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News, events, and happenings in Colquitt County agriculture.

Current Situation: Rainfall amounts this past week have ranged from 2–3 inches. The forecast for this week calls for more rain, which will make cotton and peanut planting a challenge. The cotton crop ranges from just being planted to the four leaf stage. Thrip pressure has been low to moderate, depending on what insecticide was used at planting. The peanut crop ranges from just being planted to about a month old. The corn crop ranges from V2 to V10. Growers have been trying to apply side dress nitrogen this past week.

According to Pam Knox, UGA Climatologist, “The latest 7-day rainfall map for the US shows that the Southeast is likely to see a LOT of rain this week, starting this weekend. Some areas could receive more than 5 inches! Wednesday and Thursday look like the driest days for most areas this week before the next storm moves in late in the week. This is going to make it tough for farmers to get any field work done such as planting or chemical applications. It will benefit some crops while causing negative impacts to others. Week 2 also looks like it may be wetter than normal before we swing back to more normal conditions.”

Wet Weather and Peanuts – 2024 (Prostko)

1)The current rainfall event that is occurring in many parts of Georgia will likely result in Valor (flumioxazin) injury in some peanut fields.  Below is information from last year on this subject from Dr. Prostko.

May 13, 2023: https://ugaweedscience.blogspot.com/2023/05/valorpeanut-injury-again-prostko.html


2) Peanut growers who have missed the recommended application timing for applying Valor + Strongarm + Prowl or Sonalan (PRE) should not panic.  My suggestion would be to let the peanuts emerge, then treat herbicide “naked” fields with an EPOST application of Gramoxone + Storm or Basagran + Zidua or Anthem Flex + NIS (Page 221 of 2024 UGA Pest Control Handbook).  I usually do not have a preference between the Group 15 herbicides (Anthem Flex, Dual Magnum, Outlook, Warrant, Zidua).  However in fields that were not treated with any Prowl or Sonalan, I do prefer Anthem Flex or Zidua in the first EPOST treatment because these herbicides provide slightly better control of Texas panicum (i.e. bullgrass or buffalograss).  Check out the picture below from my 2023 research plots.  No PRE herbicides were applied (on purpose) but I was still able to obtain very effective weed control.  This situation is not ideal but growers can make it work. 

Grasshoppers in cotton: I have been getting numerous calls about grasshoppers in strip till cotton fields over the last week. Dr. Phillip Roberts, UGA Cotton Entomologist, has a few words to say about this below. This is from the May 2024 UGA Cotton Team Newsletter.

Grasshopper Questions (Phillip Roberts): We have received scatter reports of grasshoppers in some reduced tillage fields, especially in lighter soils. Grasshoppers overwinter as eggs deposited in the soil; the lack of tillage allows greater survival of the eggs. Dry winters also favor overwintering survival of grasshoppers. Grasshoppers may feed on foliage, but more serious damage occurs when they feed on the main stem of seedlings. In some situations, grasshoppers may completely cut the main stem (this type damage looks like cutworm damage) whereas in others they may partially chew through the stem which weakens the plant which may eventually tip over. Treatment should be applied if the stand is threatened. Immature grasshoppers (wingless) are easily controlled with insecticides however adults (winged) are more difficult to control and high rates of labeled insecticides should be used. Acephate at 0.75 lb per acre has provided consistent control of adult grasshoppers. The insect growth regulator Dimilin provides good residual control of immature grasshoppers but has no activity on adults. When monitoring fields for grasshoppers, be sure to walk the entire field. In some situations, grasshoppers may be migrating into the field from turn rows, fences, ditches, etc. and be present at much higher populations near the margins than the interior portions of the field. When we have observed serious grasshopper injury it is generally associated with grasshopper populations that emerged from eggs laid in the field last fall. Whether or not grasshoppers will actually feed on cotton is unpredictable. We have observed fields with high infestations of grasshoppers and minimal feeding on cotton and vice versa have seen fields with moderate grasshopper counts and significant plant injury. This makes management decisions difficult.

Do I need to Spray for Thrips? (Phillip Roberts): Thrips will infest near 100 percent of cotton planted in Georgia. All cotton should include a preventive treatment at planting, regardless of planting date. Supplemental foliar sprays may be needed if environmental conditions are not conducive for uptake of systemic insecticides or if heavy infestations occur. The threshold for thrips is 2-3 thrips per plant with immatures present. Immature thrips are wingless and crème colored whereas adults are typically black or brownish and have wings. The presence of numerous immatures suggests that the at-plant systemic insecticide is not providing acceptable control. Thrips eggs were laid in the plant (interestingly a high percentage of thrips eggs are laid in cotyledon leaf tissues), the eggs hatched, and thrips are developing. Excessive thrips injury results in crinkling of leaves and stunting of plants. In reality many decisions are made based on plant injury symptoms. Ideally, we would like to scout (count thrips) and also be observant for injury. Thrips feed in unfurled leaves in the terminal bud. As new leaves unfold the injury becomes apparent, so be sure to look at newly unfolding leaves. Foliar insecticides include acephate, dicrotophos, and dimethoate. In 2023 we received numerous questions about susceptibility of thrips to acephate as some tolerance or resistance is suspected in other parts of the US. Field trials conducted during 2023 demonstrated that we continue to observe good control of thrips with acephate. Seedlings are susceptible to thrips injury until they reach the 4-leaf stage and are growing rapidly. Growing rapidly is important, if 4+-leaf cotton has lots of thrips injury and plants are stunted and not growing a spray would be justified.ThryvOn is a transgenic trait which significantly reduces thrips injury. We have conducted field trials with ThryvOn for several years and have never observed a planting which would benefit from a supplemental foliar insecticide for thrips control. ThryvOn does not result in high levels of thrips mortality, however thrips feeding and egg laying are significantly reduced. Typically, we observe about a 50 percent reduction in actual thrips numbers when scouting and sometimes we observe populations exceeding the threshold in ThryvOn cotton. However, we rarely see significant plant injury even if very high thrips infestations are present (i.e. above the threshold of 2-3 thrips per plant with immatures present). For this reason, it is important that we DO NOT make decisions to treat ThryvOn for thrips based on insect counts. The threshold for thrips on ThryvOn cotton is treat if excessive plant injury is present and immature thrips are present.

What did we do this week? This was a busy week before the rain started Thursday and Friday. We had the opportunity to plant cotton and peanut variety plots this past week.

Peanut Variety Trial, Colquitt County, May 6, 2024

Have a great week,

Jeremy M. Kichler

Colquitt County Extension Coordinator

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