NDSU Crop and Pest Report


ISSUE 9  July 1, 2004

North-Central ND

Warm weather is causing the late hatching GRASSHOPPERS to emerge and numbers will probably increase this week. Continue monitoring the field edges and entire fields of agricultural crops for young grasshopper nymphs.

Canola Insect Pest: Trap catches for DIAMONDBACK MOTHS and BERTHA ARMYWORMS are VERY LOW and pose NO THREAT to canola crop.

Trap catches continue to be low for diamondback moth (<50 per trap week) and bertha armyworm (<5 per trap week) this past week throughout the southwest, north central and northwest regions of North Dakota.

BARLEY THRIPS are moving from overwintering sites and numbers are increasing in barley fields.

Barley thrips are small (about the size of a dotted "i") dark brown to black insects that can cause economic yield losses in barley, especially during hot, dry years. Early seeded barley is the preferred host for thrips. Scouting for thrips should begin prior to heading. Peel the upper leaf sheath and count the number of dark (adult) and light (immature larval) thrips inside the leaf, and on the stem and developing head. Immature barley thrips do damage equal or greater than the adult stage by puncturing the plant cells and sucking out the content. Injury caused by barley thrips results in the loss of photosynthetic tissue, and as damage progresses, drying and death of leaves, stems and grain heads. Feeding symptoms include a characteristic whitened or bleached appearance of plants. Pollen feeding by barley thrips may result in poor head filling and reduced seed germination. At present, the economic threshold is about 8-10 thrips per plant before the crop is fully headed. Once the crop heads the insect’s damage is done and no treatment is advised. Registered insecticides for barley thrips control are methyl parathion at 4-6 fl oz per acre.

Small Grain Disease Update:

IPM Scouts have been finding increasing severity levels of RUST (>20%) on spring wheat near Upham, McHenry County.

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


Southwest ND

Weather conditions continue to be dry with most NDAWN locations in the southwest part of the State receiving less than 0.25 inches of precipitation. The exception this past week was at the site near Mandan, which received 0.43 inches. Rainfall at Hettinger for the month of June was 0.29 inches – well below the 48-year average of 3.40 inches. At Dickinson, rainfall was 0.57 inches for the month. The 105-year average for June is 3.62 inches. There was only one other June in the 105 year history of weather records kept at Dickinson where rainfall was less than 0.57 inches and that was in 1919 (0.52 inches). There have been three years when precipitation has been less than an 1 inch – 1900 (0.83), 1919, and 1936 (0.92).

Reports of grasshoppers have been received from scattered locations. In addition, as hay is being harvested soils are warming and grasshoppers hatching. Producers should monitor ditches, hatching areas, and fields for grasshopper activity and treat when threatening levels are reached.

Freeze damage has become evident from the subfreezing temperatures experienced on June 18. It should be relatively easy to spot sterile florets and heads at this point and begin making decisions as to harvesting the crop for grain or forage.

Corn and sunflower development is occurring more rapidly with the warm weather. Subsoil moisture is keeping the wheat and barley crop developing and growing but plant height is short.

The Dickinson Research Extension Center Field Day is scheduled for July 7. Activities and times are listed on our web page at:


or call us at the Center for more details. The public is invited.

Roger Ashley
Area Extension Agronomist
Dickinson Research Extension Center

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