FROM AROUND THE STATE
ISSUE #11 July 12, 2001
WHEAT MIDGE UPDATE – NORTH CENTRAL AND NORTHWEST
The Degree Day accumulations for wheat midge emergence indicates that most areas are near 1600 Degree Days when 90% of the females wheat midge have emerged; except for the northern counties where wheat midge is about 50% emerged and field scouting is just getting started in heading crop. The degree days for the weather sites located in the northwest and north central regions as of July 11, 2001 includes: Rolla = 1450, Columbus = 1450; Hofflund = 1485; Bottineau = 1555; Mohall = 1593; Baker = 1623; Cando = 1610;Turtle Lake = 1645; Minot = 1655; Watford City = 1705; Williston = 1722; and Towner = 1757.
CANOLA INSECT PESTS
Nuttall Blister Beetle is feeding and clipping the flower buds now. Look for the large beetle (>1 inch long) with a metallic purplish wing covers in the tops of canola flowers. These beetles often aggregate (swarming insect) near field edges or general spots, and tend to move around alot. There were some reports of spraying near Flaxton, Burke County and at Carrington, Foster County.
Bertha armyworm mothss are high at the Mohall and Newburg trap sites, but recent trap counts have decreased slightly. Small larvae have been observed in canola fields near Mohall and Newburg. Continue to scout canola fields until harvest in these uncertain infestation risk areas.
OTHER INSECT PEST REPORTS
Many reports of thistle caterpillar (larvae of the Painted Lady Butterfly) causing damage to mainly sunflower and soybean fields in the North Central and Northwest Regions. Different sizes of larvae can be found in fields since the butterfly is still flying around laying eggs. So, use defoliation thresholds (25% in sunflowers, and 25-30% in soybean prior to flowering, 20% in soybean after flowering or pod set) as an indication of whether fields should be sprayed.
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
During the past week (July 4-10), rainfall ranged from 0.06 inches (Carrington) to 0.53 inches (McLeod) was recorded at NDAWN sites in south-central North Dakota. The relatively dry weather has allowed haying, row crop cultivation, and pesticide application. Also, the dry weather has reduced the risk of foliar and head disease infections in wheat. However, additional rainfall is needed for cool-season crops in the seed-fill stages and for corn and beans. Estimates of daily water usage from NDAWN for timely-planted wheat, corn, soybean and sunflower ranged from 0.22 to 0.37 inches on July 10.
Foliar disease is generally low in spring wheat and barley and limited to lower leaves. Tan spot continues to be the most common foliar disease in wheat. Leaf rust can be found at very low levels in the region. Fusarium head blight spore trapping at Carrington has indicated essentially no scab spores and the operation has been temporarily suspended until significant rainfall occurs. As of July 9, the ND canola sclerotinia risk forecast map indicates this region is generally at low risk for sclerotinia (white mold) infection. A recent survey of 25 sunflower fields in this region for downy mildew has indicated incidence of 0-4%.
Emergence of orange wheat blossom midge adults should be completed throughout the region. Reports of spraying for the insect have been limited to northern Barnes County.
Thistle caterpillar presence and feeding on soybean is common. The insect can occasionally be found in canola and sunflower fields. Aphids numbers continue to be very low. Reports of European corn borer moth and larvae are limited.
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center