Adverse growing conditions such as excessive dryness, or cool, poorly-drained, infertile soils, tend to encourage root rot. Periconia circinata and species of Pythium, Rhizoctonia , and Fusarium are the fungi most frequently associated with rotted sorghum roots in Kentucky. The extent of damage from root rot depends upon a soil pathogen's ability to attack sorghum roots and the plant's ability to produce replacement roots. Generally, the plant's fine feeder roots are the first to be attacked and destroyed. At this point, vigorously-growing plants are quick to respond by replacing the diseased roots with new ones.
Plants growing under stressful conditions, however, remain weak and are unable to produce new roots.
Eventually, if enough roots are killed, the plant's growth will be retarded or plants may die. Control of grain sorghum root rot is similar to those listed for seed and seedling diseases. Sound management practices which stimulate plant vigor and development are important. Stalk Rots Stalk rots are common in Kentucky and generally follow root rot or certain combinations of specific environmental and plant developmental sequences which predispose plants to be attacked by stalk rotting organisms. Stalk rots can greatly reduce yield either directly through plant lodging, or indirectly through reduced head and grain fill.