Advisory on Pollinator Protection and the Use of Foliar Insecticides in Flowering Cotton

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We have received several calls about the issues regarding the foliar application of insecticides to flowering cotton. Because of the oil and livestock feed uses of cotton, it is considered to be a food crop—so many of the insecticides used in cotton now include pollinator protection statements on their labels. These insecticides include, but are not limited to the neonicotinoids: Admire Pro, Centric, Belay, Endigo, Leverage, and others.

According to the new label restrictions, these insecticides are not to be used on cotton while bees are foraging, and they are not to be used until flowering is complete and all petals have fallen unless one of the following conditions is met:

1) The application is made to the target site after sunset and before sunrise.

2) The application is made to the target site when temperatures are below 55˚F.

3) The application is made in accordance with a government-initiated public health response.

4) The application is made due to an imminent threat of significant crop loss, and a documented determination consistent with an IPM plan or predetermined economic threshold is met.

Conditions 1, 2, and 3 are either not practical or will likely not apply to the cotton crop.  But condition 4 could be a viable option for growers but it needs some clarification—specifically, what is an imminent threat, who makes the determination, and how is the determination documented?

WHAT CONSTITUES AN IMMINENT THREAT OF SIGNIFICANT CROP LOSS, AND WHO DECIDES?

  • According to a guidance document by the State FIFRA Issue Research and Evaluation Group (SFIREG) (further details follow), the criteria to determine when an imminent threat exists would need to be determined by the applicator in consultation with a Cooperative Extension agent, crop consultant, certified crop advisor, or a state recognized pest management model/tool.
  • According to VDACS, “….ideally the determination of what an ‘imminent threat of significant crop loss’ is would be made and supported by a subject expert, for example, extension agent, crop advisor etc., prior to the application and the decision to apply can be shown to be consistent with an IPM plan or based upon an established economic threshold.”

HOW IS THE DETERMINATION DOCUMENTED?

  • According to VDACS, regarding required documentation, “…the label does not contain, thus there does not exist, a requirement for any specific records or documentation to be kept by the applicator. It is, however, in everyone’s best interest to have thorough application records and that would include documenting ‘imminent threat’. It would be prudent for the applicator to have some ‘evidence’ to support their use of the product as an outdoor foliar application on a labeled crop. The ‘evidence’ could be a letter or email from one of many experts, or a reference to a pest management guide or other such literature.”
  • Our current insect pest management recommendations for Virginia cotton can be accessed in the VCE publications, Pest Management for Field Crops, http://www.pubs.ext.vt.edu/456/456-016/456-016.html, and Managing Stink Bugs in Cotton: Research in the Southeast Region, http://www.pubs.ext.vt.edu/444/444-390/444-390.html.
  • Also according to VDACS, the label language (regarding documentation) is purposely vague to allow flexibility and rather than making the documentation requirement too prescriptive, they are following the general guidance document from the State FIFRA Issue Research and Evaluation Group (SFIREG), http://www.aapco.org/documents/bee_label_guidance_2014.pdf, and will consider the documentation provided to satisfy the condition has been met on a case by case basis.

So, as I see it, cotton can be treated with a neonicotinoid insecticide during flowing if the need is determined by a trained professional or there is some evidence that the treatment was based on published thresholds—and it would be best to document it via a letter, email, or some other written record.  Using any insecticide with the pollinator protection label language (and it is likely that in the future these restrictions will be applied to more products) will raise the bar in terms of both understanding and adhering to insect thresholds in not only cotton, but all food crops where pollinators forage during flowering.  This would leave no room for ‘automatic’, ‘tank mix’, ‘convenience’, or ‘insurance’ treatments—as these could not be justified as adhering to thresholds.

Note that there are a number of other requirements regarding notifying nearby beekeepers prior to insecticide applications. Details are provided in the SFIREG document mentioned, above. Always read and follow the label.  If you have further questions about the pollinator protection label language or how VDACS will handle this, you should contact your local Pesticide Investigator http://www.vdacs.virginia.gov/pesticides/directoryinvest.shtml or the Office of Pesticide Services at 804-786-3798. If you need further help in understanding the thresholds, please contact your local VCE ANR Agent, or Ames Herbert at the VT Tidewater Agricultural Research and Extension Center.

Should I Apply a Foliar Feed to My Soybeans?

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The high prices over the last few years have allowed many of us to experiment with certain practices that, at best, might occasionally increase yields.  The return of investment usually only required one bushel (or less), depending on the input.  But that was when soybeans were $13, $15, and even $17 per bushel.  But now, you may be able to sell your crop for $10-11 (if you still have any in storage) and the future prices are reflecting record acreages.

So, it seems that I’ve been asked, “Should I apply a foliar feed to my soybeans?” more this year than in the past few years.

First, I still stand by what I’ve said in the past and still say today: “Feed the roots and not the foliage.”  Soybean will remove 3 to 4 lbs of nitrogen, 0.8 lbs of phosphorus, and 1.4 lbs of potassium per bushel of seed produced.  These large amounts will need to come via root uptake; it is not economically possible to apply these amounts through the foliage.

But, once the soil needs are met, will additional fertilization help?

First, an application of Manganese may be needed if your soil pH inches much above 6.5.  2010-07-20-Mn-Deficiency-002webI’ve even seen Mn deficiencies when the pH is as low as 6.2 (using fall/winter soil test levels) and the soil is “wet natured” or if lime was recently applied.  There are also certain varieties that tend to show Mn deficiency sooner than others.  So, if you see the characteristic interveinal chlorosis of Mn deficiency or if soybean are growing in a field that typically exhibits such a deficiency, then spray Mn.

Another issue that I’m seeing this year is a general yellowing of plants, usually just in seemingly random spots in the field.  Upon closer inspection, these are usually very wet areas (there are plenty of those this year) or sandy knolls.  In the saturated soils, the yellowing is likely due to lack of oxygen and/or poor nodule development.  The only cure for lack of oxygen is for the soil to dry out.  Poor nodulation is indirectly a response to lack of oxygen – the nitrogen-fixing bacteria have temporarily stopped functioning.  But they will recover and provide the nitrogen when the plant needs it the most, when the pods are forming and seed are filling.  Will a shot of foliar nitrogen help?  Yes, it will green up the plant if lack of nitrogen is the problem.  Will this shot of nitrogen (assuming that nitrogen is the problem) increase yield?  Maybe.  Maybe not.  If lack of oxygen is the problem, then probably not.  Even if lack of nitrogen is the problem, probably not.

I want to caution everyone to not make assumptions that lack of nitrogen is the problem.

Is this N or S deficiency?

Is this N or S deficiency?

The only way to know for sure is to take a tissue sample. A deficiency that closely resembles nitrogen deficiency is sulfur.  On those sandy knolls, I’ve seen sulfur deficiencies.  Sulfur will leach just like nitrogen.  But, soybean will not produce its own sulfur.  A shot of nitrogen would do nothing to help in this case.  The take home message is to determine the cause, then act on that information.

But what about other nutrients?  What if there is no visual symptoms of nutrient stress?  What if my yield potential is very good?  My attitude towards this is that it usually won’t hurt (but be careful mixing with other chemicals), so do what makes you sleep better at night.  If you think it is helping your crop, then make the application.  It’s your money.  You know your fields better than anyone.  But, I have rarely seen a response to foliar feeds if you have maintained adequate soil fertility levels and have managed the crop for maximum economic yields.  Again, yield response to foliar fertilizers is, at best, inconsistent.

Kudzu bug distribution update for July 16, 2015

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Our scouts (Ed Seymore, Jamie Hogue, and Dr. Herbert’s Entomology team) have started sampling soybean fields across Virginia for kudzu bug and brown marmorated stink bug.  The file attached at the end of this paragraph indicates the counties where kudzu bug has been found (blue counties = kudzu bug found in soybean; maroon counties = kudzu bug found on other hosts such as kudzu).  Please note that we have not yet sampled all counties on our survey route.  I will continue to provide weekly updates on this, including pest population levels, as the season progresses.   KB_7_16_2015

Black light trap captures for the week ending July 16, 2015

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Corn earworm moth catches from reporting stations were low this week.  Nightly averages were:  Warsaw=zero; Southampton (Courtland)=zero; Suffolk=0.4.  Brown marmorated stink bug nightly averages were:  Warsaw=zero; Southampton (Courtland)=1.3; Suffolk=zero.  Thanks to the following for their reports this week:  Mary Beahm, Austin Brown, and Dr. Herbert’s Entomology team.  The image of the “bucket style” black light trap is courtesy of Austin Brown.  Bioquip_universal_black_light_trap_2_low

Fungicide Resistant Frogeye Leaf Spot Present in Virginia

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Fungicides are an important and effective tool for management of fungal diseases of crops including soybean. Unfortunately, over time fungal pathogens have the potential to develop resistance to specific fungicide modes-of-action. Mutations conferring resistance to fungicides are relatively rare, but multiple applications of the same fungicide chemistry impose selection pressure on pathogen populations and increase the frequency of those mutations over relatively short periods of time. Thus, specific fungicide chemistries have the potential to lose their effectiveness over time. Fungicide resistant isolates of Cercospora sojina, the causal agent of frogeye leaf spot in soybean, have recently been confirmed throughout the southeast including in North Carolina in 2013 and Virginia in 2014. In 2014, a small preliminary survey was conducted to determine if fungicide resistance is occurring in Virginia populations of frogeye leaf spot. Four fields were tested, and two of those fields had fungicide resistant strains. The resistance is specific to strobilurin (QoI, FRAC group 11) fungicides, which are highly effective for control of fungal foliar diseases but to which resistance can rapidly occur within fungal populations. Effective foliar disease management requires appropriate fungicide chemistry selection based on the specific pathogens present and their sensitivity to different fungicide modes of action.

Additional isolates of the frogeye leaf spot pathogen from throughout Virginia need to be collected and tested for fungicide resistance so that appropriate fungicide recommendations can be made. Other states have already initiated fungicide resistance monitoring programs for the causal agent of frogeye leaf spot (C. sojina), and we will implement a similar program in Virginia. Soybean leaves with symptoms of frogeye leaf spot will be collected throughout the 2015 growing season, the fungus will be isolated, and isolates will be tested for resistance to strobilurin (QoI) fungicides. If fungicide resistance is widespread in Virginia, recommendations for foliar fungicides and/or cultivar selection may need to be modified. If incidence of fungicide resistance is low, we will continue to monitor fungal populations and assess the risk of fungicide control failures on a year-by-year basis.

Frogeye leaf spot

In order to implement an effective fungicide resistance monitoring program, we are requesting that leaf samples from soybean fields with symptoms of frogeye leaf spot (see pictures above) be submitted to the Tidewater AREC for testing. For more information on submitting samples, please contact Dr. Hillary Mehl (757) 657-6450 ext. 423 or hlmehl@vt.edu.

How Late Can You Plant Soybean?

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Heavy rains over the last two weeks have prevented timely planting of much of our double soybean acreage.  Flooded Soybean FieldWe are slowly drying out and many are anxious to get back into the field.  After mid-June, we lose about 1/2 bushel of soybean for every day we delay planting.  While this is concerning, going back into the field too early may not be your best choice.

Planting into saturated fields may do more more harm than waiting a couple more days to plant.  Tracking and rutting up fields means compaction, which can greatly lower yields and undo much of the good that continuous no-till has accomplished.  In addition, opening the soil with disk openers will smear the sidewall and this “micro-compaction” may not allow young roots to develop properly.  My general rule of thumb with no-till fields is to wait one more day to plant after you think you can get back into the field.

So, how late can I wait to plant?

With that said, today is July 9!  So, how late can you wait to plant?  I’ve planted as late as the third week of July and made decent yields (25-30 bushels) without changing varieties.  The good thing about all of this rain is that the soil profile is full of water.  That is not always the case with double-crop soybean.  So, early-season moisture stress (which I think is partially responsible for the temporary cessation of growth after emergence) should not be a problem.  Plants should grow fast and yield potential at this late planting date should still be good.  My cutoff date is usually July 15-20.

Should I move to an earlier maturing variety?

Late-planted soybean are going to develop more rapidly than those planted in May and June.  That is one reason that yields are lower.  With every 4 to 5 days delay in planting, you will delay maturity by 1 day.  If you are 15 days late planting then you will likely delay maturity by only 3 to 4 days.  Choosing an earlier-maturing variety can make up this small difference, but is that the best choice?.  This may not be an issue, as most varieties have been purchased and you may not be able to exchange them.  But if you do have a choice, and you have experienced that your favorite varieties have barely matured before frost when planted late, then yes you may want to move to a variety that would mature a few days earlier.  Half a maturity group or less should do it.

I do suggest to start planting the remainder of your latest maturing varieties first and then finish up with the earlier ones.  I would also suggest that you plant your earlier maturing varieties on your best soils as that will minimize the potential yield loss from planting an early-maturing variety late.

What if I can’t plant by the middle of July?

For “prevented planted” acres, I would suggest planting a cover crop to maintain soil quality.  With something green growing, your soil chemistry, biology, and structure will greatly benefit.  Remember that nothing but weeds grow on bare soil.

Your choice of cover should reflect your plans for next year.  If you plan to grow wheat or corn or sorghum, then a legume to fix some nitrogen would be a good choice.  If you are going to plant a non-grass crop, a grass cover such as sorghum-sudan or millet would be a good choice for the summer.  Come fall, there are several options.  Check your insurance policy and see what options are available.