Cotton: The cotton crop ranges from 7-8 leaves to 4th week of bloom. White fly populations are not exploding but are been noticed more every week. Scouts and consultants need to monitor the situation over the next few weeks. As of today (July 30, 2023), I have not seen or heard of any target spot or mildew in area cotton fields, but that can change at the drop of a hat. Target spot and mildew has been found in Bleckley County this week by county agent Cole Moon. Target spot can be and IS a problem many times when it occurs early enough in the season (somewhere around the 3rd week of bloom). Dr. Bob says that AEROLATE MILDEW is ALWAYS are problem when it occurs in a cotton field in Georgia with more than a month to go prior to defoliation AND otherwise good yield potential. We need to be out looking for areolate mildew with the current weather conditions.
Mr. Kichler, do you have any information about fungicide use in cotton? I am glad you asked because of the numerous demonstrations conducted in Colquitt County on this subject. The data can be seen at this link. Research shows that a well -timed fungicide applications (Priaxor, Miravis Top, Headline, azoxystrobin) will make you yield and money.
Refresh my memory on scouting for white flies in cotton. Growers, consultants and scouts need to monitor the whitefly situation in their fields. Lets discuss the method to check for whiteflies: 1) Count down from the terminal of the plant to the 5th vegetative leaf (starting with any leaf that is the size of a quarter or bigger), 2) Slowly turn the 5th leaf over to view the underside of the leaf, 3) See if there are any immature whiteflies present. If 50% or more of the 5th leaves checked have multiple immatures on them, then treatments should be started.
Foliar Feeding Cotton.. I received a question or two about foliar feeding cotton as the crop reaches peak bloom in Colquitt County. Lets discuss a few tips on foliar feeding cotton.
Here’s the UGA recommendations for applying foliar fertilizer to cotton:
Nitrogen: Feed grade urea is the most reliable, economical and proven foliar N material. The standard recommendation is to apply 4.5 lbs of nitrogen/acre as urea in at least 5 gallons or more of water per acre (5 gal/acre assumes aerial application, 10 to 12 gallons of water is preferred for ground application). Both liquid urea (23% N) and granular urea (46% N dissolved into water) can be used.
10 lbs of feed grade urea (granular 46% N) per acre will give you approximately the recommended 4.5 lbs of nitrogen per acre.
Potassium: Potassium nitrate is the most common material used for foliar K applications. The standard recommendation is to apply 4.4 lb of potassium per acre in 5 gallons or more water per acre. (Again 5 gallons assumes foliar application, 10 to 12 gallons is preferred for ground application). Both liquid and granular potassium nitrate can be used.
10 lbs of granular potassium nitrate (44% K2O) per acre will give you the recommended 4.4 lbs of potassium per acre.
Keep in mind that there are other products out there available to use for foliar feeding cotton. Some of these may not contain as much fertilizer as the products mentioned above and you may not be able to apply them at the same rates as mentioned above. Use caution with all fertilizer products as improper rates could cause leaf burn.
How late is too late to foliar feed cotton?
Foliar feeding is most effective when applied during peak bloom, or the first 4 weeks of bloom. Foliar feeding during weeks 5-7 of bloom may or may not be effective depending on the variety grown.
Once you pass the 8th week of bloom, it is too late. No foliar feeding is recommended after this point.
Peanuts: The peanut crop is starting to shape up. I have received a call or two about caterpillar pests in peanuts, but populations in the fields I have been in this week have been below threshold. The threshold is 4 to 8 foliage feeding caterpillars per foot of row. Use lower threshold range when vines are small and/or stressed. Spraying when caterpillars are below economic thresholds is a waste of money.
Dr. Bob made this comment to county agents this week about the peanut disease situation.
My air conditioner is set at 78F and it is running at 4:00 AM. You know what that means? That means that in peanut fields across Georgia, white mold is out there chewing on vines and pegs and pods like at some buffet. With the humidity out there now it means that the leaf spot diseases are also out there somewhere happily producing more spores and more infection. It means that sometime today those of you with peanuts in your counties are going to get on your list serve and say, “Bob may not know much about much of anything, but he is worried that diseases are about to take a toll on your peanut crop. He thinks this because our weather (heat and humidity) is nearly perfect and if you get behind it is really hard to catch up.”
Also, this past week Dr. Bob mentioned a case of early leaf spot in Jackson County, FL in a Twitter post.
Our friends to the south in Jackson Co, FL, Ethan Carter, Dr. Barry Tillman and Dr. Nickie Dufault shared with me pictures here of “early leaf spot gone wild” in a commercial peanut filed there. The concern is that the grower has 30-40 days left before an ideal digging date. The concern is that the grower seemed to use a good fungicide program, though I am not clear on the full program. Bottom line, we DO NOT want this in Georgia.
These images are picture-proof that the leaf spot threat is real. Advise your growers that as they fight white mold with Elatus and Excalia and Umbra and Convoy and Fontelis and Provost Silver and teb NOT TO FORGET the necessity to ensure protection from leaf spot at the same time, whether it is mixing something like Alto or Domark or Provysol or SPECIFIC sulfur or chlorothalonil with the white mold product (not always necessary…) or using products like Lucento and Priaxor and combination of sulfur and Alto and Domark and chlorothalonil in bookend applications. We are in the toughest disease period for white mold and leaf spot on peanuts- late July through mid-September. Don’t miss out.
TSWV Survey – Over the next few weeks, I will be surveying peanut fields for the incidence of tomato spotted wilt. I have had a few comments about the level of the virus in area fields from growers this past week. County agents in peanut-producing counties will be doing the same and gathering information about varieties, planting dates, plant insecticides used, and row patterns to help growers lower the risk of this production challenge.
Corn: Several local fields are approaching the black layer and maybe the rain we had yesterday will finish off the irrigation requirements in those fields. As we get closer to harvest growers need to clean storage bins thoroughly inside and out to eliminate starter colonies of insects. Remove any weeds, crop debris, or clutter around the facility to reduce insect and rodent activity. All grain residues from the previous year should be removed from inside the facility as soon as the old crop is shipped. Seal any gaps or holes in the sides and roof of the bin using caulk or polyurethane foam. Check to make sure the bottom seal with the concrete is intact. Prevent water from flowing underneath the bin by applying plastic roof cement. Apply an EPA-approved insecticide on the floors and sides of empty storage bins to eliminate insects hiding in cracks and crevices and to create a first line of defense against any insects that do find their way into the bin. Spray the outside of the bin to a height of 3 ft, and the surrounding concrete, gravel, or sod to a distance of 6-10 ft surrounding the bin. Insecticides shown in Table 19 are labeled for empty bin treatments. (Source: 2023 UGA Corn Production Guide)
Application of Grain Protectants
Growers who will be stored for more than 6 months should strongly consider the application of a grain protectant (Table 21). Apply an approved grain protectant directly to the moving grain stream at the bottom of the bucket elevator or auger so the material has an opportunity to contact as many kernels as possible as the grain is moved. UGA Extension recommends that grain be conditioned with a cooling cycle or similar procedure before applying the protectant. However, recent data suggest that deltamethrin (Centynal EC or Defense SC) and spinosad (Sensat) are heat stable up to 200° F, while s-methoprene (Diacon IGR) and pirimiphos-methyl (Actellic 5E) were degraded by high heat. Position the insecticide nozzle as close to the auger flighting as possible to minimize insecticide drift.
Drones – It seems like there is a lot of interest in drones in agriculture. Simer Virk, UGA Ag Engineer and Steve Li, Alabama Extension, discussed some points about drones in a blog post Pesticide application considerations with spray drones.
Also, a couple of weeks ago I had the opportunity to participate in a research project comparing drone and ground sprayer-applied fungicides for disease management cotton with Simer Virk. Hopefully, we will have some good information about coverage, disease control and yield at the end of the year about this subject. This field experiment was conducted at the Sunbelt Ag Expo. Stay tuned.
I recieved a question or two about stem maggots and army worms this week. Below is information on scouting, mechanical vs chemical control of BSM, and control options for armyworms. If you got questions let me know.
Please be careful this week in the heat. If you have questions please contact you local county Extension agent.
Have a great week.
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.