Warning out for cereal leaf beetle
Monday, July 4, 2011
by BETTER FARMING STAFF
Ontario’s field crops entomologist is warning farmers to be on the lookout for cereal leaf beetle in winter and spring wheat crops.
In the June 29 issue of CropPest Ontario, Tracey Baute noted that she was receiving calls about damage from the pests from farmers near Stayner, Bolton and Seaforth.
According to the Ontario Ministry of Agriculture, Food and Rural Affairs guide to field crop insects and pests, the cereal leaf beetle adult is “a metallic, blue-green beetle, approximately 5 mm in length with a reddish-orange head and legs.” The insects produce one generation a year.
Along with wheat, the insects will feed on oat, corn, forages and grassy weeds. Damage is caused by both adults and the larvae, which grow to 6 mm and whose yellowish colouring is disguised by “a black deposit of fecal material,” the guide says.
Farmers are advised to examine 20 plants in five locations across the field when scouting and to scout every five days. If one adult or larvae is found per stem, it’s time to spray crops that have not yet headed.
Baute says there are no threshold guidelines for crops that have already headed even though U.S. studies are showing that significant yield loss can come from insects feeding into the earlier heading stages. “I only recommend spraying for cereal leaf beetle in winter wheat if it is still in the earlier heading stages and that you have at least a month prior to harvest because of the days to harvest intervals for many of the products registered in cereals,” she writes.
Baute advises taking a cautious approach if mixing insecticide in with fungicide applications for spring wheat, noting that the combination of some insecticide and fusarium products can affect wheat pollination. “There is not a lot of research on these tank mixes to know for sure how safe they are to the crop, particularly during pollination,” she writes.
Insecticides can be less effective at temperatures above 25 C so Baute also recommends spraying in the evening if daytime temperatures are high.
In corn crops, western bean cutworm is beginning to be observed, notes Greg Stewart, the province’s corn specialist. “Scouting is important to stay on top of this pest,” Stewart writes in the June 29 field crop report.
According to OMAFRA’s website, the insect is relatively new to Ontario and was first found here in 2008 although no reports of damage were documented that year.
The insect is a pest of corn, edible beans, tomatoes and nightshade. It will feed on the fruit of the plant, such as corn ears. The adult moths have a white band along the edge of each wing as well as “a spot or ‘moon’ and boomerang-like mark,” the website says. Moths emerge in late June and early July and lay “creamy white” eggs in “clusters of five to 200 eggs” on the upper leaves of corn plants. The larvae will feed on corn tassels and silks “until they are large enough to tunnel into the ear and feed extensively on the kernels.”
One larva per ear can cause 3.7 bushel per acre yield loss, the website says. Management options include foliar insecticide application and the type of hybrid used. It’s advised to scout 20 plants in five areas of the field from the end of July to the end of August. BF