Diagnostic Guide to Common Home Orchard Diseases B 1336

Dull black sooty blotches and individual“fly specks”

Chemical Control: Captan; Thiophanate-methyl; sulfur.

Comments: This is a very important summer disease, especially when conditions are warm and moist! Pustules of spores are formed in concentric rings on the fruit. A sunken, sour-smelling rot results. Good sanitation is vital to management; remove diseased fruit, which will hang on the tree, and any cankers formed in the woody tissues.

Chemical Control: Captan; Thiophanate-methyl.

Comments: A major disease on both apples and pears in the Southeast. On leaves, a symptom known as “frog-eye” leaf spot occurs. Infection occurs early in the season at silver tip; rots become evident in the late season at the calyx or bottom end. Rot will be seen as concentric rings, and it will be dark –eventually turning black. Good sanitation is important, so prune out dead wood and remove fallen debris.

Chemical Control: Thiophanate-methyl; Myclobutanil; Captan; Lime sulfur (use in the dormant period); sulfur.

Comments: Not a consistent problem in the Southeast. Cool, wet weather favors infection. Fruit and foliage must be protected season-long for adequate management if the disease does occur. Plant resistant varieties (ask local nurseries for availability). Sanitation is important. Rake and destroy fallen leaves to reduce the amount of disease that will carry over to the next year.

Chemical Control: Captan; Thiophanate-methyl; Lime sulfur.

Comments: This is a serious and common late-season problem in apples and pears. This fruit rot is a rapidly developing soft rot (unlike bitter rot and black rot, which form harder rots). Sanitation is important (remove mummified apples – dried dead apples hanging in the tree) as well as proper pruning (prune out deadwood).

Chemical Control: Difficult and expensive to control. Streptomycin sulfate is the most effective product (2-3 sprays applied during bloom). Avoid spraying too often, as resistance may develop. Apply copper sulfate or copper hydroxide as a late-dormant application ahead of bloom.

Comments: This is a bacterial disease, and it is very destructive on both apples and pears. Succulent tissues are most vulnerable to infection, so avoid excessive nitrogen fertilization. Avoid pruning during and after the blossom period (corresponds to insect feeding). Promptly prune out any blighted tissue; remove infected plant parts through cutting 8-12 inches below diseased tissue; between cuts, disinfect pruning tools using a 10 percent bleach solution.

Chemical Control: Myclobutanil; Lime sulfur.

Comments: Can cause extensive defoliation of the apple trees. Plant resistant varieties! If possible, remove galls from nearby cedar trees (breaks the fungal life cycle, as it needs both hosts to reproduce). Only use Myclobutanil when cedar-apple rust is an annual problem.

Pathogen: Botrytis cinerea

Conidiophore and conidia

Chemical Control: Captan (apply during bloom and early fruit development)

Comments: Disease that affects green twigs, flowers, leaves, and fruit. Outbreaks often occur after freeze injury to flowers in the spring, especially when followed by cool, wet weather. Fruit rot does not generally occur until after fruit is harvested. Sanitation is important; remove infected fruit/mummies and maintain a good mulch layer.

Chemical Control: Captan (apply to early developing foliage and during bloom)

Comments: Sanitation is important; rake and remove mummies (dead fruit on the ground); prune annually.

Chemical Control: Captan

Comments: Rake and remove infected leaf debris. Summer pruning or topping will help remove older, infected tissues. Increased spacing will improve air circulation, resulting in dryer foliage.

Chemical Control: Captan (apply during bloom and early fruit development)

Comments: Twig blight – remove infected twigs in winter; choose resistant cultivars when available. Fruit rot – harvest fruit before it becomes overripe.

Chemical Control: Captan; Bordeaux mixture; copper; lime sulfur (late dormant application).

Comments: Disease affects canes, leaves, fruit and stems of berry clusters. Symptoms on canes are ash grey lesions with raised purple to brown borders. Sanitation is very important. After harvest, cut old floricanes to the ground, and remove and destroy them.

Chemical Control: NONE

Comments: Attacks all brambles except red raspberries. Establishes a systemic infection and, once infected, no cure is available. Symptoms include stunting and limited fruit production. Symptoms occur shortly after leafing out. When disease is first detected, dig up and discard/destroy any infected plants to reduce spread.

Chemical Control: NONE

Comments: Most damaging to blackberries. In the spring, infected buds from the previous year produce numerous leafy sprouts – “rosettes” or “witches brooms.” Berries do not develop from infected blossoms. Remove/destroy nearby wild brambles – they serve as reservoirs; remove infected rosettes and blossom clusters before they open.

Chemical Control: Copper sprays (high rates for late dormant and fall applications; lower rates when succulent tissue is present).

Comments: Remove old floricanes after harvest; increase air circulation in canopy; avoid stressing plants; improve drainage.

Chemical Control: Bordeaux mixture; Lime sulfur (late dormant application); Captan; Copper sprays.

Comments: Remove old floricanes after harvest; increase air circulation in canopy; avoid stressing plants; improve drainage. Sanitation is very important; remove dead and infected canes during and after harvest. Avoid stressing plants. During the summer, prune by pinching off tender primocanes when they reach 3-4 feet high – remove 1-4 inches of primocane tip; avoid making severe pruning cuts on older tissues. Do not prune ahead of predicted rains; prune when 3-4 days of dry conditions are predicted.

Chemical Control: Captan; Mancozeb; Myclobutanil; copper.

Comments: Annual pruning in February; removing infected berries both on ground and on plant. After pruning, only the permanent trunk, 1 year old fruiting canes and short spurs should remain. Sanitation is important – remove mummified fruit! Disease spread is favored by moist, wet weather.

Pathogen: Uncinula necator

Conidia


Cleistothecia

Chemical Control: Myclobutanil; copper; lime sulfur (late dormant application); sulfur (may cause damage on certain varieties and when temperatures are above 90 degrees F).

Comments: Annual pruning in February will help to remove inoculum; remove infected berries both on the ground and on the plant. After pruning, only the permanent trunk, 1 year old fruiting canes and short spurs should remain.

Chemical Control: Captan; Mancozeb; copper hydroxide.

Comments: Annual pruning in February; removing infected berries both on ground and on plant. After pruning, only the permanent trunk, 1 year old fruiting canes and short spurs should remain. Sanitation!

Chemical Control: NONE (do not plant vinifera wine or table grapes at elevations below 1,300 feet elevations). Muscadines are generally resistant, and some other native grapes have limited resistance.

Comments: Vectored by various sharpshooters (such as glassy-winged sharpshooter). New growth is stunted; yellow, deformed (resembles zinc deficiency). Choose more resistant cultivars; native grapes are generally more resistant. Do not propagate from symptomatic vines.

Chemical Control: Lime sulfur (late dormant application; Mancozeb; Captan

Comments: A late dormant application of lime sulfur is very beneficial for control of this disease. Mancozeb should be applied weekly from the time that green tissue is observed until the Preharvest Interval is reached (66 days).

Chemical Control: Captan

Comments: Apply Captan at bloom, bunch closing, veraison (ripening point of grapes), and preharvest.

Chemical Control: NONE

Comments: Prune tops to balance weakened roots; attentive watering and fertilization may prolong the life of tree. Nematode infested plants usually die sooner or later regardless of treatment. Plant new trees away from this site! Nem-A-Cide – organic amendment containing chitin that promotes growth of beneficials that feed on nematodes (unfortunately, it will reduce both parasitic and saprophytic nematode populations).

Chemical Control: Copper sprays – Bordeaux mixture

Comments: Attacks the leaves, usually in late summer. Infected leaves turn yellow-brown and drop. Underside of leaves – reddish brown spots/pustules. Sanitation is important. Not fatal but will reduce tree vigor and size and quality of fruit.

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Chemical Control: NONE

Comments: Not serious; Increase air circulation and avoid excess irrigation; Sanitation.

Chemical Control: Captan; Myclobutanil.

Comments: Remove fallen debris and mummified fruit; during the winter, remove all old fruit stems to eliminate overwintering sites for fungi. When spraying Captan or Myclobutanil as a COVER SPRAY, Captan may cause mild phytotoxicity to fruit when conditions are wet and cool.

Chemical Control: Captan; Immunox.

Comments: Remove fallen debris and mummified fruit; during the winter, remove all old fruit stems to eliminate overwintering sites for fungi.

Chemical Control: Captan

Comments: Remove fallen debris and mummified fruit. During the winter, remove all old fruit stems to eliminate overwintering sites for fungi.

Chemical Control: Captan

Comments: Remove fallen debris and mummified fruit. During the winter, remove all old fruit stems to eliminate overwintering sites for fungi.

Chemical Control: Captan

Comments: This pathogen can cause leaf spotting that can lead to rapid defoliation. Remove fallen debris and mummified fruit; during the winter, remove all old fruit stems to eliminate overwintering sites for fungi. Pruning is equally as important.

Chemical Control: Wettable sulfur

Comments: Attacks young berries – causes a russetted look. Berry drop and reduced size are results from infections. Improve air circulation and use proper sanitation practices.

Chemical Control: Chlorothalonil (do not use after shuck split); Captan; Sulfur; Lime sulfur (dormant application); Thiophanate-methyl; Myclobutanil.

Comments: Major disease of these fruits in Georgia. Disease infects blooms, stems, and fruit. Sanitation is the key! Remove and/or prune infected tissues and areas on trees. Remove and discard mummies. During wet summers, green fruit injured by insects and/or environment will develop brown rot. Remove any fruit that has fungal growth.

Chemical Control: Chlorothalonil; Captan; Sulfur; Thiophanate-methyl.

Comments: Disease infects both fruit and twigs of current years’ growth. Small, oval to round, gray to black spots on fruit. Fruit may crack because of coalescing of scabs. Pruning trees to promote penetration of sunlight and air circulation is necessary.

Chemical Control: No practical chemical control. Where gummosis is present, use of Captan for scab control is the preferred treatment.

Comments: Disease causes sunken lesions with oozing amber-colored resin or gum on trunks, limbs, and twigs. Small twigs may be killed as disease progresses. Prune out and remove dead wood; irrigation during periods of dry weather helps to reduce plant stress and may minimize disease.

Chemical Control: Chlorothalonil; copper hydroxide; liquid lime sulfur; Captan; Thiophanate-methyl; Bordeaux mixture.

Comments: Disease occurs in cooler areas of the state – primarily upper Piedmont and mountains. Apply this to nectarines and peaches only. Sanitation. For successful control, the fungicides must be applied before bud swell.

Chemical Control: Captan; Thiophanate-methyl

Comments: Leaf spot – upper leaf surface first as tiny, round, purple spot 1/8 inch in diameter; spot becomes gray with purple border. Loss of foliage is common.

Chemical Control: Captan

Comments: Anthracnose is a major disease of strawberries when conditions are wet. Anthracnose infects stolons, petioles, crowns, fruit, and leaves. Small dark lesions form on stolons and petioles in summer. Crowns can be infected, resulting in plant death. Remove infected plants or fruit and destroy or bury. Always purchase disease-free plants!

Chemical Control: Copper fungicides

Comments:

Chemical Control: Captan

Comments: Botrytis is often present in strawberry leaves, etc., even if symptoms are not present. These quiescent infections give rise to production of spores under wet conditions during bloom. Blossoms need to be protected season-long to reduce fruit infection and to prevent epidemic development.

Chemical Control: Soil fumigation

Comments: Root rot is favored by cool weather, but crown rot is worse in hot weather. Plants start collapsing as fruiting starts. The bottom of the leaves are purple and leaves curl up as the original crown is killed. Buy disease-free plants.

Chemical Control: Captan; Myclobutanil – most effective.

Comments: Disease starts in the fall or spring after planting. It spreads rapidly and can destroy most of the foliage. Remains active as long as there is green foliage. Symptoms occur as circular red to purple spots on leaflets; the spots enlarge and develop gray centers, making large V-shaped lesions. Fruit and calyx infection also occurs. Sanitation (remove infected foliage). Fruit infection is prevented by controlling foliar infection.