The old adage, “more Poa is lost on the cool, dry days than the hot, humid days” comes to mind during these dog days of August. The following scenario is all too familiar:
Deep, healthy roots are long gone and the maintenance staff may make half a dozen trips to a putting green every day to measure moisture and hand water hot spots, working overtime during heat waves to monitor moisture levels and apply just the right amount of irrigation.
Then, a long-awaited break in the weather occurs. You breathe a sigh of relief as the temperature and humidity dramatically decrease and there is a cool breeze as your cart exits the shop in the morning darkness. This will be a good day and the worn-out staff will not have to drag heavy hoses across greens all afternoon.
However, in less than a week, some of the greens that you worked so hard to keep alive during the heat begin to thin out. There is no mistaking the symptoms of anthracnose disease in the collar, along the cleanup pass, in high-traffic areas and in hot spots. These are exactly the same areas that received the most attention and hand watering during the heat, what happened?
It's easy to blame the sudden turf decline on anthracnose disease, but there may be another reason behind it. When the weather becomes mild and comfortable, many let their guards down because they think the risk of wilt has passed. The usual hot spots may have been hand watered during the morning, but there may not have been sufficient follow-up monitoring to protect against wilt. Unfortunately, it doesn't take much more than a single episode of wilt to trigger a stress-related disease like anthracnose.
Many experienced superintendents refer to this as “sneaky wilt”. The wilt sneaks up on you if you let your guard down when the weather moderates after a long stretch of heat. Weak, shallow-rooted Poa annua greens are the most vulnerable to “sneaky wilt” because there is little margin for error in their day-to-day water management.
The take-home message is to never let your guard down when putting green turf is weak and shallow-rooted. Injury from moisture stress, or the diseases that follow, can happen quickly during a hot day and perhaps even faster on a mild, breezy day with low humidity.
Don't let wilt sneak up on you.
Central Region Agronomists:
Bob Vavrek, regional director – email@example.com
John Daniels, agronomist – firstname.lastname@example.org
Zach Nicoludis, agronomist – email@example.com