Turfgrass Management Report - July 13, 2010

13 Jul 2010

Turfgrass Management Report for July 13, 2010

Welcome to the 8^th edition of the "Turfgrass Management Report" sponsored by the Ministry of Agriculture, Food and Rural Affairs for the week of July 13-23, 2010.

Past weather and the forecast for the upcoming week...
The forecast for the upcoming week is for daytime highs around 30ºC and lows around 20ºC. There are isolated showers for Thursday and showers next Monday. This weather is highly conducive to foliar (leaf) turf diseases as well as summer patch.

Disease activity...
Over the last week, there has been active fluffy white dollar spot mycelium on the research greens at GTI pretty much every morning (Fig 1). Again, with the current temperatures and either night watering or thundershowers in the evening, we’re setting up for the onset of the summer diseases such as brown patch and Pythium blight.

I received a confirmation of Pythium blight on some golf courses in the Torontoarea last week. I’ve also had brown patch reported from some areas in southwestern Ontario. Again, brown patch rarely causes damage to greens in Ontario, so there is rarely a need to apply fungicide preventatively for this disease.

If you have greens with a history of Pythium blight, it might be warranted to apply a preventative fungicide application on those areas that have had Pythium blight in the past. Samples have been coming into the Guelph Turf Diagnostics with summer patch and Waitea patch. If you weren’t on a preventative program for summer patch it is a bit hard to manage curatively.


Fig 1 Aerial Mycelium associated with dollar spot	Fig 2 Heat-streaking of Kentucky bluegrass/perennial ryegrass turf

There have been more calls this week about localized dry spots. The heat, coupled with some nice hot breezes have been drying out the turf and many superintendents are battling localized dry spots. Luckily, these are easy to diagnose. Just take a soil sample probe or a cup cutter and cut into the suspected area. If it’s localized dry spot, the soil will be bone dry below the affected areas.

Another abiotic problem (caused by non-living agents such as weather extremes, poor soil conditions, and drought) showing up is heat injury and heat tracking. I’m not a plant physiologist, but it appears that if turf gets too hot in the canopy (or top), especially if it goes from being well watered to experiencing a bit of drought stress too, it will turn yellow.

This happens when mower tires, tractors or golf carts drive over it. It also happens in areas experiencing drought stress, like under a tree (where tree roots compete with turf for water), or near the edge of a driveway where it is hotter and drier than the rest of the lawn (Fig 2). Here at the Guelph Turfgrass Institute (GTI) we can tell where soccer parents have had their cars idling on a hot evenings because the yellow grass that was under their vehicle is obvious. This type of injury has been confused with Pythium blight on home lawns and on golf courses.

Another disease very active on perennial ryegrass and Kentucky bluegrass at the moment is rust (Fig 3 below). It seems to thrive when conditions fluctuate between wet conditions and moderate temperatures & by hot, dry conditions. Turf that isn’t well fertilized and is growing slowly is most susceptible.


Fig 3 Rust Pustules on perennial ryegrass	Fig 4 Sod webworm perched upside down on a blade of grass

Insects...
European chafer adult flights are slowing down as Japanese beetle adult flights are ramping up. They will be flying for at least 2-3 more weeks. Japanese beetles seem to be on the move and infesting new areas each year. They were thought to be mainly a problem in Niagara and around the shores of Lake Erie, but they’re now much more widespread than that. On golf courses, you can still apply a preventative application of one of the preventative products until the end of July for the control of both European chafer and Japanese beetle

I’ve had some calls from the field about the beginning of hairy chinch bug damage. With the heat and dry conditions last week, hairy chinch bug damage was starting to show up. It’s pretty frustrating because there really isn’t a fully effective control for chinch bugs at the moment.

Walking around in turf over the last week there have been what seem to be thousands of sod webworm adults flying around (Fig 4, above). Not sure if that bodes well for later this summer. Sod webworm damage usually peaks in mid-September. I’ll keep you posted about the timing of damage as it starts to occur.

Weed control products...
Again, if you are adhering to the Fiesta™ label, it isn’t supposed to be applied when daytime temperatures reach 30ºC. On a positive note however, we are getting good control in our tagged weed trial with two applications of Fiesta™ four weeks apart (Fig 5). It’s working well on both dandelions and narrow-leaved plantain and not quite as well on clover or broadleaf plantain. There are also other studies going on at GTI showing Fiesta™ is also giving good control of black medick with two applications.