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ISSUE 5  June 4, 1998

North-Central ND


    Crucifer flea beetle populations peaked last week. This week, counts are expected to remain steady or decrease with the cooler, wet weather. Reports indicate that some of the fields are still being treated where populations are above the 25% damage threshold. Continue to scout critical fields in the seedling stage.

    Diamondback moth Pheromone trap counts have increased in certain areas (Minot, Ward County, and the Bottineau, Bottineau County), but in general trap counts are low. Diamondback moth eggs and larvae were observed feeding (5/29/98) on the dormant seeded canola that was planted last fall. Plants were in the budding stage with inflorescence visible at the center of rosette or raised above the level of rosette. Adult moths were also observed flying around in the canola plot. Some larval feeding was observed on the leaves and the inflorescence terminals which were cut in half. Larvae feed on all plant parts but prefer the undersides of leaves, crevices, and young buds. The main damage is the chewing of the epidermis of pods. The pheromone trapping network will help us monitor the populations as the spring planted canola matures, and hopefully give us an early warning of any potential infestations.


    Orange Blossom Wheat Midge
Wheat planted now should be at low risk for infestation. As of May 31, 1998, the following DD (using a base of 40F) has accumulated: Minot, Ward County = 816; Mohall, Renville County = 703; Bottineau, Bottineau County = 716; Towner, McHenry County = 700; Rolla, Rollete County = 651; Columbus, Burke County = 643; and Turtle Lake, McLean County = 791.


    Sunflower beetle adults and eggs are still common in early planted sunflower fields. Continue to scout fields for the economic threshold level for adult beetles—one to two per seedling.


    Grasshoppers!!! Grasshoppers!!! Still high numbers of mostly 1st-3rd instar grasshopper nymphs (young) have been observed in western North Dakota! Remember that the grasshopper threshold table is to be used as a general guide to indicate a "grasshopper threat." Seedlings, especially broadleaf crops (e.g., sunflowers), are less tolerant of grasshopper damage. So, use the average leaf defoliation (30% threshold) as a second guide to determine the need for treatment. A grasshopper project is underway at the North Central Research Extension Center to determine the effect of water pH on insecticide efficacy.

Kent McKay
Area Extension Specialist/Cropping Systems

Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
Minot, ND

South-Central ND

    Soil moisture conditions are generally adequate in south-central ND. Areas in northern Burleigh, Kidder, and Stutsman counties received significant hail damage to crops last week. A small percentage of flax, bean, and sunflower acreage is still being planted. Alfalfa harvest is about 5 to 15 percent complete, but progress should quickly accelerate because of advancing plant development and injury from cold temperatures. Alfalfa yield potential appears very good. Herbicide application in small grain continues despite wind, rain, and cool temperatures. Air temperatures ranging from the upper 20's to the low 30's were reported on June 3. Some injury is being found or reported on alfalfa, corn, small grain, canola, and beans. The major concern is potential damage or death of emerged dry bean and soybean.

    Leaf spot disease in small grain is increasing in intensity with recent rainfall. The disease includes tan spot, Septoria, and very low levels of leaf rust. Scattered wireworm and cutworm reports continue to be received and some crop is being replanted. A major infestation of Hessian fly larvae was detected in a Stutsman County wheat field. Monitoring for grasshoppers should continue especially in the southwest part of this region. Currently, a common concern with controlling the abundant weed population is herbicide application during cool temperatures.

Greg Endres
Area Extension Specialist/Cropping Systems
Carrington Research Extension Center

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