Although the cool weather tends to limit disease in new seedlings, a spike in the temperatures could trigger outbreaks in juvenile turf yet this year. Late summer is clearly the best time of the year to seed for a variety of reasons, but we must deal with two difficulties of seeding at this time:
Our driest months are usually Aug and Sep and thus irrigation is essential for success in a late summer seeding;
Increased soil and air temperatures combined with high humidity and frequent irrigation create ideal conditions for seedling diseases like damping off, caused by Pythium (and other fungi) which can destroy a new stand virtually overnight.
Limiting these diseases can be done by:
Watering in the morning and early afternoon to allow soil to dry as best you can before nightfall;
Mowing as soon as seedlings reach a mowable height will tend to keep the canopy drier and less humid, which is less conducive to infection;
Purchasing seed coating with Apron or other fungicides. These normally add about 7-10 cents/pound to the cost and will protect against infection at a very critical time. This is pretty inexpensive protection in our opinion.
Treating seedbeds or newly emerged seedlings prior to the onset of warm wet weather with Subdue or Banol to avoid Pythium damping off and/or Pythium blight. One problem is allowing the seedbed to dry in order to support foot, spreader, and/or sprayer traffic. Small sprayers will likely be necessary and Subdue is available in a granular formulation.
Send corrections, suggestions, and comments to biehlj@purdue.edu