Crop & Pest Report - All
Wheat Midge Update
Wheat midge is near the end of its flight (>1,600 accumulated DD, base of 40 degrees F; see map below). 2014 wheat midge development is behind the 5-year average, an estimated 4 to 10 days (see map below). The crop stage of wheat fields surveyed by the IPM scouts is variable, ranging from jointing to anthesis (see map below), and depends on the locality and planting date. Any late planted wheat will be at higher risk for wheat midge infestation now. If we get rainy weather, wheat midge survival can be prolonged and wheat that is in the heading crop stage will be at highest risk.
Additional information on scouting and the wheat midge forecast was printed in Crop & Pest Report No. 9.
Time to Scout for Banded Sunflower Moth
IPM scouts are detecting increasing numbers of banded sunflower moths in pheromone traps. Sunflower crop development is in the vegetative growth stages to R3 in surveyed fields of North Dakota. Sunflower should be scouted for banded sunflower moth eggs or adult moths when most of the plants in the field are at plant stage R3 (distinct bud elongated ¾ inch above the nearest leaf, yellow ray petals not visible). See NDSU YouTube Video on Banded Sunflower Moth Egg Scouting and the NDSU Extension Publication E823 Banded Sunflower Moth for more information.
Banded sunflower moth (just like sunflower moth) causes similar damage where larvae tunnel through the seeds. Larvae may consume part or all of the contents of the developing seed, and can cause significant yield losses when populations are at the economic injury level.
Sampling sites should be at least 75 to 100 feet from the field margins. In monitoring a field, use the X pattern, counting moths on 20 plants per sampling site ( 5 sampling sites) to obtain the total number of moths per 100 plants. Sampling should start in the late bud stage (R3), usually during mid-July and continue through late flowering (R5.7).
Economic Thresholds for Banded Sunflower Moth:
Oilseed sunflowers - Due to the market value of oilseed sunflowers at 19 cents per pound, the threshold is very low for adult moths this year at one moth per 100 plants when insecticide costs are ≈$8 per acre. The egg threshold is 3-4 eggs per 6 bracts assuming 18,000 to 20,000 plants per acre, $8-10 per acre for insecticide costs and 19 cents per pound.
Confection sunflowers - Industry standards are set very high for minimal insect damage, as a result insecticides are applied a minimum of two times, once at early flowering and again 5 to 7 days later. With this type of insecticide program, it should provide a window of protection and negligible seed damage from the major seed-infesting insect pests (banded sunflower moth, sunflower moth, and red sunflower seed weevil).
Sunflower Moth Detected in Traps
One to two sunflower moths per trap per week were detected in IPM scout’s pheromone traps in Golden Valley, Stark and Cass Counties. The sunflower moth migrates to North Dakota from southern states each year. The adult moth is gray, and about 0.4 inch long and 0.75 inch wingspan. Females deposit eggs on the face of the flower during bloom. Damage is caused by the larvae tunneling through the seeds of sunflower heads in late July - August. Scout for the adult moth in the early morning or evening when they are active. Inspect 20 heads at 5 sampling sites per field (total of 100 plants).
The economic threshold is 1 to 2 moths per 5 plants or an average of 4 moths per trap per day in pheromone traps. If traps catches are less than 1 moth per trap per day, the infestation is considered non-economic. Since female moths lay eggs on the face of sunflower heads, insecticide should be applied in early flowering (R5.1 - R5.3). Early maturing sunflower fields will be at higher risk.
Consult the ND Field Crop Insect Management Guide 2014, E-1143, NDSU Extension Service, for a list of insecticides registered for sunflower moth control.
Scout for Soybean Aphids
The soybean aphids have arrived right on time! The IPM Crop Scouts have surveyed over 82 soybean fields last week and soybean aphids were observed in Stutsman, Sargent and Cass Counties of North Dakota. Soybean aphids were low ≈10% incidence and <25 aphids per plant on average. Other neighboring states also have reported non-economic populations of soybean aphids.
Begin scouting soybean fields to determine if soybean aphids are present in fields. See the NDSU YouTube Video on Scouting for Soybean Aphids. No treatment is recommended until aphid densities reach the economic threshold level of 250 aphids per plant and when populations are actively increasing in 80% of field. Early treatments are discouraged so insecticides do not reduce the presence of beneficial predators and parasites.
The critical growth stages for making most soybean aphid treatment decisions is the R1 (beginning bloom) to R5 (beginning seed) stages. Soybeans surveyed are in the vegetative V1-V4 to R3 (beginning pod) crop stages. At R6 (full seed), treatment is discouraged. Research trials throughout the north central states have not demonstrated a yield benefit to treating soybean for soybean aphid management at the R6 and later stages.
Consult the ND Field Crop Insect Management Guide 2014, E-1143, NDSU Extension Service, for a list of insecticides registered for soybean aphid control.
Small Grain Herbicides with Fungicides
The following is from an email thread with Dr. Kirk Howatt, NDSU Weed Scientist.
The NDSU weed guide page 86 says not to apply 'Huskie' with strobilurin fungicides. The label says not to apply tebuconazole products with 'Huskie Complete'. I've been to agronomy company meetings where the presenter said I would get bronzing with Headline (strobulurin) but not Propimax (tebuconazol) when tankmixing with 'Wolverine'. Is there a misprint somewhere?
Answer: Propimax is propiconazole not tebuconazole. While I have seen very slight bronzing response when mixtures include tebuconazole, I have not observed when propiconazole has been associated with injury. However, this pales in comparison to the possible leaf scorch that has occurred with strobuluron combinations. It does not always happen and maybe not even that often, but when it happens it is quite noticeable. Severe leaf desiccation has not reduced yield in my trials despite the degree of visible injury.
Extension Weed Specialist
Weather/Crop Phenology Maps
Associate Professor of Climatological Practices
Immediate risk of scab and sclerotinia stem rot has decreased over the past 2 weeks with drier, less humid weather across the region. Farmers are keeping on the safe side and applying fungicide by ground and air. We are starting to see scab in the winter wheat and early seeded spring wheat. Bacterial blight on winter wheat is also being found and a little bit of blackleg in the canola. On the insect side, grain aphids are finally being found in low numbers. The region is looking forward to warmer temperatures to give our row crops a needed boost in crop development.
Area Extension Specialist/Agronomy
Unintentional (and Unware) Herbicide Movement
The following is from a ND grower who has made an interesting observation. It may be too late to rectify these ‘trespasses’ this year but we can be mindful next year to reduce this potential source of crop injury as much as possible.
Rich: I compliment you on your hard work on promoting soil applied herbicides for corn and soybeans. Now you have to inform the farmers that a lot of those products have foliar activity and they need to be careful of drift just like any other spray operation. I have lost count on how many places I have dead or injured crop from off-site herbicide movement from neighbors spraying soil applied residual products.
Extension Weed Specialist
New Corn Fertility Recommendation Circular Posted on the Web
The new North Dakota Corn Nitrogen Calculator was posted on my web site in late April. Now, the companion Corn Fertility circular is available on my web site and on the NDSU Extension web pages. For my web site, search for <Dave Franzen NDSU>, choose <Dr. Dave Franzen’s Homepage>, scroll down to <Extension Publications> and the first on the list will be the new circular. The web address is:
In about a month, the algorithms developed for use in directing corn in-season N application with either the GreenSeeker or Holland Crop Circle active-optical sensors should be published. It is presently in the final stages of review. Thanks again to the North Dakota Corn Council, Pioneer Hi-Bred, Int., and the International Plant Nutrition Institute for funding the research behind these publications.
NDSU Extension Soil Specialist
Disease Update: North Central North Dakota
Stripe rust of wheat was observed in Renville County, ND in winter wheat on July 15, 2014 (Fig. 1). The incidence of the disease was very low. The observation of this disease in Renville County indicates that stripe rust likely is present in southern North Dakota counties also, and there are chances of it spreading to spring wheat if favorable conditions prevail.
If weather conditions are favorable for rust development and rust is getting severe, then growers may want to consider a spray with an effective triazole fungicide at Feekes 10.5.1 (early flowering), which will help manage both Fusarium head blight and stripe rust. For suitable fungicide options refer to 2014-North Dakota Field Crop Plant Disease Management Guide PP-622 (Revised).
Area Extension Specialist/Crop Protection; NCREC, Minot, ND-58701