Ascochyta leaf blight is a common disease of Colorado lawns. Infected leaf
blades are straw-colored and pinched; the damage begins at the tip of the blade
and moves downward. The overall pattern of damage varies. It may appear in the
lawn as small spots, large patches or even follow mower tracks. The disease
kills leaf blades but not the entire plant.
Ascochyta is a stress-related problem that usually appears in warm, dry
weather following a cool, moist period. Ascochyta leaf blight indicates that the
soil is dry, and the canopy is moist. Improper watering (shallow, infrequent) is
often the cause of this situation.
Disease management includes watering deeply but infrequently to encourage
deeper soil exploration by turf roots. Such lawns are better able to withstand
heat and drought stresses. Applications of a wetting agent in spring and summer
may help water penetrate soils better.
Core aerate once or twice per year (spring and/or fall) to improve root
development and water and fertilizer penetration. Mow turf regularly to a height
of 3 inches; avoid scalping. Fertilize lawns 3-4 times per year with 1 pound of
nitrogen per 1000 square feet. Slow- release or combinations of slow-release
with quick- release products are preferred. Quick-release nitrogen products
stimulate excess stem and blade growth at the expense of root growth.
Ascochyta can appear most months of the growing season.
