Category Archives: Commodity

True armyworm infestation reported in small grain on Eastern Shore

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It’s been many years since we’ve seen a true armyworm (see the attached image) infestation in our small grain crop, but one is reported to be ongoing in the barley and wheat fields on the Eastern Shore. These caterpillars can do two types of damage—leaf feeding and head cutting.  Leaf feeding is rarely extensive enough to warrant control, especially if fields are within a couple of weeks of harvest.  Head cutting is less tolerable.  For some reason no one has been able to explain, caterpillars will sometimes eat through the stem below the heads casing them to drop to the ground.  Finding otherwise healthy looking heads-short stems on the ground is a good indicator that true armyworms are present and still active.  It is often hard to find them on plants during the day as they typically feed more at night and seek cover under plant residue during the day.  When we have worked with this pest, we found that fields with the most plant residue on the soil surface tended to have the heaviest infestations.

We do have thresholds for true armyworm for those motivated to scout for them. As a general rule, barley should be treated if the number of armyworms exceeds one per linear foot between rows and most of the worms are greater than 0.75-inch long. In wheat, armyworms tend to nibble on the tips of kernels rather than clip heads; thus, populations of two to three worms per linear foot between rows are required to justify control. In high management wheat fields with 4-inch rows, treatment is recommended when armyworm levels exceed 3 to 5 per square foot of surface area, or per linear foot of row.

If a treatment is warranted, there are a few good choices but the PHI (Pre Harvest Interval) may be a challenge. Some work we did many years ago showed that pyrethroids were generally effective but have a PHI of 14 days (example, Mustang Max) to 30 days (example, Baythroid), which could be a problem for barley, wheat not so much. Lannate has a PHI of 7 days but did only an OK job in our trial and not as good as the pyrethroids. We chalked that up to the fact that although Lannate has great efficacy against most caterpillar species, it has almost zero residual activity. So a day-time spray may not have had as much horsepower by the evening when caterpillars become active. Since our work was done, several new products have been introduced to the market that we have not tested, like Prevathon (PHI 14 days), and Besiege (PHI 30 days). These should work well. See the Pest Management Guide Field Crops 2016, 4-49, p. 53 for more product listings (http://www.pubs.ext.vt.edu/456/456-016/Section04-Insects-1.pdf).

With any treatment, coverage will be essential so deliver the highest volume you can live with and direct it to go as deep into the canopy as possible.

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Section 18 granted for use of Transform to control sugarcane aphid on sorghum

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EPA just granted a Section 18 for use of Transform™ WG in Virginia against sugarcane aphid in sorghum. Transform (50% a.i. sulfoxaflor), manufactured by Dow AgroSciences, may be applied through April 8, 2017 on a maximum of 16,591 acres of sorghum fields (grain and forage) in the following counties: Accomack, Albemarle, Alleghany, Amelia, Appomattox, Augusta, Bedford , Botetourt, Brunswick , Campbell, Caroline, Carroll, Charlotte, Charles City, Culpeper, Cumberland, Dinwiddie , Essex, Fauquier, Floyd, Fluvanna , Franklin, Frederick, Gloucester, Goochland, Greensville, Halifax, Hanover , Henrico, Isle of Wright, George , King William, King and queen , Loudon, Louisa, Luneburg, Madison , Mathews, Mecklenburg, New Kent, George , Prince William, Rockbridge , Rockingham , Russell, Southampton, Spotsylvania, Suffolk, Surry, Sussex, Virginia Beach, Washington, Westmoreland, and Wythe. 

The following directions, restrictions, and precautions must be observed. Foliar applications may be made by ground or air at a rate of 0.75-1.5 oz of product (0.023-0.047 lb a.i.) per acre. A maximum of 2 applications may be made per year, at least 14 days apart, resulting in a seasonal maximum application rate of 3.0 oz of product (0.09 lb a.i.) per acre per year. Do not apply product 3 days pre-bloom or until after seed set. 

To minimize spray drift and potential exposure of bees when foraging on plants adjacent to treated fields: applications are prohibited above wind speeds of 10 miles per hour (mph) and must be made with medium to course spray nozzles (i.e., with median droplet size of 341 µm or greater). A restricted entry interval (REI) of 24 hours applies to all applications. Do not apply within 14 days of grain or straw harvest or within 7 days of grazing, or forage, fodder, or hay harvest. 

Environmental Hazards Statement: “This product is highly toxic to bees exposed through contact during spraying and while spray droplets are still wet. This product may be toxic to bees exposed to treated foliage for up to 3 hours following application. Toxicity is reduced when spray droplets are dry. Risks to pollinators from contact with pesticide spray or residues can be minimized when applications are made before 7:00 am or after 7:00 pm local time or when the temperature is below 55 degrees Fahrenheit (°F) at the site of application.” 

We will provide updates on the presence and spread of sugarcane aphid as the season progresses.

 

New Label for Sandea on Cucumber

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Gowan has a new supplemental label for Sandea on cucumber, allowing for a 14 day pre-harvest interval.  This label will be on the bottle next production run, but for the time being growers wanting to use the supplemental label will need to have a copy of the supplemental label on file.  This new label will replace the 24c (Special Local Needs label) label that covers the same use.  If you have any questions do not hesitate to contact me.  Below is the supplemental label.

Sandea 81880-18 cucumbers (aprvd 5-11-16)

 

 

Avoid Seedling Disease with Quality Seed, Proper Seed Placement, & Good Soil-To-Seed Contact

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We were hoping to be about half way finished with our soybean plantings by now, but we haven’t put a planter in the field in two weeks.  The rain continues to delay us, but I hope that we will get back into the field next week.

The rain and cooler weather has lowered soil temperatures somewhat and this means that we need to take a few extra precautions, especially pertaining to seedling disease.  I wrote a detailed blog a few years ago on seedling disease; little has changed and, for more details, you can view that blog here:

Fungal Seedling Disease in Soybean

Planting soybean in cool soil will lead to delayed emergence and increased chance of seedling disease that can reduce stands, weaken emerged plants, and inhibit early-season growth. I stress that the greater time required for emergence, the greater probability that the seed will become infected with soil-borne disease.  If you are planting into cool soils, I strongly suggest using fungicide-treated seed as an insurance against seedling disease. These treatments will protect the seed and seedling if emergence is delayed.

But, seed treatments should not be a substitute for other practices that encourage rapid seedling emergence.  Here is my checklist for insuring a good stand free of seedling disease:

  • Know the germination and vigor of your seed; adjust the seeding rate accordingly.
  • Insure good soil-to-seed contact by properly setting your planter to cut through the residue and penetrate to the proper depth.
  • Plant soybean seed ¾ to 1 inch deep into good soil moisture.  Planting deeper will delay emergence
  • Consider fungicide seed treatments if planting into cool soils.

Restriction to fungicide use that concerns peanut shellers

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I was recently made aware of a long list of fungicides involving the European Union and their restriction on some chemical residues on peanuts. Over the last couple of weeks there were rumors that these restrictions have been relaxed but apparently these rumors are unfounded, I was told. Well, for the industry that exports peanut this is quite serious because any trace of any of the chemical on that list may result in failure to their business. The list includes many fungicides for bacterial diseases, which are not a common problem in the VC region; others, however, like Tilt Bravo SE are. For the sake of staying informed and alerted at what it is and what may come, here I provide that list, with the recommendation that growers do not use any product on that list. Notice to Growers – Products Not To Be Used

Slug problems on corn

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Slug damage on no-till corn.

Slug damage on no-till corn.

With all of the rain during the first week of May, and with seedling corn having emerged, we are hearing about slug pest problems, particularly in no-till corn.  Eastern Shore of Virginia is one area reporting issues.  Slug problems are a common concern in no-till systems when conditions are wet in the spring (see VCE Factsheet No. 444-109  https://pubs.ext.vt.edu/444/444-109/444-109.html) .  Another useful VCE factsheet on slug management in no-till corn from Bobby clark and Rod Youngman is:  http://offices.ext.vt.edu/shenandoah/programs/anr/CropandSoilEnvironmentalSciences/Slug_Fact_Sheet.pdf

Growers must keep four things in mind right off the bat: 1) corn plants are often not killed outright by the slugs and quite often have the ability to outgrow the leaf feeding injury by these slimy little beasts unless populations are very high and weather conditions are bad.  Soybean cotyledons, however, are more susceptible to being killed because their growing point can be damaged; 2) if it stops raining for a few days, then the slugs will go away and hide as they require high moisture levels; 3) replanting is an option, but a grower needs to factor in the economics see VCE Fact Sheet https://pubs.ext.vt.edu/2905/2905-1293/2905-1293_pdf;  and 4) if you are considering a chemical control measure, keep in mind that there are only a select few effective options such as slug bait products containing metaldehyde or iron phosphate.  These are not easy to apply (need to be broadcasted) and are fairly expensive.  However, these products are efficacious and will most often alleviate the slug problem long enough for your seedling plants to reach a sufficient size to no longer be economically damaged by slugs.  See VCE Fact sheet No. ENTO-178 for a recent efficacy evaluation that we did with slug baits.  http://pubs.ext.vt.edu/ENTO/ENTO-178/ENTO-178-PDF.pdf

 

Screening for Herbicide-resistant Italian Ryegrass

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Italian ryegrass is one of the most troublesome weeds infesting small grain fields throughout Virginia.  Currently, only Hoelon-resistant ryegrass has been confirmed in Virginia.  However, many growers have complained the ALS-inhibitors (Osprey and PowerFlex) and Axial XL (ACCase-inhibitor) have failed to control ryegrass.  To get a better handle on herbicide-resistant Italian ryegrass in Virginia, the VT weed team plans to screen ryegrass from across the state for herbicide resistance.  Year 1 of the project will focus on the I95 corridor east.  We will be traveling this area and collecting ryegrass seed for herbicide screening this fall.  However, if you have had complaints of resistant ryegrass in your neck of the woods and are interested in screening it this year, we welcome your samples and will add them to our screen this fall.

If you are interested, see the sample information sheet below for sample, handling, and shipping information.  For the sample, GPS coordinates are critical.  If you have any questions, feel free to contact me.

HR Ryegrass Sample Info Sheet

“One year to seed; seven to weed”

Wheat Disease Update – May 3, 2016

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Due to the recent rain, scab risk is increasing in portions of Virginia, especially on the Eastern Shore and coastal areas. The scab risk assessment tool can be found at http://www.wheatscab.psu.edu. Many fields are at or near flowering. In most areas, moderately resistant (MR) varieties are in the low to medium scab risk category, but keep in mind that many acres are still planted to moderately susceptible (MS) or susceptible (S) varieties such as Shirley. In the eastern portions of the state, scab risk is projected to be high for susceptible varieties over the next week, and it will likely be necessary to work in fungicide applications between rain events. Fungicides targeting scab should be applied within 5-6 days of flowering (50% of main tillers starting to flower from the center of the head). Do NOT apply a strobilurin or fungicide pre-mix containing a strobilurin after flag leaf emergence (Feekes 9) since this can increase DON contamination in the grain. Prosaro, Caramba, and Proline are the most effective products for reducing scab and DON contamination. These fungicides will also control foliar diseases such as leaf blotch, stripe and leaf rust, and powdery mildew. Stripe rust has been observed on susceptible wheat cultivars in some fields for several weeks now, but levels remained low due to dry conditions. The recent rain and humid conditions have resulted in spread of the disease in some areas. Similar conditions are forecasted over the next week and the disease has the potential to spread rapidly, so growers should scout their fields immediately to determine if stripe rust is present.

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Do You Need To Inoculate Your Soybean?

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Do soybean inoculants work?  Yes.  Soybean cannot fix its own nitrogen without the symbiotic relationship formed between the roots and a soil bacteria called Bradyrhizobium japonicum. Soybean inoculant contains this bacteria.

Do you need to inoculate your soybean seed?  Maybe.  If you’ve never grown soybean in the field that you plan to plant them, definitely add the inoculant to your seed.  Or better, inject some liquid into the furrow (you’ll get 3 to 4 times the amount of bacteria).  Also, if you don’t have a long history of soybean in the field, inoculate; it will likely pay off.

But what if you are rotating the land to soybean on a regular basis?  You are not likely to get a yield response.  In a 2-year study on soils that were rotated regularly with soybean, I only found 1 of 18 sites that responded to an inoculant.  And the site that responded was land that had only been in production for less than 5 years (formerly pine trees).  In all fairness, one inoculant product at one other location (SUF DC, 2012) did yield more than the untreated check.

Inoculant Expts 2012-13There are some caveats that I should mention.  Sometimes, a yield response if more probable.  If you haven’t grown soybean in the last 4 to 5 years, then it may be good insurance.  If the field was flooded or if it experienced extreme drought conditions in the previous year, bacteria might have died off; therefore, there is a greater likelihood of a yield response to the inoculant.

In summary, inoculants do work and they are good insurance treatments.  But, they will rarely result in a yield benefit if the field has been regularly rotated to soybean.

If you do decide to use an inoculant, follow the label closely.  I prefer to apply the inoculant as close to planting as possible.  Note that certain chemical seed treatments (including molybdenum or “Moly”) can injure or kill the bacteria.  The less time that these chemicals are in contact with the bacteria, the better.

Should I Plant Soybean in April?

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My usually answer to this question is “No…at least not on a big part of your acreage.”  But, let’s rephrase the question to “Can you plant soybean in April?”  The answer is clearly “Yes, you can…but don’t plant the entire farm in April.”  Below, I’ll discuss the reasons for these answers.

What are the advantages to planting in April?   One advantage is that the crop mature earlier.  A general rule of thumb is that planting 30 days earlier will allow you to harvest about 10 days earlier?  Only you can decide if harvesting 10 days earlier is an advantage though.  So, ask yourself if this fits into your operation.

You can also gain another 10 or so days by selecting a variety that is at least a full maturity group earlier (e.g., MG 4.5 instead of a 5.5, or a 3.7 instead of a 5.0).  You’ve then changed your systems substantially.  Such a system is commonly referred to as the Early Soybean Production System (ESPS), which is now the most common soybean production system in the Mid-South/Delta growing region of the country.

But choosing an earlier variety and/or planting early is not just about harvesting earlier.  You will also place the most critical time of soybean development (pod and seed fill) earlier in the season.  For the Mid-South that regularly experiences drought in August, the ESPS puts those critical stages into July and early August; thereby avoiding the driest (and maybe hottest) time of the year.  In addition, this system captures more sunlight per day during the pod and seed development stages (i.e., the days are longer in July than in August which are longer than in September),  With more photosynthesis per day during these stages, we can gain yield potential.  Early planting was also found to be beneficial in the Midwest; I suspect that the longer days were the primary benefit there.  So theoretically, yield potential is greater with early planting of early-maturing varieties, even if drought in August is not the major concern.

Although similar benefits are possible in Virginia, planting early with an early-maturing variety can result in lower yields.  Why?   First, droughts in Virginia are intermittent.  In some years, August is our driest month, in others it is July or June or September or….  Furthermore, most of our soils hold very little water.  In some soils, we are 10 days from the last rainfall to a drought.  Add to this that the hottest and usually driest time is late-July and early-August, and you have a recipe for disaster with early planting and/or early maturity groups.

But, what if you irrigate?  These are the fields that I would use an early soybean production system.  A high plant-available water-holding capacity soil also helps.  At least you can avoid the drought stress.  And because the season is naturally shorter, you will likely spend less on irrigation.  But, there is still the heat risk. Only  time will tell if the benefits outweigh the risks.  Even in irrigated fields, you may only want to dedicate a small portion of your acreage to an early system.

A final risk from planting early is seedling diseases.  It may take 2 to 3 weeks for soybean to emerge if planted in April.  So, be sure to use a fungicide seed treatment.

In summary, there may be benefits to planting early and/or using earlier-maturing varieties.  But, I think that the risks outweigh the benefits, especially in rainfed conditions.