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ISSUE 4  May 28, 1998

 

CRISIS EXEMPTION ISSUED FOR THE USE OF WARRIOR ON CANOLA TO CONTROL FLEA BEETLES

    A Crisis Exemption has been issued by the North Dakota Department of Agriculture permitting the use of WarriorŽ (lambda cyhalothrin) on canola to control the Crucifer flea beetle. The dates that the exemption are in effect are May 22 - July 1, 1998.

    The approved rate of application is 2.56 to 3.84 fluid ounces per acre (0.02 to 0.03 pounds Active Ingredient per acre). Applications may be made by air at a minimum of 2 gallons of water per acre, or by ground at a minimum of 10 gallons of water per acre.

    Before using this product, be sure to obtain a copy of the crisis exemption label. WarriorŽ is a restricted use insecticide for use by certified applicators. Observe all restrictions and spray drift precautions listed on the label.

    This crisis has been declared in response to intense flea beetle feeding reported in the north central counties. The combination of large populations and dry conditions has put seedling canola in the cotyledon stage at risk to feeding injury. Canola planted without seed treatments or treated with lindane is at the greatest risk and should be monitored daily until fully expanded true leaves are present. Canola treated with GauchoŽ should also be monitored, though risk of injury will be less.

PLANTING DATES FOR SPRING WHEAT EXPECTED TO BE HEADING DURING WHEAT MIDGE EMERGENCE

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    We have reached the point where 600 degree days (40 F) have been accumulated around the state. The first date corresponds with the accumulation of 200 DD; the second is when 600 DD were reached. Now is a good time to review planting dates for individual fields, and begin to prioritize scouting efforts for adult midge based on those planting dates and expected head emergence.

    The overwintering midge population determined from the fall collected soil samples reveal slightly higher larval numbers for the 1998 season. The wheat midge soil survey was conducted again this year with financial support from the North Dakota Wheat Commission and Dow AgroSciences. Under the direction of the Department of Entomology at NDSU, soil samples collected by local extension agents last fall were processed. The computer generated map below summarizes the distribution of wheat midge.

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    The northeast quarter of the state continues to have the largest populations of wheat midge. There are four focal points where midge numbered greater than 1200 midge larvae per square meter. These are located near Lakota in northwestern Nelson and southeastern Ramsey counties, near Wolford in northeast Pierce county, near Perth in Towner county, and in Southwest Bottineau county near Gardena. There are also areas in northwest Barnes and southern Griggs counties and a location in northcentral Stutsman county where populations ranged from 500 to 1190 midge per square meter.

    Armed with information about the overwintering population and high risk planting dates, growers should be prepared to react to the presence of wheat midge when emergence gets underway. Due to the earlier accumulation of degree days this season, wheat midge will be emerging earlier than the previous three seasons.


BUG BRIEFS

    Grasshopper spraying is becoming more common in the Red River Valley. Treatments are being made in the central and northern areas of the valley. Some treatments have been made to entire fields, particularly where late season crops attracted adult grasshoppers last fall. In these cases, egglaying occurred throughout the field. In the north central and southwest areas, hot spots where large numbers are present in non-crop areas adjacent to fields are being found. Treatments in McLean, Bottineau, and Renvile Counties have begun.


Phillip Glogoza
Extension Entomologist
Mike Weiss
NDSU Entomologist


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