Crop & Pest Report - All
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
Soybean Root Rots
We have received many questions about dying soybeans. The cause is, at least in part, severe root rot in much of the state. The reason we are seeing so much disease this year is related to our long wet spring. The abundant soil moisture provided a perfect environment for infection and disease development right after planting.
Most of the photos we have seen show classic symptoms of pre- and post-emergence damping off (the only difference is whether the plant dies before it has emerged or after it has emerged; the result is the same). Damping off and root rots can be caused by many different pathogens; Pythium species, Phytophthora sojae, Fusarium species and Rhizoctonia solani all come to mind. Unfortunately, it can be very difficult to determine which pathogen is causing the primary disease. In many cases, it is likely that multiple pathogens are acting synergistically to cause the damping off. In some cases there may be one primary pathogen, but as soon as the plant begins to die it is often colonized by other fungi, making identification difficult.
What to expect later in the season?
There are many small areas of dead plants in soybean fields in the area. The disease generally won’t ‘spread’, but it is possible that ‘healthy’ plants may not look very healthy a month from now. The reason is related to the severity of the root rot infection and plant stress. While the most severely infected plants are already dying, plants that aren’t as severely infected may appear unaffected. However, those moderately infected plants have compromised root systems and may struggle as the season progresses. This is particularly true if we turn dry and/or hot in August. In that situation, it is possible that the damage to soybeans may be more extensive than we are currently seeing. If temperatures remain moderate and rainfall is sufficient, we may not see any ‘spread’ of disease.
What to do next year?
There is no management tool that we can use to help the soybeans this season, but it is important to consider your options for upcoming seasons. If you have severe root rots, you might consider lengthening your rotation, using a fungicide seed treatment, using a ‘defensive’ variety, and incorporating a Phytophthora resistance gene (or switching it if you know for certain Phyophthora is your pathogen). Ultimately, the environment is going to make a huge difference on how much root rot we have, but if you stack the deck in your favor, you will be better off.
Not Sudden Death Syndrome.
Sudden Death Syndrome refers to a specific disease can suddenly kill plants in the mid-reproductive stages. The plants look healthy, are setting pods, and then suddenly die. Fortunately, Sudden Death has not been confirmed in North Dakota. For now, this is one severe disease issue that we are watching for, but don’t have to actively manage yet!
Extension Plant Pathologist, Broad-leaf Crops
Glyphosate as a Pre-Harvest Aid in Small-Grains
Winter wheat is approaching maturity and early planted barley is not far behind and therefore, harvest will soon be upon us. Glyphosate can be used as a pre-harvest aid in small grains to control green weeds and to speed up uniform ripening of the crop. Control of perennial and other green weeds with glyphosate just prior to harvest is usually disappointing as weeds at this time are tall, nearing maturity and slow-growing. Glyphosate has been shown to reduce the amount of time that it takes for a crop to reach harvest moisture if conditions are not favorable for drying. The reduction in the time to harvest is usually on the order of a couple of days, however. Since glyphosate is a systemic herbicide it can take from seven to ten days to effectively kill the growing parts of the crop, and therefore the dry down process is not immediately visible. Applying glyphosate too early can reduce yield, test weight and seed germination. Because germination of the developing kernel can be affected when glyphosate is applied too early, it should not be applied to fields that will be used for seed or on barley intended for malt. The optimum time to apply glyphosate pre-harvest is when the crop has reached physiological maturity. For most varieties of wheat this occurs at a grain moisture content of about 30% (20% moisture is the recommended timing for barley). At this moisture content the grain will be in the hard dough stage and if you run your thumb nail across the kernel, the indentation will remain. Since not all kernels arrive at physiological maturity at the same time, be sure to sample multiple kernels to be sure that you are not spraying too early. A visual indicator that can also be used to determine physiological maturity is when the peduncle, the portion of the stem just below the spike, turns from green to yellow. Jochum Wiersma (University of Minnesota Extension Service) has published photos that nicely show these differences. Pre-harvest applications of glyphosate must be made at least seven days before harvest. Always read and follow label directions.
Extension Agronomist for Cereal Crops