Weather
There was a pretty steady rain on Tues. last week that greatly relieved the moisture stress on most turf. Many non-irrigated areas that were just going into dormancy have bounced back. Some of the drier areas are not bouncing back yet. There is a climb in relative humidity and temperature for the weekend and then back to the type of weather with clear skies and no humidex. There are thundershowers forecast for Sat. and Sun and Mon. they are calling for isolated or scattered showers and thundershowers again on Wed.
Dollar spot, brown patch and summer patch have been active over the past week. The thundershowers and rain brought on some summer patch symptoms and the low relative humidity and the high ET’s are making the symptoms worse. You many continue to see new symptoms of summer patch for the next week or so. This is also the case with take-all patch where the disease was infecting turf in the spring, but now that we have the dry conditions and high ET’s the symptoms will continue to be visible. I would say there will be a slight risk of Pythium blight over the weekend but after that the temperatures will be cooler and more seasonal. Even the brown patch that we have here at GTI is looking a bit less severe over the last couple of days with the lower humidity, but it will probably flare up over the weekend.
There continues to be more and more necrotic ring spot noticeable. More rust is showing up this week on perennial ryegrass in lawns and sports fields. Sometime in the next two weeks, a shot of nitrogen will help keep this disease in check. If you do encounter a turf problem that you can’t identify, you can always send a sample to GTI Turf Diagnostics. Information on this service is available on the GTI web site. You can also email them at diagnostics@guelphturfgrass.ca or telephone at (519) 824-4120 x 58873.
There is still a little bit of new damage from black turfgrass ataenius feeding and now the 2nd adult flight is in full flight. This is a tricky time of year because there is rarely any damage from the second generation grubs feeding. If adult populations are high, an insecticide treatment now will lower the number of overwintering adults and hopefully work as a preventative treatment for next season. The GTI Turf Diagnostics lab had a sample with a 2nd generation pupa of annual bluegrass weevil. There are still a lot of Japanese beetle adults flying around at the moment. If Japanese beetle is the only grub species you have on your golf course, you can still apply a preventative grub product for their control this fall.
We did yet another post-treatment count on our hairy chinch bug trial and where surprised to see that there still were not many adult chinch bugs yet. Most are still in the late instars (4th and 5th). Again, the scary part about that is that there will still be more damage occurring as the later instars and adults feed. Unfortunately there is no efficacious registered treatment for hairy chinch bugs in Ontario at the moment.
We are coming up to the time when lawn care companies will be planning to apply insect parasitic nematodes to clients that had grub damage last fall and this spring. It is still too early. We are only now just starting to see the very young first instar. Most years the timing for applying nematodes to control European chafer grubs in toward the end of August and beginning of September.
As the heat dissipates and the cooler, wetter conditions prevail, you can begin applying broadleaf herbicides again. It is however best to wait a little later until the winter annuals have germinated. That way you will control them as well as any perennial weeds that you have in a turf stand. On the note of broadleaf weeds, this is just a reminder that only products with PCP numbers can legally be used to control weeds. Some companies are marketing iron based fertilizers that are not registered for use as herbicides. Little is know about the safety of these products on turf. Crabgrass is at the multi-tillering stage and putting out seedheads now. It is too late to apply Acclaim Super on golf courses. For lawn care, this is a good time to map areas that have crabgrass and apply a preventative treatment of corn gluten meal next spring.
It is probably a good idea to minimize any aggressive cultural practices for at least another week. One of the Northeast Region USGA Agronomists had an interesting tip on the web last week about putting down carpets or a piece of lattice on the collar of greens where you turn the mower to reduce mechanical injury during stressful periods. Some superintendents have reported that they have vented (punching holes to get oxygen to the roots) their greens several weeks ago and that is helping them get through the heat stress. Keep the mowing height high at the moment. As the stress diminishes, mowing heights can be lowered again.
Once things cool down, it is also a good time for a fertilizer application. Plans should also be underway for overseeding any areas that were weakened or damaged this summer. The best overseeding window is Aug. 15th – Sept. 15th in most areas of southwestern Ontario.
I appreciate the feedback. You can reach me by phone at (519-824-4120 x 52597) or by email at pamela.charbonneau@ontario.ca.
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