Issue 13 August 14th, 2015 Angie Johnson, Agriculture & Natural Resources Extension Agent Steele County County Highlights Harvest of small grains continues to move along nicely with the warm temperatures up in the 90s with relatively low dew points. A common response this year in regards to small grain harvest is that the straw portion of the plant is staying relatively wet, while the grain moisture is just right. Keep in mind, that if you are planning to store your wheat in the bin for long term storage (storage greater than six months), your percent moisture in the wheat must be no greater than 13%. In barley, a 12% moisture is suffice for long term storage. Soybean aphids are still an ongoing issue since we (Finley NDAWN Station) experienced temperatures in the mid 70s last week. Aphids thrive within that particular temperature range. However, this week with extremely high temperature s in the 90s have helped slow down aphid populations. Keep an eye out for aphids, especially in later planted fields. Remember an economic threshold has been established for the control of soybean aphids. Apply an insecticide when aphid populations have reached 250 aphids per plant on 80% of the soybean field. Please be mindful of protecting our beneficial insects and pollinators by applying insecticides towards evening when bee activity is reduced. Local Rainfall & GGD Finley Mayville Pillsbury Cooperstown Corn GDD (Plant Date: 5/1/15) 1589 1602 1585 1577 Compared to 2014 NA 1500 1520 NA Compared to 5 year average NA 1629 1596 NA Wheat Accumulated GDD (Plant Date: 4/15/15) Local Rainfall & GDD 3557 3550 3552 3521 Compared to 2014 NA 3425 3444 NA Compared to 5 year average NA 3603 3564 NA Sunflower GDD (Plant Date: 5/11/15) 2033 2048 2040 2025 Rain Since May 1 12.78 11.90 14.61 14.00 Please feel free to share your crop reports! Have a safe harvest! Phone 701.524.2253 Cell 701.799.9951 angela.b.johnson@ndsu.edu
Soybean Aphids & Hot Temperatures By: Jan Knodel NDSU Extension Entomologist Soybean aphids increased with the favorable temperatures in the low 80s F last week. However, the recent hot weather (>90 F), will slow population growth. However, soybean aphids will continue to produce nymphs as long as night temperatures are in the lower in 70s F, but at a slower rate. We will see increased mortality with the nymphs, since they do not survive well when it is > 90s F. Winged soybean aphids are common this time of year as they move around to find younger soybean fields that are more suitable for colonization. Continue to scout fields, especially any late planted soybean fields. If soybean aphid populations are at E.T. (average of 250 aphids/plant, 80% incidence, and increasing populations), important things to consider are the growth stage of soybeans, presence of natural enemies and how hot temperatures impact insect control and insecticide performance. The USDA NASS reports that 86% of the soybeans were setting pods and 1% dropping leaves in North Dakota (USDA NASS News Release August 10, 2015). Soybeans are approaching or in the R6 stage (full seed) where treatments are not advised, because the cost of the insecticide + application will not be recovered with the marginal to no yield increase. It takes an average of 15 days to go from R5 (beginning seed) to R6 (NDSU Extension Publication A1172 Soybean Production Guide). Natural Enemies: Natural enemies (lady beetles, aphid lions, syrphid flies and parasitic wasps) are often effective in reducing aphid populations. When natural enemies are present in large numbers, aphid populations are below the E.T., and soybeans are near R6 (full seed), producers are discouraged from spraying fields. Hot Temperatures: 1. The metabolic activity of insects increases with hot temperatures. This can result in decreased insect control due to the insect s ability to detoxify the chemical. Optimal control of insect is usually when the temperatures are cooler or moderate. Producers should consider spraying in the evening or early morning when it is cooler. 2. Control of insects with pyrethroid insecticide declines as temperatures rise. Some examples of pyrethroid insecticides include: Asana XL (esfenvalerate), Baythroid XL (beta-cyfluthrin), Delta Gold (deltamethrin), Mustang Max (zeta-cypermethrin), or Warrior II (lambda-cyhalothrin). In contrast, the toxicity of organophosphate insecticides, such as chlorpyrifos (Lorsban) or dimethoate, increases as temperature increases.
3. When it hot, secondary pests such as spider mites are at increased risk of developing. Selecting an organophosphate insecticides would be a wise decision since it performs better in hot conditions and controls both soybean aphids and spider mites. 4. High temperatures and low humidity may cause small insecticide droplets to evaporate before reaching and penetrating the canopy, and reduce insect control. Since soybean aphids are usually found in the mid to lower canopy during the late reproductive stages of soybeans, and aphids usually move to the lower canopy to moderate the effects of hot temperatures, it important to get the insecticide into the lower canopy. To reduce the negative effects of evaporation, producers should avoid spraying during the hottest part of the day, increase water volume to 15-20 gpa by ground / 3-5 gpa by air, use adequate spray pressure (40 psi) to penetrate canopy, and/or add crop oils or non-ionic surfactants (consult labels or companies for specific recommendations). Dry Edible Bean Rust Continues to Develop By: Sam Markell NDSU Extension Broadleaf Pathologist Frequent dews and warm temperatures continue to provide a favorable environment for rust to develop on dry edible beans. Samples from all over North Dakota have been sent to NDSU over the past two weeks and it is clear that rust is widespread throughout the state. However, severity is highly variable and many fields have no rust (or very little) while some hot spots in some fields are severely infected and will lose yield. Since the appearance of a new rust race several years ago, it is best to assume that all market classes and all varieties are susceptible to rust. Rust can spread quickly when temperatures are relatively warm and heavy dews occur frequently. It is important to scout for rust until the beans are at growth stage R7 (this is when pintos begin to stripe). At that stage, there is no benefit to managing rust. Figure 1. Close up of a rust hot spot Figure 2. Pustules on the top side of a leaf Figure 3. Pustules on underside of leaf Figure 4. Dusty cinnamon-brown spores can easily rub off of pustule
If rust is developing in relatively young beans and are considering a fungicide application, numerous products are available. Strobilurin fungicides (Aproach, Headline, Quadris, etc.), triazole fungicides (tebuconazole products, Proline, Propulse, etc.) and fungicide premixes containing strobilurin or triazole chemistries are efficacious on dry edible bean rust. Monitoring for Sunflower Rust By: Sam Markell NDSU Extension Broadleaf Pathologist Conditions for rust development have been very favorable in much of the state. It is particularly important to keep an eye on confection sunflowers; they tend to be more susceptible to rust than oilseeds. However, there are distinct resistant differences among hybrids; some are resistant and some are susceptible. If rust is found on the top of the canopy (the top four fully-expanded sunflower leaves) at 1% severity or higher in R5 (bloom) a fungicide application may be warranted. By R6 (flowering is complete) research trials have shown no benefit to a fungicide application. Similar to dry edible bean rust; strobilurin and triazole fungicides are efficacious on rust. Heat Will Express Root Rots By: Sam Markell NDSU Extension Broadleaf Pathologist Figure 1. Computer generated assessment diagram of approximately 1% rust Less frequent rains and high temperatures are going to stress plants with root problems. Root rot infections often occur early in the growing season, particularly when the soil is wet. However, many of those infected plants do not show symptoms until there is less available moisture, forcing the roots to struggle to obtain enough water. The heat we have had in the last few weeks (and the very hot forecast) will stress plants, and those with root rots infections will show themselves. We are beginning to see this already, as healthy-looking plants are beginning to wilt and die. Soybeans are notorious for surviving early root-rot infections, only to begin to wilt later in the season when conditions dry out. There is nothing that can be done to manage root rots this late in the season, but it is important to take note of where the damage is so you can manage root rots when you plant back into that field. Resistant or tolerant varieties, fungicide seed treatments and lengthening crop rotations can all help mitigate future root rot problems. In addition to root rots, heat will also express other root and stem problems. It is expected to see some plants showing damage from diseases such as soybean cyst nematode and charcoal rot later in the month. Foxtail Barley Control By: Rich Zollinger NDSU Extension Weed Specialist At this time of the year foxtail barley is in full view along roads, in ditches and on field perimeters. With its characteristic foxtail type heads with long awns it is hard to mistaken this grass weed. Growers not remembering the location of foxtail barley from last year and growers not knowing effective control measures make this weed proliferate. Plants head out in early summer and by that time most control tools are ineffective. Question: What chemical options will control foxtail barley in rangeland, pasture, and non-crop areas? Headed foxtail barley
Answer: If these areas do not contain desirable grass species then a clethodim product (Select) or Assure II applied to plants in the tiller stage and especially before plants head out will be successful. If the areas contain desirable grass species then Plateau is labeled for control. It is important to follow label direction to apply at the proper timing, to use recommended adjuvants, and follow other label information. Soil Sampling Following Early Crop Harvest By: Dave Franzen NDSU Extension Soils Soil sampling is encouraged immediately following early crop harvest, including winter wheat, barley, spring wheat, any wheat, rye, canola and early flax. The following are concepts to keep in mind during interpretation for next years crop: Soil nitrate may or may not increase or decrease as the fall season continues. Experiments conducted in the 1970s, where soil samples from the same area across ND were sampled from summer to major winter freeze-up and on into spring showed that sometimes nitrate increased, sometimes decreased, and sometimes stayed the same. It was later tried to relate it to soil moisture content and didn t get anywhere. So anytime is a good time for nitrate sampling and earlier means it gets done. The majority of our soil nutrient factors, P, K, ph, Zn, rely on a 0-6 inch soil test. Anyone care to tell how a consistent 0-6 inch core can be taken following chisel plowing wheat stubble? The best we can do is drive over the intended soil sample area, then probe into the track. Is this representative of the depth that the soil test is calibrated for? We think so, but sampling immediately after the combine is better. It is believed that some of the variability in P tests is sometimes due to inconsistent soil core depth because of having to sample worked fields. Potassium soil test values vary with monthly time of sampling. Potassium nutrition is complex. Clay chemistry plays a much larger role than taught in school, and minerals such as potassium feldspar, which are prevalent in many ND soils, contribute much more to seasonal plant nutrition than previously thought. But, we know that soil K is highest in the early spring, with rapid or gradually decreasing K into June, holding relatively steady at a low level until fall when rain leaches K from standing stubble before and after grain harvest which causes soil K values to again start to increase. Potassium needs to only be sampled for in most soils (except low K sands) once every 3-4 years. Choose a time period and stick with it. Soil P, Zn, and ph are relatively stable over a growing season (except ph after N application), so time of year is not very important for them. A Look Back at Sidedress By: Dave Franzen NDSU Extension Soils It is satisfying to see side-dress become more common in ND on soils with a high susceptibility to in-season N loss from leaching or denitrification. As plans are made this winter on strategies for next season, please consider the following: - Apply about half the needed N for corn based on the higher productivity corn N calculator rate at preplant. - If the season is relatively dry, the other half can be applied at sidedress starting about V5 based on the ND Corn N Calculator for the higher productivity soil in your tillage/soil textural category. - If the fall season freeze-up is late and/or early season is wet, then a decision has to be made regarding early season losses. A good recommendation is to establish an N-rich strip in the field on the major soil category defined in our NDSU corn activeoptical sensor algorithm circular, or two strips if there are two major soil categories represented in the field or two varieties (don t split a planter with multiple varieties when you plan to do this). If the grower has the proper algorithms loaded into the computer/controller, on-the-go N based on yield potential of the N-nonlimiting portion of the field can be conducted using an active-optical sensor, which is a much more scientific approach than a guess.
NDSU Extension Service Steele County PO Box 316 Finley, ND 58230 Phone 701.524.2253 Fax 701.524.1715 August 13th through August 19th Weather Forecast By: Daryl Ritchison Asst. State Climatologist/Meteorologist Maximum temperatures may vary by as much as 30 degrees over the course of the next 7 days. Thursday through Saturday the heat that began on Tuesday will continue to be the dominate weather issue. Although a few locations did record some precipitation Wednesday Night, the heat during the next few days will bring little if any moisture as a large ridge of high pressure in the upper atmosphere is expected to keep the storms north and east of North Dakota. Perhaps the warmest temperatures of 2015 will be recorded during this period with maximums in the 90s with some locations in the low 100s in western North Dakota. This high heat will mostly come with tolerable dew points (50s and 60s) meaning extremely humid conditions are not expected allowing for some evaporate cooling potential that will offer some heat stress relief for cattle (and humans) and limiting the hours of relative humidity above 85% for disease potential on plants. The well above average temperatures will exacerbate the moisture stress already present in many areas, but the heat will come to a quick end on Saturday as a cold front sweeps through the northern plains. Not only will the front bring cooler temperatures to the region, but also the potential for widespread thunderstorms on Saturday into Saturday Night. Although there will probably be some severe weather associated with the changeover from well above to below average temperatures, it will bring the best chance of rainfall to the region until the middle of next week. Temperatures are projected to average between 10 to 15 degrees above normal through Saturday, then behind the cold front from temperatures may be as much as 10 to 15 degrees below normal. The strong ridge of high pressure currently in place will be replaced by an equally strong, if not stronger, trough of low pressure by the middle of next week. Maximum temperatures may only reach the mid to upper 60s for some locations for a couple of days during that time period. Plus, that upper level wind change may induce a storm to form and travel through ND later on Tuesday into Wednesday that would enhance the cooler air that will already be in place. EXTENDING KNOWLEDGE. CHANGING LIVES. County commissions, North Dakota State University and U.S. Department of Agriculture cooperating. North Dakota State University does not discriminate on the basis of age, color, disability, gender expression/identity, genetic information, marital status, national origin, public assistance status, race, religion, sex, sexual orientation, or status as a U.S. veteran. Direct inquiries to the Vice President for Equity, Diversity and Global Outreach, 205 Old Main, (701) 231-7708. This publication will be made available in alternative formats for people with disabilities upon request, (701) 231-7881.