Mid-Season Management Decisions

ARIZONA | Randy Norton

 This year has been an interesting year for cotton production in Arizona. The summer has been mild thus far with some of our warmest desert areas only having a handful of days over 100 degrees through mid-June. Cotton development has been delayed because of the lower temperatures and lack of heat unit accumulations. Under these circumstances, it becomes more critical than ever to protect the fruit set that is currently being developed on the crop. It is important to monitor for any insect populations that achieve actionable levels that may result in reduced yield potential.

The bright spot with the milder summer this year is a reduced level of heat stress on the crop. Our research and experience have shown that with reduced levels of heat stress, we observe lower incidence of small boll shed, which is good news for developing a good fruit load. Conditions of higher-than-average fruit retention can effectively manage vegetative growth and reduce the need for plant growth regulators. Maintaining proper plant-water relations and fertility levels is also essential for supporting a potential increased fruit load. Time will tell how the remainder of the season progresses, and even though the crop is slightly behind where we would like to see it for early July, conditions could be setting up for a good fruit set and potentially high yield.

Make sure you are prepared to respond to those potential crop scenarios with proper management decisions. For more information on these topics and other cotton production related topics, visit our website at extension.arizona.edu/crops-soils. rnorton@cals.arizona.edu

TEXAS | Ben McKnight

As of June 7, many areas of the state that have been impacted by extended periods of drought have had some relief. Over the past week, good amounts of rainfall were welcomed in parts of the High Plains, Rolling Plains and Blackland Prairie. Hopefully, the drought monitor map will continue to show lighter shades of color as we continue to move through the 2023 growing season.

The majority of cotton in the Lower Rio Grande Valley and Coastal Bend ranges from the squaring growth stage to blooming. Cotton
fleahoppers have been found above threshold in some fields and treatments have been effective. In the LRGV, Verde plant bugs and tarnished plant bugs have been found in fields, and growers are keeping an eye on these pests as well. In both areas, the extended weather forecast is showing temperatures above 100 degrees, and these temperatures should provide plenty of heat units to keep the crop moving along. 

Soil moisture conditions are favorable in the Upper Gulf Coast currently in early June, but more timely rainfall throughout the remainder of the growing season would benefit dryland cotton fields as summer sets in and temperatures heat up. Decent rainfall has improved conditions east of Interstate 35, but more rainfall would certainly help to finish out dryland cotton plantings in the Blackland Prairie west of the interstate. 

Following rainfall in many areas of the state, I’m starting to see some mid-season weed flushes occurring in fields where residual herbicides have played out. I’d encourage growers to remain active in scouting for not only insect pests, but also for weed pests that can grow rapidly with favorable moisture and temperature conditions. This time of year, a pigweed has the capability to grow an inch per day. Targeting small, actively growing weeds with a timely postemergence product application will improve our overall weed control efforts. Additionally, overlaying a residual product when applying postemergence products can extend our weed control efforts further into the season. bmcknight@tamu.edu

LOUISIANA | Matt Foster

As I write this June 7, cotton planting in Louisiana is complete. May and June have been unusually dry in most areas of the state, which increases supplemental irrigation needs. Precisely timing irrigation when soil moisture is less than optimal can help preserve crop yield potential. Research has shown that a one-inch water deficit at the wrong time can result in the loss of at least 60-100 pounds of lint. The goal in Louisiana is to irrigate before plant stress occurs with a water amount that won’t waterlog the soil if subsequent rainfall is received. 

Approximately 60% of cotton acres in Louisiana are irrigated, with furrow irrigation being the main method. Irrigation timing varies due to weather, cultural practices, soil type and the status of the crop. One method to aid in timing the first irrigation is to install soil moisture sensors that can determine soil moisture at six- or 12-inch intervals in and below the root zone. 

In general, the first irrigation should begin when 50% of the available moisture has been depleted from the root zone. This ensures good root development and reduces the risk of soil saturation early in the growing season. At bloom, irrigation shouldn’t promote rank growth or hinder root development. In general, irrigation is terminated just prior to the first open boll. Caution should be used as excess soil moisture at this time can delay maturity and make defoliation more difficult. 

Despite dry conditions, the cotton crop throughout the state looks good. Insect pressure from thrips was heavy enough in some areas to justify foliar insecticide applications. Multiple growth stages are present throughout the state due to a wide range of planting dates. Approximately 10% of the crop is squaring. As more of the crop begins to square, growers and consultants will focus on square retention and managing plant height with plant growth regulator (PGR). Once cotton reaches match head square stage, plant growth, environmental conditions and square load should be monitored. 

A few factors to take into consideration when planning for pre-bloom applications of PGR include variety growth habits, soil type and total nitrogen available to the crop. PGR applications should be based on current plant growth characteristics and the anticipated growth rate based on expected growing conditions for the next seven to 10 days. mfoster@agcenter.lsu.edu

MISSISSIPPI | Brian Pieralisi

In Mississippi, most input management decisions are in place by mid-season. As leaf area expansion and canopy closure occurs, weed pressure is hopefully under control. Nitrogen is applied and soil profile is charged with moisture as cotton advances through bloom and boll development.  

If potassium deficiencies are showing up early in reproductive stages, it is a good idea to apply potash as early as possible in an irrigated environment or if rainfall is imminent. It is possible to recover yield losses in these scenarios. If dry fertilizer is not an option, up to 10 pounds per week of foliar K can be applied, which can offset some leaf drop in certain circumstances. In 2022, some K deficiency appeared due to drought conditions, which caused leaf shed, reducing photosynthesis. Allowing for photosynthesis to continue through bloom/boll fill will justify the application.

Finally, with primarily three-gene Bt cotton, monitoring insect pests mid-season is critical. Plant bugs are the most important economic pest to monitor, especially near maturing corn fields. Mississippi State Extension insect control guide recommends terminating insecticide application at NAWF=5 + 350 DD60s.  This is typically 10 to 14 days after NAWF=5 depending on environmental conditions. In irrigated cotton, water demand is pretty low until mid-season. Generally, initiating irrigation to avoid excessive plant stress is recommended until the first open boll.

Hopefully, mid-season management will contribute to high fruit retention and ultimately, maximum yields! Good luck. bkp4@msstate.edu

NORTH CAROLINA | Guy Collins

As I write this May 31, the North Carolina crop is planted for the most part. Emergence and final stands have been quite good across the state. Planting conditions were decent this year once we got to the week of May 8, and the spring planting window ranged from slightly dry to somewhat wet at various times. Cooler temperatures set in toward the latter end of May, which slowed things down for us, but all in all, emergence has been quite good with very few acres requiring replanting. 

Early season growth was slower than normal, primarily due to cooler weather at the end of May. Additionally, thrips pressure was quite intense during the latter half of May, which was exacerbated by slower growth, thus necessitating several foliar sprays late May and early June. The crop is somewhat behind at this point but can easily catch up with a little heat.

June is the time for continued weed control, the early onset of lygus insects in some parts of the state and fertilizer applications. These fertilizer applications should be made in a timely manner to avoid yield penalties, especially if very little was applied at or around planting.

July marks the beginning of the bloom period. The date of first bloom is determined by both planting date and heat unit accumulation. It is important to note when first bloom is reached for many reasons. One, this helps us to know if the crop is ahead, on-time or behind schedule, which may influence plant growth regulator decisions. For irrigated growers, it is important to document when each field enters the bloom period so that weekly water rates can be adjusted. 

For all growers, it is important to keep track of each week of bloom for each field so that insect thresholds can be adjusted by week (stinkbugs for example). The length of the bloom period is often dictated by weather during July and into August. As we’ve learned in previous years, a sudden and severe drought period can drastically shorten the bloom period if a premature cutout occurs with a heavy boll load. Timely irrigation can be critical if such events occur this year. 

Although lygus insects could be a problem at any time June through August, other insect pests come into play during the latter half of July and into August, so it will be important to scout thoroughly and frequently.  guy_collins@ncsu.edu

TENNESSEE | Tyson Raper

Calls are beginning to trickle in, here on the eighth of June, on how to manage plant growth on several of our new varieties, including ThryvOn. From our limited experience, many of these cultivars in our region tend to fall under the moderate to passive classifications. I have personally not yet seen a ThryvOn require the aggressive management that DP 1646 B2XF or DP 2038 B3XF required.  

By the time you read this in July, most will have begun PGR applications. On decent ground planted to a moderately responsive variety with adequate moisture, I have moved many of my trials into an 8-, 16- and 24-ounce plan (4.2% mepiquat chloride), targeting the second/third week of square, first/second week of flower and third/fourth week of flower, respectively. I will shift rate and timing of these applications based on the expansion of the internode between the fourth and fifth node. I’ve found I can often reduce the last application rate back to 16 ounces if my first two applications were properly timed and fruit retention remained high. 

If you are consistently requiring more PGR late in the year to control growth on varieties that are not classified as aggressive, I would urge you to look critically at your applied nitrogen and consider shifting all applications up earlier in the year. traper@utk.edu

GEORGIA | Camp Hand

Conditions for stand establishment were phenomenal in Georgia throughout our planting window. Mild temperatures and frequent rainfall prevailed throughout May and early June across the state, leading to perhaps the best stands we have seen in a long time. We are off to a great start, and I hope we are able to capitalize on that!

As we enter the middle of the season, there are a few things we need to keep in mind. The first is that many growers will be applying growth regulators to their crop. Keep in mind the responsiveness of the variety you planted to growth regulators, as well as your field history. Generally, mepiquat chloride applications benefit growers in two ways. First, it reduces plant height, and second, it hastens maturity. Although there are other benefits, these are the two most consistent plant responses. In Georgia, I believe that extremely aggressive PGR management strategies should be reserved for late-planted cotton to promote earliness and hasten maturity. 

In terms of pest management, pests I would be looking out for are stinkbugs and fungal pathogens like target spot or areolate mildew. Recommendations for all of these pests in Georgia can be found in the UGA Cotton Production Guide. 

As always, if you ever have any questions, please don’t hesitate to reach out to your local UGA county Extension agent. They, along with your UGA specialists, are here to help! camphand@uga.edu 

ALABAMA | Steve M. Brown

On the Auburn University campus, we have the two oldest cotton experiments in the world. I walk them frequently and appreciate the lessons they continue to teach. 

One experiment was established to show the benefits of crop rotation and winter cover crops. The other is a fertility study that addressed the problem of cotton “rust,” which proved to be related to insufficient potassium. It demonstrates the in-season progression of nutrient deficiency symptoms associated with low/no potassium, nitrogen, sulfur and boron, as well as low pH. Cotton is the focus of the experiments, but corn, soybeans and wheat are rotational crops. 

These sites have been farmed for 110-plus years. Yet, WE STILL HAVE WEEDS. Pre and post herbicides and hand weeding are employed, and weeds have no impact on crop yields. But, we don’t do a great job of keeping the entire area weed free throughout the season and after harvest. Cotton layby treatments are not used in order to minimize effects on late summer clover germination and establishment.

With the increasing list of herbicide-resistant weeds, the aim of minimizing weed reproduction seems increasingly important. In cotton, we have the opportunity to help this with layby herbicides. Yes, the Roundup Ready/Roundup Flex era ushered in the ease of post applications at 10 mph, and post-directed and layby applications became a tedious, time-consuming bygone. Where these are gone contributes to problem weeds NOT being gone.

Layby herbicides in cotton limit mid-season weed establishment and late-season weed seed production. Layby options are generally economical but admittedly cost much in time. If you’re committed to a piece of land, season long with control, aided with layby treatments, makes good sense, as does post-harvest weed control. 

I remember a long-ago class when my professor asked, “If you had 1 cocklebur in a soybean field, would you take the time to pull it?” The general consensus — which in hindsight I strongly consider foolish — was “No.” He asked, “What about 2? Or 3? Or 4?” I’m no fan of soybeans, but I would do whatever to rid the field of weeds.

Layby herbicide programs purchase future weed control. cottonbrown@auburn.edu