Peanut Disease Guide

Diagnosing the Cause of Disease

For disease diagnosis, it is necessary to know the normal appearance of the peanut plant at different times of the year or after certain kinds of weather. If the plant shows an abnormal condition, checking the symptoms according to the following list will help in identifying the cause.

Symptoms of disease:

• Determine what plant parts are affected. Examine roots, stems, leaves, pods, etc.
• Check for internal as well as external damage in roots, stems, and pods.
• Note color, condition and limits of area(s) affected.
• Include several plants in your survey and collect what appear to be various stages of disease development. Try to determine which part of the plant was first affected.

Signs of disease causal agent:

• Examine affected tissues and adjacent areas for mold, fungal fruiting structures, fungal survival structures, etc.
• Examine plant parts for insects and mites.

Distribution and location of diseased plants in field: The pattern of occurrence may indicate cause.

Previous weather conditions: Heavy rains or drought, lightning, hail, cold temperatures, etc.

Cultural practices: land preparation methods, too close or too deep cultivation, dirting vines during cultivation, etc.

Chemical treatments: time, rate, and method of application of fertilizers, herbicides, fungicides, insecticides, tank mixes of chemicals, surfactants, etc.

Soil conditions: fertility, pH, soil type, drainage, etc.

Animal activity: deer, raccoons, etc.

Once a complete picture of the disorder has been developed, this guide can be used to identify most of the common peanut diseases that occur in North Carolina and Virginia. To simplify the process of matching pictures and descriptions of diseases to field problems, the diseases have been separated into various categories in the next section. When two or more diseases occur on one plant at the same time, the matching procedure may be difficult. If the symptoms and signs of a disease do not match any description given, plant samples should be submitted to a plant disease clinic for examination. County agents in North Carolina and Virginia are equipped to collect and prepare specimens for analysis.