FROM AROUND THE STATE
ISSUE 11 July 11, 2002
WHEAT MIDGE EMERGENCE IN NC AND NW REGIONS
The Degree Day accumulations for wheat midge emergence indicates that most areas are near 1300 Degree Days when the females wheat midge begins to emerge. The degree days for the weather sites located in the northwest and north central regions as of July 8, 2002 includes: Bowbells = 1204; Rolla = 1241, Berthold = 1304; Bottineau = 1320; Mohall = 1329; Cando = 1345; Baker = 1371; Harvey = 1376; ; Towner = 1413; Minot = 1415; Turtle Lake = 1423; Watford City = 1424; Karlsruhe = 1441; Williston = 1454.
It is time to get out and scout fields in the heading to early flower stages. The economic thresholds are:
Note: The plate traps do NOT indicate if fields are at threshold. It only indicates whether wheat midge are flying.
When to scout:
Spray timing based on:
- late heading (80-100%) = optimal control
- early flowering still give good control
- mid-late flowering - poor control, too late!
time of day
- spray in evening (after 6 PM) = optimal timing
- morning is the next best timing before 10 AM
- avoid mid afternoon applications especially when its hot!
Consider using the <25% flowering crop stage, when spraying for both wheat midge and Fusarium head blight (scab) control.
SUNFLOWER: SUNFLOWER BEETLES
Sunflower beetles has caused some localized problems north of Carpio. Larval counts are above the economic level of 10-15 larvae per plant. A few adults and eggs can still be found on sunflowers. Most of these eggs will hatch by the end of the week. These fields will need to be sprayed soon to prevent further defoliation.
CANOLA: BERTHA ARMYWORM
Pheromone trap catches from Bottineau and Renville Counties continue to be high. Some cumulative trap catches for bertha armyworms are: Bottineau=346, Gardena=590; Westhope= 252-544, Souris= 130; Newburg=147, and E. Mohall=550 moths. Trap catches in other areas, like Minot and southwest ND, are much lower, about 40-80 cumulative trap catches. As cumulative trap catches approach 900-1200 moths, canola fields are at moderate risk and should be scouted regularly for larvae or damage. If cumulative trap catches are 1200-1500 moths, canola fields are at high risk and should be scouted frequently for larvae or damage. Check out the trap counts on the "Canola Insect Trapping Network" website:
Growers in this "HOT" spot should continue to keep a close watch on their blooming canola and mustard fields for localized infestations. Bertha armyworm eggs have been found in fields in Bottineau County. These eggs will hatch in about 7 days into the larvae that will start to feed on the foliage and pods for six weeks. Fields should be scouted next week for threshold levels. The economic threshold is 18-22 larvae per square yard when larvae are feeding on the leaves. If larvae are feeding on the seed pods, the threshold should be lowered.
GRASSHOPPERS HOPPING ON FLAX AND SMALL GRAINS
Grasshopper damage to flax and small grains have been reported for McLean, Ward, and Divide Counties. A wide range of instars can be found in the field from 2nd to 4th instars. Grasshoppers will feed more aggressively as they mature. For flax, the only insecticides registered are sevin and malathion. Malathion is a quicker knock-down than sevin, but the residual is short. As the ditches are hayed, more grasshoppers will start moving into crop lands. Consider spraying the ditches around the fields as well as the field / field edges to keep numbers low. Asana and Warrior are labeled for non-crop situations but have a "no haying restriction". Further, the Warrior label limits use to treating sites adjacent to labeled crops only, like wheat or sunflowers.
Area Extension Specialist/Cropping Systems
North Central Research Extension Center
During July 3-9, 2 to 2.5 inches of rain was received at Carrington, Dazey, McLeod, Streeter, and Wishek, while other areas received at least an inch as recorded at NDAWN sites. Estimated daily crop water use on July 9 in south-central ND: corn (May 15 emergence) = 0.08-0.26 inches; wheat (May 15 emergence) = 0.09-0.29 inches; soybean (May 29 emergence) = 0.06-0.21 inches; and sunflower (June 5 emergence) = 0.08-0.25 inches. The small grain crop condition generally is poor south of Highway 200, especially westward from Highway 281. Cool-season crops generally are in good condition north of Highway 200. Across the region, recent rains have improved the condition and outlook for corn, soybean, dry bean, and sunflower.
Herbicide application continues in soybean, dry bean and sunflower. In southern counties, winter cereal and barley harvest will start soon. Haying is in progress, including small grain fields and CRP in drought-stricken counties. Forage and livestock water supplies are being tested for nitrate levels in drought-stricken counties. Growers should continue monitoring for grasshoppers. In the drought areas, hoppers will likely move into the green, late-planted crops.
Sheridan, Wells, Eddy, and Foster county wheat nearing the heading stage should be closely monitored for leaf disease including leaf rust. Foliar fungicide application for scab and leaf disease should be considered if adequate yield potential exists. According to the NDSU small grain disease forecasting model, during June 26 to July 8 for flowering wheat at Carrington, conditions favorable for tan spot infection were present 7 of 13 days and favorable conditions for leaf rust occurred 4 of 13 days. Disease forecasting models including Fusarium head blight can be viewed at the following website:
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center