Weather
The weather has changed for the better. As you know temperatures have been cooler than normal for the past two weeks and the long term forecast is that this cool weather will last for another two weeks. Conditions have gone from totally saturated soils and overcast conditions to clear skies, low relative humidity and some windy conditions. The current conditions result in high ET’s and turf can dry out very, very quickly. Localized dry spots will be a problem. Here at GTI, Dr. Ken Carey and Dr. Lyons are conducting a wetting agent trial and the results are pretty spectacular this year because of all the localized dry spots we have on our research greens.
Diseases
The very cool weather over the last couple of weeks had virtually ground the dollar spot to a halt. The warmer temperatures and the heavy dew formation are favouring dollar spot again. All that being said, dollar spot pressure is not as high so far this season as it has been in previous years. There have been a couple of samples of anthracnose basal rot submitted to the GTI Turf Diagnostics over the past week. Keeping up with topdressing will help keep the crowns of the plants drier and may aid in preventing anthracnose basal rot. One thing that we have noticed here at the GTI on our closely mowed turf is leaf tip scorch. This has also been happening in the northeast US and there have been many samples of this submitted to Dr. Rick Buckley, Director of Diagnositic Services, Rutgers University. The cause is most likely the rapid change in weather that is mentioned above and resulting moisture stress on turf. On Kentucky bluegrass turf there has been lots of leaf spot during the two week rainy period and now there is some melting out occurring on some of this turf. If you encounter a disease that you can’t diagnose, there is information on submitting a sample to the GTI Turf Diagnostics at the link.
Insects
A couple weeks ago I said that annual bluegrass weevil damage should be almost finished. Well, there are still annual bluegrass weevil larvae out there. The cool weather this spring prolonged the period of annual bluegrass weevil migrating from their overwintering sites so the damage has lasted later in the summer than usual. We found late instar larvae, pupae and adults all in one plug of turf in our research trials and a similar sample was submitted to the GTI Turf Diagnostics. I have not had too many report of black turfgrass ataenius damage. The damage should have peaked by now. The wet conditions may have slightly masked the damage or the grub populations may have declined because they have been attacked by soil dwelling fungi.
European chafer flights have tapered off drastically over the last week. Adult flights should be almost finished in the southwest now. It is a good idea to make note of areas with heavy European chafer flights. These areas can be monitored in the late summer early fall for the presence of chafer grubs. At that point if lots of grubs are found, they can be treated with insect parasitic nematodes. For golf courses your choices are chlorantraniliprole or imidacloprid as a preventative or carbaryl as a curative. Chlorantraniliprole can be used until mid-late August, so there is an opportunity to monitor for young grubs and use this product as an early curative. On the subjects of grubs, again this year, I am searching for a site to conduct a grub control trial with alternative products. The ideal site would be an estate property that had a heavy European chafer grub infestation this spring. If you know of such a site, please send me an email at Pamela.charbonneau@ontario.ca
Japanese beetles are in full flight right now. On golf courses that have them, the adults can be seen on the turf forming a ball. This is usually one female surrounded by a large group of males. The peak egg laying of hairy chinch bugs is over. We are probably about 2 weeks away from the peak damage period. I am not sure what we will see this year as far as hairy chinch bug damage. The conventional wisdom is that chinch bug damage is usually much less severe in wet years compared to dry years, but research by Dr. Dave Shetlar, Ohio State University has indicated that this is not the case. We don’t really know yet if it will be a wet or a dry summer. Obviously, so far it has been wet, but the last week has been dry. The verdict is still out. It is about time to start seeing bluegrass billbug damage. It can be distinguished from chinch bug damage because the dead or dying turf plants will pull out easily with billbug damage and they will not pull out for chinch bug damage. Bluegrass billbug also leave sawdust like frass in the thatch of the turf.
Weeds
White clover is still in flower in lawns that have not been fertilized regularly for the last few years. With the cosmetic pesticide ban, white clover in lawns is going to become a more familiar site. It isn’t necessarily a bad thing in that it has its own ability to fix nitrogen. What isn’t clear is how it reacts to drought stress. – See more at: https://lawnsavers.com/turf-hotline-2009/turfgrass-management-agriphone-for-july-17-2009.html#sthash.HPuStjKZ.dpuf
