Diseases

Use the Search and Filter options to help select only the crops, types of disease, and timing of disease you are interested in from the list below. Only articles meeting your chosen criteria will be shown. These articles contain information and images for identification and basic management of crop diseases.

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Alfalfa Mosaic of Soybean

Symptoms caused by Alfalfa mosaic virus (AMV) are patterns of bright yellow and dark green leaf tissue. Newly emerged leaves may be small with bright yellow spots and brown discoloration and plants may be stunted. Alfalfa mosaic is transmitted by more than 15 aphid species, including the soybean aphid. Alternate hosts of AMV include alfalfa, other legumes, and solanaceous... Read More

Anthracnose Leaf Blight of Corn

Anthracnose leaf blight seldom causes yield loss. Early in the season, lower leaves usually show symptoms first. Later, symptoms can occasionally be found on upper leaves. Leaf lesions are oval or spindle shaped, tan or brown with dark brown or purple margins, up to 1 inch long and ½ inch wide. As... Read More

Anthracnose Stalk Rot of Corn

Anthracnose is likely the most prevalent stalk rot in the eastern United States. Affected plants have shredded pith and die prematurely. Anthracnose also causes a distinctive blackening of the stalk rind. Initially, these areas are narrow, water-soaked lesions, but they turn very dark and shiny and can join together to form large black blotches or streaks over the gro... Read More

Anthracnose Stem Blight of Soybean

Anthracnose stem blight is generally a late season disease prevalent on maturing soybeans. Irregularly shaped red to dark brown blotches on stems and petioles can appear during early reproductive stages. Petiole infection can result in a shepherd's crook (curling or "hooking" of plant tissue). Near matur... Read More

Aspergillus Ear Rot of Corn

Aspergillus ear rot is one of the most important diseases of corn. Typically, this disease is more common in the southern United States than in other areas. Aspergillus ear rot appears as an olive-green mold on the kernels that may begin at the tip of the ear or... Read More

Aster Yellows of Wheat

Aster yellows is caused by a phytoplasma spread by leafhoppers during feeding. Leafhopper feeding can cause white flecking or stippling on leaves. When the plant is infected, leaves become yellowish and progressively turn red-brown or purple, usually starting at the tips. Discoloration typically occurs as streaks. Plants may be stunted and... Read More

Bacterial Blight of Soybean

Bacterial blight is usually one of the first foliar diseases to occur on soybean. Bacterial blight seldom causes serious yield loss. Symptoms usually begin in the upper canopy because young leaves are most susceptible. Small, angular, reddish-brown lesions are surrounded by a yellow halo. As the disease progresses, l... Read More

Bacterial Leaf Blight of Wheat

Bacterial leaf blight is not of major economic importance in wheat. After prolonged periods of high humidity, water-soaked spots develop on flag leaves and below on infected plants. Affected areas can range from small flecks to large blotches on leaves. Once humidity decreases, spots will turn gray/green, become tan and... Read More

Bacterial Leaf Streak of Corn

Bacterial leaf streak has been observed on field corn, seed corn, popcorn, and sweet corn. Symptoms are tan, brown, or orange lesions that occur between the veins of the corn leaves. Lesions are long, narrow, and less than 1 inch to several inches long. Lesions also can occur close to the leaf midrib or acro... Read More

Bacterial Pustule of Soybean

Bacterial pustule occurs mid- to late season when temperatures are warmer. Lesions are found on outer leaves in the mid- to upper canopy. Lesions start as small, pale green specks with elevated centers and develop into large, irregularly shaped infected areas. A greenish-yellow halo surrounds each lesion. A... Read More

Bacterial Stalk Rot of Corn

Bacterial stalk rot can occur any time during the season, particularly if conditions are very wet. It causes decay of the first internode above the soil. The rind and the pith become soft, brown, and water-soaked. Affected plants have a foul odor. The stalk typically twists and falls over, but the plant may remain green for several we... Read More

Bacterial Streak and Black Chaff of Wheat

Bacterial streak appears first as small water-soaked lesions that rapidly develop into long, thin, tan-brown, water-soaked lesions, confined between the leaf veins. Lesions may appear translucent when backlit, especially when leaves are wet. Unless leaves remain wet or there is high humidity, the water-soaked... Read More

Barley Yellow Dwarf of Wheat

Barley yellow dwarf is widespread throughout the U.S. and Canada and can affect a variety of cereal crops. It is caused by multiple viruses. Symptoms of barley yellow dwarf (BYD) include stunting; yellow, red, and/or purple discoloration of leaves (particularly the flag leaf); and tip burn. Leaves can be distorted and roots underdeveloped. S... Read More

Bean Pod Mottle of Soybean

Foliar symptoms caused by Bean pod mottle virus (BPMV) include distorted and wrinkled leaves that have a mottled color pattern. Symptoms appear more severe on young leaves, sometimes with a raised, blistered, or distorted appearance. Symptoms are most obvious at cooler temperatures and often disappear when it is hot. Infection by BPMV decreases pod formation, reduces see... Read More

Black Head Molds of Wheat

The various fungi that cause black head mold primarily live on dead plant tissue and are typically only a problem when wheat dies prematurely. Also known as sooty head molds, black head molds appear dirty and come in a variety of colors (black, white, pink, or green) depending on the causal fungi. Growing on dead leaves, stems, and heads, these fungi are of most concern w... Read More

Black Point of Wheat

Black point does not typically cause yield loss, but reduces grain quality. It is caused by several pathogens. As the name implies, kernels that develop black point will have a black, smudge-like discoloration. This typically occurs at the proximal or embryo end of the kernel. Symptoms can be obs... Read More

Brown Stem Rot of Soybean

Brown stem rot (BSR) is caused by the fungus Cadophora gregata. Characteristic foliar symptoms of BSR include chlorosis and necrosis between leaf veins, followed by leaf curling and leaf death. Leaf symptoms vary depending on soybean variety, fungal strain, and environmental conditions. In some instances, no foliar symptoms occur. Foliar symptoms can be similar to those o... Read More

Cephalosporium Stripe of Wheat

The fungus that causes Cephalosporium stripe infects wheat below ground in fall and winter. This results in stunting and dead standing stems called white heads. Early symptoms include a chlorotic mottle appearing as the plant breaks dormancy in spring. As the plant matures, one to three distinct, yellow stripes appear near leaf veins. Stripe... Read More

Cercospora Leaf Blight of Soybean

Cercospora leaf blight is frequently seen but rarely causes yield loss. Foliar symptoms usually are seen at the beginning of seed set and occur in the uppermost canopy on leaves exposed to the sun. Leaves are typically only discolored on the upper surface with symptoms ranging from light purple, pinpoint sp... Read More

Cereal Cyst Nematode of Wheat

Cereal cyst nematodes are some of the most economically damaging nematodes to wheat production. Most small grain cereals and some grasses are hosts. Common symptoms on wheat include stunting and poor plant growth appearing in patches across a field, reduced number of tillers, and plants appearing more yellow than surrounding healthier plants. Cl... Read More