FROM AROUND THE STATE
ISSUE 4 May 28, 1998
Small grain seeding is wrapping up except in areas where wheat midge has been a concern. In those areas, many growers have waited for the growing degree days to past 600 before seeding wheat. Seeding of sunflowers and dry beans is about 85 % complete which is way ahead of the five year average.
Top soil conditions are dry to very dry in about 30% of the area, especially southern Ward County, McLean and Mountrial counties. Most growers are now turning to spraying weeds. Most troublesome weeds are kochia, russian thistle, wild oat, and Canada thistle.
No disease problems being reported. The main problems have been in the insect arena.CANOLA
Crucifer flea beetle populations have increased dramatically this past week, and are expected to continue into this week. Trap and field counts have doubled in numbers! Growers have begun to spray Warrior for flea beetle in Canola in isolated areas, especially in Renville and Bottineau Counties. Gaucho treated canola is performing very well compared to the untreated with research studies this spring at the North Central Res/Ext Center, Minot. Continue to scout critical fields in the seedling stage.
Diamondback moth Pheromone traps continue to be set out in newly emerged canola fields for the cooperative trapping network. Trap counts remain relatively low (<10 moths per trap day) and unchanged from the previous week. Trap counts are expected to increase as new migrates move into the area, probably in June.
Orange Wheat Blossom Midge Most of the area is past the high risk window of 600 Degree Days (DD) for planting wheat to avoid peak emergence of the midge. Wheat planted after this window should be at lower risk for damage. As of May 25, 1998, the following DD (using a base of 40°F) have accumulated: Minot, Ward County = 696; Mohall, Renville County = 597; Bottineau, Bottineau County = 609; Towner, McHenry County = 600; Rolla, Rollete County = 555; Columbus, Burke County = 542; and Turtle Lake, McLean County = 670.
Thrips were observed feeding on spring wheat, winter rye, barley, and peas in a cropping system trial, south of Minot! Look for thrips underneath the stem sheath, joint, collar and on the head of grain crops. Barley thrips are very small between 1.1 to 1.8 mm long and usually dark brown-black in color. An infestation of one adult thrips per stem can result in a loss of 0.4 bushel per acre.
Wheat streak mosaic virus and tan spot was observed and confirmed on winter wheat at the North Central Research Extension Center in Minot last week.
Sunflower beetle adults have increased in numbers, and can be observed feeding on the foliage, mating, and egg laying. Eggs are present on the underside of leaves of mostly young plants in the vegetative stage (V4). Egg laying occurs over two or more weeks and approximately 200 eggs are produced by one female. Larvae will emerge from the egg in about one week. Larvae chew on foliage for about six weeks, usually at night. If adults or larvae are numerous, field can be severely defoliated. Scout fields for economic threshold levels: Adult - one to two per seedling. Larvae - 10 to 15 per plant will cause 25% defoliation on the upper 8-12 leaves. Control is warranted if the average defoliation is 25-30% and larvae is in the early stages of feeding.
Cutworms have progressed into the pupal or resting stage in many areas. Control is NOT effective at this stage. Some late instar larvae can still be observed.
PASTURES AND FIELD CROPS
Grasshoppers High numbers of mostly 1st-2nd instar
grasshopper nymphs (young) have been observed in western North Dakota! Some fields have
been above economic thresholds of 50-100 nymphs per square yard and have required an
insecticide treatment to save crops. Some "hot" spots that have been reported
are Bottineau County near Newburgh, Renville County near Mohall, and McLean County near
Washburn. As grasshopper nymphs continue to emerge from egg-laying sites, newly planted
fields should be monitored until plants are past the seedling stage. If numbers are
threatening, inspect fields every other day, otherwise, every week. Broadleaf crop
seedlings (sugar beets, sunflowers, canola, dry beans, and soybeans) are less tolerant of
grasshopper damage than small grains. Hatching grasshoppers can disperse quickly and
devastate these broadleaf crops in the seedling stage.
Area Extension Specialist/Cropping Systems
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center