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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Charcoal Rot of Corn

Charcoal rot causes the pith and rind of affected plants to appear gray because of the numerous tiny black microsclerotia that develop. The pith tissue is disintegrated, leaving the vascular tissue with a granular, gray appearance. The fungus overwinters as sclerotia in crop residue and soil and infects plants through roots. It may occur... Read More

Charcoal Rot of Soybean

Initial symptoms of charcoal rot are patches of stunted or wilted plants. Leaves remain attached after plant death. The fungus produces numerous tiny, black fungal structures called microsclerotia that are scattered throughout the pith and on the surface of taproots and lower stems. These microsclerotia give the lower stem and... Read More

Cladosporium Ear Rot of Corn

Cladosporium ear rot appears as dark green or black powdery mold and black streaks on kernels. It usually forms first where the kernels attach to the cob. Dark green, fuzzy mold also may be observed on and between kernels. This ear rot is often associated with hail, frost, or insect injury and is favored by wet weather... Read More

Common Bunt of Wheat

Common bunt is also known as covered smut or stinking smut, and reduces yield and grain quality. Though historically important, current management practices typically prevent major losses. Evidence of common bunt is rarely present before ripening, but some stunting may occur. As heads ripen (FGS 10.5.3), spikelets may develop a... Read More

Common Root and Foot Rot of Wheat

Common root and foot rot occurs in all wheat production areas of the U.S. and Canada. The causal pathogen has a wide host range and also causes a foliar disease known as spot blotch. Symptoms include dark, chocolate brown to black lesions on the coleoptile, stem, roots, and/or subcrown internode (the area above the seed to the soil line). Heavily... Read More

Common Rust of Corn

Common rust of corn occurs every growing season. It is seldom a concern in hybrid corn. Rust pustules usually first appear in late June. Early symptoms of common rust are chlorotic flecks on the leaf surface. These soon develop into powdery, brick-red pustules as the spores break through the leaf surface. Pustules are oval or elongated, about... Read More

Common Smut of Corn

Common smut galls can form on stalks, leaves, ears, and tassels; actively growing tissue is especially susceptible. Galls are swollen, distorted growths that are at first covered with a glistening white membrane. The membrane eventually ruptures to reveal a mass of dark brown or black powdery spores. Common smut galls on co... Read More

Crazy Top of Corn

Crazy top-affected plants are distorted and/or stunted. The leaves below the tassel may proliferate, resulting in a very bushy appearance of the top of the plant, which lends this disease its name. Internodes may be short or long; there may be a proliferation of ear shoots, leaves that are narrow... Read More

Diagnosing Interveinal Chlorosis in Soybeans — it’s not just SDS

Interveinal chlorosis is a common symptom in soybean production systems. More often than not, it is assumed that interveinal chlorosis indicates the presence of soybean sudden death syndrome (SDS). However, there are several other soybean diseases and disorders that can cause interveinal chlorosis besides SDS. Read More

Diplodia Ear Rot of Corn

Diplodia ear rot has become a common (and troublesome) disease on corn. The causal fungi produce mycotoxins in South America and Africa, but no mycotoxins have been associated with Diplodia ear rot in the United States and Canada. This ear rot is recognized as a white mold beginning at the base of the ear that... Read More

Diplodia Stalk Rot of Corn

Plants affected by Diplodia stalk rot have shredded pith and die prematurely. Numerous black dots, about the size of a pinhead or smaller, can be observed in the lower internodes of the stalk. Under very wet conditions, a white mold may develop on the stalk surface. Infections occur through the crown, roots... Read More

Don’t Get Lost in the Weeds: Additional Factors to Consider when Selecting Xtend Soybean Varieties

Selecting the most appropriate soybean varieties each year is critical for farming operations to remain profitable. Although your top factor is often high yield potential, there are other characteristics you should consider. These other characteristics include disease-, insect-, and herbicide-resistance traits; maturity date; and target market. If you focus on only one of these aspects during the... Read More

Downy Mildew of Soybean

Downy mildew of soybean is common but seldom causes serious yield loss. Lesions occur on upper leaf surfaces as irregularly shaped, pale green to light yellow spots that enlarge into pale to bright yellow spots. Older lesions turn brown with yellow-green margins. Young leaves are more susceptible, so disease is often found in the up... Read More

Dwarf Bunt of Wheat

Dwarf bunt is also known as dwarf smut. It typically occurs with long periods of snow cover, and only impacts winter wheat. Symptoms prior to heading (FGS 10.5) include yellow leaf flecking at late seedling stage, stunting, and excessive tillering. Once the head emerges, the fungus transforms kernels in... Read More

Ergot of Wheat

Ergot has played an important role in history as it impacts human and animal health. Though less problematic today, the disease can still cause issues, particularly in male-sterile wheat lines. During early infection, some kernels go through a "honeydew" stage where infected ovaries swell and emit a yellow, slime-like fluid. This fluid attracts insects and is full of spores. Ova... Read More

Ergot: Six things to be mindful of with ergot in small grains and grasses

The pathogen that causes ergot generates toxic alkaloids that potentially could create problems with livestock feeding, and when trying to market a small grain crop. This article reviews some of the commonly asked questions pertaining to ergot. Read More

Eyespot of Corn

The initial symptoms of eyespot are small, water-soaked or chlorotic circular spots. The tissue at the center of the spot later dies and turns tan-colored with a brown ring at the margin. The spot is surrounded by a yellow "halo" that can be seen clearly when the leaf is lighted from behind. Spots may join together into large... Read More

Eyespot of Wheat

Eyespot, also called strawbreaker foot rot, can cause yield losses up to 50%. Winter wheat is affected more than spring wheat because environmental conditions are more conducive. Symptoms appear on stems directly above or below the soil surface. Stems develop a light tan to yellow-brown, eye-shaped l... Read More

Foliar Fungicide Decisions for Late-Planted Crops

Many farmers are now asking if fungicide application(s) will provide an adequate return on investment. The answer to this question will be crop, region, state and field specific. However, there are guidelines that can aid in determining if a fungicide application will be a sound investment in 2019. Read More

Four ways to get ahead of ear rots and mycotoxins

Ear rots and moldy grain have been observed in harvested grain, corn for silage, and corn that has yet to be harvested across the U.S. and Canada. Ear rots are some of the most important diseases to look for because they decrease yield and grain quality and several produce mycotoxins. Read More