Crop & Pest Report - All
Weather/Crop Phenology Maps
Associate Professor of Climatological Practices
According to NDAWN, rainfall during August 1-25 ranged from 1.6 inches (Carrington and Harvey) to 5.5 inches (Linton). In general, there should be sufficient stored soil moisture to support row crop seed development during the next several weeks. As of August 25, accumulated growing degree day units for corn planted on May 15 ranged from minus 53 (Wishek) to plus 51 (Harvey) compared to the period’s 5-year average.
The region’s cereal harvest is about 25% completed. Harvest should restart this week but with challenges including wet soils, lodged fields, high moisture seed, and seed quality (test weight, protein, vomitoxin, and/or sprouting). Corn stages generally range from milk (R3) to dough (R4) – a frost-free September will be needed for corn to reach complete maturity. Dry bean fields are beginning to reach physiological maturity; soybean is in the seed formation stages (R5-6); and sunflower have ray pedals dropping (R6 stage).
Row Crop tour – Carrington Research Extension Center, September 3, 4:30 p.m.
* Corn growing season review and plant nutrition
* Dry bean plant establishment
* Soybean variety selection, planting dates and herbicide-resistant kochia management
* Disease management in dry bean and soybean, with an emphasis on white mold (sclerotinia) and soybean cyst nematode
* Industrial beets project update
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center
The region received 1 to 3 inches of rain over the past week. This rain was welcome especially in the soybean crop. Soybean aphid numbers have been increasing, so continue to scout. Harvest is slowly moving forward in winter wheat, barley, field peas, and extremely early seeded spring wheat. Harvest reports are noticing increased DON levels in pocketed areas in the winter wheat.
Area Extension Specialist/Agronomy
White mold in crops such as canola (Figure1), sunflowers (Figure 2), soybeans (Figure 3) and dry beans (Figure 4) has been found in various counties in this region. Crop rotation with non-host crops is highly recommended for the next cropping season.
Downy Mildew of Soybeans:
Downy mildew of soybeans is a disease caused by a fungus like organism (Oomycete) Peronospora manshurica, has been detected in various counties of north central North Dakota. This disease rarely impacts yield, but at high enough levels, may result in reduction of seed quality or marketability.
Major symptoms include initial small, irregular pale yellow spots on upper leaf surfaces (Figure 5); eventually turn in to gray-brown with a yellowish margin. On the underside of the leaves, the spots have a greyish, fuzzy appearance (Figure 6). Infected pods are seen with mass of fungal-like growth inside and infected seed has a dull white appearance with partially or fully covered fungal-like growth. Heavy dews and cool nights increase downy mildew in soybeans.
Management options are not often recommended because the disease is rare and usually non-economic. However, crop rotation and use of resistant varieties (if known, or available) can be used in future crops.
Area Extension Specialist/Crop Protection
NCREC, Minot, ND-58701
The rainfall total for the last two weeks at the NCREC has been 3.54”. The wet conditions have impacted harvest of small grains and canola. The majority of winter wheat and field pea has been harvested. Yield of winter wheat has been favorable; however, the crop has been significantly impacted by scab. Please see the article “High levels of DON being reported in small grains” for more information.
Field pea yields varied depending on disease and/or environmental pressures. Reports of field pea yields range from 10 to 65 bu/A. Producers who swath canola are currently waiting for dry conditions in order to begin harvest.
Corn and soybean are still on track and benefitted from the August rains. The accumulated corn growing degree days at the NCREC based on a May 1 planting are 1617. The average for this time period is 1677. Sclerotinia can be found in many broadleaf crops in the area. Levels may not be at economical. Please see photo for sclerotinia in lentil.
Area Extension Specialist/Cropping Systems
From web sources there appears to be a recipe for making your herbicide from common household products. Sources call it a “magical, natural, weed killing potion” with high “safety, effectiveness, and naturalness” and recommend as “an alternative to chemical weed killers.” The recipe is a derivative of: ½ gallon of vinegar + ½ cup of salt + 2 tablespoons of dish soap.
For those avoiding use of chemicals to kill weeds - vinegar and salt are chemicals! Vinegar contains acetic acid, a chemical that has been investigated by USDA and academia with herbicidal properties. It has been used as an organic herbicide. Salt (sodium chloride) is a chemical that predates 2,4-D for use as a herbicide, and soap (detergent) is another name for “surfactants” that is applied with herbicides to stick spray droplets (retention) on leaf surfaces, reduce droplet surface tension (spread the droplet), and aid forming a herbicide deposit (close interface of the chemical active ingredients with the leaf surface). Most commercial herbicides formulated as a liquid also contain detergents/soaps (emulsifiers) for this purpose.
As this mixture of acetic acid, salt, and soap can kill many SMALL annual weeds, this presents the questions, “how does it compare to commercial herbicides – namely Roundup/glyphosate?” This question is especially relevant since several websites tout the mixture as a safe and an inexpensive alternative to glyphosate. Effectiveness is relative to the situation – the homemade herbicide can simulate glyphosate activity if spraying SMALL, annual weeds. The vinegar + salt solution will simulate a contact herbicide and may burn/desiccate weeds faster than glyphosate with full sunlight and hot temperatures. Weed researchers at NDSU conducted trials with acetic acid in the early 2000s but were not able to duplicate favorable results shown from other sources. We found several important factors that affect performance:
- Table vinegar contains only 4-5% acetic acid while industrial vinegar contains ~20% acetic acid. Table vinegar was not effective in any treatment while industrial vinegar gave greater results but still considered unacceptable weed control.
- Grasses were much more difficult to control than broadleaf weeds.
- Sunlight and temperature was a very important factor penalizing northern regions where temperature is lower than in the mid-west and southern regions.
- Complete coverage and spray volume were the most discriminatory factors. Spray volume of at least 60 gpa was required to get a significant weed response while 80 to 100 gpa would be considered minimum. Incomplete coverage of the plant leaves with the vinegar + salt solution would allow plants to re-grow from the living tissues. The burning action of vinegar + salt solution is not effective on perennial weeds. It will burn off the top growth of perennials (which may be desirable), but it will not provide long-term control.
Glyphosate is systemic, that is, it will travel throughout the plant – down to roots and up to forming buds and seeds (known as “sinks) to effectively kill all plant parts. This difference between systemic and contact herbicides is very important in how to best use each product. Because glyphosate travels through the plant, it can control perennial weeds, such as Canada thistle and quackgrass. Coverage with glyphosate is less crucial, since the herbicide molecule will travel to parts of the plant that were not sprayed. Glyphosate will be more effective on large weeds, perennial weeds, and when applied under cool, cloudy conditions.
The contact nature of the vinegar + salt mixture can be a benefit, though. If you need to kill weeds in close proximity to a desirable plant (say, killing chickweed in a flower bed), then glyphosate can be problematic. Only a few stray drops from the glyphosate spray bottle onto a flower might be enough to kill the entire plant. A few stray drops of the vinegar + salt solution may only produce a few localized spots/speckling but won’t kill desirable plants. The exception would be if you continually spray salt in the same area, you can end up with too much salt in the soil and will damage all plants. Acetic acid will break down quickly in the soil and won’t cause long-term soil problems.
So there are certainly some scenarios where the homemade herbicide mixture might be preferable to glyphosate for practical reasons. Comparing effectiveness between the two herbicides is difficult; they both have a potential fit depending on the situation. But what about the “inexpensive” and “safe” claims? A quick trip to Wal-Mart reveals pricing of all products.
Walmart stores selling a half-gallon of glyphosate based Eliminator Weed & Grass Killer Concentrate for $27.97 is more expensive than a gallon of the homemade mixture; however, to mix up 1 gallon of spray solution, you only need to add 1.5 fluid ounces of the concentrated product. At that rate, the cost of the glyphosate solution is only $0.66/gallon. The label states that for “Tough Weed Control” you can mix up to 2.5 fluid ounces per gallon, raising the cost to $1.09/gallon. Even then, glyphosate is actually less expensive than the homemade mixture on a per-gallon, ready-to-spray basis.
In toxicity measures, acetic acid is more toxic than glyphosate. Salt is more toxic to rats compared to glyphosate when exposed orally. The dermal toxicity numbers are a little more difficult to interpret, since for both glyphosate and salt, the values are listed as greater than a value. This typically means that the experimenters did not kill enough of the test rabbits at the highest doses used in the studies; so we know that glyphosate is safe at least up to 2,000 mg/kg and salt is safe at least up to 10,000 mg/kg. But we can determine from this data that acetic acid is more toxic than either glyphosate or salt. Pound per pound, glyphosate actually appears to be less acutely toxic to the mammalian test organisms compared to acetic acid or salt.
But this is only half the story with respect to toxicity. To estimate the actual risk of these products, we need to know not only the toxicity, but also the use rate; the dose makes the poison. Even highly toxic substances can be used safely if the dose is sufficiently low, and seemingly safe chemicals can be problematic if the dose is too high.
To figure out the actual risk, we need to calculate the amount of the toxic substances being applied. Most distilled white vinegar is 5% acetic acid (50 grain). At this concentration, one gallon of the homemade mixture would contain 6.4 fluid ounces of acetic acid (the active ingredient). One gallon of acetic acid weighs 8.74 lbs; so 6.4 fluid ounces would weigh 0.437 lbs; so there is 0.44 lbs of acetic acid per gallon of homemade mixture. To convert this to similar units as the LD50 values, 0.44 lbs equals 198,220 mg.
Eliminate Grass & Weed Killer contains 3.7 lbs of glyphosate acid per gallon; or 0.0289 lbs glyphosate acid per fluid ounce. At the higher labeled rate of 2.5 fluid ounces of product per gallon, there would be 0.07 lbs of glyphosate acid per gallon of mixed product. Similarly converting this to the same units as the LD50 values, 0.07 lbs equals 31,751.5 mg. So it appears that glyphosate, the less toxic chemical, is being applied at a rate 6-times lower compared to acetic acid.
Let’s do one more calculation to put these toxicity numbers into perspective. Male rats can weigh up to 500 g, or 0.5 kg. One gallon of the homemade mixture contains 198,200 mg of acetic acid, or approximately enough to kill 59 rats, if administered orally. One gallon of mixed glyphosate solution contains 31,752 mg glyphosate, or enough to kill 6 rats. The acetic acid in the homemade mixture is nearly 10 times more lethal than the glyphosate in the Eliminate mixture. And this doesn’t include the salt. The internet has ample documented and suggested information on benefits and liabilities of glyphosate but a quick google on sodium chloride, acetic acid, and salt can also produce less than positive information regarding effect on mammalian life.
If you are not worried about the safety aspect but simply don’t want to purchase a Monsanto product - don’t forget that vinegar is often made from corn, and most corn in the US has the Roundup Ready trait developed by Monsanto. So the vinegar you are using to spray your weeds is probably made from corn that was sprayed with glyphosate: the very herbicide you were trying to avoid.
Both the homemade vinegar + salt mixture and Roundup are safe when used properly, they’re both relatively inexpensive, and both can provide effective weed control in the appropriate situation.
Extension Weed Specialist
Dr. Andrew Kniss
NDSU Weed Scientist
Sharpen Desiccation Labels
BASF has issued Supplemental labels for Sharpen as a desiccant for field pea, lentil, chickpea, and canola. The rate cannot exceed 2 fl oz/A. MSO and ammonium sulfate adjuvants must be added in accordance with the federal label. Refer to labels for minimum crop maturity stage requirements before application can be made. Consult with a BASF representative for the latest labels for these crops.
The Supplemental labels will expire December 31, 2014. In addition to pesticide registration through EPA, ALL pesticides labels must also be registered in each state for legal use. These supplemental labels must also be registered in ND before legal use. Refer to the NDOA web site for status of registration in ND – see #4 on back of ND Weed Guide.
Extension Weed Specialist
High Levels of DON Being Reported in Small Grains
With winter wheat and barley harvest in full swing, several specialists and crop professionals have reported high deoxynivalenol (DON) levels in the harvested crop. DON, also referred to as vomitoxin, is a mycotoxin that can be produced by Fusarium graminearum and is found in kernels and on other parts of the wheat spike. DON levels as high as 30 ppm and 5 ppm have been reported this year in winter wheat and barley, respectively. Furthermore, some elevators are no longer taking winter wheat over certain DON levels. Contributing to this problem is the lack of market for high DON level wheat and the inability to move the crop out of the state using the railroad.
Numerous limiting factors were experienced by the winter wheat crop this year. The below average winter temperatures and lack of snowfall had a considerable impact on the crop’s survival. This resulted in a significant portion of acres being taken out of production and fields that were left had stand variability. Most of the winter wheat crop was flowering during the last week of June into early July. During this time frame, the risk of scab development was high for the majority of the state. However, growers found it difficult to apply properly timed fungicides due to uneven flowering and wet conditions. Scab development in winter wheat was exacerbated by the lack of genetic resistance in currently available varieties. The vast majority of the winter wheat acres were planted to varieties that, when compared to spring wheat, would be rated as having little or no resistance. Scab levels varied across ND but areas with high scab incidence and severity have translated into high DON levels at the elevator.
Barley producers are noticing considerable levels of DON in their crop. Malting barley markets are more stringent and DON levels above 1 ppm do not meet quality guidelines. The high DON levels in the barley crop caught numerous producers by surprise as they did not observe much scab in their fields this year. However, low levels of scab do not necessarily translate into low DON levels.
Strategies for handling grain with DON
At this point, there are no management tools to prevent the small grain crop from having DON. However, there are a few options on how to handle the grain.
1) Cleaning – Cleaning the seed will reduce the number of scabby kernels in the seed lot. This can be accomplished using an airflow system or a gravity table. If you harvest a field with a relatively high scab incidence, consider turning up the fan speed to eliminate the incidence of scabby kernels in the hopper.
2) Store the grain – Discounts for grains is generally strictest at the beginning of harvest. Holding onto the grain will allow time for the markets to stabilize and open avenues into alternative markets (i.e.: feed for poultry). When storing the grain, make sure to have adequate aeration and store at levels lower than 22% moisture. Even though research has shown that Fusarium growth and DON accumulation stop at levels below 22% moisture, make sure that you are moving air through the grain until it reaches a safe storage moisture (13% for longer term storage).
As a point of reference, here are the Food and Drug Administration advisory levels for DON in feed and food products:
- 1 ppm for finished grain products for human consumption
- 10 ppm for cattle over 4 months, provided the grain doesn’t exceed 50% of the diet
- 10 ppm for poultry, provided the grain doesn’t exceed 50% of the diet
- 5 ppm for swine, provided the grain doesn’t exceed 20% of the ration
- 5 ppm for all other animals, provided the grain doesn’t exceed 40% of the diet
For more information on handling wheat with DON, please review the Extension bulletin entitled “DON (Vomitoxin) in Wheat – Basic Questions and Answers”: www.ag.ndsu.edu/pubs/plantsci/pests/pp1302.pdf
Extension Plant Pathology, Cereal Crops
Joel Ransom Extension Agronomist for Cereal Crops
Area Extension Specialist/Crop Protection
NCREC, Minot, ND-58701
Area Extension Specialist/Cropping System
Downy Mildew in 2014
Michelle Gilley, a research specialist at NDSU and the USDA sunflower unit, surveyed 105 sunflower fields this summer. She assessed the incidence of infected plants and, when possible, collected pathogen samples for race determination and fungicide sensitivity work that will be done this winter.
Approximately 2/3 of the fields (68 of 105) had downy mildew, and in the majority of the fields the incidence of infected plants was low. A higher incidence of downy mildew was recorded throughout the sampling area, and severely infected fields did not appear to be concentrated in any one region. Infected plants do not contribute to yield. However, neighboring healthy-plants may be able to compensate for infected sunflowers. The greatest yield loss to downy mildew typically occurs in localized areas in fields where infected plants cluster.
The high level of downy mildew observed is largely a result of frequent rainstorms right after sunflowers were planted. Fields with downy mildew will harbor the pathogen for up to ten years, so growers should use management tools the next time sunflowers are planted in that field.
Extension Plant Pathologist, Broad-leaf Crops
Late Season Soybean Stem Diseases
Now is a great time to examine your soybeans for diseases; particularly stem disease whose symptoms appear late in the season; brown stem rot, charcoal rot and sudden death syndrome (not yet found in North Dakota).
To maximize your ability to check for soybean diseases bring a knife, and if needed, a magnifying glass.
Brown Stem Rot (BSR)
BSR has been found in multiple locations in North Dakota. Symptoms and signs of begin to occur in mid-August.
Leaf symptoms may or may not occur, and are not particularly diagnostic. Leaf symptoms of BSR rot include a yellowing (chlorotic) and browning (necrotic) between the leaf veins (Figure 1).
Stem symptoms are much more important. To check plants for brown stem rot take a knife and slice the lower stem longitudinally. Brown stem rot will cause a browning of the center of the stem. Plants with BSR have ‘lead in a pencil look’; only the center of the stem is dark (Figure 2).
Charcoal rot is caused by a pathogen that can infect soybeans, corn, and sunflowers. Symptoms of the disease don’t generally appear until the reproductive stages of growth, and the disease is more common when the latter half of summer is dry.
Field-wide symptoms appear as patches of plants that matured quicker than healthy plants, resulting in prematurely dead soybeans. The top leaves may turn brown and premature leaf drop will occur.
Stem symptoms. The roots and lower stem of plants with charcoal rot may appear may appear gray. Scrape or shave off the outer tissue of the lower stem with a knife. Infected plants will be covered with black microsclerotia, giving the appearance of being dipped in charcoal dust (Figure 3). Sometimes, a squiggly black line, like a drawing a child would make with a marker, can be observed. Microsclerotia can be observed with a magnifying glass, but they are very small. Links to more information about charcoal rot is available at: http://www.planthealth.info/charcoal_links.htm
Sudden Death Syndrome (SDS)
SDS has not yet been confirmed in North Dakota, but it has been found in Ottertail County, MN. SDS is not usually observed until early August, is typically associated with soybean cyst nematode, and when the two act together significant yield loss can occur.
Foliar symptoms of the SDS include chlorosis and necrosis between the leaf veins (Figure 4). Unlike BSR, these foliar symptoms consistently occur when plants are infected with SDS.
Stem symptoms. Take a knife and longitudinally slice open the lower stem AND root ball. With SDS, the center of the stem remains white, but a light brown discoloration may occur on the outer stem tissue.
Several excellent resources are available at
Extension Plant Pathologist, Broad-leaf Crops