Diseases can negatively affect stand establishment, limit yields and hasten stand decline in established forage crops. Effects of disease on individual plants vary widely. Some diseases are lethal while others cause only stunting or leaf loss, reducing yields and forage nutritive value. Sound crop production practices will lower the chances for serious losses to forage productivity due to disease because they help maintain a vigorous stand. Any practice that improves plant vigor is likely to reduce the chance of plants becoming diseased.
More importantly, good growing conditions will allow surrounding uninfected plants to achieve their maximum potential and compensate for the loss in stand or productivity due to diseased plants. Important considerations for managing diseases include matching forage species to soils where they are adapted, practicing crop rotation (especially important for forage legumes), maintaining adequate soil pH and fertility, using proper harvest schedules that don’t unduly stress plants, and selecting disease resistant varieties.
It is very important to avoid compaction damage in forages as much as possible. Traffic damage allows disease organisms to invade the plants, resulting in stand and yield losses. Forage varieties with some tolerance to traffic have been developed in recent years, but every effort should be made to control and reduce compaction damage as much as possible. Especially important is avoiding traffic on wet soils. In addition, minimize traffic on the field, designate traffic lanes to reduce the field area subjected to compaction, and use lighter equipment whenever feasible.
Disease organisms are often spread from infested to healthy fields by transport of harvesting equipment, hay, or manure on the farm. Care should be taken to harvest fields that are obviously diseased after harvesting healthy fields, and to clean equipment thoroughly prior to entering healthy fields.
Few fungicide options are available for most forage species, but more options are becoming available especially for foliar and stem diseases in alfalfa. Fungicides can reduce disease infestations, and increase yield and forage quality under conditions that are conducive to disease development, such as humid or wet conditions in spring and early summer. Check with Extension plant pathologists and forage specialists for available fungicide options that might be of benefit.