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Tent Caterpillars (06/02/16)

Forest tent caterpillars (Malacosoma disstria) and Eastern tent caterpillars (Malacosoma americanum) are feeding on tree foliage this time of year.

Tent Caterpillars

Forest tent caterpillars (Malacosoma disstria) andhort.1 Eastern tent caterpillars (Malacosoma americanum) are feeding on tree foliage this time of year. The eastern tent caterpillars make the webbed tents in the forks of tree branches, which are used as shelters and resting places. People consider the webbed tents unsightly in trees. The forest tent caterpillar does not make any webbed tents, but they wander around in masses of larvae and crawl over trees, picnic tables, patios, lawns, etc. which people consider extremely objectionable. Fortunately, they do not bite. Large numbers of forest tent caterpillars crushed on roads causes the roadway surfaces to become greasy and slippery. They infest many trees hosts:  ash, aspen, basswood, birch, chokecherry, cottonwood, elm, maple, oak, pin cherry, poplar, and other hardwoods.

There is one generation per year for either species. Both overwinter as eggs. Larvae hatch in early spring. For the forest tent caterpillar, larvae are easily identified by the keyhole shaped spots along their backs and broad bluish lateral bands. For the eastern tent caterpillar, larvae are black and somewhat hairy with a whitish-yellow stripe down the middle of the back, narrow broken orange-colored subdorsal stripes, and lateral white and blue markings. In five to six weeks, the larvae pass through five larval instars and are about 2 inches long. Mature larvae then form silken cocoons to pupate. Adult moths will emerge from cocoons during early summer (late June or early July).

Damage:  Defoliation is caused by larvae of both species. Light defoliation has little effect on tree health. Two or more years of moderate-to-severe defoliation by forest tent caterpillar is necessary to affect radial growth and cause branch and twig mortality. When populations of eastern tent caterpillars are high, whole trees can become covered with webbing and defoliated.hort.2

Pest Management:  Bt (or Bacillus thuringiensis var. kurstaki; Dipel, Thuricide), a natural occurring soil bacterium, works well to control young caterpillars and conserves beneficial insects. Other insecticides available to homeowners include:  acephate (Orthene), azadiracthin (Azatin), carbaryl (Sevin), esfenvalerate (Bug-B-Gon), malathion, permethrin, spinosad (Conserve), or other insecticides registered for trees. Always read, understand and follow the insecticide label directions.

 

Janet J. Knodel

Extension Entomologist

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Scout for Waterhemp in Sugarbeet (06/02/16)

Most areas in the sugarbeet growing region received precipitation last week.

Scout for Waterhemp in Sugarbeet

Most areas in thewdsci.peters.1 sugarbeet growing region received precipitation last week. However, soil-applied herbicides applied early postemergence for waterhemp control in sugarbeet laid on the soil surface up to 14 days before activation in some cases. Scout fields for waterhemp escapes and take a proactive and aggressive approach to control them, especially when waterhemp is small.

Small weeds (less than 3 inches) are more susceptible to herbicides than large weeds. Even weeds with a low level herbicide resistance are more susceptible at 1 inch than at a larger growth stage. Apply glyphosate at full rates with effective herbicides tank-mixes and adjuvants to control waterhemp.

The following table is a summary of multiple experiments targeting waterhemp control from glyphosate alone and glyphosate in mixtures in sugarbeet. Herbicide treatments were repeat application targeting two to three inch waterhemp.

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Waterhemp is a tough to control weed in sugarbeet, especially resistant populations. Best opportunity for control is small weeds, full glyphosate rates and a tank-mix strategy that includes ethofumesate, Betamix and/or UpBeet.

 

Tom Peters

 Extension Sugarbeet Agronomist

NDSU & U of MN

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ND SLN Labels Renewed (06/02/16)

Dow petitioned the ND Department of Ag to renew two SLN labels for the product Sonalan 10G.

ND SLN Labels Renewed

Dow petitioned the ND Department of Ag to renew two SLN labels for the product Sonalan 10G.

  1. Fall application to lentils.
  2. Fall application to yellow mustard.

The ND DOA renewed these state labels based on the limited number of weed control products available.

 

Rich Zollinger

Extension Weed Specialist

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Waterpod (06/02/16)

Each year it seems a different weed becomes the mystery weed to identify.

Waterpod

Each year it seems a different weed becomes the mystery weed to identify. To this point, waterpod seems to have the crown. Waterpod (Ellisia nyctelea L.) is an annual broadleaf plant in the Waterleaf family (Hydrophyllaceae). There are no other (common) weeds in this family that infests cropland in the northern plains. My experience with waterpod has been intermittent – it has been more of a “nuisance” weed and it shows here and there and rarely in high densities. It does not seem to be tolerant to many POST herbicides. Our observations and data base shows 2,4-D, and many ALS herbicides are effective in controlling waterpod. I suspect the cool and moist conditions must be conducive to emergence and growth and glyphosate and most POST herbicides will control it. Refer to photos below for help in identification.

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Rich Zollinger

Extension Weed Specialist

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Group 2 Herbicide Resistance – ND Update (06/02/16)

Another herbicide resistance issue was identified in 2015.

Group 2 Herbicide Resistance – ND Update

Another herbicide resistance issue was identified in 2015. A grower sprayed his wheat with Starane Flex and Varro, but redroot pigweed was not controlled. We know Starane provides little activity on pigweed, but pigweed is normally controlled by Group 2 herbicides (see bottom half of picture). Seed was collected in late summer of 2015. In a greenhouse screen, the pigweed was not controlled by Everest or Varro and only suppressed slightly by Starane Flex and Affinity BS (see top half of picture). It is interesting that the pigweed was still susceptible to Ally, GoldSky, and PerfectMatch. In other greenhouse treatments where we sprayed these same Group 2 herbicides with 2,4-D, the pigweed was controlled. Thus, we recommend adding another mode of action to the tank (e.g., 2,4-D) to control weeds in wheat and not rely solely on Group 2 herbicides. Having multiple modes of action will help delay or avoid resistance.

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Brian Jenks

Weed scientist, North Central R&E Center, Minot

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Sidedress Time Approaches (06/02/16)

Corn in some areas is approaching V5 growth stage, which is the stage in which most side-dress N application should begin in this region.

Sidedress Time Approaches

Corn in some areas is approaching V5 growth stage, which is the stage in which most side-dress N application should begin in this region. In areas where rainfall has been low to modest, with no flooding rains, standing water, or in high clay soils, no continuously muddy conditions, the difference in corn N calculator values between what is recommended preplant and what was applied preplant should be a good rate. In soils with water issues, the rate should be higher. If you were wise and used a nitrogen-nonlimiting area as a standard when applying the preplant N application, and now will use an active-optical sensor to direct your sidedress, the sidedress rate will be directed by the active-sensor algorithm in the NDSU circular. If use of an active-sensor is not part of the side-dress strategy, educated guessing is required.  In a high-clay soil, any saturated muddy conditions results in about a 1.5% N loss per day. In a sandy soil with high (2 inch+) individual rainfall event or events, downward movement of N is likely, so increasing N rates by 20-40% depending on how much rain fell until the time of sidedress is probably a good estimate. If a nitrapyrin or DCD nitrification inhibitor or ESN® was used preplant, then losses in a high clay soil or in a sandy soil will be less. If Nutrisphere® or NZone®, which are not nitrification inhibitors, was used, then no modification of loss should be expected.

If the soil will allow, anhydrous ammonia can be used as a sidedress fertilizer. It can be applied to every other row. Apply at least 4 inches deep. Somewhere around 6 inches is a normal application depth. Consider (strongly consider) some kind of trench-covering tool to use on the applicator. I told a cooperator friend of mine 15 years ago that a covering tool would help his ammonia application, but he was reluctant to be the only farmer in North Dakota to use one I think. About 5 years ago, he decided to take my advice and put them on. He told me that he wished he had paid attention to me when I first suggested it. In high clay soils, a coulter UAN applicator can be used, with a coulter every-other-row, since the trench made by an anhydrous ammonia applicator will be resistant to closure even with a closing tool. A coulter UAN applicator can be used in other soils, and has the advantage of moving the UAN deep without additional rainfall in years where that may be a problem for surface applied N. For surface application options in our area, a drop tube down the middle between every row is just as effective as the y-drop option for side-dress N and is less expensive to set up. Both will perform similarly in our climate. The other alternative is urea over the top. Rates should not exceed 50 pounds N per acre, the urea should be treated with Agrotain® (or any NBPT containing brother or sister product at the proper a.i. per ton rate) or Limus® (NBPT + NPPT) to keep the urea safe from ammonia volatility for about 10 days.

In spring wheat, the best post-N treatment for yield is stream-bar applied UAN at 4 leaf to early jointing. N application after this growth stage may increase grain protein, but not yield. Post N treatment for barley is not recommended, unless the barley is designated as feed barley. The best time for N application for protein increase in wheat is immediately post-anthesis, not before or at heading regardless of the N product used.

Dave Franzen

NDSU Extension Soil Specialist

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Field Pea Disease Resources: (06/02/16)

Sam Markell

Extension Plant Pathologist, Broad-leaf Crops

&

Julie Pasche

Research Plant Pathologist

NDSU Dept. of Plant Pathology

&

Michael Wunsch

Research and Extension Pathologist

NDSU Carrington REC

 

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Fusarium Head Blight (Scab) Risk in Winter Wheat (06/02/16)

Fusarium head blight (scab) risk season has begun in North Dakota as some of the winter wheat fields in the state have headed.

Fusarium Head Blight (Scab) Risk in Winter Wheat

Fusarium head blight (scab) risk season has begun in North Dakota as some of the winter wheat fields in the state have headed. Scab risk is highest when warm weather, high humidity and prolonged periods of moisture occur prior to and throughout the flowering stages of wheat. The best way to manage scab is to use less susceptible varieties and a well-timed triazole fungicide (ie: Prosaro, Caramba, Tebuconazole generics) application when 50% of the field is at early-flowering. However, recent research in wheat and barley have indicated post-flowering fungicide applications (up to 7 days after early-flowering) still offer scab and DON (mycotoxin) suppression.

Currently, the two scab forecasting models (NDSU Small Grains Disease Model and National Fusarium Head Blight Model) have different estimations of scab risk for flowering wheat in the state. For susceptible varieties, the NDSU model indicates most of the state is at moderate to high scab risk (Figure 1) and the National FHB model indicates low scab risk for the entire state (Figure 2). For moderately susceptible varieties, the NDSU model indicates moderate risk in the northwest and northeast portions of the state. Areas indicated to have the greatest scab risk in ND have received significant precipitation over the past seven days.

As a final note, scab models are a good guideline when making the decision to apply a fungicide. However, remember that other factors such as field location, yield potential and future weather conditions will influence the decision to apply a fungicide.

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ppth.friskop.2. 

Andrew Friskop

Extension Plant Pathology, Cereal Crops

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Field Pea Diseases Review: Bacterial Blight and Brown Spot: (06/02/16)

Bacterial blight is generally not considered an economically important disease of field peas in North Dakota, but severe losses to the disease have been reported in neighboring states.

Field Pea Diseases Review: Bacterial Blight and Brown Spot:

Importance.  Bacterial blight is generally not considered an economically important disease of field peas in North Dakota, but severe losses to the disease have been reported in neighboring states.  The disease is caused by a bacterial pathogen; fungicides have not efficacy against bacterial pathogens, and fungicides are NOT recommended for management. However, bacterial blight is often confused with Ascochyta blight, which is an economically important disease that can be managed with fungicides. Consequently, accurate identification of this disease is critical. Bacterial blight can be common when frequent rains occur with conditions that damage plant tissue (hail, high winds).

Symptoms.  Lesions can occur on all above-ground plant parts. Lesions begin as small greasy or water-soaked spots that will quickly turn necrotic. Unlike Mycosphaerella/Ascochyta blight lesions, bacterial blight lesions do not readily cross leaf veins and will take on an angular shape and appearance. Under high humidity, bacterial ooze may be visible from the lesions. Eventually, the centers of the lesions may dry up and fall out.

Disease Cycle and Development. The pathogen is primarily residue-borne but can also be seed-borne. Infection begins when spores produced in bacterial ooze are splashed onto pea growth. Typically, a combination of plant injury (such as from hail or wind-driven soil) and moisture is needed for infection to occur. The disease will progress if frequent rains persist but will slow or stop if dry conditions occur.

Management: The most important consideration when examining peas for bacterial blight is to accurately distinguish it from Mycosphaerella/Ascochyta Blight. Fungicides may be recommended for Mycosphaerella/Ascochyta blight, but are NOT recommended for bacterial blight. Misdiagnosis of these two disease can result in an unnecessary fungicide application, or, an erroneous no-spray recommendation – both situations can be costly.  If Bacterial blight occurs, stay out of the fields when wet to avoid mechanical transmission of the disease.  Because the disease is seed-borne and seed-transmitted, it is advisable to avoid seed lots originating from fields where bacterial blight developed above low levels.

ppth.markell.bacterial blight

Sam Markell

Extension Plant Pathologist, Broad-leaf Crops

&

Julie Pasche

Research Plant Pathologist

NDSU Dept. of Plant Pathology

&

Michael Wunsch

Research and Extension Pathologist

NDSU Carrington REC


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Field Pea Diseases Review: White Mold/Sclerotinia: (06/02/16)

White mold is rarely a disease of economic importance in dryland field pea production but can be important in irrigated peas.

Field Pea Diseases Review: White Mold/Sclerotinia:

Importance.  White mold is rarely a disease of economic importance in dryland field pea production but can be important in irrigated peas. The pathogen that causes white mold is the same pathogen that causes white mold on other broadleaf crops (canola, dry edible beans, soybeans, sunflower, etc…).  Your fields may be at lower/higher risk depending on the history of white mold in your previous broadleaf crop, and the level of white mold in your current field peas could decrease/increase the white-mold risk to future broadleaf crops planted into that field in the future.

Symptoms.  Lesions and white fluffy mold can occur on all above ground plant parts. Lesions being as water-soaked spots but take on the characteristic white, bleached color as they age. White fluffy growth may occur on lesions, particularly when canopies are wet for long periods of time. Sclerotia, black resting structures of the causal pathogen, are produced in and on diseased tissue.

Disease Cycle and Development.  The disease cycle and favorable conditions for white mold on peas are essentially the same as on canola, dry edible beans, soybeans and other crops (sunflowers is a little different). The pathogen overwinters in the mouse-dropping size black fungal structures (sclerotia) at the end of the season. When adequate rain occurs in the spring and the soil is saturated (or near saturated), these sclerotia produce small mushrooms (apothecia) that release airborne spores.  The infection process begins when spores land on flower petals, begin to digest them, and the subsequent fungal growth moves into healthy tissue. Consequently, field peas are not at risk for infection until bloom begins. For infection to occur, the soils must be wet enough to produce the small mushrooms 1-2 weeks before bloom.  White mold is very dependent on cool and wet conditions for disease to develop.

Management.  Data on the comparative efficacy of fungicides for control of white mold on field peas are not available, but testing conducted on other crops suggests that Proline and Aproach may be useful for managing white mold if applied when excellent fungicide deposition to the lower canopy can be achieved. If it is difficult to obtain excellent fungicide deposition to the lower canopy, Endura is likely to be the most effective registered product.  Fungicide applications targeting white mold in field peas are unlikely to be profitable unless field peas are produced under irrigation and the weather is cool (highs in the 60s to 70s Fahrenheit) during bloom.

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Sam Markell

Extension Plant Pathologist, Broad-leaf Crops

&

Julie Pasche

Research Plant Pathologist

NDSU Dept. of Plant Pathology

&

Michael Wunsch

Research and Extension Pathologist

NDSU Carrington REC


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