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Alabama Cotton Shorts

May 11, 2020

May 11, 2020
 
Situation. Below normal temperatures delayed planting throughout much of April. With a favorable window around May 1, we commenced planting only to see lows dip into the 40s in Central Alabama and even into the 30s in North Alabama over the past several days. Hopefully, we’re now turning the corner and will see sustained warm conditions. Lack of soil moisture is an on-going challenge for Central and South Alabama, while North Alabama has contended with extremely wet conditions throughout the winter and into spring. It’s too early to determine the fate of what’s in the ground. Concerns include chilling injury, thrips injury, seedling disease, and crusting. Warm weather with an occasional soaking rain will improve everything.
 
Forecasters expect Alabama producers to plant about 500,000 acres in 2020, similar to 2019. So many factors are in play – weather delays, depressed commodity prices, credit challenges, COVID-19 – that uncertainty abounds. We’ll probably be flat to down 5 to 10 percent in acres compared to last year.  (Brown)
“Our wagon was hitched to cotton’s star, where it had been hitched for a hundred years… We have been growing cotton since the time of the grandfather of our grandfather’s father. Cotton is a state of mind with us, a philosophy… The truth is we like to grow cotton. It is a beautiful crop to cultivate and gather…” from Red Hills and Cotton – An Upcountry Memory, by Ben Robertson, Univ South Carolina Press, 1940
Considerations about Planting Depth. How deep should you plant cotton? The simple, easy answer is:  to the first knuckle of your index finger. For most of us, that’s about an inch. We commonly, rightly, routinely plant cotton at about 0.75 to 1 inch.
 
Cotton is a subtropical, perennial plant that’s been bred and adapted for 200-plus years to grow as an annual. As a perennial, it’s inherently a slow starter. Obviously, some varieties start more slowly than others. We readily make depth adjustments for soil moisture with considerations for pending weather, seed vigor, and seed size.
  • Ideal conditions. If soil moisture is plentiful and conditions are warm, you’ve got flexibility, and the likelihood of successful stand establishment is good. You almost can’t go wrong... as long as you avoid the extremes in depth -- too shallow or too deep.
  • Pending weather. If rain or crusting are expected, it makes sense to shallow up slightly. If a gully washer (heavy rain in a short period) is coming, stop planting. Good cotton stands are rarely achieved behind a 3 or 4 inch hard rain. If drying conditions are expected and moisture is moving deeper into the profile, maybe you plant a little deeper… if you have good seed vigor. Planting beyond a depth of 1.25 is almost never a good idea.
  • Seed vigor. Growers pay a lot for cotton seed and should know what they’re getting in terms of seed vigor. Retailers can provide warm and cool germination data on each bag of seed. Cool germ, which is determined by exposing seed to a constant 64.4oF, is a marginal temperature for cotton growth and provides a prediction of seedling vigor. The common industry minimum for cool germ is 60 percent, a benchmark which suggests acceptable seedling vigor. Seed with cool germs in the 70s are quite good, in the 80s are exceptional, and in the 90s are extraordinary. Know what you have. Given challenging planting conditions, higher cool germ seed, particularly with larger seed size, should be planted before those with lesser cool germ.
  • Seed size. While there is some link between seed size and seedling vigor, it is not absolute. Some smaller seeded varieties (or lots) may have superior cool germ and vigor. Conversely, large seed may have variable seedling vigor.  
Extremely shallow planting depths may expose seed to injury from PRE herbicides and/or from extremely high temperatures near the soil surface.
 
What about “dusting in,” planting shallowly in dry soil with the hopes or prospects of sufficient rainfall to germinate the crop? Often, this is a desperation practice compelled in the later portions of the planting window by prevailing dry weather, crop insurance deadlines, or limited planter capacity. Because of the potential risks – a limited shower which germinates the seed but is insufficient for plant establishment – this practice should be used only sparingly and carefully. Yes, in contrast to some other crops, cotton seed can remain viable in the soil for weeks and successfully establish with a significant rainfall event.   (Brown)
How to Economize on 2020 Cotton Insect Control Costs. With the current outlook for cotton prices, it is critical to hold all production inputs to a minimum. This is especially true for insect control since this is a major variable cost each year.
 
As we plan for the season, growers need to realize that poor economizing with cotton insects can come from two perspectives. It is poor economics to treat for insects when the damage potential is low or below threshold levels. On the other hand, it is poor economics to NOT treat when insect pest damage is causing an economic reduction in yield potential. We need to steer our cotton insect management between these two boundaries.
 
How can we accomplish this objective in 2020? A critical starting point is SCOUTING. There is no way to efficiently and economically manage insect pests without knowing the insect conditions at all times during the season. An experienced scout or consultant who is up to date on monitoring 2-gene Bt cotton and pests such as plant bugs, escaped bollworms, stinkbugs, spider mites, aphids, and whiteflies is a must in 2020. Scouts, agri-fieldmen, and consultants must also know current pest thresholds and the effectiveness of all recommended insecticides AND have sufficient time to do the job properly.  (Smith and Graham)
Thrips Update. In the northern part of the state weather conditions are driving thrips risk predictions. Thrips injury is often worse in cool, wet conditions when cotton seedlings are growing slowly. In these situations, fewer numbers of thrips can cause significant injury to plants. The CottonTIP model will give an indication on risk of thrips injury and which fields should be monitored for thrips and thrips injury. We recently posted a blog on the ACES website giving details on how to use the CottonTIP model and what some of the outputs mean. You can find the article here.  

North Alabama. In the Tennessee Valley and Sand Mountain Regions, cotton planted from around May 9th through the end of the month will be at highest risk of thrips injury.

Central Alabama. Along I-20, north of Birmingham, cotton planted from May 5-15th and May 24th through the end of the month will be at highest risk of thrips injury. Cotton planted south of Birmingham along I-20 is at relatively low risk of thrips for all May planting dates.

South Alabama. Cotton planted in the Gulf Coast, Southwest and Wiregrass Regions during the first three weeks of April have the highest risk of thrips injury and cotton planted in May will have relatively low risk of thrips injury.

Remember that cotton is only susceptible to thrips injury until about the 4th true leaf stage. Foliar insecticide applications are most effective when sprayed at the first true leaf stage. Recommended foliar insecticides and thresholds for thrips can be found in the Alabama Cotton IPM Guide.   (Graham and Smith)
True Armyworms are Still Hanging Around. Growers were still finding true armyworms in and under heavy burndown residues on Monday, May 4, in Central Alabama. These caterpillars only feed at night and spend the day under desiccated vegetation. Look for them early in the morning – that’s when they are most readily found. Where present, they are a serious threat to seedling cotton soon after emergence. These armyworms are easily controlled with a medium rate of any pyrethroid. Broadcast applications work best and will also provide protection from cutworms.   (Smith and Graham)
Tarnished Plant Bugs Building on Daisy Fleabane. Daisy fleabane, the most prominent early-season wild host for plant bugs (TPB), is currently covered with TPB. This is not unusual. However, when surveying fleabane in Henry County (in Southeast AL) on April 30, we noted that fleabane was more mature than normal for this time of the season, and that the TPB population was also more mature. All stages of TPB – from old, dark adults to young immatures -- were observed. The majority of the population was early to mid-immatures; they will become adults about June 1 as fleabane dries down. These TPB will begin searching for new hosts, and cotton is the best choice in the landscape. May-planted cotton may not yet be squaring when adult TPB move into fields. If pinhead squares are not present, TPB will feed in the tender terminals, damaging bud tissue and causing “crazy cotton” and delayed fruiting. Fleabane surveys in Lee County (near Auburn, which is 130 miles north of Henry County), showed TPB populations about 10 to 14 days later in development, so the expected movement to cotton should begin about mid-June.  (Smith and Graham)
Large Palmer Amaranth Suppression in Xtend and Enlist Cotton Using Rescue Treatments. Given its tolerance to herbicides, Palmer amaranth greater than 12 inches ranks among the most difficult weeds to control in row crops. When it reaches a foot or more in height, the only consistent options are hand weeding, mechanical control, or Gramoxone (through a weed wiper or similar device). Every effort should be made to address Palmer pre-plant, at-plant, and early in the season. Residual herbicides and early season, timely post treatments are critical to limit its emergence, establishment, and proliferation.
 
Trials were conducted in Alabama in 2018 and 2019 to compare rescue treatments for large, escaped Palmer amaranth. Treatments were applied in June in non-crop plots with high densities of Palmer amaranth 10-35 inches tall. Other weeds present in high numbers were annual grasses, morningglories, sicklepod, and Florida beggarweed. Xtend and Enlist treatments were applied with TTI 11002 nozzles and Liberty with TT 11002 nozzles. A NIS surfactant was used with all Liberty treatments. Weed control ratings were made 4 weeks after the initial treatment (WAIT) and biomass was collected 5 WAIT. Since treated Palmer can frequently recover from injury, biomass reduction is a better indicator of the efficacy of each program. Control with the Xtend systems varied significantly by year, while results with the Enlist programs were similar over years.
Palmer amaranth was almost 15 inches tall at the initial application in 2018, and due to weather delays, almost 24 inches in 2019. A week’s delay in 2019 resulted in 9 inches in additional weed height and very poor control with Xtend programs. Some of the treatments which worked very well in 2018 (ex. Xtendimax followed by Liberty 3 or 7 DAIT) did not perform in 2019. This is a reminder for growers who hold unrealistic expectations that new technology will always bail them out. Enlist programs provided better Palmer control in this study due to the fact that Enlist One can be tank mixed Liberty, as allowed by the label. The combination of auxin plus Liberty improves control. Another observation seen in the pictures below is that grass control was superior in 2018 versus 2019. Wet, moderate conditions prevailed in 2018, while extremely hot, dry conditions persisted in mid-May through late summer of 2019.
 
Control of Palmer amaranth over 12 inches tall is erratic. The sooner growers spray emerged Palmer, the better and more consistent control they achieve. Differences in environmental conditions, weed size, etc. create differences in control across fields and years. Weeds surviving the rescue treatments should be pulled to eliminate seed production and harvest interference.
Final Thoughts:  Dealing with Palmer amaranth before they come up is a lot easier than after they emerge. Many soil herbicides such as Valor, Reflex, Warrant, Dual Magnum, Outlook, and Brake provide excellent control in cotton if activated properly by rainfall or irrigation. Old chemistry such as Cotoran, Diuron, Caparol and yellow herbicides can also provide residual control. Rotations with corn, deep turning soil every 4 to 5 years, and utilizing cover crops are also viable methods to manage Palmer amaranth. Group 15 herbicides (Warrant, Dual Magnum and Outlook) also provide excellent control and can be sprayed over the top of cotton to provide residual Palmer amaranth and grass control further into crop season. Combinations of Group 15 herbicides with dicamba (new formulation), Enlist One, or Liberty are good early post options to prevent mid-season escapes of Palmer amaranth and annual grasses. These tank mixtures typically should be used when cotton is 2 to 3 leaves (about 3 to 4 weeks after planting) and in an overall control program that will hopefully minimize the need for rescue treatments.  (Li with Frances Browne and Katelyn Price)
Cotton Scout Schools Postponed (later dates TBD). Cotton scouting schools have been conducted annually by Entomologists and cotton team members in June each year since 1951 (for 61 years). This year’s schools will be postponed due to COVID-19 and safety concerns. If conditions permit, they will be conducted later in the summer with emphasis on mid to late season pests such as plant bugs, escaped bollworms (on 2-gene Bt cotton), stink bugs, and silverleaf white flies (in South AL).   (Smith and Graham)
This issue contributors:
Dr. Scott Graham, Extension Entomologist
Dr. Steve Li, Extension Weed Scientist
Dr. Ron Smith, Professor Emeritus, Extension Entomologist
Dr. Steve M. Brown, Extension Agronomist  (Editor) typos and other mistakes are mine 

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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