Title Image
Image
Caption
Diamondback Moth stages (photo from Dr. M Vankosky Photo taken by Jon Williams, AAFC-Saskatoon.)
Portal
Title Image Caption
Daimondback Moth stages - Photo's taken by Jon Williams, AAFC-Saskatoon.
Categories

Farmers are scouting fields on a regular basis for signs of insect damage or disease.

Insect activity varies from area to area and province to province with producers reporting issues with wireworms, grasshoppers, aphids, the pea leaf weevil and more.

Dr  Meghan Vankosky, a research scientist in field crop entamology with Agriculture and Agri-Food Canada says it definitely proving to be a very interesting growing season.

They've just wrapped up the annual phermone trap monitoring program for bertha armyworm in Manitoba, Saskatchewan and Alberta.

She says there's only a few traps where they caught more than 300 moths over the course of the trapping season.

"So that indicates that Bertha Armyworm risk across the prairies is is still probably quite low, like it's been the last few years. But if you are farming in areas where the traps have caught more moths, it is still going to be important to be scouting with this hot weather. Larvae can develop quite quickly and so we might start to see damage that you might not have expected, so scouting is always important."

We tend to see outbreaks in canola and mustard but bertha armyworn can be found in other crops inclusing alfalfa, peas, flax and potatoes, the larvae tend to do the damage.

Vankosky points out that Diamondback Moth could be another very interesting insect to watch for this year.

"They thrive in warmer weather, it speeds up their rate of development leading to more generations in the growing season. We're already seeing some areas with our pheromone trap program where trap catches were rather high for adult moths this spring. I've heard about high numbers of larvae in some fields in different parts of the prairies. So, I think it is going to be quite important to be aware that there could be some risk associated with diamondback moth again this year."

She says with the next two weeks of hot weather that's going to speed up their development and could add a couple of extra generations to the growing season adding that we could start seeing pod damage just a few weeks before harvest.

Diamondback moth are also quite problematic in crucifer vegetables, cabbage, brussels sprouts, and broccoli. So it could be really important to be scouting those crops as well, especially if it does stay warm.

When scouting its important to go out and look for larvae on the plants.  Go to five to 15 different sites in the field (from the edge and the interior) and pull up plants to get an idea of what's happening in the field.  Take the plants and bang them on the hood of the truck and count the larvae that you see.

She notes for diamondback moth when the canola is flowering to the end of flowering, the economic threshold would be 100 to 150 larvae per square metre, towards podding that number would be higher about 200 to 300 larvae per square metre.

For bertha armyworm the economic threshold for action is actually a calculation based on the cost of the insecticide, the expected price for the crop and the density of the larvae.

Farmers are also reporting the cabbage seedpod weevil showing up in canola and mustard plants in the prairies.

More information on insect scouting and the economic threshold for action can be found here, through the provincial agriculture websites or the Prairie Pest Monitoring Network.