RHIZOCTONIA DAMPING OFF AND STEM ROT:
Symptoms:
Rhizoctonia damage may occur at
any time during the growing season, but it is more severe on young seedlings. Rhizoctonia
solani can cause seed rot, root rot, and lesions on hypocotyls. Damping-off
occurs when germinating seedlings are infected prior to or just after
emergence. On hypocotyls, lesions are reddish-brown and sunken. Diseased
seedlings collapse from the firm, dry canker that girdles the hypocotyl.
Diseased older plants become chlorotic, resembling plants with nitrogen
deficiency. Symptoms on older plants, or on those plants that survive seedling
infections, include the characteristic sunken, reddish-brown cankers on the
lower stem near the soil surface. Rhizoctonia stem rot—yellowed, stunted,
infected plants.
Controls: Varietal differences have been noted but
routine screening for resistance is available from few sources. Crop rotation with wheat and corn to allow for
soybean residues to degrade. Improve soil drainage. Based on soil tests, adequate fertilization
but not over fertilization.
No comments:
Post a Comment