R - Rust
Scientific Name: Puccinia asparagi, Puccinia sorghi
Type: Fungus
Rust, also known as Common Rust, is a world-wide soil borne disease that affects the growth of asparagus, cantaloupes & melons, corn, and lettuce. It is one of the most destructive disease in growing asparagus in the United States. The disease affects the ferns on asparagus. Lesions develop and turn cream-orange color, then turn a reddish-brown color, then eventually turn a brick red or rust color. During the winter the lesions will turn a black color. Severe infestation stunts or kills young asparagus shoots. The infected plants should be removed to avoid further infestation. When corn is infected the disease affects the upper and lower leaf surfaces, where small specks appear on the leaves, then develops into small tan spots, and distinguished by cinnamon-brown pustules. These pustules blister and turn dark brown to black late in the season. Corn stalks are weakened and stalk rot potential increases. Significant damage to upper leaves results in significant yield losses. Common rust spreads by windblown spores. The disease is also favorable cool and moist conditions when temperatures are 68-72 F, and usually occurs when there is nine hours of wet weather. The best option is to maximize air movement between the plants and to use disease resistant varieties.
SCLB – Southern Corn Leaf Blight
Scientific Name: Bipolaris maydis (Cochliobolus heterostrophus)
Type: Fungus
Southern Corn Leaf Blight is a fungal disease that affects the growth of corn and is considered the most devastating disease of corn crop. Southern corn leaf blight occurs commonly in the Southeastern regions of the United States. Symptoms are tan colored lesions on the leaves measuring 1/8 to 1/4 inch wide by 1/8 to 1 inch long. The diamond-shaped elongated shaped lesions begin on the lower leaves and then spread to upper leaves. The disease can cause significant loss of leaves. It can cause significant yield loss in corn. Losses are greater and more severe when plants are infected at the early stage of growth. The disease will spread by rain or wind. The disease is favorable when temperatures are 68-89 F and usually occur when moisture and humidity are very high. Plan on using a 3 year crop rotation and avoid planting in the same location, year after year, as the disease can survive in over winter on corn leaf debris. Proper tillage practices may be helpful in managing the disease. Fungicides can help manage the disease. The best option is to use hybrid disease resistant varieties.