants, or buy healthy transplants. Plant your plants in well-drained soil.

Anthracnose diseases typically do not kill the host directly, however, repeated infections on woody plants over a period of years may lead to a general decline and dieback. Control of anthracnose diseases becomes important when the host is economically important and the goal is production for fruit or lumber. Otherwise, anthracnose diseases generally go unattended and raise concern only when premature leaf drop calls attention to the situation.

Anthracnose

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

Botryosphaeria obtusa enters the fruit through wounds. These can be made by insects, birds or growth cracks. At first a brown spot, near the calyx, appears on the fruit. The spot on the fruit then enlarges and black/brown rings appear on the fruit. The fruit holds its shape, however, unlike other fruit diseases. The fruit will then wither up and can remain on the tree for another year before falling off. During this time pycnidia appear on the surface of the rotted fruit.

Start with clean seed. In warm, humid weather, a single infected seed in as many as 10,000 could lead to a black rot outbreak.

The most effective treatment is to prune out the infected areas on trees, to ensure transfer between trees does not occur. Fruit that is infected can stay on the tree for over a year, and therefore remaining fruit should be removed to avoid another source of inoculation for other trees. The trimmed branches or dead fruit should then be burned or disposed of immediately as the organism can survive on the dead tissue for a long period of time. Infection of leaves and fruit can be avoided by spraying them with a fungicide. The treatment for the fungicide should be also kept up to date via the manufacturer's instructions.

Black rot

Canker, plant disease, caused by numerous species of fungi and bacteria, that occurs primarily on woody species. Symptoms include round-to-irregular sunken, swollen, flattened, cracked, discoloured, or dead areas on the stems (canes), twigs, limbs, or trunk.

Control includes removing diseased parts in dry weather; growing adapted or resistant varieties in warm well-drained fertile soil; avoiding overcrowding, overwatering, and mechanical wounds; treating bark and wood injuries promptly; controlling insect and rodent disease carriers; wrapping young trees to prevent.

The main measures for controlling the residue are the destruction of vegetation after harvest; cutting and burning of plant parts most severely damaged by anthracnose; spraying with 1% Bordeaux liquid.

Canker

Leaves - abnormal colours, abnormal leaf fall, abnormal leaf fall, internal feeding, wilting.

Avoid heat sources such as radiators. Protect the plant from direct sunlight during the hotter hours if placed behind a window. The temperature must never drop below 60°F (15°C).

Maintain a regular watering schedule. Water stephanotis regularly during the first growing season. Fertilize with a balanced mix. Scatter about 1/4 cup of dry fertilizer on the soil around the plant in early spring.  Prune in late winter or early spring.

Stephanitis

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

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

Signs of sap-sucking insect injury consist of enlarged growths or galls, leaf curling, bleaching, or yellowing of foliage. Conifers are more severely injured than hardwoods.

Use insecticidal soap, kelthane, or malathion to control the mites. Control of sucking insects with insecticides is often difficult because of the insects' capacity to reproduce rapidly. Also, they may develop resistance to the chemicals. Often a blast of water from a garden hose will knock the pests off the plant.

There are many natural enemies that help control sap-sucking insects and mites. Insecticide use can sometimes prolong infestations by killing natural enemies of these insects.

Impact of sap-sucking insects

The leaves become narrower and longer, and with severe damage, the plants become chlorotic and die.

There is no cure for nectria canker, so it is important to take steps to prevent it affecting young and vulnerable trees. Pruning injuries can be a major source of infection, so avoid pruning trees in the fall, especially in wet conditions. Restrict pruning to dry weather and remove any branches or stems that have been infected with the fungus.

Freezing damage is another important way in which trees get infected. For young transplants, providing protection from freezing can prevent the disease. Avoid other types of injury and keep your trees healthy to minimize the risks from nectria infection. This means being careful with the lawnmower around trees, preventing or managing pests, and providing adequate water and nutrients.

Nectriaceae

Leaf spots start as small brown spots, often with a yellow halo, and grow into irregular brown spots (up to 3/4"). Leaf spots sometimes develop a target-like pattern of rings. Severely infected leaves turn brown, curl upward, wither and die.

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.

Alternaria blight

Springtails occasionally feed on plant roots, but the damage is minimal. Problems arise when these pests congregate in moist areas and multiply. Thousands of springtails blanket walls, foundations and patios as their numbers grow. If not stopped outdoors, springtails multiply indoors in damp basements, kitchens and bathrooms — anywhere with sufficient moisture.

It is not difficult to keep this insect at bay. First of all ensure that house plants are always grown in sterile potting compost (this will also help keep away the diseases that the soil can contain).
If there is insufficient drainage, the compost can become waterlogged, so, next, always ‘crock’ a pot with a layer of grit or clay pellets before adding compost. If the compost to be used is too compact, coarse sand or perlite can be added to make it more free-draining.
If you find it difficult to assess when to water use a moisture meter, a self-watering cone or a container with a reservoir. In the latter cases, the compost takes up water gradually as it dries out, ensuring an even supply.

1 First of all, stop watering the plant and allow it almost to dry Out before re-watering. ‘This may be enough to eradicate these pests. It not, then you will need to use a chemical.
2 Use a suitable chemical, in granule form or diluted with water, to soak the potting mixture.
3 Insecticides containing diazmon, lindanc, malathion, pyrethrum or resmethrin are suitable. Make sure that due ingredients of an insecticide are listed on its label. One application of the chemical should be enough but repeat the application after 8 days to ensure eradicating ideal conditions for springtails.
4 If your plants are infested with Springtails, you will know as soon as you water them, as these tiny insects will start jumping about on top of the potting mixture.
5 Springtails will thrive in waterlogged soil so always water very carefully and ensure that the plant has good drainage.

Springtails

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

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

As a general rule, common symptoms of a bad root knot nematode infestation can include chlorosis (yellowing of the leaves/stems), stunted growth, wilting, and a lack of production of fruit.
However, these may be nonexistent to severe depending on the population of nematodes, the health of the plant, the natural resistance of the plant, and any number of other factors in the soil makeup. It can also be hard to separate the symptoms from other pest/disease issues.
The only real way to be sure that it is in fact root knot nematodes is to carefully remove a plant from the soil and examine its roots. If there are a lot of galls growing along the root system, it’s likely root knot nematodes at work.
While these microscopic nematode parasites can be problematic, root knot nematodes are not uncontrollable. They may be tricky, but with good garden management, you won’t have negative consequences!

Prevention is always the best cure for a pest problem, and root knot nematodes are no exception. So let’s talk about prevention.
First off, plant nematode-resistant varieties. There are a wide variety of different seed suppliers who carry nematode-resistant seed stock, usually notated as an N in the resistance charts.
If you cannot plant nematode-resistant strains, practice good crop rotation. Some species of root knot nematodes are more selective than others. Planting cover crops like marigolds or sudangrass between at-risk crops will also bring down the nematode population.
Remove the roots of old plants when clearing the bed. As root knot nematode juveniles can live in the galls they form on the roots, they will continue to multiply even as the roots are dying out. Removing the remaining root mass can extract those juveniles.
Till the soil 2-3 times in the fall. This breaks up the soil, turning the nematodes up to the surface where they will die off from exposure to the sunlight. This will impact both beneficial and parasitic nematodes, so you may need to re-add beneficial nematodes again in the spring.
Plant overwintering grass cover crops like wheatgrass, ryegrass, or rye. Sudangrass is also good and offers some nematicide properties. Keep these mowed down to a manageable level, and till them under in the spring to add more plant matter to the soil.
Regularly add more organic material to your soil. Adding more composted leaves, grass clippings, and manure to your beds will help naturally control the population of nematodes in the soil, since nematodes prefer living material to decaying plant matter.

There are two organic nematicide variants available: ones based on geraniol (the oil of geraniums), and ones based on quillaja saponaria, the soap bark root. Remember, though, that nematicides will kill off both beneficial and parasitic nematodes.
Quillaja saponaria compounds such as Monterey Nematode Control use the saponins from the soap bark tree to help reduce nematode populations.
You can also use an azdirachtin product such as AzaMax, which is a pure azdirachtin extracted from neem oil. This may work as a light nematicide, but tends to be better against other pests such as spider mites, thrips, aphids, and more.
Add neem seed meal, crab meal, or oyster shell flour to your soil. All three are fertilizers, but they’re great soil builders in the war against root knot nematodes.
Neem seed meal is a gentle fertilizer which is made from the leftover material after making neem oil. It helps reduce a number of pests naturally, plus it breaks down to add low levels of nitrogen to the soil. It also can help strengthen the roots of plants to make them resistant.
Crab meal encourages beneficial soil microorganisms which reduce nematode population. It also helps plants to increase the strength of their cell walls, making them more naturally resistant to many conditions.
Oyster shell flour is in essence a form of diatomaceous earth. While it has less effect when it’s wet, it can help make the soil less hospitable to nematode populations and reduce other pests as well.
Black walnut leaves and hulls have a natural compound in them which is called juglone. This compound is an extremely effective killer of root knot nematodes, but can have an adverse effect on some plants. That’s why there’s few weeds around walnut trees!
If you want to put an organic source of juglone to work in your garden, use fresh walnut leaves or smashed hulls as a thick layer of compost on your bed, or just build a tall pile there. Regularly turn it to keep it composting. I use leaves, as they’re quick to break down.
The juglone compounds will seep into the soil when you wet down the pile, and after three to six months should have broken down enough that they will no longer be toxic to other plants. This also helps wipe out weeds or other pests that may be in your beds during composting.

Root-knot Nematodes

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

Southern blight on plants is most likely to occur in the summer months when the soil is warm and moist. Symptoms include discolored lower leaves, wilted foliage, and plant collapse and it usually results in the death of the plant.

Preventing entry of the pathogen. Use of healthy, certified seeds of known origin. Careful cleaning of agricultural tools. Avoiding environmental conditions that favour development of the pathogen. Irrigation management. Plant density and growth habitats.

Soil solarization and certain organic amendments (e.g. composted chicken manure and rye-vetch green manure), as well as introducing certain Trichoderma spp. have also been shown to reduce plant death and number of sclerotia produced in the field in tomatoes. In addition to these cultural methods, chemical methods (e.g. fungicides) can also be employed.These methods all disrupt the production of mycelium and sclerotia, thus reducing the spread of disease.

Southern blight

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.

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.

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.

Phoma blights

The term “abiotic disorders” refers to a wide array of plant problems. We use the word “abiotic” to indicate that the symptom is not caused by a biological agent such as an insect, mite or pathogen.

Examine where symptoms first appear on a plant—on new leaves, old leaves or all over? Note the pattern of any discolouration or yellowing—is it all over, between the veins or around the edges? If only the veins are yellow, deficiency is probably not involved. Note general patterns rather than looking at Individual plants—are the symptoms distributed throughout a group of plants of the same type growing together? In the case of a deficiency all of the plants should be similarly effected, although distribution will depend on past treatments applied to the soil. Soil analysis, such as determining pH, can help to confirm the presence of physiological disorders. Considering recent conditions, such as heavy rains, dry spells, frosts, etc., may also help to determine the cause of plant disorders.

Testing soil and fertilizing accordingly. Collecting and testing samples to identify and treat pests or diseases. Aerating compacted soil with an air tool to “fluff” it without damaging roots. Pruning to help a tree recover from damage caused by storms, road salt, or extreme temperatures.

Abiotic

Common, Persian, Chinese, and Japanese lilac leaves develop round to irregularly shaped brown spots with yellow halos. These spots enlarge and blight entire leaves. Succulent twigs are girdled, killed, and turn black.

1. Exclusion or eradication of the pathogen (quarantine and use of pathogen-tested seeds and propagated materials)
2. Use of clean transplants.
3. Monitor crops regularly and use predictive models.
4. Reduce the pathogen levels by crop rotation.
5. Remove weeds and incorporate crop residues that can host the disease.

The most common strategy for controlling diseases caused by Pseudomonas syringae is, as it has been for more than 5 decades, to spray bactericides. These mainly include a variety of copper compounds or other heavy metals, with or without various combinations of fungicides or other pest-control chemicals.

Pseudomonas

Mosaic symptoms are variable but commonly include irregular leaf mottling (light and dark green or yellow patches or streaks). Leaves are commonly stunted, curled, or puckered; veins may be lighter than normal or banded with dark green or yellow.

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

Control measures are the use of resistant varieties, the destruction of resistant vectors and weeds - pathogen reserves, removal of diseased plants and plant debris, crop rotation, sterilization of tools for plant care.

Mosaic virus (general)

The black spots are circular with a perforated edge, and reach a diameter of 14 mm (1⁄2 inch). Badly affected plants, however, will not show the circular patterning, as they combine to cause a large, black mass. The common treatment of the disease is to remove the affected leaves and spray with antifungal solutions. Some stems of the roses may become affected if untreated, and will cause progressive weakening of the rose.

Keep the foliage as dry as possible, since the spores need a wet surface in order to germinate. Avoid overhead watering, or water early in the day so the foliage has time to dry before nightfall. Improve the air circulation around your roses by spacing them properly and pruning them regularly.

Removing infected leaves from the plant and fallen leaves from the ground will slow the spread of the infection, as does avoiding wetting the leaves of plants during watering. An infected plant can be removed from the area, which will slow the spread of infection to other plants, but this often is not desirable. Fungicides, such as mancozeb, chlorothalonil, flutriafol, penconazole, or a copper-based product, applied upon new leaf emergence or first appearance of black spot, can be used to control the disease. If a more natural and nontoxic approach is desired, diluted neem oil is effective both against black spot and as an insecticide against aphids, or cows milk diluted 1:3 with water is effective if sprayed on to the leaves. It is usually necessary to repeat the spraying at seven- to 10-day intervals throughout the warmest part of the growing season, as the fungus is most active at temperatures from 24 to 32 °C (75 to 90 °F).

Black spot

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

Tan to brown leaf spots, small black fruiting bodies (pycnidia) may be visible in the lesions. Lesions on Rudbeckia and Echinacea are purple. Lesions may be more severe on older foliage.

Avoid overhead irrigation or carefully time it such that the duration of leaf wetness is minimized.

Protectant fungicides can be used to manage Septoria leaf spot.

Aloinopsis rubrolineata

(Aloinopsis rubrolineata)

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