Crop & Pest Report - All
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
Sub-Surface Water Management
Tile drainage does not remove “plant available” water from the soil; it merely removes “gravitational” water that would drain naturally, if unimpeded by confining layers in the soil. The greatest benefits of tile drainage are typically realized in wet years. Drainage promotes deep root development and crops will often have better access to soil moisture during drier parts of the year. During extremely dry growing seasons it is certainly possible that a tile-drained field might have less available water at some point during the growing season than a non-drained field. Whether or not such an effect would offset the early-season positive effects of drainage is unknown, and is highly site- and year-specific. In general, where poorly drained soils exist, crop yields will be more uniform from year to year with tile drainage. Drainage control structures (also known as controlled drainage or drainage water management) can be installed to provide the potential for limiting the release of drainage water to conserve more soil water in the root-zone. Similarly, the pump in a lift station can be turned off when there is a concern about drier growing conditions.
The economics of tile drainage systems depend on crop yield response, initial capital investment for the materials and installation of the system, and any annual operation and maintenance costs (such as electricity for pumped outlets). Although crop yield response to drainage can be assessed directly, the impacts of inadequate drainage on soil quality (structure, microbial activity, etc.) are more difficult to measure and assign economic value. Many field crops show a positive response to drainage (on previously poorly drained soils), often with the best response from a combination of surface and tile drainage. The level of yield increase for a given year depends greatly on how poorly drained the soil was prior to drainage, and the timing of seasonal rainfall. Research, in various regions, has shown that over many growing seasons, average yields may increase around 10 to 15 percent, depending on the aforementioned factors. In addition to yield increases associated with adequate drainage, there may also be reductions in operating expenses on the farm due to reduced cropping inputs, less power consumption, and timely field operations. The cost of tiling depends on the materials used and the price of installation.
For more information see NDSU publication Frequently Asked Questions about Subsurface (Tile) Drainage AE1690
Tom Scherer Gary Sands
Extension Ag-Engineer U of Minnesota Extension Engineer
Hans Kandel Chris Hay
Extension Agronomist SDSU Extension Engineer
Wheat Midge Degree Day Map
Continue to scout for wheat midge from heading through early flowering (<50% flowered), especially in areas where the 2013 fall soil survey indicated moderate to high risk for wheat midge larvae (see map on right). This includes Burke, Renville, Ward, Pierce, Divide, Williams and Rolette Counties. Based on the degree day model for wheat midge, much of the north central region is at 10% to 50% emerged for the female midge (1,300 to 1,475 accumulated DD, base of 40 degrees F; see map below).
Watch For Increasing Grasshoppers
Grasshopper nymphs are increasing in some areas (see maps below) and may start moving into field edges of crops. The ditches have adequate green grass for grasshopper feeding. However, as grassy ditches are mowed for hay, grasshoppers may start moving into field edges or fields. Grasshoppers are easiest to control when they are small nymphs and concentrated in the ditches or border of fields. Any crop (wheat, barley, corn, sunflower, flax, soybean, dry bean) is susceptible to infestation from grasshoppers. Several conditions that favor increasing grasshopper populations have occurred:
- Cool and wet early spring prevented premature grasshopper hatch and insured an adequate food supply.
- Warm and dry late spring promoted uniform hatching time and good weather conditions for feeding.
Most grasshoppers are still nymphs, but a few adults have been observed. Adult grasshoppers have wings and can readily fly around to find green fields. It is important to scout field edges and within the field to determine if the field needs to be treated for grasshoppers. The action threshold for nymphs (immature grasshopper without wings) is 50-75 per square yard in field margins and 30-45 per square yard within the field. For adult grasshoppers, the action threshold is lower: 21-40 per square yard in field margins and 8-14 per square yard within the field. Consult the ND Field Crop Insect Management Guide 2014, E-1143, NDSU Extension Service, for insecticides for grasshopper control by crop.
Banded Sunflower Moth Emerging
IPM scouts trapped banded sunflower moth at one location near Carrington REC in Foster County, so emergence is beginning. Trapping results were zero for sunflower moth and Arthuri sunflower moth at all locations. Sunflower should be scouted for banded sunflower moth eggs 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). Scouting and threshold information will be provided in upcoming issues of the Crop & Pest Report.
No Soybean Aphids
The IPM Crop Scouts have surveyed over 80 soybean fields last week and no soybean aphids were observed in North Dakota. However, soybean aphids have been reported sporadically in Iowa at low densities (Source: E. Hodgson, Iowa State University). So, continue to be vigilant in scouting. We usually observe our first soybean aphids the last week of July or early August.