FROM AROUND THE STATE
ISSUE 12 July 19, 2001
WHEAT MIDGE UPDATE
The Degree Day accumulations for wheat midge emergence indicates that most areas are pass 1600 Degree Days, when 90% of the females wheat midge have emerged. The average Degree Day accumulation for our region is 1800 Degree Days. Wheat midge flight should continue until 2000 depending on favorable weather condition. Unfortunately, midge activity is flavored by the recent moist and humid weather conditions. The degree days for weather sites located in the northwest and north central regions as of July 16, 2001 include: Rolla = 1622, Columbus = 1666; Hofflund = 1777; Bottineau = 1730; Mohall = 1728; Baker = ; Cando = 1798;Turtle Lake = 1833; Minot = 1836; Watford City = 1894; Williston = 1914; and Towner = 1950.
Fields in the heading to early flower stages should be scouted for damaging levels, especially in the Northwest. Flights should begin to slow down next week in the central-southern tier of the North Central Region.
NEW Wheat Midge Night Scouting Reports
Areas with HIGH wheat midge pressures - HOT!
Areas with MODERATE pressures and limited spraying:
Areas with LOW pressures:
CANOLA INSECT PESTS
Canola fields that were attacked by the Diamondback moth during flowering are now readily apparent in the Minot area. Aborted flowers and pod feeding are visible symptoms. The second moth flight is underway now and moths should be attracted to later planted canola for egg laying.
Trap counts for Bertha armyworms are DECREASING in the "HOT" spot in Mohall-Newburg area as well as other trap sites in the North Central and Northwest Region! Check out the Canola Insect Trapping Network at:
OTHER INSECT PEST REPORTS
More 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. The chrysalis (pupae or non-feeding stage) and viral infected caterpillars (caterpillars become limp and often hang from upper leaves) can be found in the field now.
Caterpillars of the LEAFY SPURGE HAWKMOTH (Hyles euphorbiae) has been observed feeding on the leaves and bracts of leafy spurge. This biocontrol agent was introduced into North Dakota in the 1980s from Europe. In the North Central Region, it was originally released in McLean and Ward Counties. Sightings in July 2001 include: Ward (Burlington), McHenry (Velva), Pierce (Rugby), Bottineau (Bottineau), and Renville (Sherwood) Counties. The mature caterpillar (4.3 inch long) is black with yellowish-whitish spots, and a red line down the center of the back with a red rear horn or tail. The horn can look quite frightening, but it is harmless. This caterpillar becomes a large moth (>1 inch long) in 45-60 days. Although this caterpillar is very visible and its feeding damage quite noticeable, it is not considered to be a good biocontrol agent by itself.
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
During the past week (July 11-17), rainfall occurred over the entire region. Isolated areas received 3-5 inches or more of rain. Also, high winds and hail have occasionally been present in the numerous and intense thunderstorms causing lodged and damaged crops. The rainfall generally has been beneficial for small grain and canola in the seed-fill stages, and warm-season crops. Advanced development stages and warm temperatures have increased water demands by most crops. Estimates of daily water usage from NDAWN for wheat and corn emerged May 15, soybean emerged May 26, and sunflower emerged June 5 have ranged from 0.2 to 0.3 inches north of Interstate 94 and 0.3 to 0.4 inches south of I94 on July 17. Winter wheat fields and most barley fields south of I94 are nearing maturity.
Growers with late-planted wheat should be monitoring the crop for foliar and head disease. Recent weather has been favorable for disease development. For example, the NDSU small grain disease forecasting model for Carrington for flowering wheat indicated 11 of 12 days during July 6-17 were favorable for tan spot infection and 6 of 12 days favorable for leaf rust infection. As of July 16, the ND canola sclerotinia risk forecast map indicates this region is generally at low risk for sclerotinia (white mold) infection. Risk of white mold in dry bean has increased with recent weather. Thistle caterpillar continues to be a common insect concern in sunflower and soybean. Other larvae are being found in soybean including the alfalfa caterpillar. Aphids numbers in small grain appear to be rapidly increasing. POST herbicide application in soybean, dry bean, and sunflower is nearing completion.
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center