Recent Updates

Cutworms in Seedling Corn

I’ve received a few calls in the past couple days on cutworms appearing in seedling corn. Below are some take home points on cutworms:

Cutworm in Corn
  1. You probably do not need to worry about cutworms if you have kept a weed free seed bed for 2-3 weeks prior to planting, and this is especially true if using some of the Bt corn technologies (see below). However, the weather this year has not generally allowed for burndown applications made 3-4 weeks before planting.
  2. Consider making an insecticide application near planting time. Relatively low rates of pyrethroid insecticides are typically effective for cutworm control. I do not recommend including an insecticide with herbicide applications that are made more than a couple weeks in advance of planting. Tank mixing an insecticide with an early burndown application may not be that effective. Cutworms you kill would have probably ‘cycled out’ before you planted. And because you cannot expect much residual control, there is the possibility of re-infestation between application and planting. The best time to make this application is within a few days before or after planting.
  3. Using Capture LFR or other in-furrow pyrethroid insecticide as an in-furrow spray can add some protection against insect pests not completely controlled by seed treatments (e.g., cutworms and sugarcane beetles). I would prefer a T-banded type application where some of the product is applied to the “shoulders” of the seed furrow. This should improve control of cutworms compared with an application where 100% of the product is applied in-furrow. However, in-furrow applications appear to provide adequate control of cutworms in most circumstances.
  4. No insecticide seed treatments should be expected to provide substantial control of cutworms. However, I have seen Poncho 1250 kill small cutworms in the past, don’t bet the farm on this though. Some Pioneer corn seed now includes a base treatment of Lumivia (chlorantraniliprole). This product should provide at least some control cutworm, but data is limited.
  5. Although Bt corn and cotton traits provide some protection against cutworms, planting into fields that are heavily infested can be risky. Bt corn traits such as Leptra, VT2 Pro, SmartStax, Viptera, ad nTrecepta corn can reduce cutworm injury. Vip corn (Leptra, Trecepta, Viptera) will provide the best protection from a Bt stand point. However, large larvae are much less susceptible to Bt toxins.
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Estimating Sidedress N for Corn Fields with Poultry Litter Application

By Nutifafa Adotey, Assistant Professor & Soil and Nutr. Magt Specialist, Forbes R Walker, Professor & Envt. Soil Specialist, and Frank Yin, Professor & Cropping System Scientist, University of Tennessee

Poultry litter has become readily available to producers in Tennessee. However, poultry litter cannot supply all the nitrogen needed for corn and thus supplemental N is required to obtain optimal yield. The amount of supplemental N can be estimated using the Pre-Sidedress Nitrate Test. The Pre-Sidedress Nitrate Test is recommended only for corn producers using animal manure, poultry litter or biosolids, who want to estimate and fine-tune their sidedress N fertilizer applications following manure/poultry litter application. This article provides a guide for Tennessee corn producers using poultry litter on how to estimate sidedress N rate using the Pre-Sidedress Nitrate Test. Continue reading

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Ryegrass Weed Control in April

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Picture 1. Roundup PM 32 ozs/A 21 days after application

A good many reports from the field reflect what our research this spring has shown.  In short, clethodim is the herbicide of choice to control ryegrass.  Often clethodim tankmixed with glyphosate can improve the probability of better overall control.  Ryegrass control with glyphosate alone is much more hit and miss both in our research and in many fields this year (Picture 1). Continue reading

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Wheat Disease Update and Fungicide Options

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As wheat is approaching flag leaf stage in Tennessee, start scouting if you haven’t already for disease. Depending on variety susceptibility you may already see powdery mildew and/or wheat blotch (Septoria and/or Stagonospora blotch); but if no disease present start considering Fusarium Head Blight management. Continue reading

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Ammonia volatilization from unincorporated, surface-applied UAN on soils with pH >7

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By Nutifafa Adotey, Assistant Professor & Soil and Nutr. Magt Specialist, Forbes R Walker, Professor & Envt. Soil Specialist, and Frank Yin, Professor & Cropping System Scientist, University of Tennessee

In Tennessee, the primary N fertilizer sources used are urea and urea ammonium nitrate (UAN). Other sources of N fertilizers, such as anhydrous ammonia, are used in some counties in Central and West Tennessee.  It is a known fact that ammonia volatilization from applied N fertilizers may occurs from (1) unincorporated, surface-applied urea-based fertilizer; (2) anhydrous ammonia due to poor equipment calibration; and (3) unincorporated, surface-applied ammonium-based fertilizer on alkaline soils. This N loss from these fertilizers is governed by a complex interaction of prevailing environmental conditions, soil properties and management practices. Soil properties determine the potential of ammonia loss while the extent of the loss is dictated by environmental conditions and management practices. Continue reading

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Cover Crop Burndown

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Good soybean stand in cover crop cereal rye

It is cover crop burndown time. There is no one size fits all recommendation for cover crop control.  It really depends on the environment and the cover crop species in the field.  With rain predicted over the next few days, one should be mindful that cover crop burndown can be tricky during periods of saturated soil conditions. This is particularly true with systemic herbicides where translocation of those herbicides to growing points can become limited. Continue reading

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