Window for grub control closing quickly

grubs at the soil surface

The grubs are near the surface of the turf, feeding voraciously and growing like crazy. The damage association with grub feeding is starting to show up. There is still a small window in which insect parasitic nematodes can be applied, but these applications should be done as soon as possible. The recommended nematode species for European chafer and Japanese beetle grubs is Heterorhabditis bacteriophora. There is rain in the forecast tonight and showers for tomorrow. That is a good time to apply because the soils will be nice and moist. The best time to apply would be on an overcast day or in the rain. Nematodes need to be watered in to reach the grubs but if you are applying in the rain that wouldn’t be necessary. Because the grubs are so high up in the soil profile, you won’t need as much water to water them in. That would not have been the case a couple of weeks ago when the grubs were deep in the soil trying to survive the very dry conditions.

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A harbinger of fall

adult crane fly on turf

pupal casings on closely mown turf

Returning to work after the long weekend, I was greated by a European crane fly adult on the front door of GTI. That time already, I thought. There is a new OMAF and MRA factsheet on European crane flys available at the following link http://www.omafra.gov.on.ca/english/crops/facts/13-023.htm. There are two ways to monitor for the adults. One is to walk and area of turf and see how many adults are dispersed and the second, which is easier on short mown turf is to look for the leatherjacket pupal casings in the morning before mowing the turf. For golf courses there are several preventative insecticide options for European crane fly/leatherjacket control. The timing for these products is during adult flights and egg laying. We are just at the beginning of the adult flight period and flights are predicted to peak in about 10 days in the Guelph area. I will keep you posted via this blog with estimates of when the peak adult flights are in this area.

For homelawn turf, the best treatment that we have so far is insect parasitic nematodes. The timing for applying nematodes is in mid-October to early November after all of the eggs have hatched. Unfortunately, our results with nematodes have been variable from season to season. The best recommendation to date is a 50/50 mixture of Hetehorhabditis bacteriophora and Steinernema feltiae. Follow the best management practices for applying nematodes to insure the best possible control.

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