Republished with permission from Frank S. Rossi, Associate Professor and Extension Turfgrass Specialist, Cornell University Turfgrass Program http://turf.cals.cornell.edu
The residual effects of the six week stretch of high temperature, high humidity and rainfall is revealing more and more stressed turf. It is likely that if you are seeing turf decline at this time, the actual stress that caused the decline occurred one-two weeks ago. Even with ideal fungicide programs, stress related diseases such as anthracnose and summer patch are on the rise. Hot soggy soils are causing severe wet wilt conditions to the south of the region that are not easily fixed at this time. Water management, especially moving water through the upper soil profile, is critical for minimizing the most intense summer stress conditions that can lead to catastrophic failure. On the other end of the spectrum are the facilities in the driest areas that are learning first hand about the weaknesses of their irrigation systems. I’ve taken many drive-by pictures like the inset picture above where it is obvious irrigation water is not being applied properly. Obviously when rainfall returns these areas should green-up, however now is the time to note these areas and begin to focus on making adjustments to correct these design, spacing, nozzles, pressure, etc. issues. Rich Buckley mentioned a call from Joe Rimmelspach at Ohio State who mentioned the presence of gray leaf spot in OH. This would be considered a high pressure year for many that have been dry and now rains return. Be sure to watch drought stressed turf closely to determine if it is GLS, as irrigating an infested turf will lead severe damage.
My sports fields have responded slightly to the recent rains and I now have a “Water-Wheel”. What is best prep program for Fall Sports fields with practice starting in two weeks?
Thankfully you have rec’d some rainfall to loosen up the soil that might help water applied from the water cannon to penetrate more deeply. That is the key—wetting the soil deeply at this time so it will allow for surface drying for play but also enhance fertilizer effectiveness and even seed germination. As soon as the soil is moist enough—not too wet and not too dry, consider som form of cultivation. Ideally, bringing up some soil that can serve as both a topdressing and seedbed for overseeding. At this point the best seeding option with play in the next two weeks is perennial ryegrass. While there are reports of gray leaf spot coming from the Midwest and we have had some ideal conditions for an outbreak, most are just going to have to take their chances. If you have the ability to treat, an application of certain fungicides when seedlings emerge will assist in reducing risk. Keep in mind it is best to select gray leaf spot resistant varieties, but even the resistant varieties are susceptible to GLS when they are seedlings. Fertilization at this time is best with products that can supply between 50-75% of the Nitrogen in slow release form to avoid excessive growth at this time, but still encourage the seedlings and existing turf to become more dense. So water then cultivate, seed and feed. When fertilizer begins to kick in be sure you are increasing your mowing frequency. If you normal mow once per week, time to start 2-3x per week at whatever height you normal keep the field, generally little need to cut below 2″ for most scholastic fields. Some collegiate fields can be as low as 1″ but most should not be below that.
I’ve been seeing some Japanese and other adult beetles flying around. How will the weather effect egg laying and grub feeding?
Turfgrass entomologists across the northeast US have been referring to the delayed activity of the insects this season. Much of this may have begun with smaller instars starting the season after late emergence last season. This was further delayed by extremely dry Spring and for many dry Summer conditions. A good scouting program should be looking at plugs to determine insect pressure, before the animals show you! Keep a close eye on irrigated turf as JapBeetles often prefer the locations.