Alabama Cotton Shorts
June 6, 2020
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June 6, 2020
Situation. It hasn’t been a fun start to the 2020 growing season. By now, almost everything except late double cropped cotton should be planted. While March was unusually warm, April and the first half of May were abnormally cool if not COLD. Conditions were very wet in the north and by early May were parched in the south. Both made for challenges to planting. Insect pressure was sporadic and perhaps even upside down in what we expected. There were fields in Central and South Alabama that were pummeled with thrips injury. Slow-growing cotton is always more vulnerable. And grasshoppers have damaged cotton in numerous places.
The good news is that we seem to have turned the corner weather-wise in both temperature and rainfall. The first week of June brought temperatures at least into the mid-80s, though it still seems slightly below normal, and scattered showers are touching most areas. Tropical Storm Cristobal is expected to bring rain into our region as this newsletter is completed.
Even some fields that looked rough early are beginning to look like cotton. (Brown)
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Sidedress and Total Nitrogen. Cotton fields throughout Alabama will soon approach time for nitrogen (N) sidedress applications. Nitrogen is the nutrient which is most likely to limit yield in cotton production systems, and it is important to apply N out at the right time and at the right rate to maximize yields.
How much N should I apply at sidedress?
Most research throughout the Southeast shows that a rate of 90 lbs of N per acre maximizes yield and return on N investment. If 20 to 30 lbs N per acre was applied at plant, this means 60 to 70 lbs N per acre should be applied at sidedress. Remember, it is possible to apply too much N. Not only does excess N reduce producers’ return on investment, it can also result in lint yield reductions. Nitrogen rates exceeding 120 lbs N per acre may cause excessive vegetative growth, delayed maturity, and increased susceptibility to insect damage. Arguably, some of the foliar diseases observed in recent years are worsened by aggressive N rates.
Should I increase my N rate if heavy rains have occurred in my fields?
In fields that experienced excessive rainfall following “at plant” N applications, consider adding an additional 10 lbs N per acre on sandy soil types. Repeated heavy rains in sandy soils can lead to some leaching losses of N.
When and how should I apply N?
Sidedress N should be applied between 1st square and 1stt bloom to maximize uptake of N when the plant needs it most. Most N is applied by broadcast application of granular products or dribbling of liquid products between the rows. If UAN (liquid N in the form of urea ammonium nitrate) is applied, it is important to minimize the amount of UAN which contacts the leaves and stems, since UAN can burn plant tissues. For urea-based fertilizers, significant volatilization losses can occur if fertilizers are not applied before a rain or irrigation event. If a rain is not predicted within 2 to 3 days after urea application, addition of a urease inhibitor with the active ingredient NBPT can reduce potential N loss. (Gamble)
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“...Then there was the boll weevil scare. Every year it got closer and closer and everybody said we would have to go out of the cotton business for sure when the boll weevil hit us. But what happened – we learned to plant earlier, to rush and dust the crop, and the boll weevil did not knock us out; it just made us more determined…” from Red Hills and Cotton – An Upcountry Memory, by Ben Robertson, Univ South Carolina Press, 1940
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No Two the Same. We all have made the statement that no two seasons are alike. At this point, it does not appear that the 2020 season is going to break this streak. A mild winter was followed by a warm to hot March, followed by a dry or wet and cold April, (depending on which end of the state you live and farm), followed by a dry early and wet late May. Now here we are in early June with cotton ranging from still in the bag unplanted to the 7th or 8th true leaf. Dr. Scott Graham and I, new and old cotton entomologists, have received as many calls about grasshoppers and cutworm damage as we have thrips.
Early on, we expected our thrips pressure to peak in April in south Al and May in north Al. However, due to the April drought in the south, too much rain in the north, and unusually cool weather, especially cool nights, thrips damage has been heavy state wide up until early June. Many fields still need to be scouted and managed for thrips, cutworms, and grasshoppers for several more weeks.
However, our limited acres that are beginning to put on pinhead squares will need to be scouted for adult tarnished plant bugs throughout the month of June. Plant bugs normally are attracted to the oldest cotton as their previous wild host, daisy fleabane, dries down. This process has already begun in south Alabama. Scouts, consultants, and agri-fieldmen should keep a sharp eye out for adult plant bugs and/or pinhead square loss throughout the month of June. The highest number of adults and heaviest damage will initially be found in our earliest planted fields. Sweep nets are a valuable tool in detecting adults. Our threshold for adult plant bugs in pre-bloom cotton is 8 per 100 sweeps or 2 per 25 sweeps. If a sweep net is not available, the threshold for pinhead squares loss is about 20 percent – we want to retain at least 80 percent of these early squares. Remember, in addition to damaging fruit, adult plant bugs also deposit eggs in cotton plant stems that emerge as adults in about 3 weeks.
We have several chemical options for current cotton insect pests. The presence of aphids, which will be beginning to appear in some fields, may dictate the choices. Transform and Centric are a good treatments for both tarnished plant bug (tpb) and aphids. Other choices include acephate or bifenthrin and imidacloprid (Admire Pro). After first bloom, Bidrin comes back as an option for adult plant bugs and can also be tank mixed with imidacloprid. After first bloom, we may also begin to see immature plant bugs that have hatched in the field. Under high tbp pressure, Diamond is an excellent tool as a tank mix with products we have mentioned already for adults. Diamond at 6-9 g/acre will give 2 to 3 weeks control of the hatching tbp nymphs, which will begin about first bloom. (Smith and Graham)
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Snails and Slugs. We have seen and heard reports of snails and slugs across the state this week (June 5th). We normally can expect some issues in cool, wet years and in reduced till fields, particularly when cover crops are involved. Slugs can pose much more of a threat to stands than snails. Little information is available on snails, but many species are detritivores – they feed on dead plant matter, not living plants and do not feed on or damage cotton. Slugs on the other hand will feed on developing seedlings. There are a couple of easy ways to tell the difference. The first is that snails have shells and slugs do not. Another is that slugs tend to hide out under the soil surface once the sun comes out while snails will stay on plants during the day. Slug feeding typically results in irregularly shaped holes on the edges of leaves and slugs may cut plant stems in heavy infestations. Slug damage is often worse in situations where the furrow is not closed, leading to “slug highways” where they will work their way down the furrow clipping several plants in a row. In some rare occasions, snails may damage plants from the number of snails on the leaves weighing the plant down and bending it to the soil surface.
The question remains: what do we do about this? The answer, not much at this point. Snails and slugs are not insects, so insecticides do not have activity on them. We know these issues tend to be more likely in reduced till fields, but it is too late for that. Some baits are available containing metaldehyde or iron phosphate. These products can be effective but are quite expensive and not always readily available. Baits can be broadcast at 10-40 lbs per acre but should be done when no rain is in the forecast. If a re-plant is warranted, tilling the field is important to kill the population of slugs in the field; otherwise you are planting into the same situation. Making “trash cleaners” more aggressive at-planting may help remove plant debris from the row, which may lead to reduced injury from slugs on emerging plants. If possible, increasing seeding rates by 5 to 10 percent may also help reduce impacts of lost stand. The best answer to this problem is hot, dry growing conditions which are conducive for seedling growth and bad for slugs.
In summary, slugs may cause damage, snails very likely will not. Insecticides won’t help. We need to plan ahead with at-risk fields. (Graham and Smith)
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On-Farm Cotton Variety Trials. Variety selection continues to be among the most important decisions growers will make with respect to cotton production. Alabama has several regions in which variety selection, production practices, and environments differ. Varietal performance and stability within regions and across the state are of the utmost importance. Knowing this, in our on-farm testing program, we have determined it best to plant two different variety sets to account for North and South Alabama. Variety sets are listed in the tables below.
We would like to express sincere appreciation to growers and research centers for cooperating in these trials. We would also like to express great appreciation to the Alabama Cotton Commission, Cotton Incorporated, and participating seed companies for support in these trials. We look forward to tracking these trials throughout the growing season and delivering harvest results at season’s end. (Sandlin)
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CLRDV Update.The image above is from Dr. Bob Kemeriat, UGA Extension Plant Pathologist. It is ratoon cotton and displays symptoms of Cotton Blue Disease. Most likely, this cotton crown survived the winter infected with the CLRDV and the reddening and bronzing often associated with blue disease in cotton are on full display.
It is hard to say what this might mean for cotton for 2020. In Brazil, ratoon cotton is a major source for the virus and certainly can result in early movement of the virus into cotton and increased risk of sizable yield losses. Before COVID-19 hit, sampling showed that cotton crowns succumbed to the hard freeze in November, so ratoon cotton is not going to be a virus source in Alabama. However, the virus was detected in several weed hosts, mainly henbit and Carolina geranium, in mid- to late winter. Unfortunately, the weed sampling program was suspended in March due to issues relating to COVID-19.
Sentinel plots, with planting date as a variable, were established in early May at the Brewton Agricultural Research Unit and Prattville Agricultural Research Unit. Additional sentinel plots will be planted at several additional AAES outlying units later this month. Dr. Alana Jacobson will be monitoring aphid populations and their relationship with cotton blue disease incidence as well. The trial will be monitored for the appearance of symptomatic plants and information will be distributed as we receive it. If you see symptomatic plants, particularly in early cotton, please notify Drs. Amanda Scherer, Austin Hagan, or Kassie Conner. (Scherer)
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In the “Old Days”... Long ago when I was an Extension Agent in Lawrence County, I remember farmers ordering cotton seed by the ton. Yes, it was still in bags, but they knew how much they needed for planting and ordered accordingly. The cost was probably around $30 to 35 per bag, and bags weighed 50 pounds. The 50 pound bag was standard. Years later a prominent seed company sold a premium variety in 40 pound bags at a price comparable to the rest of the market, which was in 50 pound bags. That didn’t go over well. In 2020, bags with premium seed treatments list for over $700, which includes seed, technology, and insecticide/fungicide/nematicide (seed) treatments.
Transgenic varieties appeared in small quantities in 1995 but made their real introduction in 1996 with Bollgard Cotton. Initially, the technology charge was based on grower-reported acres, “I planted X acres with NuCotn 33B or NuCotn 35B.” It was akin to the honor system on acreage reporting. That pricing scheme lasted only a couple of years and then a switch was made to price a specific variety on the average seed count (per pound) of all the lots of that variety. That prompted some growers to search for the smallest seed – which of course had the largest count per pound – to spread a bag over as many acres as possible … which reduced seed/technology cost per acre. This wasn’t always the best plan, since small seed tend to create more challenges with stand establishment. Also, while a grower (and dealer) knew the seed count of his bags, there was no external check on the average seed size of the variety – only the company saw the whole data. What followed next was where we are today. Pricing was per bag, and there was a targeted number of seeds per bag (220,000 to 250,000 seeds, depending on the seed brand). Ultimately, this is probably the fairest way to price and purchase seed and technology, though of course, every grower would agree that seed are too costly.
Throughout the transgenic era, seed/technology has been priced according to zones based on common seeding rates and technology values. For example, a bag of seed/technology cost growers in central and south Alabama more than those in north Alabama or West Texas. The average seeding rates vary considerably between regions. Until 3 or 4 years ago, seed and technology were priced and billed separately. That changed to bag pricing –that is, a single price with seed and technology lumped together. Still, differences in pricing zones remain.
Alabama growers made the jump to transgenic varieties in 1996, coming off the heels of a couple of disaster years fighting pyrethroid-resistant tobacco budworms. They followed the strong advice of Dr. Ron Smith, who said, “In 1996, if you can’t plant Bt cotton, don’t plant cotton in Alabama.” That season Alabama farmers planted Bt cotton on 77 percent of their acres. (Brown)
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PGR Publication. There's a new publication on PGR use in cotton entitled, How to Think about Cotton: Plant Growth Regulators. It can be accessed at the following link:
https://www.aces.edu/blog/topics/crop-production/how-to-think-about-cotton-plant-growth-regulators/
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This issue contributors:
Dr. Audrey Gamble, Extension Soil Scientist
Dr. Scott Graham, Extension Entomologist
Tyler Sandlin, Extension Agronomist
Dr. Amanda Scherer, Extension Plant Pathologist
Dr. Ron Smith, Professor Emeritus, Extension Entomologist
Dr. Steve M. Brown, Extension Agronomist (Editor) typos and other mistakes are mine
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About the Alabama Cotton Shorts Newsletter
Alabama Cotton Shorts is a newsletter designed to keep cotton producers in the know. From planting dates to crop inputs—there are many factors to consider. The Alabama Cooperative Extension System is dedicated to providing science- and research-based information, derived from field experience and observations. A team of Extension specialists are working to provide Alabama farmers with timely information throughout the growing and harvest seasons.
By subscribing to the newsletter you will receive pest updates, weed management suggestions, market updates, industry news, and other information. Specialists are making field observations and reporting their findings in hopes of helping producers make more informed choices in the field.
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