This is the 6th edition of the OMAFRA Turf Management Update for June 6, 2008.
Just a general note about the turf updates. There will sometimes be pesticide recommendations for controlling different turf pests. If you are in a municipality that currently has a pesticide by-law, it is important that you know all the restrictions on pesticide use in your particular municipality.
What a change in the weather. Environment Canada is calling for this heat wave to last until Tues.. There is a chance of a thunderstorm over the next 3-4 days and temperatures will be in the low 30’s with night time lows in the low 20’s and high relative humidity. The temperatures will cool by Tues. to the mid-twenties.
These weekend temperatures will probably result in some dollar spot starting this weekend and there will also be a risk of brown patch and Pythium blight developing. Preventative treatments for dollar spot should be starting. We have seen individual dollar spot lesions on grass blades, so the dollar spot symptoms are not far behind. Just a reminder to send any unknown turf problems to the GTI Turf Diagnostics. Information on this service is available at the link below. You can email them at diagnostics@guelphturfgrass.ca or telephone at (519) 824-4120 x 58873.
I have had a few calls about annual bluegrass weevil damage from the Windsor area. Expect to start seeing annual bluegrass weevil damage in the rest of southwestern Ontario soon. The phenological indicators that signal peak adult black turfgrass ataenius migration are flowering now (horse chestnut and bridal wreath spirea). Flights should be tailing off over the next week. In areas with a history of black turfgrass ataenius damage, we now are still well within the window to apply imidacloprid preventatively.
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You can expect to see June beetle adults flying now. I have seen a few on golf courses and in my garden. They have not been abundant, only one or two flying. They can be seen at night bumping into lamp posts and such. They are pretty clumsy, fly at night and are attracted to lights.
Leatherjackets have almost reached full size and there have been very few reports about damage. We have been doing some leatherjacket counts here at GTI and we are finding that the numbers are down from previous years. It is quite feasible that the dry weather that we had last fall during the peak adult flights did interfere with egg hatch. If there is no damage to date, it is probably unlikely that there will be damage now. Insecticide control at this point in the season is probably not warranted unless they are found on a sod farm where there would be zero tolerance for leatherjackets. Options for control for this time of year are chlorpyrifos and carbaryl for sod farms and golf courses and carbaryl only for home lawns.
Turfgrass ants on golf courses have been very active over the last couple of weeks. They do not eat the turf but feed on other insects present in the turf and soil beneath the turf. The reason that they are a problem is that they form sandy mounds in golf course greens, tees and fairways. These mounds can suffocate the turf, they increase maintenance costs by dulling mower blades and on greens they can disrupt the playing surface. They tend to be more of a problem on new golf courses that have never been treated with the persistent organochlorine insecticides that were used on older golf courses in the past. They are usually within 1-2 m of the edge of a green. Chlorpyrifos, carbaryl and lambda-cyhalothrin are registered to control ants in Ontario.
I noticed the first flush of crabgrass plants this week and with this current moisture and the heat we can expect to see an explosion or crabgrass soon. It is no longer recommended to apply corn gluten meal. You can also still apply Dimension. It has the early post emergence activity, so even if you have a few germinated crabgrass plants, you will still get good control if applied according to this timing. Hopefully, everyone made note of the areas with serious crabgrass problems last year so that only those areas need to be treated this spring. An alternative approach, especially if the turf has thickened up over the fall and spring, is to wait and apply a post-emergence herbicide like Acclaim, on the small crabgrass plants, once they have germinated. This might be the best approach for golf courses, especially in areas that may need to be overseeded sometime during the growing season. Post-emergence products are not residual the way the pre- and early post-emergence products are. Both of the above approaches fit nicely into an IPM program.
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The flush of dandelion seedhead production is finished and turf that is mowed regularly is looking better because the seedheads have been mowed off. It is not recommended to apply broadleaf herbicides when temperatures are above 27°C. Once the temperatures go down next week there will be another short window in which to apply broadleaf herbicides.
Speaking of seedheads, there are some cultivars of Kentucky bluegrass that are quite prolific seed producers. The dry and cool conditions probably brought the flowering on. At this point it is important to keep your mower sharp because the seed stalks are very tough to mow and can make turf unsightly. Many superintendents are reporting more annual bluegrass than normal this spring. This is certainly true of our greens here at GTI. Annual bluegrass is still flowering profusely and as a result many golf greens are looking very patchy at the moment. Remember that after flowering there is some tiller thinning of annual bluegrass.
Once this heat spell is over it is still a good time for the first application of fertilizer for the season. Our research here at GTI has shown that proper fertility is key to keeping weeds in check. With fertilizer alone applied 4 times a season at 0.5 kg of N per 100m2 weed populations could be kept below 10%.
This message will be updated on Fri. June 13, 2008.
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