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Organic Disease Control (and other issues)
The primary cause of insect and disease pest problems is the regular use of high-nitrogen synthetic fertilizers and toxic chemical pesticides. These products treat symptoms rather than the true problems and injure more beneficial life than the targeted pests. It’s as simple as that! Research has shown that pests are actually attracted to weak unhealthy plants that resulted from using toxic chemicals and plants fertilized with artificial fertilizers.
Plant diseases are usually caused by three major types of living organisms: fungi, bacteria and viruses. Diseases are an imbalance of microorganisms and reestablishing that balance is the key to disease control.
Disease control in an organic program is an easy. Increased resistance to most diseases results as a nice side benefit from the Basic Organic Program. All organic products help control disease to some degree. When soil and plants are healthy, there is a never-ending microscopic war being waged between the good and bad microorganisms, and the good guys win. Disease problems are simply situations where the microorganisms have gotten out of balance.
Drainage is a key ingredient for the prevention of diseases. Beds, lawns and tree pits that hold water and don’t drain properly are the ideal breeding place for many disease organisms.
As with insects, spraying for diseases is only treating symptoms, not the major problems - plus the toxic sprays kill more beneficials than the targeted pests. The primary cause of problems is usually related to the soil and the root system. Therefore it is critical to improve drainage, increase air circulation, add quality composted products, and stimulate and protect the living organisms in the soil.
Plant Diseases and Other Related Issues
Anthracnose: A fungal problem in sycamore trees, beans, and ornamentals where the foliage turns a tan color overnight. Sycamore leaves brown, remaining on the tree. Not normally fatal. Spray Garrett Juice plus garlic tea on emerging new foliage in early spring. Apply The Sick Treatment. Sprays of potassium bicarbonate, garlic and quality neem products are also effective. Avoiding planting American sycamores is the best control. The Mexican sycamore is a far better tree. This disease also attacks beans and ornamentals. The foliage turns a tan color overnight. Control is difficult other than by avoiding the use of susceptible plants. Also called bird’s-eye spot, it is a fungal disease that causes small dead spots with a raised border, sunken center, and concentric rings of pink and brown. Symptoms of bean anthracnose manifest on the pods as circular, black, sunken spots that may ooze pink slime and develop red borders as they age. Thoroughly compost infected plants. Treat the soil with cornmeal and use the overall Sick Tree Treatment. Soil improvement is the best solution. Spray infected plants with 2% hydrogen peroxide, and a horticultural soap (to clean plants).
Asparagus rust: Fungal disease that appears as a browning or reddening of the foliage, and a release of rusty, powdery spores. It can overwinter and infect new shoots as they emerge the following spring. Rust is moved from plant to plant by wind. To control, spread plants to allow air circulation and plant resistant varieties. Remove infected plants and thoroughly compost them. Spray plants with horticultural soap.
Bacteria: Single-cell microorganisms that reproduce by simple cell division. Rots cause decay of leaves, stems, branches, and tubers. Vascular system blockage causes wilting. Galls result from an overgrowth of the affected cells. Bacterial problems are encouraged by poor drainage, wet soil, high humidity and high temperatures. Feeding plants with slow-release natural organic fertilizers will help prevent bacterial infection. Use disease-free seed and resistant varieties. Remove infected plants promptly and compost. You need a microscope to see the actual bacteria, but the symptoms they cause are easy to see with the naked eye. Most bacteria break down dead organic matter and are beneficial. A few, however, cause plant diseases. Bacteria usually reproduce by splitting in half. Wind, water, insects, garden tools and gardeners’ hands spread the spores. Bacterial diseases are more difficult to control than fungal diseases but the hydrogen peroxide products are effective.
A bacterial disease that causes dark-green water spots that turn brown and may die leaving a hole in the leaves of tomatoes, plums, and several ornamental plants. Controls include healthy soil, garlic tea, hydrogen peroxide (to clean plants). Horticultural soaps are excellent commercial products labeled for use on this disease.
Bacterial blight on lambs ear.
Bacterial blight on rough leaf dogwood
Bacterial leaf scorch: A fatal disease of sycamores and other plants. It causes a browning between the veins of the leaves. It kills limbs from the tips and moves back quickly. Often incorrectly diagnosed as anthracnose. The solution is increased soil health by applying the Sick Tree Treatment.
Common name of fungal leaf spot. Black spot attacks the foliage of plants such as roses. There is usually a yellow halo around the dark spot. Entire leaves then turn yellow and ultimately die. Best controls include selection of resistant plants and Garrett Juice plus garlic tea and diluted milk. Keep bare soil mulched. Apply cornmeal to the soil or cornmeal juice to the foliage. Horticultural soaps are the commercial products labeled for this treatment.
Back spot fungus on rose
Blights: When plants suffer from blight, leaves, infected branches suddenly wither, stop growing, die and may rot. Drench the soil with neem.
Cool-weather, fungal disease of St. Augustine. Brown leaves pull loose easily from the runners. Small spots in lawn grow into large circles that look bad and weaken the turf but rarely kill the grass. Soil health, drainage, and low nitrogen input are the best preventatives. Treat diseased turf with cornmeal at 10-20 lbs. per 1,000 sq. ft. or dry granulated garlic at 2lbs. per 1000 sq. ft. Spray Garrett Juice with a Plant Wash (to clean plants) added. Good quality compost can also be used as both a preventative and curative for brown patch.
Brown patch fungus in St. Augstinegrass
Brown rot: A fungal disease that is common in fruit trees not using an organic program. It that may cause serious damage to stone fruits during wet seasons. Prolonged wet weather during bloom may result in extensive blossom infection. Early infections appear as a blossom blight or twig canker. Later infections appear as a rot of ripening fruit on the tree and in storage. Spring infections arise from mummified fruit of the previous season that remains attached to the tree or has fallen to the ground. Brown rot of stone fruits is a fungus that the most common during prolonged wet seasons during the bloom period. Early infections appear as blossom blight or twig canker. Later infections appear as a rot of ripening fruit on the tree and in storage. Mummified fruit of the previous season that remains attached to the tree or left on bare soil on the ground can spread the disease. The solution is the organic program and preventative spraying with garlic pepper tea, neem, hydrogen peroxide or Bio Wash (to clean plants). Aerated compost tea is also very effective. And did I mention root flares - make sure they are visible and not covered with mulch or soil.
Canker: A stress-related disease of trees and shrubs that causes decay of the bark and wood. Cankers have to start with a wound through the bark. Healthy soil and plants are the best solution. Use Tree Trunk Goop on the injured spots, improve the environmental conditions and apply the Sick Tree Treatment. Synthetic fungicides do not work on this disease. Hypoxolyn canker is a common disease of certain oaks such as stressed post oaks, especially after droughts or long rainy seasons. The brown spores rub off easily and the bark sloughs off the trunks. No treatment is necessary other than improving the immune system of the tree. This is the #1 disease seen on post oaks. The stress leading to this disease is often caused by herbicide treatment to the root zone or the trees being too deep in the soil. Look for cracks, sunken areas, or raised areas of dead or abnormal tissue on woody stems. Cankers ooze sometimes. Cankers can girdle shoots or trunks, causing the plant above the canker to wilt and die. Blights and canker diebacks look quite similar. Cold-injury symptoms can look like or lead to the development of cankers.
Cedar apple rust:
Cedar-apple rust is just one of several similar fungal diseases that could be broadly classified as Juniper-Rosaceous rusts. All have very similar disease cycles but differ by which juniper and rosaceous species they infect. The fungus spends part of its life cycle on a juniper host and part on a host in the rose family. It requires both hosts to complete its life cycle. Cedar-apple rust is caused by the fungus known as Gymnosporangium juniperi-virginianae
. Two other common juniper-rosaceous rusts are hawthorn rust and quince rust, although there are many more. Examples of juniper hosts include eastern red cedar, southern red cedar, Rocky Mountain juniper, some prostrate junipers, and Chinese juniper. Examples of rosaceous hosts are apple, crabapple, hawthorn, quince, serviceberry, and pear. Some commercial apple varieties are highly susceptible to cedar-apple rust with both direct fruit infection and defoliation of infected leaves. Apply the Sick Tree Treatment and spray a horticultural soap (to clean plants).
A condition caused in various plants by trace mineral deficiency. Iron scarcity is usually blamed, but the cause can be the lack of several trace minerals or magnesium or soils out of balance. To cure - improve the health of the soil in order to improve trace mineral availability to plants by applying greensand, humate, Magic Sand, Azomite, natural organic fertilizer and foliar feeding. After minerals are applied, apply native mulch for continued control. For trees and other woody plants, the entire Sick Tree Treatment is in order.
Club root: Fungal disease that attacks vegetables and flowers in the cabbage family. Plants wilt during the heat of the day. Older leaves turn yellow and drop, roots are distorted and swollen. To control, select resistant cultivars, rotate related crops and thoroughly compost sick plants. Apply liquid biological activators and cornmeal.
Construction damage: Construction activity causes compaction of the soil which squeezes out oxygen and kills beneficial microbes and root hairs of trees and other plants. Prevent it - don’t allow it - use physical barriers. Build strong fences so contractors cannot access the root zone. Use coarse mulch on all work areas and areas of vehicle access (roads and parking). Three inches of coarse shredded native tree trimmings mulch is as effective as ¾” plywood at preventing compaction. The mulch also prevents tracking of mud and dirt into new construction.
Cotton root rot: A fungal disease common in alkaline soils that attacks poorly adapted plants. The best preventative is healthy soil with a balance of nutrients and soil biology.. Treat the soil with cornmeal at 10-20 lbs. per 1,000 sq. ft. Adding sulfur to the soil at 5 pounds per 1,000 square feet annually will help. Do annual soil tests and stop when enough sulfur is in the soil. In no-till agriculture the organic content comes up and cotton root rot is less a problem. This disease is a manmade to a great extent; chemicals destroyed the humus and protective living organisms. The best solution is healthy soil with a balance of nutrients and soil biology.
Crown gall: Crown gall is bacterial disease that infects and kills grapes, roses, fruit trees, shade trees, flowers and vegetables. Galls are rounded with rough surfaces and are made up of corky tissue. They can appear on stems near the soil line, on graft unions and on roots or branches. Don’t buy suspicious looking plants and don’t replant in an area where you have had crown gall. Avoid wounding stems, and disinfect tools between plants when pruning with hydrogen peroxide. Destroy infected plants or prune away galls.
Crown rot: Caused by Phytophthora fungus, which attacks the roots and, most notably, the crown of plants such as African violets. Plants are most susceptible when allowed to sit in soil that is heavy and soggy. Crown rot is often fatal. The best control is prevention. Symptoms: Crown is mushy and may appear translucent brown with a soft, jelly-like consistency. It appears brown or black in color not to be confused with the web left behind by spider mites, which clings to the flowers and plant hairs of the leaves. Leaves darken. They appear brown or black in color. Leaves wilt and may appear translucent brown with a soft, jelly-like consistency. Controls include cinnamon, hydrogen peroxide, cornmeal tea and a plant wash (to clean plants). Horticultural soaps are commercially available disease control.
Curly top: A viral disease that attacks vegetable crops such as tomatoes. To prevent, control the aphids that spread the disease. Use shiny material such as silver Mylar under plants. Drench soil with neem product. Spray plants with 3% hydrogen peroxide - it really works but can burn plants during hot weather. Spray during the coolest part of the day.
A fungal disease of emerging seedlings where tiny plants fall over as if severed at the ground line. Avoid by using living organic (not sterilized) potting soil and by placing rock phosphate on the surface of planting media. Treat the soil with cornmeal and spray with a plant wash (to clean plants). This disease is caused by a number of fungi, mainly Pythium
. The symptoms include decay of seeds prior to germination rot of seedlings before emergence from the root medium and development of stem rot at the soil line after emergence. The collapse of seedlings at or just below soil level is very common in synthetic programs where unhealthy potting soil is used. It is especially bad when there is over-watering and/or poor drainage. Avoid this disease by using colloidal phosphate or cornmeal on the surface of planting media. Keep soil moist, but not waterlogged. Provide good air movement and always use living organic material such as earthworm castings or compost in the seedbeds. Wait until soil is warm enough for the specific plant before seeding.
Dollar spot: A fungal disease (Sclerotinia homeocarpa) that forms small brown spots on golf green grasses and other Bermuda turf grasses. It can be controlled with various cornmeal products. Tierra Verde Golf Club controlled it with corn gluten meal at fertilizer rates. It attacks most turfgrasses grown in the South. Bentgrass, hybrid Bermuda grasses and zoysia are most susceptible to this disease. It occurs from spring through fall, and is most active during moist periods of warm days (70-85°F) and cool nights (60°F) in the spring, early summer and fall. It is spread by water, mowers, other equipment and foot traffic. To prevent dollar spot, use proper cultural practices and the organic program to promote healthy turf. Avoid light frequent waterings. To cure dollar spot infection, apply a cornmeal or garlic in dry or liquid forms as needed. Applications are most critical during moist weather in the spring, early summer and fall when temperatures are between 70º and 80ºF.
Downy mildew: Fungal diseases that attack fruits, vegetables, flowers, and grasses. The primary symptom is a white to purple, downy growth, usually on the underside of leaves and along stems, which turns black with age. Upper leaf surfaces have a pale color. It can overwinter on infected plant parts and remains viable in the soil for several years. It is spread by wind, rain, and in seeds. To control, thoroughly compost sick plants and apply cornmeal to the soil surface.
Early blight: A fungal disease that infects ornamental plants, vegetables, fruit trees, tomatoes, potatoes and peppers and shade trees. Brown to black spots form and enlarge on lower leaves developing concentric rings like a target. Heavily infected leaves dry up and die as spots grow together. Target like, sunken spots will sometimes develop on tomato branches and stems. Both fruits and tubers can also develop dark, sunken spots. Spores are carried by the air and are a common cause of hay fever allergies. Control this disease by planting resistant cultivars and soaking seed in a disinfecting solution such as a hydrogen peroxide mixture before planting. Spray plants with compost tea, treat soil with cornmeal products.
Entomosporium leaf spot:
A fungal disease of photinia, hawthorns, and other related plants. It primarily hits large monoculture plantings. It can be controlled by improving soil conditions and avoiding susceptible plants. It is most active in spring and fall. Use the Sick Tree Treatment and try to avoid watering the foliage. Although it shows up on the foliage as round dark purple spots, it is really disease of the root system. Baking soda or potassium bicarbonate spray will stop the spotting on the leaves if caught early. Improving the health of the root system with aeration, compost and rock powder is the long range cure. Products for the soil containing alfalfa will also help. Use the Sick Tree Treatment for ultimate control. Drenching the soil with mycorrhizal laced compost products is the most effective solution if only one treatment is to be done.
Entomosporium leaf spot on red tip photinia.
Fairy Rings, Toadstools, Mushrooms:
Mushrooms in lawns are common especially during rainy weather. They live off decaying organic matter in the soil, often decaying tree roots and are not harmful to the lawn. They will naturally disappear with age or they may be collected and composted, knocked down with a rake or hoe or mowed over with mower. Mushrooms should never be collected and eaten unless you are expert in their identification. To many gardeners, poisonous mushrooms can look very similar to edible ones. Don’t take a chance. Fairy rings are the fruiting bodies of fungi growing on decaying organic matter. The white caps look like golf balls when young but expand to 4’-8” in diameter at maturity. Usually appear in lawns in summer after rainy periods. Caps are white at first, then turn gray-green and have distinctive green spores, reddish brown “scales” on the cap and a ring on the smooth stalk. Fairy rings usually grow in soil where wood of dead roots, lumber or old stumps are decaying. These organisms are toxic and known for their tendency to collect heavy metals from the air and soil.Fasciation
: Fasciation, or cresting, is a rare of abnormal growth in vascular plants where the growing tips becomes elongated perpendicularly to the direction of growth, producing flattened, ribbon-like, crested or contorted tissue. Fasciation can also cause plant parts to increase in weight and volume. It can happen in stems, roots, fruit or flower heads. Some plants are grown and prized for their development of exotic fasciation. It has several possible causes including hormonal, genetic, bacterial, fungal, viral, insect or mite attacks, exposure to chemicals, physical damage to a plant’s growing tip, weather changes and extremes and other environmental impacts.
Fasciation of Texas Mountain Laurel Flower.Fireblight:
A bacterial disease of plants in the rose family in which blossoms, new shoots, twigs and limbs die back as though they have been burned. Leaves usually remain attached but often turn black or dark brown. Prune back into healthy tissue and disinfect pruning tools with a 3-5 percent solution of hydrogen peroxide. Spray plants at first sign of disease with Garrett Juice plus garlic and/or neem. Consan 20 and agricultural streptomycin are also effective controls. Kocide 101 is a copper based fungicide often recommended, some consider this organic, I don’t. The best recommendation is to spray Garrett Juice plus garlic, treat the soil with horticultural cornmeal, apply the Sick Tree Treatment and reduce the nitrogen fertilizer. High-nitrogen, synthetic fertilizers are the primary cause of this disease. Spray plants at first sign of disease with 3% hydrogen peroxide or a plant wash (to clean plants). Treat plants with the Sick Tree Treatment and cut back on the amount of nitrogen fertilizer.
Fruit rot: Grapes infected with black rot turn brown, (so why don’t they call it brown rot?) then harden into small, black, mummified berries. Brown rot of stone fruits causes whole fruit to turn brown and soft. (Why don’t they call that whole rot?) Control fruit rots by planting resistant cultivars, removing and destroying infected fruit and pruning to increase air movement. Seaweed, garlic, compost tea and sulfur spray throughout the season also help. The Sick Tree Treatment will help prevent or cure this disease.
Fungi: Fungi are microscopic primitive plants that lack chlorophyll, and produce tiny spores that are spread by wind, water, insects, and gardeners. Spores germinate to form mycelia, which are the fruiting bodies. Mycelia rarely survive winter, but spores easily survive from season to season. Many fungi live on and decompose dead organic materials. These beneficial fungi are allies in the organic garden. Parasitic fungi, on the other hand, are leading of plant diseases. Most disease fungi live on a host plant, in the soil or on organic matter at various times during their life cycle. Some attack only one species of plants, while others attack a wide array of plants. Fungi are the microbes that are the easiest to see with the naked eye. They are sometimes seen as round or free form shapes on plant foliage. Downy mildew grows from within a plant and sends out branches through the stomata to create pale patches on leaves. Powdery mildew lives on the leaf surface, and sends hollow tubes into the plants. Rust fungi are named for the reddish color of their pustules. Leaf spot fungi cause yellow-green spots with black exterior rings. Soil-inhabiting fungi cause damping-off, which kills small seedlings. Many fungi are encouraged by constant moisture on foliage.
Fungal Leaf Spot: See Entomosporium Leaf Spot.
Fusarium and verticillium wilt: Fungal wilts that attack a wide range of flowers, vegetables, fruits, and ornamentals. Plants wilt and usually turn yellow. To control, plant resistant cultivars, or treat with cornmeal products. Remove effected branches and thoroughly compost them or the entire plants.
Galls: Swollen masses of abnormal plant tissue caused by fungi, bacteria or insects. There are many different kinds of galls primarily caused by wasp, fly, and aphid insects, they are usually more cosmetic than damaging. Insects “sting” a plant, which causes a growth that the insect uses as a home for its young. The gall serves as a shelter and food supply. Although unsightly, most galls are not considered very damaging. Natural control is biodiversity. Healthy plants seem to have fewer galls. Improve the general health of trees using the Basic Organic Program.
Gray leaf spot:
A disease of St. Augustine grass that forms gray vertical spots on the grass blades. A light baking-soda or potassium bicarbonate spray is the best curative. Prevent by spraying compost tea and improving soil health. Treat the soil with cornmeal at 10-20 lbs. per 1,000 sq. ft. A horiticultural soap (to clean plants) is also effective.
Iron deficiency: A nutrient deficiency that causes leaves to turn yellow with the veins remaining green. Advanced stage is yellow then dead. Treat with Texas Greensand and compost. Insufficient iron in plants is characterized by striped, yellow or colorless areas on young leaves. Yellow leaves appear on the new growth. The growth of new shoots is affected and plant tissues may die. Too much lime causes iron deficiency to develop. Treatment: Plenty of manure, compost, blood or cottonseed meal, greensand and tankage are the best materials to use in correcting iron deficiency. Magnesium deficiency looks identical.
Junipers die back: Fungal disease of cedars and junipers. Also called twig die back. Spores look like a yellow worm oozing out. Treat by pick pruning and mulching. Spray hydrogen peroxide and apply the Sick Tree Treatment.
Leaf blisters and curls: Fungal diseases that cause distorted, curled leaves on many trees. Oak leaf blister can defoliate and even kill oak trees. Blisters are yellow bumps on the upper surface of the leaves, with gray depressions on the lower surface. This disease can defoliate and even kill oak trees. Peach leaf curl attacks peaches and almonds. New leaves are pale or reddish. The leaf’s midrib doesn’t grow, causing the leaves to become puckered and curled. Fruit is often damaged and bad cases can kill the tree. Both diseases are controlled with a single horticultural spray just before buds begin to swell in late winter and again in autumn when the leaves start to fall.
Leaf spots: Generic term for cosmetic diseases of oak and elm. No control is needed. A vast number of fungi can cause spots on the leaves of plants. Most of them are of little consequence. A typical spot has a definite edge and often a darker border. When lots of spots are present, they can grown together and become blight or a blotch.
Growth seen on rocks and the trunks of trees commonly growing in flat greenish, gray, brown, yellow or black patches. Lichen consists of two separate and different microscopic plant forms - algae and fungi that live together in a symbiotic relationship. The fungi absorb and conserve moisture and provide shelter, without which the algae cannot live. The algae conducts photosynthesis as it grows and provides protein for the fungi. Lichen’s are generally not harmful and mostly beneficial.
Lichen - not harmful in any way.
Lightning damage: If your tree gets hit, keep your fingers crossed. Install lightning protection to prevent future damage. There are two kinds of lightning damage. When the lightning travels along the outside of the tree in the rainwater, bark is knocked off but damage is usually minimal. If the lightning goes through the center of the tree, the bark is blown off all round the trunk and the tree is a goner. Treatment for damaged trees is the Sick Tree Treatment.
Molds: Fungi that have a powdery or woolly appearance. Botrytis thrives in moist conditions and is often seen on dropped flower petals or overripe fruit. Look for a thick gray mold or water-soaked spots on petals, leaves, or stems. It first infects dead or dying tissue, so removing faded flowers and blighted buds or shoots to control the problem. Peonies, tulips, and lilies can be particularly sensitive in wet weather. Remove and compost infected material. Space, prune, and support plants to encourage good air movement. Spray plants with Garrett Juice plus potassium bicarbonate.
Oak leaf blister: A rare disease that needs no control. It usually results from a heavy rainy season. Leaves change from light green to a light brown dry blister and only happens in isolated spots on the tree.
Oak Wilt: A disease of the vascular system of oak trees which is transmitted through the air by insects and through the root system of neighboring trees by natural grafting. Apply the Sick Tree Treatment.
Oak wilt attacks red oaks and live oaks especially when they occur in large monocultures and are treated with synthetic fertilizers and pesticides. The disease on red oaks shows up first as greasy green leaves that then turn brown starting on the ends, usually seen on one limb at a time. Live oak leaves have veinal necrosis (brown veins and green in between). Some leaves will be dead on the end half. Red oaks have sweet smelling fungal mats on the trunks. Dutch elm disease is closely related. I do not recommend injecting fungicides into trees or trees that are near sick trees. The chemical injection hurts the tree, wastes money and doesn’t address the real problem. This procedure has been pushed by Texas A&M and the Texas Forest Service for many years and we have yet had anyone report that the fungicide injections have ever saved a single infected tree.
Biodiversity and soil health are the best deterrents. The disease is spread in the spring by a small beetle called nitidulid. Some people advise painting pruning cuts of live oak and red oak in the spring. I’m not so sure this is important. If you do, use Lac Balsam or natural shellac.
Peach leaf curl: Fungal disease that causes leaves to be puckered and reddish at first, but later in the season turn pale green, shrivel, and drop. Fruits may have a reddish, irregular, rough surface and decreased fruit production. This disease causes deformed leaves and can affect the quality and quantity of the fruit crop. Spray Garrett Juice plus garlic tea in fall.
Phytophthora: A genus of fungi that is generally a root and crown rot pathogen. This is a common disease in periwinkles that are being grown using synthetic fertilizers and pesticides. Beneficial microbes in healthy organic soil will normally keep this disease organism under control. Lilacs, rhododendrons, azaleas, and some hollies are sometimes infected by Phytophthora fungi. Plants suffer shoot dieback and develop stem cankers. Prune to remove infected branches and to increase air movement. Add compost and rock powders to the soil. In healthy soil, plants rarely have this problem. On peppers, potatoes, and tomatoes, Phytophthora infection is known as late blight. The first symptom is water-soaked spots on the lower leaves that enlarge and are mirrored under the leaf with a white downy growth. Dark-colored blotches sometimes like sunken lesions penetrate the flesh of tubers. During a wet season, plants will rot and die. Phytophthora overwinter on underground parts and in plant debris. To control, dispose of all infected plants and tubers, presoak seed in a disinfecting solution such as hydrogen peroxide and plant resistant cultivars. Sprays of potassium sulfate can help control outbreaks during wet weather. This is the disease that has greatly reduced the use of periwinkles as a bedding plant. Healthy soil through the use of compost, natural organic fertilizers, and rock powders will help control the pathogen. Good drainage is critical. Whole ground cornmeal in the soil and cornmeal tea on the tea are both effective on this disease.
Pierce’s disease: A manmade bacterial disease of grapes. It lives on but does not infect alfalfa, blackberries, cedar elm, grasses, red oaks, and willows. Leafhoppers are one of the main vectors. Management includes removal of host plants around vineyards and stimulation of beneficial microorganisms. This is stress problem caused by pushing the plants with too much fertilizer and pesticides.
Pine tip blight: A pine disease that forms black bumps on the needles. It resembles pine tip moth damage and can be controlled with The Sick Tree Treatment.
Potassium deficiency: Potassium deficiency causes reduced vigor and poor plant growth. Frequently, the older leaves turn white and curl, later becoming bronzed. Severe deficiencies cause poorly developed root systems. To treat deficiencies, add rock, granite dust, wood ash, or other potassium-rich organic material to the compost and directly to the soil. Heavy consistent mulching also helps maintain the potassium supply.
Powdery mildew: This fungal disease is a white or gray, powdery, growth on the lower leaf surface and flower buds of zinnias, crape myrtles, and many vegetables, phlox, lilac, melons, cucumbers, and many other plants. It is common during cool, humid, cloudy days. Leaves turn yellow on the top. Controls include compost tea, baking soda spray, potassium bicarbonate spray, neem, garlic, and horticultural oil. A horticultural soap (to clean plants) seems to be the best immediate cure. Garrett Juice plus garlic tea is best for long-term results. Treat soil with horticultural cornmeal and use the entire Sick Tree Treatment for serious problems. This disease can cause long term weakness when it occurs early in the growing season. This common fungal disease is increased by humidity but actually deterred by water. Mildew forms a white to grayish powdery growth, usually on the upper surfaces of leaves. Small black dots contain spores that are blown by wind to infect new plants. Leaves will become brown and shrivel and fruits ripen prematurely and have poor texture and flavor. Prune plants to improve air circulation. Thoroughly compost infected plants before spores form and spread.
Powdery mildew fungus on crape myrtle.
Powdery mildew on euonymus.
Pythium: A fungal pathogen that’s a water mold, soil inhabitant, and common cause of root rot and damping off of seedlings. Horticultural cornmeal is the best treatment. This is one of the damping off fungal diseases.
Root and Stem Rot: These rots can usually be controlled with good drainage, good air circulation, and healthy soil. Only use healthy plants. Compost all infected plant material. Be careful to watch for physical injury, which may invite problems on woody plants.
: Saying there is no cure for rose rosette is lazy and wrong. Destroying the plants as the only solution is goofy. There is certainly a different route I would try before taking this give-up approach. I don’t recommend taking the plants out before trimming the damaged growth out and at least trying the Sick Tree Treatment, just as we would for diseased trees. Cut away the diseased stems and clean the tool blades immediately using hydrogen peroxide (never bleach). The Sick Tree Treatment should be applied throughout all the rose beds. The addition of granulated garlic at 2 lbs per 1000 sq. ft. is also helpful.
Fungal disease that forms an orange stain on the surface of foliage. Pustules form on the underside of leaves. This is mostly a cosmetic disease but can be treated with Garrett Juice with garlic or potassium bicarbonate. Rusts require two different plant species as hosts to complete their life cycle. Typical rust symptoms have a powdery tan to rust colored coating or soft tentacles.
Fungal diseases that cause fruit, leaves, and tubers to develop areas of hardened and sometimes cracked tissue. Fruit scab can be a major problem on apples and peaches. It is recommended to dispose of fallen leaves, pruning to increase air movement, and spraying during the growing season with sulfur. Regular sprays of garlic and seaweed will also help. Compost tea is also beneficial and horticultural cornmeal should be applied to the soil.
Slime flux is the foul-smelling sap that oozes out of wounds in the bark and wood, particularly on such trees as elm, maple, and birch. The sap ferments and produces chemicals which kill the bark over which if flows. If the seepage continues over a period of a month or more, considerable injury and even death to the bark will occur. Applying the Sick Tree Treatment will lessen the presence of this condition.
Slime mold: Slime mold sounds worse than it is. Slime molds cover above-ground plants with a dusty-gray, black, or dirty yellow mass. There will be tiny round balls scattered over the plant. If you rub these balls between your fingers, a minute sooty-like powder will cover them. You can do nothing or spray with garlic tea for control. Dusting dry cornmeal will also help. In turf slime mold spore masses coat the grass and look like cigarette ash on the surface of the blades. The spores can be easily wiped off. Remove the mold spores from the grass by rinsing with water during dry weather, or mowing and raking at any time. Baking soda spray will kill it but potassium bicarbonate is better.
Smut: Fungal diseases common to grasses, grains, and corn. Corn smut attacks kernels, tassels, stalks, and leaves. Smut galls ripen, rupture and release spores through the air to infect other plants and overwinter in the soil. Select resistant cultivars, remove and compost galls before they break open and rotate crops. Spray a horiticultural soap (to clean plants) as preventative.
Sooty mold: Black fungal growth on the foliage of plants such as gardenias, crape myrtles, and other plants infested with aphids, scale, or whiteflies. It is caused by honeydew (excrement) of the insect pests. Best control is the release beneficial insects to control the pest bugs. Also spray Garrett Juice plus garlic. Treat soil with horticultural cornmeal and use the entire Sick Tree Treatment. A horticultural soap will be the properly labeled commercial product.
St. Augustine decline: Is caused by the panicum mosaic virus in common St. Augustine grass that causes a yellow mottling. The grass slowly dies away. The answer is to replace turf with a healthier grass. The best St. Augustine at the moment is “Raleigh.” Switching to the organic program will eliminate the problem in most cases. Hydrogen peroxide at 2% has eliminated mosaic virus in squash plantings and will help on this grass disease.
Take all patch: A disease that can attack several species of grass. It is caused by the fungus Gaeumannomyces graminis var. graminis, and is mostly found in St. Augustine grass but can also cause problems in Bermuda grass. It is most active during the fall, winter and spring especially during moist weather.
The first symptom is often yellow leaves and dark roots. Area of discolored and dying leaves will be circular to irregular in shape and up to 20 feet in diameter and thinning occurs. Unlike brown patch, the leaves of take-all infected plants do not easily separate from the plant when pulled. Stolons will often have discolored areas with brown to black roots.
Regrowth of the grass into the affected area is often slow and unsuccessful because the new growth becomes infected. Controlling take-all patch is said to be difficult but isn’t with organic techniques. Good surface and subsurface drainage is important. Cut back on watering and fertilizing. Use only organic fertilizers and apply quality compost. If soil compaction exists, aeration will help to alleviate this condition and allow the grass to establish a deeper, more vigorous root system.
Prevent this disease by maintaining healthy soil. Control the active disease by aeration, cornmeal and compost and the Basic Organic Program.
Tree decline: A generic term referring to a sick, declining tree. Not a specific disease but rather a result of planting an ill-adapted tree, construction damage, drought, lightning, salt fertilizer, chemical, contamination, etc.
Viruses: The smallest and most difficult to control of all microorganism pathogens. Plastic mulch reflects ultraviolet light which repels insects like that carry various devastating diseases including viral diseases. University research using silver colored plastic mulch has been used under tomatoes and other plants to show significant insect control. Although it may work we don’t really like it as much as natural mulch. Mosaic viruses destroy chlorophyll causing leaf yellowing. Another virus blocks the plant’s vascular system, restricting the flow of water and nutrients. Viruses are transmitted by vegetative propagation, in seeds, on pollen, and on tools and gardeners’ hands. Viruses are also transmitted by insects, mites, nematodes, and parasitic plants. Viruses slow plant growth and reduce yields. Infected leaves may deform and develop mottling, streaking, or ring-shaped spots. Identification is sometimes the elimination of all other possible causes. Purchase certified plants, control insects that spread viruses and remove and thoroughly compost all infected plants. We have several reports of curing mosaic virus with a spray of 2% generic hydrogen peroxide or one of the commercial Horticultual soap products.
Wet wood: Bacterial wet wood on trees shows up as oozing cell sap, a white frosty material that attracts insects. Increase the tree’s health so it can wall off the problem area. Use the Sick Tree Treatment.
Wilt: When fungi or bacteria clog a plant’s water conducting or vascular system, they can cause permanent wilting and death. Wilt symptoms may resemble those of blights.
Wind damage: Don’t over prune. Remember that heavy pruning is weakening and detrimental to tree health. Pruning is done for your benefit in most cases, not the tree’s benefit. Research does exist now showing that proper pruning will help prevent trunk damage in severe wind events.
Wood rot: These rots are usually the result of physical injury and normally don’t kill healthy trees. Treat by removing decaying dead wood and spray with hydrogen peroxide. Don’t cut back into healthy tissue. That only spreads the decay. Don’t paint the area - leave it exposed to air to speed healing.
Xylella: Also called xylem limited disease, it plugs the vascular system of elms, oaks, sycamore, pecans and other trees. It looks like heat stress damage and can be easily diagnosed by lab tests. Use the Sick Tree Treatment.
DISEASE CONTROL IN THE GARDEN
Use cornmeal for root or soil borne fungus problems at 10-20 pounds per 1,000 square feet. Cornmeal works as a disease fighter in the soil by providing and stimulating existing beneficial microorganisms that feed on pathogens such as rhizoctonia
, better known as brown patch in St. Augustine. Cornmeal at about two pounds per one hundred square feet also works on seedlings to prevent damping off, also on any other soil borne fungal diseases on both food and ornamental crops. One application may be all that is needed, but multiple applications are okay if necessary because cornmeal serves as a mild organic fertilizer and soil builder. The cornmeal needs moisture to activate. Rain won’t hurt cornmeal’s efficacy because, like all organic products, it is not water soluble.ALGAE CONTROL
For floating paint-like and filamentous algae in water, use cornmeal at 5 pounds per 1,000 square feet or 150-200 pounds per surface acre. The cellulose in the cornmeal helps to tie up the excess phosphorous in water, balances the water chemistry and thus kills off the algae. The organic carbon in the cornmeal enables the beneficial bacteria in the water to flourish at the expense of the algae. Then the decomposing algae provide a source of carbon for the bacteria. One or two treatments is usually enough to control the algae for several months.
Caution: any fast algae kill from any product can cause an oxygen depravation and result in fish kill!
Some of this information came from the following publications: “Cornmeal – It’s Not Just Hog Feed Anymore,” The Peanut Farmer, May 1996, and Aquaculture Engineering (1990) 175-186. Neither is in print any more.
P.S. Cornmeal only works in an organic program. When toxic chemical products are used, the effect of the cornmeal will be lost.
CORN GLUTEN MEAL – It does not have the same disease fighting qualities. It is the natural “weed and feed” fertilizer. See separate entry for details.
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