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News, events, and happenings in Colquitt County agriculture.

Current Situation: Rain over the last week has ranged from 0.5 to 3 inches. The accumulated rainfall for last week is in the illustration below. The forecast for this week shows an increased chance for rain. Cotton crop ranges from third week of squaring to 5th week of bloom. Southern rust was found in Colquitt County yesterday at low levels (July 22, 2024) but most of the corn crop is past the dent stage of development. The peanut crop ranges from 50-90 days old. The insect situation has calmed down and white mold is being reported in area fields. The crop progress report for Georgia from NASS is post below. It was released yesterday (July 22, 2024).

Carpetweed has been an interesting topic over the last couple of weeks.  I have received pictures from consultants and growers about carpetweed in peanut.  Below is an example of carpetweed. 

Below are a few comments from Dr. Eric Prostko, UGA Peanut Weed Specialist, on carpetweed.

A few things to chew on:

1) Carpetweed is summer annual weed native to the U.S.

2) Other common names for this weed include green carpetweed, Indian chickweed, whorled chickweed, and devil’s grip. 

3) Carpetweed is listed as a controlled weed on EVERY peanut herbicide label except for Basagran (bentazon), Butyrac (2,4-DB), Strongarm (diclosulam), and the POST grass herbicides [Fusilade (fluazifop), Poast (sethoxydim), and Select (clethodim)]. So…?

4) No confirmed cases of herbicide-resistance in carpetweed have been reported worldwide. (https://www.weedscience.org/summary/species.aspx)

5) Carpetweed has been in my research plots for 15+ years.  I have never failed to control it with my recommended peanut weed control programs (http://www.gaweed.com/newest-prostko-2024-control-peanut-corn-soy.pdf).

6) Possible reasons for lack of carpetweed control in 2024 are as follows:

a) Too wet?  Residual herbicides do not last as long; growers cannot get into fields on timely basis; unexpected pop-up showers occur before rain-free period is reached. 

b) Too dry? Residual herbicides do not get activated on a timely basis; big weeds + dry weather are a POST herbicide’s Achilles heel.

c) Reduced herbicide rates?  Many growers are not using full labeled rates of herbicides such as Cadre (imazapic) to help prevent carryover in 2025.  We proved many years ago that this strategy does not really work.  Cotton will find Cadre in the soil when a lab analysis will not.  More importantly, when reduced rates are used and less than 100% weed control is obtained, the evolution of herbicide-resistance is greatly increased.  Yes, we can control some weeds with reduced herbicide rates (i.e. bristly starbur/Strongarm) but this tactic does not work for every weed and every herbicide. 

Cotton:  This week, I received numerous questions and concerns about the cotton leaf roll dwarf virus (CLRVD) from scouts and consultants. Pictures below show symptomatic plants from a few area cotton fields in certain varieties. 

CLRDV -Colquitt County July 2024
CLRDV – Colquitt County July 2024

According to Dr. Bob Kemerait, the early severe symptoms are also showing up elsewhere. Why? Not sure, but as we have had some problems this season with cotton aphids, which spread this CLRDV, that may be part of it, as might recent heat and drought stress.  All I know to tell you now is a) the only possible management is to try and reduce water stress on an affected crop, b) let us know when you find fields affected and what variety is planted.  Sudden, rapid reddening and wilting/collapse of some cotton plants in a field, but by no means all. If it were drought, the wilt would be more uniform and likely less reddening, bronzing.

We cut the stems, looking for the discoloration associated with bronze wilt; there was none. Young cotton, reddening, sporadic collapse of some plants but not all, this is most likely a severe symptom of the cotton leaf roll virus that appears often in a few particular varieties but rarely in others.

Below is a Beltwide abstract writen by Dr. Steve Brown, retired UGA and Alabama Extension cotton agronomist from 25 years ago. 

Comments from Dr. Bob. 

Reading the abstract now, what was called “bronze wilt” then sounds exactly like what we are seeing now with much greater severity in some varieties than in others. I am calling this “severe early season CLRDV” (cotton leaf roll dwarf virus) and I note the symptoms are “like the old bronze wilt”.

So, Bob, it looks like a duck and quacks like a duck, why don’t you call it “bronze wilt”?? 

Answer: because I do not know if they are the same thing or not. A pathogen was never identified in bronze wilt and the problem went away after certain breeding lines were culled from the breeding program. 

In 2024, Dr Sudeep Bag can document that CLRDV (vectored by cotton aphids) is found in plants with the severe-early-season-bronze-wilt-like symptoms. Who knows, maybe it was there 25 years ago; the problem is we didn’t have the same diagnostic tools back then.

But Bob, Dr Bag can document this virus in plants with milder symptoms that develop much later. Heck, Bob, Dr Bag can even find CLRDV in plants with NO symptoms.

All of that may be true- but how is it possible? I believe that some varieties are simply MUCH more susceptible to CLRDV than are others, especially the early season wilt.

More information subject

Cotton leafroll dwarf virus in GA: Symptomatology, and Diagnosis   by Dr. Sudeep Bag

https://www.cottoninc.com/wp-content/uploads/2019/11/01-Sudeep-Bag-UGA-CLRDV-Identification.pdf

https://www.cottoninc.com/wp-content/uploads/2019/11/01-Sudeep-Bag-UGA-CLRDV-Identification.pdf

Cotton leafroll dwarf virus: Opening the locks in Georgia  by Dr. Sudeep Bag

https://www.planthealthexchange.org/cotton/Documents/GROW-COT-12-22-362.pdf

Brown wilt in Cotton – Texas A and M

http://cotton.tamu.edu/Nematodes/bronzewilt.pdf

What about white mold? As growers start their soil borne programs questions about what to use come regularly. The management of white mold can be improved in several ways. One way is to protect the crop during the critical time 60–105 days after planting, initiating a program prior to 60 DAP, and extending beyond 105 DAP when conditions favor the development of white mold or where disease is active in the field later in the season. Growers can be timely with irrigation between 8 and 24 hours after a fungicide application. Also, applying fungicides for white mold control at night can improve control. What is the best fungicide for white mold? One applied on time at right rate and that reaches the crown and limbs of the plant. The table below is from the 2024 UGA Peanut Pest Management Guide

Whitemold, Colquitt County. July 2024

The insect situation in peanuts have calmed down over the last week. I have been receiving reports of beet armyworm in fields about 10 days ago and some fields were treated. The threshold for foliage feeding caterpillars is 4 to 8 per foot of row.

I had a question or two about applying Dimilin in peanut insect programs.  According to Mark Abney, we would rather scout fields and treat at threshold, Dimilin has long residual activity and does not flair secondary pests.  Dimilin is really good for managing velvetbean caterpillars, but you will still need to scout for other species like the soybean looper, which is not controlled.  

A few words from Dr. Mark Abney on the current insect situation in Georgia peanuts.

Many peanut fields in Georgia received much needed rain over the past two weeks. This does not mean that lesser cornstalk borers (LCB) will be gone from those fields. Rain DOES NOT kill LCBs. Cool moist conditions are not favorable for the pest, but in situations where populations are already high, sporadic rainfall will have little effect on infestations. The bottom line is that peanut fields should be scouted soon and scouted every week to determine if LCB is present and if an insecticide application is needed. The reports I have gotten, and the results of my own trials, indicate that the insecticides recommended by UGA Extension for LCB management are doing a good job against the pest. When scouting for LCB, be certain to check plants randomly. Stopping to check only plants in skips or those with wilted leaves will bias the count and could result in an unnecessary insecticide application. Finding a live LCB larva at 3 out of 10 stops in a field (checking 3 feet of row at each stop) is enough to warrant a spray.

Foliage feeding caterpillars continue to exceed thresholds in peanut fields across the state. Though caterpillar populations are made up of several species, it is the beet armyworm (BAW) that has been present at much higher than “normal” levels. County agents, growers, and consultants across the state have reported problems controlling BAW with products containing the active ingredient chlorantraniliprole (Vantacor, Besiege, and Shenzi). The UGA Peanut Entomology program conducted a trial over the last week to test the efficacy of several different insecticide active ingredients against BAW. Caterpillar mortality in the chlorantraniliprole treatments did not differ from the non-treated check. The products Intrepid and Intrepid Edge resulted in 91% and 100% mortality respectively at 5 days after treatment.

The next few weeks will be critical for setting this year’s crop; lets make sure we do not suffer any unnecessary losses from LCB or foliage feeding caterpillars. Fields need to be scouted regularly and treated when thresholds are reached. If you have questions about caterpillar management or any other pest concerns in peanut, please contact your local UGA County Extension agent.

What about applying manganese in peanut?    A tissue sample is a great way to detect manganese deficiency in peanuts.  Manganese deficiencies may occur on sandy soils with a pH greater than 6.3. If Mn deficiency occurs, apply a broadcast spray of Mn using 1/2 pound Mn per acre as manganese sulfate or 0.15 to 0.25 pound Mn per acre as chelated Mn in 20 gallons of water per acre. If symptoms persist, the spray should be repeated at 2 week intervals. 

How much boron do I need for peanuts?  For peanuts, 0.5 lb B/A is recommended, preferably split in 2 applications of 0.25 lb B/a each with early fungicide sprays.  It takes 1.25 lb/a Solubor to get 0.25 lb B/a and 1 quart (32 oz) of 10 % Liquid Boron to get 0.25 lb B/a.  Also beware of products recommended at very low rates. For example, 6 oz of a 5 % liquid boron only gives you 0.025 lb B/a. 

 Excessive foliar boron may be toxic to peanuts so do not exceed 0.5 lb B/a for a seasonal total

A few words from Dr. Scott Monfort, UGA Peanut Agronomist, on PGR use in peanut.

The crop is finally looking better and GROWING as a result of the recent rains across Georgia along with a break in the 95+-degree temperatures. Like I mentioned earlier, a majority of the crop is between 60 – 75 DAP. Several agents/growers/consultants are asking questions regarding the application of a growth regulator (APOGEE WDG, KUDOS WDG, and KUDOS OD). Below are a few comments based on the questions I’ve received.

  • Is there any concern in applying the growth regulator in 95+ temperatures and dry conditions?
    • Remember, I do not recommend a growth regulator on non-irrigated peanuts. I cannot predict  whether a grower will continue to get rains. Give me a call and we can discuss.
    • Based on last year, in irrigated peanut, I would not use a growth regulator when conditions are 95 degrees and extremely dry unless the grower can keep up on the water needs of the plant. 
    • When growers want to apply a peanut growth regulator (PGR), and conditions are hot and dry, irrigate first before applying the growth regulator.
  • The recommended rates for the PGR are 3.5 to 5.4 oz/A, applied twice. Initial application is at 90-100% lap with the 2nd application 14-21 days later. Remind growers the higher the rate the more yield they could risk losing.
  • The PGR is not for all growers, fields or cultivars.
  • What about mixing with other pesticides or fertility products?
    • I would not recommend applying with any herbicide at this time (Cobra, 2,4 DB, etc.).
    • For the initial application (65-70 DAP), 1.) do not apply early to save a trip with the 60 DAP fungicide application and 2.) do not wait until 65 to 70 DAP to apply the fungicide either. Go ahead and recommend them splitting the applications to make sure we stay on time with all products.
    • I have not tested with micro fertilizer packages.
    • The more you mix the more you risk causing burn to the crop. The more the burn the less management of vines you will receive.
  • Remember, 1lb (16 oz) of a Nitrogen source is needed for the PGR to work properly. One quart of Crop Oil Concentrate (COC) is also recommended.  However, when you mix with fungicides you can leave the COC out.
  • I am currently evaluating different rate structures and application timings.

Corn: Early irrigation termination on corn is a common mistake and it can hurt your yield depending on when you cut the water off. Although kernels outwardly appear mature and corn water use begins declining at the dent stage, this is far too early to terminate irrigation. Potential kernel weight is only about 75% complete at the dent stage. Thus, termination of irrigation at the dent stage can reduce grain yields as much as 15-20% when hot, dry conditions persist. Early irrigation termination will also likely reduce stalk strength and promote lodging, because plants will cannibalize energy from vegetative organs to fill kernels when they are stressed. So water corn until black layer…

I have been questions about checking milk line in corn. Corn kernels mature from the outside-in when hard starch forms beginning at the top of the kernel at dent and steadily progresses towards the base of the kernel (where it attaches to the cob). This final stage of grain development normally takes about 20 days to complete. The most reliable method for you to monitor kernel maturity for irrigation scheduling purposes is to observe this progression of the milk-line (or hard starch layer) between dent stage and black-layer or physiological maturity. The milk-line is more relevant than the black-layer, because it indicates maturation progress, before the black layer is evident. The milk-line is the borderline between the bright, clear yellow color of the hard seed coat outside the hard starch, compared to the milky, dull yellow color of the soft seed coat adjacent the dough layer. To observe the milk line, break a corn ear in half and observe the cross-section of the top half of the ear (the side of kernels opposite the embryo). If you have difficulty seeing this color disparity between layers, you can find it by pressing your fingernail into the soft, doughy seed, starting at the kernel base and repeating this procedure progressively toward the tip, until you feel the hard starch.

I have received numerous calls about nitrates in summer annual forages this past week. Growers need to identify and test all forages that may have accumulated nitrates.  Below are a few points to consider about nitrates in forages. 

  • Nitrogen fertilization increases the risk of nitrate accumulation.
  • Some plants accumulate nitrates at a greater rate.
  • Split applications of nitrogen fertilizer (organic or inorganic) within the growing season.
  • Do not harvest or graze forage within seven days following a drought-ending rain.
  • Do not feed green chop until the whole plant has been tested for elevated nitrate concentrations.
  • Harvest the crop as silage when possible.
  • Nitrates tend to be highest in the lower stem and leaves.
  • Increase the harvest height to minimize the inclusion of lower plant parts and low growing weeds.
  • Do not graze crops closely.
  • Use field test kits to rule out samples low in nitrates but confirm field results with a laboratory analysis when results indicate moderate or higher levels of nitrate (>2,500 parts per million–ppm).
  • Dilute high nitrate forages with feedstuffs that are high in energy.
  • Provide plenty of clean water and supplement with sufficient vitamins and minerals.
  • Avoid or minimize feeding forages that are high in nitrates to lactating, pregnant, or sick animals.
  • Limit animals to 3 or 4 hours of access to high-nitrate hay per day so that intake is limited to approximately 50 percent of normal. Supplement the lower hay intake by feeding a grain or by-product feed (6 to 10 pounds per day depending on lactation status and forage quality) BEFORE allowing the animals to access the high-nitrate hay.

Have a safe week and if you have questions please call the office,

Jeremy M. Kichler

Colquitt County Extension Coordinator

The University of Georgia Cooperative Extension does not endorse or guarantee the performance of any products mentioned in this update.