Black spot disease

AK-Toxin. The causal agent of black spot disease of Japanese pear, Alternarla kikuchlana. produces two host-selective toxins AK-toxIn... 

The toxins of many members of the fungal genus Al-ternaria produce phytotoxins of these, many [such as AM-toxin I (18)] are peptides. The fungal pathogen Alternaria mali on apples produce necrotic lesions on the leaves, shoots, and fruits of susceptible cultivars (Natori et al, 1981). Alternaria kikuchiana, which causes black spot disease on the Japanese pear (Pyrus serotina) produces phytotoxins which are based on A -acetylphenylalanine and a Cio fatty acid (Harbome, 1986). 

Hill G K 1982 Studies of the enzymic activity of Phomopsis viticola Sace, the cause of black spot disease. Wein-Wiss 37 333-339... 

Resistant roses Roses are often thought to be terribly prone to diseases, such as black spot and powdery mildew. The trick is not to grow roses all together In a "rose bed," where disease can spread choose resistant roses (see also p.l69) such as Buff Beauty, above, and mingle them in with other garden plants. 

Fruh with raised Mack spots or hrown sMidges on the surface. Causes Ry speck scoty blotch. Black spots are fly speck brown CTudges are sooty blotch. Both of these blem-sfaes are fungal diseases and both can be con-nv>lled with sulfur sprays. But since both are superficial, you can just rub them off the fruit. 

Heads with black spots on surfoce. Cause Downy mildew. Control this fungal disease by spraying plants with a baking-soda-and-soap spray (1 teaspoon baking soda, 1 teaspoon liquid dish soap, 1 quart water) or copper at the first sign of disease. Repeat weekly if weather is wet. Prevent problems by planting Cloud Nine , which is somewhat tolerant of downy mildew. 

Brown to gray spots on leaves and stems, and dark, gummy stems are caused by gummy stem blight. Infected leaves turn yellow and die. Disease begins as spots on stems, which become streaks stems then turn dark and gummy. When it attacks fruit, the disease is called black rot Infected fruit has round, black spots and the fruit flesh collapses. For an illustration of this disease, see page 148. 

Potatoes with brown or black spots or patches on skin. Cause Scurf. Peel off spots before using tubers. Soak seed pieces in compost tea before planting to help suppress fungal diseases. Do not plant spotted tubers The resulting plants will produce only small tubers, many of which will rot. 

Leaves and stems with black spots. Cause Black spot. While most of the species and shrub roses are little troubled by diseases, such is not the case with hybrid teas, floribundas, and grandifloras. The most serious disease is black spot, caused by a fungus. Black spots appear on the leaves, surrounded by yellow patches. The disease, prevalent throughout the country, is most likely to occur under warm, moist conditions. Left unchecked, the plant may become entirely defoliated. For an illustration of the damage, see the opposite page. 

Both the adults and the A", black-spotted, yellow larvae feed on the leaves, eating everything but the veins. For an illustration of the damage, see below. Trees are often defoliated and so weakened that they are susceptible to other insect and disease problems. Control beetles by spraying leaves with BTSD, particularly in June. 

A few sprays that you can make yourself arc effective against some diseases. Baking soda sprays can prevent damage from black spot on roses. And some gardeners use garlic sprays to treat a range of disease problems. 

Symptoms This disease appears as circular black spots on infected leaves. The spots usually have fringed or indistinct margins and are often surrounded by a ring of yellow tissue. Severely infected leaves may fall early. Black spot fungus can also infect stems, causing purplish or black blisters on young canes. 

Prevention and Control Black spot fungus thrives in moist conditions. Avoid wetting plant leaves when watering. Prune plants to increase air circulation. Plant resistant species or cultivars. If you expect black spot to be a problem based on past infections, spray plants weekly with sulfur or fungicidal soap. Once symptoms appear, black spot is very difficult to control. Remove and destroy infected leaves and canes. A 0.5 percent solution of baking soda (1 teaspoon baking soda in 1 quart water) may help to control the disease. Spray infected plants thoroughly. 

Protection Offered Research has shown that a 0.5 percent solution of baking soda will help prei ent roses from being damaged by black spot. It may also control other fungal diseases, such as powdery mildew. 

Protection Offered Bordeaux mix acts as a fungicide with insecticidal and insect repellent properties. Use it to control common plant diseases like anthracnose, bacterial leaf spots and wilts, black spot, fire blight, peach leaf curl, powdery mildew, and rust. 

Protection Offered Sulfur can be purchased alone or mixed with other insecticides and inorganic fungicides to control a wide variety of garden pests. Use sulfur as an insecticide to control insects and mites on fruit trees and citrus. You can also use sulfur as a protectant fungicide. It is effective against apple scab, brown rot of stone fruits, powdery mildews, rose black spot, rusts, and other plant diseases on many crops, including grapes, potatoes strawberries, and tomatoes. 

The next thing he noticed was "black spots" in his vision, and his eyeballs hurt. Next, he became wobbly. "I couldn t walk a straight line." As the disease worsened, his entire left side became paralyzed. 

Cercospora species are responsible for various leaf-spot diseases. C. rosicola produces small brown lesions surrounded by a red-violet ring on rose leaves. The common black spot is caused by a different fungus, Diplocarpon rosae. A severe Cercospora infection can cause loss of the leaf. The phytotoxic fungus... 

Mintzer RA, Gore RM, Vogelzang RL, Holz S (1981) Rounded atelectasis and its association with asbestos-induced pleural disease. Radiology 139 567-570 Mitchev K, Dumortier P, De Vuyst P (2002) Black spots and hyaline pleural plaques on the parietal pleura of 150 urban necropsy cases. Am J Surg Pathol 26 1198-1206 Monchaux G, Bignon J, Hirsch A, Sebastien P (1982) Translocation of mineral fibers through the respiratory system after injection into the pleural cavity of rats. Ann Occup Hyg 26 309-318... 

For control of certain fungal diseases of ornamentals, roses (Powdery Mildew and Black Spot), fruits, vegetables and lawn grasses. 

Leaves with dark streaks black petioles and veins on undersides of leaves. Cause Anthracnose. Spots exude salmon-colored ooze in cool, moist weather. See page 34 for an illustration of this fungal disease. This disease thrives in wet, humid conditions. Spray plants with sulfur to control. Prevent problems by planting tolerant cultivars such as Espada , Marbel, Morgane , and Rocdor . 

Leaves with numerous small holes. Causes Rea beetles billbugs. Leaves may develop bleached-out spots or stripes. Rea beetles are tiny black insects that hop when disturbed. They can transmit disease and are likely to be more numerous after mild winters. Cover plants with row cover as soon as they come up to exclude beetles. Remove row cover when tassels form. Treat plants with a commercial neem or pyrethrin spray to control severe infestations. 

Fruit with spots flesh may rot. Causes Angular leaf spot Alternaria blight black rot scab other fungal or bacterial diseases. See "Leaves with spots, blotches, or brown areas on page 85 for controls. 

Leaves yellow plant dies early. Cause Dry rot. Other symptoms of this fungal disease include dry, brown or black, corky spots on corms and husk coverings. You may see black fungal growth spots on decayed leaf bases. Plants may turn yellow and die prematurely. Choose corms carefully to avoid infected specimens. Destroy infected plants. Do not replant in same area. Replant only in well-drained soil. 

Fruit with light hrown spots that enlarge and darken. Cause Black rot. Common east of the Rockies, especially in hot, humid weather, black rot causes fruit to shrivel into hard, black shriveled berries (known as mummies) that remain on the cluster. Overwintering mummies and infected canes or shoots carry the disease from one growing season to the next. For control, remove and destroy all mummies. For persistent infection, apply copper sprays. Cultivars moderately resistant to black rot include Beta , Campbell s Early , Cascade , Chancellor , De Chaunac , Delaware , Elvira , Fredonia , Hunt , Ives , James , Scuppemong , Sheridan , and Worden . See page 109 for an illustration of this disease. 

Leaves with circular brown spots. Cause Bacterial leaf spot. This bacteria can cause water-soaked spots on lower leaves. These spots turn brownish black and may spread to form large patches of dead tissue. To prevent the spread of this disease, avoid working around wet plants. Remove and destroy affected parts spray bordeaux mix on remaining plants. 

Yellow spots that turn brown are caused by anthracnose. Infected leaves eventually die. This disease causes fruit with circular black cankers. Prevent problems by planting anthracnose-resistant muskmelon cultivars, such as Passport , and resistant watermelon cultivars, such as All Sweet , Crimson Sweet , Dixie Lee , and Sweet Favorite . 

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