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Archive for June, 2013

Bird'sfoot trefoil in bloom

Bird’sfoot trefoil in bloom

The cooler than normal weather has insect development lagging behind a normal season. For instance, our GTI site superintendent was working up one of the research ranges last week and tilled up a mass of 3rd instar European chafers. There was no sign of pupae or adults yet. In most years the first European chafer adult flights usually begin by mid-June. Annual bluegrass weevil adults are still being found in the turf and there are mostly the early instar weevil larvae being found in salt solution soaking up until now. The cool, wet conditions will also help mask the annual bluegrass weevil damage. We are also still finding large numbers of black turfgrass ataenius adults in our bi-weekly soap flushes here at GTI. Another weevil that is on the move now is the bluegrass billbug. We have observed a small number or adults moving in to the turf over the past two weeks.

The plant phenological indicator for peak egglaying for hairy chinch bug is birds’foot trefoil. It is in full bloom at the moment. On the whole, if conditions continue to be as wet as they have been this spring, it bodes well for a year with less than the average amount of turf damage from insects.

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Microdochium patch and dollar spot side by side.

Microdochium patch and dollar spot side by side.

The continuation of the cool, wet weather has made conditions ideal for the foliar disease that attack turf. There is lots of leaf spot evident on Kentucky bluegrass and as the temperatures rise and if it remains wet or humid, the conditions will again favour the “melting out phase” of leaf spot. These symptoms usually are bronze to yellow patches of thinning turf. The cultural practices that help turf recover from this phase of the disease include a light application on nitrogen and raising the mowing height.

Because of the mix of cool and warm weather and lots of rain there are two foliar disease active at the moment on closely mowed turf on golf courses (tees and greens mainly) and those are dollar spot and Microdochium patch. For the next couple of days with the night time lows going into the single digits the pressure from Microdochium patch will continue. As the temperatures ramp up later in the week the dollar spot pressure will increase. There is no need for a fungicide application directed at the Microdochium patch because the warmer weather will bring that disease to a halt. There is a need to keep up the preventative fungicide applications for dollar spot control and continue the cultural practices that help minimize this disease such as dew removal by mowing, poling or rolling and light and frequent nitrogen applications.

Another disease which isn’t a foliar disease, but is favoured by the current weather pattern is anthracnose basal rot. Some of the cultural practices which help manage this disease are adequate nitrogen applications and spring topdressing. There is a good article on best management practices for this disease at http://usgatero.msu.edu/v12/n2-16.pdf

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My summer student (Emily Hartwig) and I have been conducting soap flushes to monitor annual bluegrass weevil adult and black turfgrass ataenius adult migration from overwintering sites back into the turf this spring twice a week. The results have been interesting, but they will probably complicate or compromise your ABW control success. What we have observed this year is a bimodal emergence pattern for the annual bluegrass weevil adults with a peak May 2 to May 6th and then a second wave that peaked around May 31st. We continue to find a few adults in our soap flushes this week (24 adults in 12 soap flushes). For those of you that applied an adulticide in early May, you would have missed the second migration wave. If you have applied a larvaecide toward the end of May, the results might be a bit better. We are only monitoring and not treating for this pest. It would be very useful to get some feedback from blog subscriber in a few weeks to see if the adulticide application and/or the larvaecide applications were successful and what the specific timing for each was in your location. Maybe I will try a poll with a blog in the future.

On to the black turfgrass ataenius, the adult populations have been steady from May 22 to 31st and they are starting to fall off slightly. For anyone that is monitoring and finding large numbers of adults or for courses where there is a history of BTA damage, the insecticides registered for preventative control of BTA grubs can be applied prior to egg hatch, which is anytime now.

Lastly, my crop entomology colleagues have reported armyworms in the southwestern part of Ontario. Last year there was a fairly big invasion of them on turf as they marched through crop land. Just something to be on the lookout for. Our experience has been that the turf blades are munched off but the crown of the plant is intact and the turf will recover from armyworm damage.

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Flowering Kentucky bluegrass

Flowering Kentucky bluegrass

Around this time of year the turf species that comprise home lawns, sportsfield and golf course roughs (Kentucky bluegrass and perennial ryegrass) are putting out seedheads. Some of this is related to weather conditions and some of it is genetic. One of the qualities that turfgrass breeders look for in a turfgrass cultivar is prolific seed production. This makes those cultivars cheaper to produce. The downside of this in a turfgrass setting is that they will producer lots of seedheads once they are sown in a turf situation as well. Once the seedheads are mowed, the stemmy stalk that is left behind gives that stand of grass a yellow bleached appearance which can be a bit unsightly and can be mistaken for a leaf disease. Keeping the mower blades sharp will help a bit and so will a light application of fertilizer to help the turf recover. Now is the ideal time for an application of turf fertilizer, especially if you have not applied any this season.

Stemmy Kentucky bluegrass with bleached appearance

Stemmy Kentucky bluegrass with bleached appearance

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Seeing spots?

Dollar spot on fairway

Dollar spot on fairway

Dollar spot symptoms on the edge of a green

Dollar spot symptoms on the edge of a green

Dollar spot symtoms started showing up on the weekend of June 1st and 2nd on low cut turf in the Guelph area, which was a little later than predicted.  This was probably due to the cold front that came in a couple of weeks ago.  A preventative fungicide program accompanied by sound cultural practices such as infrequent and deep irrigation, irrigating in the late night/early morning, dew removal, adequate nitrogen fertility, thatch and compaction management.  Be sure to rotate fungicide chemistries  to minimize the risk of fungicide resistance to dollar spot.

 

 

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