Category Archives: Commodity

Flooded Soybeans – How Much Damage? What to do?

Rainfall across the state resulted in in saturated soils and sometimes flooded soybeans or fields to be planted in soybean.  Although fields are drying out, more rain is expected this weekend.

It’s difficult to know the long-term effect of flooding on soybean fields. Research is limited, but we do know that the fate of flooded fields will largely depend on 1) the development stage during which the flood took place; 2) the duration of the flood; 3) the temperature during and right after the flood; and 4) the drying rate after the flood.

Basically a flooded field depletes the roots of oxygen (O2), causing photosynthesis to slow.  After several days without O2, the plant may turn yellow, grown very slowly, and possibly die.  Other indirect effects of flooding can include reduced nitrogen-fixing bacteria (but they will recover), nutrient imbalances, and increased disease pressure.

For more detailed information, see a blog post that I wrote  in 2013 at the Virginia Soybean Update site.

In short, here are a few pointers for flooded fields.  If soybean have not yet been planted:

  1.   I don’t recommend tillage to dry the soil out for continuous no-till fields.  Tillage will destroy the soil structure that you’ve built since tillage was stopped.  The field is probably draining better than it ever was; tillage will just cause water to stand longer in the future.
  2. Bradyrhizobia japonicum, the nitrogen-fixing bacteria that helps provide soybean with that nutrient, is harmed by lack of oxygen caused by the flood.  Although the bacteria will recover, it may be prudent to add inoculant to the seed in areas that were flooded.

For flooded fields that have been planted:

    1.  Minimize any addition stress by staying out of the field.  Do not try to plant or replant too soon.  More damage can be done to the soil and more yield can be lost from planting into we soils than from planting too late.
    2. If soybean have not yet emerged and crusting evident, light tillage with a rotary hoe will help emergence.
    3. Evaluate the stand. If a stand reduction occurred, determine if it’s worthwhile to replant. Remember that after mid-June, every day delay in planting will cost you about ½ of a bushel in yield. The plants that remain are still higher yielding than seed that can now be planted, even if the stand has been substantially reduced.
    4. Stress such as herbicide injury can slow the crop down further. Still, weeds need controlling. But you may want to select herbicides (usually as tank-mix partners to glyphosate) that don’t cause a significant amount of burning.
    5. Finally, some will want to apply some type of foliar fertilizer to the crop to “kick-start” it back to health.  I see little advantage of this.  Remember that the real problem is lack of O2 to the roots and CO2 buildup in the soil; only after the roots begin to receive O2 will the recovery process start.Hopefully you haven’t experienced severe flooding (> 24 hours).  But if so, be patient and evaluate the field.  Then make good decisions on how to handle it.

 

 

New Crop Disease Management Resources

Though it has been around for several years, the Crop Protection Network (CPN) has recently added several publications on disease management in corn, soybean, and small grains that are relevant to growers, crop consultants, and extension personnel in Virginia and the surrounding region. These can be accessed at the CPN website cropprotectionnetwork.org. As stated on the website:

“The Crop Protection Network (CPN) is a multi-state and international partnership of university and provincial Extension specialists, and public and private professionals that provides unbiased, research-based information. Our goal is to communicate relevant information to farmers and agricultural personnel to help with decisions related to protecting field crops.

Extension specialists throughout the country (including myself) contribute to the publications and other resources posted on the website. An example of a recent publication on optimizing fungicide use for control of Fusarium head blight can be downloaded below. The CPN library includes over 30 publications on crop management, and additional publications are in development.

CPN-3001-Optimizing Fungicide Use for FHB

Wheat Disease Update – May 24, 2018

Fusarium head blight (FHB) risk for Virginia continues to be to high throughout the state due to recent wet, warm weather (http://www.wheatscab.psu.edu/). Most of the wheat is past the flowering stage and no longer at risk, but later flowering wheat may still need a fungicide application. Triazole fungicides including Prosaro, Caramba, and Proline are recommended. Do not apply fungicides containing a strobilurin since this can increase DON. For wheat that is past flowering, a fungicide application will not reduce FHB or DON contamination of the grain. Grain harvested from fields with signs and symptoms of FHB should be kept separate from non-infested grain.

For assistance with disease identification or management recommendations, contact Dr. Hillary L. Mehl, Extension Plant Pathologist (hlmehl@vt.edu).

Be Careful Planting Into Wet Fields – We Still Have Time to Maximize Soybean Yield

Recent heavy rains have led to temporary flooding of numerous soybean fields throughout Virginia and put us behind with soybean planting .  Only 26% of the crop was planted as of last week.  And it looks as if we will have another bout of rain this weekend.

Although you will be tempted to get back into these fields as soon as possible, I caution you to hold off until the entire field dries to a point where you will not damage the soil, especially around the seed.  Planting into wet soils can compact the soil around the seed, making rapid seedling growth difficult.  For continuous no-till fields, you can also cause some long-term compaction that will not be easily removed without tillage.  I usually advise to wait another half or full day before you think you can get back into the field.  In the long run, it will likely pay off.

When should we get into a big hurry to plant?  Planting date research indicates that we usually don’t see a rapid decline in yield until mid-June.  Below is some Virginia research to verify this.

Although the below multi-state data is double-crop soybean, it also illustrates the point well.So, you are likely to lower your yield much more by planting too wet than delaying the planting (or re-planting) until the last week of May or the first week of June.  Still, only you know your operation.  If you still have hundreds, or maybe even thousand acres to go, you may not want to wait too late.

armyworm in VA small grains

I have received several reports from Virginia Beach and Chesapeake of armyworms infesting wheat and hay in large numbers. Neighboring regions of NC are experiencing similar outbreaks.

Overall, these infestations are rare in our state, but scouting is recommended. Fields treated previously with pyrethroids may be at higher risk because they contain fewer natural enemies to combat pest outbreaks. Armyworms feed at night and may be found under residue and at the base of plants during the day. Oftentimes, they can be seen curled into a c-shape (see photos below). Thresholds are one larvae (0.75 in or longer) per linear foot in barley and 2-3 per foot in wheat. Refer to Chapter 4 of Virginia Tech’s “Pest Management guide: Field Crops” for products and rates labeled for armyworm control in our state. Pay attention to PHI before making an application. Pyrethroids can be effective against armyworm. Good coverage is critical, especially in high residue fields.

Photos courtesy of JB Rigg, Helena Chemical.

Wheat Disease Update – May 15, 2018

Three-day forecast for Fusarium head blight (FHB) risk on susceptible wheat varieties.

FHB risk is increasing in Virginia and will continue to increase over the next several days. Risk is highest on the Eastern Shore, but susceptible varieties such as Shirley that are flowering over the next week will be at moderate to high risk in many portions of the state. Growers should monitor the FHB risk tool (www.wheatscab.psu.edu) as their wheat crop begins to flower. Consider applying a fungicide if risk is moderate to high, especially on susceptible or moderately susceptible varieties. Wheat that has completed flowering is no longer at risk. Fungicides should be applied at early flowering or up to one week later. Do not apply a strobilurin-containing fungicide since this can increase DON contamination. Recommended fungicides include Prosaro, Caramba, and Proline.

Steve Rideout, Extension Plant Pathologist at the Eastern Shore AREC, confirmed stripe rust on research plots of Shirley on Monday. FHB risk continues to be high on the Eastern Shore, so growers in this part of the state with varieties that are susceptible to stripe rust should consider an application of Prosaro, Caramba, or Proline since these will control both FHB and rust.

Stripe rust on wheat.

For assistance with disease identification or management recommendations, contact Dr. Hillary L. Mehl, Extension Plant Pathologist (hlmehl@vt.edu).

 

Recommended Peanut Seeding Rates for Virginia

Research data, such as those here Seeding Rate-May 2018, showed that saving seed at planting does not return high yields or economic profit. To achieve high yields, we recommend planting 5 or 6 seeds per foot of row, assuming a germination of 80% and above. This is in particular necessary for large seeded cultivars like Emery and Wynne, and under irrigation.  If germination is lower than 80%, which may be the case this spring for some seed lots of Wynne and Sullivan, 6 to 7 seeds are safe to plant but nothing above that. At least, we have not recently tested or heard of a benefit to increase the seeding rate above 7.

Imidacloprid effect on inoculant in peanut

There are concerns that imidacloprid-based insecticides for thrips control may negatively affect Rhizobia in inoculants when tank-mixed and applied in the furrow when plating peanut. As we are just a week (or less) from starting peanut planting in Virginia, I thought this issue be addressed for the farmer’s peace of mind if they decide to mix Optimize Lift inoculant with Admire-Pro insecticide for in-furrow seed treatment. I personally have not looked into this issue before, because we have not seen any effects in research plots or received complaints from farmers.  However, we will research this aspect in 2018.

Meanwhile, colleague Dan Anco, Peanut Specialist at Clemson University, tested the effect of different tank-mixtures for in-furrow applications on the nodule number and peanut yield in 2015 and 2017.  Graciously, Dan shared this information included in the In_furrow tank mixes tables.  The results clearly show no effect of mixing Optimize Lift with Admire-Pro on peanut yield in both years (Tables 1 and 2), even when the number of nodules from this mixture appeared to be reduced by the use of Admire-Pro in 2017 (Table 2). David Jordan, Peanut Specialist at North Carolina State University, reported similar findings Peanut Science Inoculant CFTGM Peanut Inoculant.

Wheat Disease Update – April 30, 2018

As wheat starts flowering in the region, it is time to consider whether or not to make a fungicide application for Fusarium head blight (FHB). Currently, risk is low in most parts of Virginia. There are a few exceptions, including portions of the Eastern Shore, where risk is moderate to high.

The most effective fungicides for control of FHB and DON are Caramba (metconazole), Prosaro (prothioconazole + tebuconazole), and Proline (prothioconazole). Less expensive triazoles such as Tilt (propiconazole) and Folicur (tebuconazole) will provide some control, but if FHB risk is high these fungicides are unlikely to prevent unacceptable levels of DON contamination. Keep in mind that fungicides containing a strobilurin should not be applied after the flag leaf stage since they can increase DON contamination.

Current FHB risk in Virginia and the surrounding region. Green, yellow, and red indicate low, moderate, and high risk, respectively. FHB risk can be monitored using the Fusarium Risk Assessment Tool (http://www.wheatscab.psu.edu/).

To maximize their effectiveness, fungicides for FHB and DON control should be applied at early flowering or up to one week later. Fungicides that control FHB and DON will also control foliar diseases including powdery mildew, leaf rust, stripe rust, and leaf blotch. Stripe rust has been found in NC and was recently reported from a single field in Warsaw, VA so be sure to scout susceptible varieties for this disease. For specific wheat disease management recommendations or assistance with disease identification, contact Dr. Hillary L. Mehl (hlmehl@vt.edu).

 

Section 18 for sulfoxaflor (Transform WG) on sorghum for sugarcane aphid

The EPA has granted a Section 18 for the use of Transform WG (50% a.i. sulfoxaflor) on sorghum for managing sugarcane aphid in certain counties in Virginia. The expiration date is November 30, 2018. All applicable directions for use, restrictions, and precautions on the label, and Worker Protection Standards, must be followed except as modified in the Section 18 document. In part, the Section 18 lists a foliar application rate of 0.75-1.5 oz of product per acre, with a maximum of 2 applications per year, resulting in a seasonal maximum application rate of 3.0 oz of product per acre per year. Please be sure to read and follow the entire label and Section 18. Thanks to the Virginia Department of Agriculture and Consumer Services, Office of Pesticide Services, for their assistance.