FROM AROUND THE STATE
ISSUE 15 August 19, 2004
Red sunflower seed weevils are easy to find in heads of sunflowers in North Central Region. Some areas are finding numbers above the economic threshold level of 7 weevils per head for oilseeds and 1 weevil per head for confections. There has been a wide range reported from 3 to as many as 50 weevils per head. Remember to scout fields early – starting to bloom and late bud stages. Apply insecticides (if necessary) when 50% of the plants in the fields are beginning to show yellow ray petals or 30% pollen shed, and the rest of plants in the fields are still in late bud stage. An early application of insecticide will provide the optimal timing for weevil control. Since many sunflower fields were planted late and this summer has been unusually cool, sunflower maturity is delayed and slow. Will our sunflowers mature for combining this year? I wish that I could tell you "Yes", but this is a big unknown. Producers should consider this before spending the money on spraying insecticides for controlling seed weevils, especially if their field was planted extremely late.
Concerns about sunflower head maggots, Neotephritis finalis, in the heads of sunflower are being reported. This year sunflower head maggots are being found throughout fields, not just on the edges. The larvae of the sunflower head maggot tunnels through the corolla of young blooms and seeds causing seed sterility and destroying seeds. The amount of injury depends on the stage of the sunflower crop when infested. Older sunflower heads may only have one to three seeds damaged, while younger flowers can have up to 12 ovaries of sunflower seeds damaged. The golden colored pupae about ¼ inch is easy to find in sunflower heads now. Unfortunately, little is know about its biology or control. There are no established scouting methods or economic thresholds, so control of sunflower head maggots has not been recommended in sunflowers. Although it is interesting to note that fields that were sprayed with insecticides for grasshoppers or late infestations of sunflower beetle larvae during late June or early July are absent of this sunflower head maggot. This insecticide application may have killed the adult fly, which usually emerges in early July.
The summer generation of adult crucifer flea beetles in canola has emerged and is actively feeding on green canola plants and pods in the North Central Region. Their numbers generally appear to be slightly lower than last year. Canola survey work is underway to determine the potential of overwintering populations. Reports from Langdon REC, Cavalier County, indicate that flea beetles have not emerged there yet (source: B. Hanson).
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
ROW CROP FIELD TOURS AT CARRINGTON
Farmers, crop advisers, and industry representatives are invited to attend two field tours scheduled for Thursday, September 9 at the North Dakota State University Carrington Research Extension Center. The tours will provide updates on sunflower, corn and soybean production research and recommendations.
The sunflower and corn tour will begin at 2 p.m. NDSU and USDA crop production specialists will discuss sunflower topics including hybrid selection, weed management, research update on hybrid tolerance to sclerotinia, and pest management – downy mildew, insects, and blackbirds. The corn session will include discussion on hybrid selection and corn production tips. Due to our cool growing season, the remaining portion of the corn session will focus on utilizing this year’s corn either as a grain crop or livestock forage.
NDSU, North Dakota Soybean Council, and North Dakota Soybean Growers Association will host the soybean tour, which begins at 5:00 p.m. Tour participants will be able to view research trials and hear discussion by NDSU crop specialists on soybean varieties, stand establishment, seed inoculation and plant nutrition, and pest management – aphids, disease, and weed challenges in conventional soybean. The Soybean Council at 1-888-469-6409, Web site http://www.ndsoybean.org may be contacted for more details about the soybean tour.
Additional information about the day’s tours is available from the Carrington Center at (701)652-2951, Web site: http://www.ag.ndsu.nodak.edu/carringt/.
Area Extension Specialist/Cropping Systems
Carrington Research and Extension Center