Populations of crucifer and striped flea beetles have increased this week in canola near Langdon. Canola planted in April is emerged but still in the seedling stage. Seedling to 4-6-leaf stage canola is susceptible to yield loss from flea beetles, and should be scouted for flea beetle and feeding injury (pitting). Commercially applied seed treatments, such as Helix XTRA and Prosper are only effective in controlling flea beetles for ?25 days after planting. Flea beetles are small (? in. or 2-3 mm), oval-shaped, and will be most active feeding on warm, calm days. If injury is at 25% defoliation (action threshold), a foliar insecticide should be applied as a rescue treatment. A listing of insecticides registered in canola is available from the ND Field Crop Insect Management Guide 2012, E-1143, NDSU Extension Service.
Janet J. Knodel
Extension Entomologist
janet.knodel@ndsu.edu
http://www.ag.ndsu.nodak.edu/aginfo/entomology/entupdates/ICG_12/e1143_all.pdf#page=23
Update on Aster Leafhoppers in Wheat
Ian MacRae, Jan Knodel, Bruce Potter and Jochum Wiersma
High populations of aster leafhopper (also called 6-spotted leafhopper) have been reported in small grains over the past couple of weeks. Starting in the south but now spreading to northern MN and ND. Aster leafhoppers are greyish leafhoppers; the adults have clear wings and 6 spots between the compound eyes (Figure 1 below). Other than their coloration, the adults and nymphs both very much resemble potato leafhopper. The leafhopper uses it's piercing sucking mouthparts to feed on the plant's sap. The damage caused by Aster leafhopper feeding is more localized than that produced by potato leafhopper. Feeding may produce localized necrosis or stippling (Figure 2 below), however, damage is much less than that caused by the potato leafhopper.
While they may overwinter as eggs in parts of MN, the sudden arrival of large populations of adults, together with the lack of nymphs present, indicates they arrived here from somewhere else. Like many other snowbirds in this area, part of the northern plain's populations overwinter somewhere warmer and return to the north when the weather once again becomes bearable! Once active in the region, Aster leafhoppers feed on a wide variety of grass and broadleaf plants, crop and non-crop alike. Adults may move between host plants and follow what's green and available.
Disease Vectors - These insects can be economically important in wheat when they vector of Aster Yellows (AY). Feeding injury of aster leafhoppers is less important than disease vectoring. AY has a very wide host range and causes economic losses in several vegetables and ornamentals. If you have seen purple coneflowers with green distorted flowers, you have seen the aster yellows plant disease. Aster yellows is caused be a phytoplasm; an organism similar to a bacterium but without cell walls. When AY infects wheat, it produces symptoms very similar to Barley Yellow Dwarf Virus (BYDV).
Research has shown that heavy infections of AY can cause yield loss in susceptible wheat varieties. There are anecdotal observations from wheat varietal plots in northern Minnesota, which indicate that AY symptoms may be more severe, or that the disease is aggravated under wet conditions.
NDSU has just issued its first Crop & Pest Report for the 2012 season. Click on the link below for information on early season insect activity. Cutworms are being observed in southwestern North Dakota.
http://www.ag.ndsu.edu/cpr/entomology/scout-for-early-season-insects-cutworms-cereal-aphids-flea-beetles-4-26-12
Reports are coming in from several market participants that the European rapeseed crop will drop to a five-year low this season. Abnormally harsh winter conditions are to blame for the decreased production prospects.
Hamburg-based Oil World estimates the crop will come in at approximately 18.5 million tons, down sharply from last year's 19.1 million tons.
Alarming reports have been received recently from Germany, Poland and France indicating greater-than-expected damage from winter killing.
It appears that the European food processing and biodiesel industry will again be facing tight supplies, which will support prices.
