ISSUE 13 August 12, 2010
North Central ND
Fields in the area are in the R2 (early bud) to R6 (wilted ray petals) stage. Early flowering (R5.1) is a good timing for managing several key insect pests, including banded sunflower moth, sunflower moth, red sunflower seed weevil, and Lygus bugs (confection only) with a follow-up spray approximately one week later, especially in confection sunflowers. It is generally not possible to control all insect pests in sunflower with one insecticide application.
I’ve received questions this week about sunflower insecticides and bee toxicity. In general, earlier applications before most of the sunflowers are in bloom, will be better to protect foraging bees. In terms of time of day, the best for protection of bees is late evening, followed by early morning, with the worst during the middle of the day when bees are actively foraging. In regards to toxicity of registered insecticides, Asana, Baythroid, Cobalt, and the lamda-cyhalothrin formulations (e.g., Grizzly, Kaiso, Lamda-Cy, Silencer, and Warrior) have the highest toxicity to bees, with chlorpyrifos (e.g., Lorsban , Warhawk, Yuma), Sevin, deltamethrin (Delta Gold) and Mustang with less toxicity to bees than the first group of insecticides (nysipm.cornell.edu/publications/EIQ.html).
Banded sunflower moth trap catches have continued to be high with counts of more than 100 moths per week. Sunflower moth trap catches, however, have remained quite low. Sporadic sunflower midge damage has been found in fields throughout the area with a report of a severe outbreak south of Harvey. A number of fields in the Mohall area have been impacted by sunflower head clipping weevil. Damage was heavy along the edges of fields with little or no damage in the interior. Insecticides are generally not recommended for control of this pest.
Sunflower head clipping weevil damage.
Downy mildew was found at low levels in 30% of sunflower fields scouted in
Bottineau, McHenry, and Renville Counties. Foliar fungicides are not effective
against this disease.
Sunflower rust has been seen at low levels in the area. Be on the look-out for this disease, especially with increased occurrence of rain.
The recent rain showers have increased our risk for scab in late planted wheat in the area. Winter wheat harvest is well underway. Preliminary indications are that yields are above average to exceptional.
We have continued to find wheat streak mosaic virus in spring wheat and durum
fields in north central and the northwestern counties. As producers consider
planting winter wheat this fall, proper management for wheat streak mosaic virus
(WSMV) will be critical. For more information, please refer to the article on
WSMV in this week’s version of the Crop and Pest Report and the information on
our North Central Research Extension Center website (www.ag.ndsu.edu/NorthCentralREC).
Soybean aphid populations have been low throughout the area. Grasshopper populations are building but still below threshold in the fields we have scouted. Green cloverworms are common in soybean fields but generally below threshold.
Field Peas and Lentils:
Pea harvest has begun in the area. We have received some reports of white mold problems in lentil in the area. In general, it is not economical to apply a fungicide on lentils this late in the season.
Crop Protection Specialist
North Central Res. Ext. Center
According to NDAWN (North Dakota Ag Weather Network) data, the region
received 0.2 inch (Linton) to 1.9 inches (Pillsbury) of rain during August 1-10.
The region’s August 10 rain was welcomed in most areas for row crops. According
to NDAWN, corn water use during the week of Aug. 4-10 averaged 0.2 to 0.25
Winter wheat, barley and field pea harvest is near completion. Harvested spring wheat acres may average in the range of 30 to 50 percent complete for the region. Preliminary harvest reports indicate good yield and generally acceptable protein levels for wheat. Most corn is in the blister (R2) to milk (R3) growth stages. Accumulated growing degree day units for April 25 planted corn and up to August 10, ranges from +72 units at Fingal to -159 units at Carrington, compared to the long-term average for this period. Soybean and dry bean are in the seed development stages, with some early-maturing dry bean varieties showing striped pods.
Sunflower is in the flowering (R5) to wilting ray flower (R6) stages. Yield potential for corn and broadleaf crops continues to be generally positive. Continue checking for insect threats, including aphids and spider mites in soybean, and grasshoppers for all ‘green’ crops. Sunflower growers should continue to monitor for leaf rust.
The Carrington RE Center’s annual row crop tour, featuring production research and recommendations for corn, dry bean, soybean and sunflower is scheduled for September 2.
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center