Heavy rains and hail also adversely affect turf areas. Our recent weather pattern has also brought slightly below average temperatures. Cooler temperatures, physical damage to turf material, and extended periods of wetness promote a few very damaging turf pathogens. Leaf blights and leaf spots are among the most prevalent diseases in turf.

Ascochyta leaf blight:

• Large uniform areas of affected turf will turn straw-colored.

• Leaves usually start dying back from the tips.

• Ascochyta can occur throughout the growing season, but is more prevalent in the spring when there are extended wet periods.

• The first line of defense against Ascochyta leaf blight is to manage the turf properly

Ascochyta leaf spot symptoms may develop throughout the growing season but are more common during hot, droughty periods that were preceded by cool, rainy conditions. Large irregular patches of turf rapidly turn a straw-color and appear dead. The overall appearance of the disease may resemble drought stress, except that the symptoms of Asochyta blight appear quickly (i.e. sometimes overnight). Although the blighting within an area appears complete from a distance, healthy leaves are interspersed within the patch. Blighting is usually restricted to the leaves; bluegrass crowns and roots typically are not killed.

Leaves infected with the Ascochyta fungus often exhibit a bleached tip dieback that extends approximately a third to halfway down the leaf blade. The margin between healthy and diseased tissue is abrupt and slightly pinched, but doesn’t have the dark brown to purple banding that is characteristic of another disease called dollar spot. In other cases leaves may exhibit white banding or entirely collapse and shrivel. These leaf symptoms resemble heat or drought stress.

The Ascochyta fungus produces minute yellow to dark brown, flask-shaped fungal fruiting bodies called pycnidia in diseased leaf tissue. These fruiting bodies, which are easier to view with the aid of a hand lens, are peppered throughout the dead leaves and can be very useful as a diagnostic feature.