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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Frogeye Leaf Spot of Soybean

Frogeye leaf spot of soybean occurs across the United States and in Ontario, Canada. Frogeye leaf spot can cause significant yield loss when widespread within a field. Leaf lesions are small, irregular to circular in shape, and gray with reddish-brown borders. Most commonly occurring on the upper leaf surface, lesions start a... Read More

Fusarium Ear Rot of Corn

Fusarium ear rot is the most common ear disease. Symptoms are a white to pink or salmon-colored, cottony mold that occurs on single or multiple kernels scattered or clustered on the ear. Decay often begins with insect-damaged kernels. Infected kernels are frequently tan or brown or have white streaks. Causal fungi overwinter... Read More

Fusarium Head Blight of Wheat

Fusarium head blight (FHB) is currently the most economically important wheat disease in the U.S. and Canada. This disease is also known as scab or head blight. It reduces yield and produces mycotoxins that impact human and animal health. Infected spikelets are bleached and disease spreads upward and downwar... Read More

Fusarium Root, Crown, and Foot Rot of Wheat

Fusarium root, crown, and foot rot of wheat is widespread and can be found in all wheat production regions of the U.S. and Canada. Seedling blight occurs when Fusarium-infected seed is sown. Infected seedlings tend to be reddish with poor vigor and poor tiller production. Root, crown, and foot rot symptoms include da... Read More

Fusarium Root Rot and Wilt of Soybean

Fusarium is a very common soil fungus, and more than 10 different species are known to cause root rot. However, the economic impact on yield is not well documented. Infected seedlings exhibit poor or slow emergence and are often stunted. Root rot appears as reddish-brown to dark brown discolored roots and poor nodulation. Foliar symptoms of Fusarium wilt includ... Read More

Fusarium Stalk Rot of Corn

Fusarium stalk rot of corn is among the most common stalk rots in the Midwest. Affected plants have shredded pith that may be a whitish-pink to salmon color and die prematurely. Brown streaks may be observed on the lower internodes. Pith shredding indicative of... Read More

Gibberella Ear Rot of Corn

Gibberella ear rot of corn is a consistently important mycotoxigenic fungus in the northern Corn Belt, producing vomitoxin, zearalenone, and other toxins. Gibberella ear rot can be identified most readily by the red or pink color of the mold. It almost always begins at the tip of the ear. Excessive mold may cause silks and husks to adh... Read More

Gibberella Stalk Rot of Corn

Gibberella stalk rot affected plants have shredded pith that is discolored a distinct pink or red and will die prematurely. Gibberella stalk rot causes dark streaks on the lower internodes. In moist conditions, round black specks may form at the lower nodes. These specks can be scratched off the stalk surface easily using a fing... Read More

Goss's Wilt of Corn

Goss's wilt of corn is caused by a bacteria which can infect leaves at any stage of plant growth. Leaf lesions are long, gray-green to black, water-soaked, and have wavy edges. Streaks resembling freckles within the lesions are a distinctive symptom of this disease. Droplets of bacterial exudate eventually ooze from these freckles. As... Read More

Gray Leaf Spot of Corn

Gray leaf spot of corn occurs virtually every growing season. If conditions favor disease development, economic losses can occur. Symptoms first appear on lower leaves about two to three weeks before tasseling. The leaf lesions are long (up to 2 inches), narrow, rectangular, and light tan colored. Later, the lesions can turn gray. They a... Read More

Head Smut of Corn

Head smut of corn forms on the tassels and ears, galls are at first covered with a thin layer of tissue that breaks open to expose the black spore masses and threadlike remains of the vascular bundles. Leaf-like proliferations develop on the tassel and ears. Ears may be aborted and replaced with a proliferation of leafy tissue. Plants als... Read More

Holcus Leaf Spot of Corn

Holcus leaf spot usually does not cause major losses. Leaf spots are initially oval to irregular, dark green, water-soaked at the margins, and may have a light brown border. Later, lesions dry out and turn light tan, usually without a border. The dry lesions have a papery texture. Holcus leaf spo... Read More

How seed-applied nematicides work

Nematicides are an important part of an integrated pest management system to control plant-parasitic nematodes. Over the past 15 years, seed-applied nematicides have increased in popularity, becoming one of the most commonly used nematicide-application methods in row-crop agriculture. Read More

How Tar Spot of Corn Impacted Hybrid Yields During the 2018 Midwest Epidemic

Tar spot of corn is a new disease to the United States that was first observed in 2015 in Indiana and Illinois. Since then, it has also been confirmed in Florida, Iowa, Michigan, Ohio, and Wisconsin. In 2018, a tar spot epidemic occurred in the upper Midwest, which had a significant impact on corn grain and silage yield and quality. Little field screening has been done in the US for corn germplasm... Read More

Leaf Rust of Wheat

Leaf rust, also called brown rust, occurs across the U.S. and Canada and can cause severe yield loss in epidemic years. Leaf rust pustules rupture the leaf epidermis, but lack conspicuous tear marks. These pustules contain orange-brown, rusty colored spores. Later in the season, dark brown to black spores are produced whic... Read More

Loose Smut of Wheat

Loose smut has a wide distribution and can occur anywhere wheat is produced. Mild symptoms may be present prior to heading, including yellowish leaf streaks and stiff, dark green leaves. Affected plants head out early, producing sterile heads with clumped, sooty olive-black spores in place of healthy glumes and kernels. Spores are... Read More

Maize Dwarf Mosaic of Corn

Maize dwarf mosaic is caused by the Maize dwarf mosaic virus. Infected plants have a stippled (small, discolored specks) mottle or mosaic of light and dark green that may develop into narrow streaks on the youngest leaves. There may be a shortening of internodes causing a stunted, bunchy appearance of the plant. As plants mature and temperatures rise, mosaic symptoms oft... Read More

Nematodes that Feed on Corn

Multiple plant-parasitic nematodes feed on corn roots. Although prevalent, they rarely cause economic damage. Symptoms of nematode damage can occur any time during the season and include poor or uneven stands, chlorosis, stunting, and small or poorly filled ears. Often, symptoms occur... Read More

Northern Corn Leaf Blight of Corn

Northern corn leaf blight (NCLB) symptoms usually appear first on the lower leaves. Leaf lesions are long (1 to 6 inches) and elliptical, gray-green at first but then turn pale gray or tan. Under moist conditions, dark gray spores are produced, usually on the lower leaf surface, which give lesions a "dirty" gray ap... Read More

Northern Corn Leaf Spot of Corn

Northern corn leaf spot, also known as Carbonum leaf spot, is occasionally seen in the lower canopy during periods of high humidity and moderate temperatures. There are five known races of this fungus. Races 2 and 3 are the most common in the Midwest. Race 2 causes oblong, somewhat rectangular, brown spots (¼ to ½ by 1... Read More