Crop & Pest Report - All
Weather/Crop Phenology Maps
Professor of Climatological Practices
A ridge of high pressure currently over the Pacific Northwest has adjusted the upper level wind flow over the northern plains. Currently, the flow is from the northwest and this will continue to allow cooler Canadian air to dominate our weather for a couple of more days. Western North Dakota will start recording warmer temperatures on Saturday, but eastern North Dakota will continue on the cool side until Sunday afternoon. The warmer temperatures this weekend into the middle of next week will be associated with that ridge of high pressure to our west moving slowly over our region this weekend into the middle of next week. This will bring back average to even slightly above average temperatures to the region.
Maximum temperatures in the 90s are foreseen on Sunday afternoon in western North Dakota and certainly a few other days the maximums may be near 90° in other locations throughout North Dakota into northwestern Minnesota. Yet, the upcoming period of warmer temperatures does not look as warm, nor as humid, as the last surge of warm air from earlier this week into late last week. This will mean fewer hours of relative humidity (RH) values above 85% as were recorded this past week (Figure 1). Plus, with this period starting cool and with the expected upcoming warmth not being as extreme as what we recorded in the middle of July, these next seven days are expected to record about 10% fewer growing degree days (GDDs) than we measured in the past week.
Precipitation is expected to be either non-existent or not very widespread for the next few days. With the cooler air from Canada also comes in drier air, meaning the wet locations will have an opportunity to dry off in the short term. It does appear as the next surge of warmer air moves in, that the upper-level wind flow will transition to a southwesterly direction ushering in thunderstorms early next week (Sunday night into Monday Night). Then there will probaby be another threat of rain toward the middle of next week (late Wednesday/Thursday, August 3,4) as a period of cooler air moves back into the region. Beyond this period there are indications that a warmer and drier pattern will emerge as we move toward the middle of August. Meaning, there is still plenty of summer ahead of us.
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In the past week between July 19th and July 26th there has been some rainfall. According to NDAWN Dickinson received 0.45 inch and Mott received 1.22 inch of rainfall. Hettinger continues to be dry with no rainfall recorded. The recent precipitation has slowed harvest, however most peas and winter wheat in the region have been harvested. Spring cereals and canola are reaching maturity and will be harvested soon. Some sunflower fields are just starting to flower.
Area Extension Specialist/Cropping Systems
NDSU Dickinson Research Extension Center
Wet weather continues for much of the region. Combined with humidity, risks for sclerotinia infection are high, the highest in the last four years. I observed dozens of apothecia in 2015 canola fields when I looked under this year’s soybean crop canopy in a single location. Canola, dry beans and sunflowers are our most sensitive crops. Signs of infection are showing up: early stem infections of canola (pictured), wilted sunflowers with root sclerotinia infection and sunflower stalks with infection.
The humid and wet weather have been conducive for scab for several weeks. Soybean aphids are in the northern tier counties. Low levels will not harm yields and frequent rainfalls also decrease populations. Follow IPM guidelines of 250 aphids per plant and increasing on 85% of plants.
Area Extension Specialist/Agronomy
NDSU Langdon Research Extension Center
Hot weather has been pushing crops along in the Northwest and harvest has started. Harvest of winter wheat and peas began last week and barley is getting under way. Early-planted spring wheat and durum fields are starting to turn from green to brown. Some lentil fields are starting to dry down but in areas that have received a lot of rain, progress is a bit slower.
The annual field days at the Williston REC were held at the main station on July 14 and at the irrigated Nesson Valley site on July 15. Attendance was strong at both events and the weather was perfect. A new feature this year was a “Stump the Plant Doctors” booth where the public could ask research and extension specialists about their plant-related problems. The booth went well as we had many attendees bring us their weeds, tree branches, and leaves for diagnosis.
Area Extension Specialist/Cropping Systems
NDSU Williston Research Extension Center
Again, spotty showers were present throughout the North Central Region over the past week: Minot: 1.35”, Rugby: 0.35”, Berthold: 0.74”, Bottineau 0.12”, and Mohall: 0.67” (July 17th – July 24th).
Over the last week, growers were invited to participate in several field days throughout the North Central Region (NCREC, Mohall, and Rugby). Topics included weed science and entomological updates, wheat variety trials, as well as an agricultural drone demonstration by the lab of Dr. John Nowatzki.
Area Extension Specialist/Crop Protection
NDSU North Central Research Extension Center
Lack of Canola Seed Fill
Question: I have a customer whose peas have made pods, but they are not filling up with peas.
No fertilizer was applied, although the peas were inoculated. Prior to spraying this field the applicator had treated a field using Spartan Charge. The field was treated with Shadow (Clethodim) and no other herbicides. The peas showed some yellowing after treatment, but seemed to recover. A sample was sent to SD Lab to detect herbicides a couple weeks ago – no results yet.
Could one of the herbicides cause the pods to not fill? I know Clethodim generally does not affect broadleaves. From Spartan spray tank contamination the symptoms does not look like PPO inhibitor herbicides. Could the peas have phosphorus deficiency?
Answer: Please read the Remarks information on page 35 from the Canola section in the weed guide.
Remarks of the POST grass herbicide section (Assure II, Poast, Select/others):
"Clethodim may injure peas when applied during bloom".
The same restriction of no application during bloom includes field pea, flax, canola, tame mustard.
The injury is specifically to the reproductive tissue on the crop plants listed above resulting in lack of seed development and yield loss. The reproductive tissue does not exhibit the same level as tolerance as the vegetative tissue. I suspect that is your answer. I also suspect we need to make this more visible in the guide. See study below conducted in 1999 for a representation of injury and yield loss from canola.
Extension Weed Specialist
Roundup Ready 2 Xtend Soybeans Gain Eu Import Approval
The European Commission has granted import approval for Roundup Ready 2 Xtend® soybeans which for allows for the import and food/feed use of Roundup Ready 2 Xtend soybeans into the European Union. With both the EU and Chinese import approvals and the U.S. Environmental Protection Agency (EPA) in the final stages of review for postemergence, the likelihood of full registration in 2017 is possible.
A full system launch also is planned for Canadian soybean growers in 2017 given the previous Canadian regulatory approval of the herbicide and technology.
Extension Weed Specialist
Molecular Herbicide Resistance Testing
This may not apply to most of you but there is molecular testing available to confirm herbicide resistance to herbicides.
U. of Illinois:
PPO resistance has developed in waterhemp in the mid-west and with the preferential use of PPO herbicide for kochia, ragweed, and waterhemp control in ND soybean production there is a high risk of PPO resistant waterhemp and possibly ragweed development in ND.
There are many PPO herbicides registered in soybean and some other broadleaf crops. Some include:
- Preemergence - Spartan/Authority, Valor, and Sharpen.
- Postemergence – Ultra Blazer, Cobra, Cadet, Flexstar/Reflex, Vida, and Aim.
Waterhemp and ragweed expansion in ND has not decreased but continues to move west and north in ND. With territory movement there will also likely result in additional herbicide resistance beyond the present ALS and glyphosate resistance. NDSU weed scientists are interested to help confirm new herbicide resistant biotypes. Please contact us if you suspect new resistant types.
Extension Weed Specialist
Why was 2016 a "Bad" Year for IDC IN SOYBEANS?
One question I have been asked very often over the years is, "Why is the chlorosis so bad this year?" Answering this question isn't easy, but it might be helpful to review what we know about the factors that cause and intensify IDC in soybeans.
#1. Calcium carbonate in the topsoil. This is the root of the problem and iron deficiency chlorosis (IDC) cannot occur without carbonates in the root zone. "Lime" in the topsoil buffers the pH of the soil around 8. Soils contain a lot of iron, but iron is much less soluble in the soil solution at a pH of 8 than, say, a pH of 7. The soluble product of carbonates (bicarbonate) neutralizes soybean root surface acidity and in doing so, the activity of the compound that soybean roots exude that make iron a trillion times more soluble is rendered ineffective.
#2. Wetness. If a soil has a seasonal high water table, water cannot flow downwards, and the topsoil will stay wet for extended periods after snowmelt or heavy rain. The main reason this intensifies chlorosis is that wet topsoil containing "lime" will generate a lot of the bicarbonate ion (HCO3-) in the soil solution when the field is wet. The bicarbonate ion is very good at suppressing the solubility of iron, suppressing plant uptake of iron. Plant roots can also take up bicarbonate, and iron can be precipitated within the plant. Wetness can also increase the availability of manganese (Mn2+) in the soil, and this can intensify IDC.
Soybean plants with IDC in North Dakota usually contain very high, sometimes excessive, levels of manganese in the leaves. Fertilizer dealers commonly offer micronutrient "packages" that contain manganese. Save your money, the last thing you need is additional manganese on soils that produce IDC.
#3. Nitrates. Excess nitrate in the soil intensifies IDC in soybeans. Areas in a field that produce severe IDC in soybeans are often less productive for other crops, too. If a farmer fertilizes that field uniformly with nitrogen, it is common for IDC "hot spots" to become, over time, very high in nitrate. Use of cover crops in the fall, or a companion crop of oats or barley planted with the soybeans in the spring may reduce nitrate levels in the soil and decrease surface wetness.
#4. Salinity. Elevated salinity is associated with more intense IDC in soybeans. On level terrain, elevated salinity, like the presence of CaCO3 in the topsoil, is associated with the presence of a water table during at least part of the growing season. The presence of salinity indicates a water table problem, and greenhouse work has shown that just adding the common components of salinity (sodium and magnesium sulfate) can intensify chlorosis. Increased salinity is a major stress on soybeans and the plants are not able to cope with IDC as well.
#5. Your variety may not be as resistant to IDC as the seed company says. It is an educational exercise to look at NDSU's chlorosis ratings each year. Take the five or ten weakest varieties in NDSU's trials, the ones with the worst chlorosis, and look up their IDC ratings on the web sites of the respective seed companies. Give it a try, and draw your own conclusions.
So, why was 2016 a "bad" chlorosis year? Nobody knows for sure, and certainly the weather is variable across the soybean production area of North Dakota. But it does seem that some of the factors listed above were in play. From about June of 2015 until after planting in 2016, the weather was drier than normal. If crop yields in 2015 were reduced by water stress, there may have been higher than normal nitrates in the soil. The long, dry period allowed for upward movement of salts in some soils. In April this year, the visual extent of saline ‘whiteness’ in many fields was astounding. After emergence, significant rain was received in many areas, causing the wetness factor.
The control measures for IDC are well-known.
- First, select the proper fields for soybeans. Just because soybeans are $10 per bushel and barley might be $3, doesn’t mean that soybeans in a field with high salt and carbonate content will be more profitable. 10 bushel per acre soybeans isn’t profitable at any price, whereas barley at $3 could easily make 70 bushels per acre in the same field.
- Second, grow a resistant variety. Don't depend on the information from seed dealers alone. Take into consideration the NDSU IDC ratings. Talk to neighbors, ask them which varieties are working.
- Third, chlorosis seems to be somewhat less severe when the soybeans are planted in wider rows (22 or 30 inch) versus narrow rows (6-7 inch).
- Fourth consider trying a barley cover crop at soybean planting time. This could be barley broadcast at about a bushel per acre and lightly worked in, or seeded with a two-compartment seeder unit. Kill out the barley when it reaches 3 leaf if dry, and up to 5 leaf if there are wet conditions.
- Fifth, apply an effective chelate, in-furrow at planting. Two or three pounds per acre of a high-quality FeEDDHA product has proven to alleviate IDC and increase yields, but not with susceptible varieties. An application of FeEDDHA cannot make a susceptible variety grow like a resistant variety. For fields with the worst problems of IDC, use of a resistant variety, cover crop, wider row spacing, and an in-furrow application of an effective chelate are required to yield profitably.