FROM AROUND THE STATE
ISSUE 5 May 31, 2001
INSECT PEST UPDATE
Crucifer Flea Beetle: For the north central region, the peak flight activity for flea beetles started late last week and is expected to continue into this week based on Minot trap catches. Overall, the feeding activity or damage levels are still lower than last year except for some "hot"spots like McLean, Mountrail, southern Ward, and Renville-Bottineau Counties. There are more reports for this week of fields being treated with Capture (FMC) for flea beetle control. Capture should provide at least 7-10 days of residual protection. Most of the early planted fields should be getting to the 4-6 leaf stage and will hopefully outgrow any more flea beetle damage.
Diamondback moths (DBM) were trapped in very high numbers (273-393 per trap week) near Belden and Parshall in Mountrail County during May 15-24. There’s increasing trap counts in other areas like Minot and Carrington, but very low numbers at other trap sites in McHenry, McKenzie, and Divide Counties. There are three generations of DBM per year in North Dakota. The second generation is usually the most threatening to the canola crop, because the larvae feed on the developing flower buds and pods. However, this early infestation will need to be monitored in areas with high trap catches. A canola field near Birtle, Manitoba had an average of at least 2 DBM larvae per plant with most plants were showing some feeding damage at the 2-3 leaf stage. The field is scheduled to be sprayed with insecticide shortly (source: J. Gavloski). DBM larvae have been observed in canola fields at the NCREC in Minot. There is no economic threshold for DMB larvae in young canola plants. For field identification, the larvae are lime green in color with a forked posterior end, and about a ½ inch when mature. When disturbed, the larvae also have the peculiar habit of dropping down from a plant on a silken thread.
Sunflower beetle and Apion Stem Weevil are emerging and actively searching for those early seeded sunflower fields.
Tree & Shrubs
Yellow-headed Spruce Sawflies have been observed feeding on spruce trees already! Check your spruces in your shelterbelts and ornamental plantings. Mature larvae are ¾ inch long, and dark glossy green witha light lateral stripe and reddish brown head. Larvae feed for 30-40 days consuming the new foliage first and then the older needles. Sawflies tend to attack the same trees year after year, which can kill the tree or make it susceptible to attack by other insects or adverse weather conditions like drought. Tempo, Acephate, and Sevin are a few of the insecticides labeled for use against sawflies in ND.
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
During the past week (May 23-29), rainfall recorded at NDAWN sites in south-central North Dakota ranged from 0.04 inches (Oakes) to 0.63 inches (Harvey and McHenry). Most of the region received at least 0.1 inch of rain. On May 29, black soil temperatures at the 4-inch depth ranged from 58 to 66 degrees F at NDAWN sites.
South of I-94, seeding of small grain and silage corn acreage is nearly complete. Soybean, dry bean and sunflower planting continues and should be completed within a week. Alfalfa harvest has begun or will begin soon in counties bordering South Dakota. Also, winter rye is heading in southern counties. North of I-94, percent of small grain seed seeded ranges from <50 to complete. Bean and sunflower planting continues. The prevented planting program is a common consideration, especially for growers in Eddy and Wells counties. Based on growing degree day units, wheat emerged on May 1 was in the 5- to 6-leaf stage and wheat emerged on May 15 was in the 3 to 3.5-leaf stage as of May 29.
Reports of crop insect and disease problems are low. Late-planted canola should be frequently monitored for damage from flea beetle and other warm-season crops should be scouted for presence of cutworms. Wheat seeded on last year’s wheat ground should be monitored for tan spot. Fungicide tank mixtures with POST herbicides is an option if leafspot disease is present on susceptible wheat varieties and wet weather continues.
Late-season weeds are present including nightshade species, annual smartweed, and common purslane. Besides crop planting, POST herbicide application in small grain, canola, and corn is a common activity when weather conditions are cooperative.
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center