Crop & Pest Report - All
Weather/Crop Phenology Maps
Professor of Climatological Practices
Weather Forecast: May 26 – June 1
During the past 7 days, twoprecipitation events brought much needed moisture to many parts of North Dakota. The second of those events occurred yesterday and that system will continue to bring at least some scattered rain to especially the northern portion of the state today (Thursday). Additional rain possibilities are expected in the next several days as well.
If fact, this upcoming week, the pattern will be one that some portion of North Dakota may record rain on most days. Meaning, that although precipitation amounts will be highly variable, the persistent dry pattern that much of the region experienced during the first half of May has now transitioned to one that will bring more frequent rainfall events to the state. As previously noted, there should be some scattered activity today, but a more widespread rain system is expected to arrive on Friday into Saturday. The rest of the Memorial Day weekend the precipitation chances will become more isolated for Sunday and Monday with another more widespread rain expected next Tuesday or Wednesday.
Even with the associated clouds with the rain moving in and out of the area for the next several days, temperatures are expected to be slightly above average through the middle of next week (Figure 1). The projected Growing Degree Days (GDDs), base 34°, 44° and 50° for the period May 26 through June 1, 2016 are presented in Figure 2.
Assistant State Climatologist/Meteorologist
(701-231-8209) Twitter: @darylritchison
Spotty rains occurred across the region over the past week. Most fields in the southwest could use a good shot of rain. Saline spots in fields are showing through with the dry weather over the past week. While there hasn’t been much for rain the weather has allowed local producers to nearly finish planting corn and get a good start on sunflower planting. Early planted corn is beginning to emerge.
Stripe rust was found in Hettinger on a susceptible variety of winter wheat this week. Be sure to scout fields to identify any potential issues whether it is diseases, insects, nutrient deficiencies, or weeds.
Area Extension Specialist/Cropping Systems
The region’s NDAWN stations indicate rainfall ranging from 0.1 inch (Harvey and Oakes) to 2 inches (Cooperstown), with the eastern half of the region generally receiving an inch or more during the past week (May 18-24).
Winter cereals are in the flag leaf to heading growth stages. Barley and spring wheat seeded the first-half April are at the 4-leaf to early jointing stages. Corn planted on April 30 has accumulated 215 to 200 growing degree day (GDD) units through May 24. April-planted corn is in the two-leaf (V2) stage. Nodal roots are developing on corn (see picture) and will be the primary root system by the V6 stage. Soybean planted the first week of May or earlier is in the unifoliate stage (VC). Planting of dry bean and sunflower should be essentially complete by the end of May. Post-emergence herbicide application in barley, spring wheat and corn is in progress.
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center
Seeding activity is wrapping up for canola, soybean and edible beans. A welcome rainfall event occurred over the weekend, bringing much of the region at least 0.6”, up to 3”. A few areas were skipped in this rainfall and are still in need of rain. The water soaked in quickly, and we still see a lot of soil movement with the winds or during field activity.
Small grains are staging at 3 leaf to tillering. Overall, stands are looking lush. There are scattered fields with wheel tracks showing through or in sandier soils, general unevenness due to this spring’s limited seedbed moisture environment. Grain aphids can be found fairly easily on the LREC’s winter wheat plots.
Scout for flea beetles this week on canola as they continue to emerge.
Area Extension Specialist/Agronomy
The northwest did not get any of the rain that fell further to the east Sunday night and top soil is dry in most of the region. The area is hoping to catch rain from storms predicted for later this week and over Memorial Day weekend.
Due to the early heat and now dry conditions, winter rye and winter wheat is heading out. In variety trials at the Williston REC dryland site, most winter wheat is late boot to heading and starting to show signs of water stress. Rain will be needed soon to promote good kernel development. The dry conditions have allowed planting to continue and seeding of corn, soybean, and other warm-season crops should wrap up by the end of the weekend unless rain delays things.
Wheat streak mosaic virus (WSMV) has been confirmed in both Williston and Sidney in winter wheat and producers are advised to scout winter and spring wheat fields for symptoms. Confirmation of WSMV can be obtained by submitting samples to the NDSU Plant Diagnostic Lab. Peas and lentils in the region look good with no incidence of root rot or other diseases that are problematic in wet and cool conditions reported.
Area Extension Specialist/Cropping Systems
NDSU Williston Research Extension Center
Sprayer Cleanout – Avoiding Crop Injury due to Contamination
Growers may use the same spray equipment to apply selective herbicides in multiple crops in the spring or summer. Crop injury due to contamination is a preventable problem if the appropriate precautions are used in advance to clean spray equipment. How does it happen? Why can I sometimes spray multiple loads before the contamination occurs? What can be done about it?
Certain herbicides can be adsorbed to sprayer components including the spray tank, screens, filter, and hoses. Herbicides, in some cases, may remain adsorbed to sprayer components even following thorough water rinsing. It is not uncommon to hear that several loads were applied before a product was used that desorbed attached herbicides and dispersed them into the spray solution, causing contamination and damage to susceptible crops.
Sprayer cleanout is analogous to making a pit stop during a NASCAR race. That is, the cleanout procedure needs to follow a rehearsed plan. The first step is to access resource materials such as the North Dakota Weed control Guide, pg. 75, or other on-line information. Second, review herbicide-specific tank-cleanout guidelines provided in the herbicide label. Third, develop a sprayer cleanout routine that is followed every time herbicides are changed. Fourth, depending on the herbicide, know the appropriate cleaning agent including water, bleach, ammonia, or a commercial tank cleaner. Finally, take notes. Document what herbicides are the most difficult to remove from sprayer equipment or which adjuvants or herbicides seem to desorb herbicides.
Extension Sugarbeet Agronomist
NDSU & U of MN
Question: I have a few clients growing SU resistant canola. I have been told they need to use Draft herbicide. In the herbicide compendium in the weed guide it says it is composed of rimsulfuron and thifensulfuron. Is this correct? I was told it contained Harmony and Express?
Answer: Thanks for catching the mistake in the compendium section of the 2016 ND Weed Control Guide. Draft contains the active ingredients tribenuron (Express) and thifensulfuron (Harmony). (Continued next page)
See page 43 in the weed guide where SU canola has been added to the Canola section and Draft is the only herbicide registered for use in that SU herbicide resistant crop. That information is correct. There many brands of tribenuron and thifensulfuron on the market but Draft has the only label that allows use on SU canola.
Extension Weed Specialist
Fate of Soil-Applied Herbicides
Question: What happens to my soil-applied herbicides if there is no rain to activate them for several days after application? Are they gone?
Answer: Most soil-applied herbicides are stable under prolonged periods without moisture to activate them. Most soil-applied herbicides are not affected by breakdown from the UV spectrum of sunlight and do not volatilize from the soil surface. There are exceptions. All Group 8 herbicides (Ro-Neet, Eptam, and Far-Go) are volatile and require immediate incorporation after application through tillage. All Group 3 herbicides (Treflan, Sonalan, and Prowl) are volatile and susceptible to degradation from UV light. Prowl is much less volatile and affected by UV light which allows PRE labeling in sunflower. However activity of Prowl is greater when incorporated. The requirement to incorporate Treflan and Sonalan soon after application reduces risk of volatility and deactivation from sunlight. Recently, s-metolachlor (Dual Magnum, Dual II Magnum) has been found to be susceptible to breakdown from sunlight. However, other similar herbicides like Outlook, Surpass, Harness, and Warrant are not broken down by sunlight.
The good news: With the exception of those herbicides listed above, soil-applied herbicides can remain on the soil for an extended period of time. The ‘activity ‘clock starts when sufficient rain (or irrigation) moves the herbicide into water phase in the soil profile and it is moved into the germination zone of weed seed, providing PRE weed control on germinating weeds at that time. Generally soil-applied herbicides require 0.5 to 1 inch of water for activation depending on the herbicide. For example, a rain event of 0.5 inch may activate Outlook but Dual and Zidua products may require 0.75 to 1 inch of rain. Researchers have seen enhanced activity from Zidua after more than one rain event.
The bad news: The problem with lack of activating moisture soon after application is that weeds may emerge and generally soil-applied herbicides will not kill weeds once they emerge. A few soil-applied herbicides including Zidua (pyroxasulfone), Spartan/Authority (sulfentrazone), Valor (flumioxazin), and Sharpen (saflufenacil) have shown a phenomenon some call ‘reach-back’ where they may kill small emerged weeds (0.5 inch tall) after an activating rain.
More good news: If weeds that emerge through the PRE herbicides are killed following an activating rain, then the residue of the PRE herbicide will prevent labeled weeds from emerging until the herbicides are degraded through microbial activity and chemical reactions in the soil.
Extension Weed Specialist
Effect of MSO and AMS on Group 14 Herbicides
Glyphosate-resistant kochia has been identified in several locations across North Dakota. This raises the question as to how emerged kochia will be controlled without glyphosate. Group 14 herbicides include Sharpen, Aim, Spartan, and Valor. There are several premixes that also contain these Group 14 herbicides such as Spartan Charge (Spartan + Aim), Authority MTZ (Spartan + Metribuzin), Fierce (Valor + Zidua), etc. We have known for many years that foliar activity with Sharpen is much more effective when applied with AMS + MSO. Preplant and desiccation studies showed greater weed control with MSO > COC > NIS. Aim and Valor are used as desiccants and have also been shown to be more effective with AMS + MSO. We have known that you don’t want to apply Spartan after crop emergence due to potential crop injury, but never believed that Spartan had as much foliar activity as Sharpen and Aim.
We conducted studies from 2013-2015 to help answer the question of how to control emerged glyphosate-resistant kochia in preplant or preemergence applications. We came across this inadvertently, but in the studies we applied herbicides with and without AMS and MSO. I expected Sharpen + AMS and MSO to control kochia, but did not expect good control from Spartan or Authority MTZ. It was apparent that all the Group 14 herbicides provided much better kochia control when tank mixed with AMS + MSO. As a follow-up, we conducted a greenhouse study to confirm what we were seeing in the field (see picture). Again, the Group 14 herbicides provided good kochia control when tank mixed with AMS + MSO. We did not include Valor in the study, but assume Valor will also provide better kochia control with AMS + MSO. (Continued next page)
In the 2013 and 2014 field studies, kochia control was good to excellent. However, in 2015, kochia control was much lower than the previous two years. One of the main differences may have been that in 2015, temperatures were much lower during and after application. Thus, in 2015, even with AMS and MSO, the Group 14 herbicides provided only fair kochia control, possibly due to cold temperatures. Thus, under optimal spring temperatures, I expect kochia control with Group 14 herbicides will be enhanced with the addition of AMS + MSO.
Several people have asked “What about other weeds? Will we see enhanced control of other weeds as well?” I believe it is possible that we will see enhanced control of other annual weeds. However, one of my concerns is the effect on perennial weeds. For example, we have observed that the rapid desiccation provided by Sharpen will reduce Canada thistle control by glyphosate. Thus, my recommendation is that if Canada thistle is one of your primary targets, you should not tank mix glyphosate with Sharpen. We have not observed antagonism with Sharpen + glyphosate on annual weeds. We are currently conducting a study with dandelion, where we have glyphosate applied alone compared to glyphosate applied with all Group 14 herbicides to determine if the Group 14 herbicides antagonize dandelion control with glyphosate.
Weed scientist, North Central R&E Center, Minot