Double-Cropping Cotton and Wheat

Effects of Cotton Maturity on Lint YieldGrowers may consider the feasibility of double-cropping cotton behind wheat because of high commodity prices and the availability of high-yielding, shorter season cotton varieties. Cotton acres may be double-cropped with wheat in areas that will support a longer growing season. Although research is limited in cotton and wheat double-cropping systems, testing has shown that cotton can be a profitable option for planting behind wheat.1

 

 

Maximizing Double-Crop Cotton Opportunities

Genetic Potential: Advancements in cotton seed genetics and technology are helping to maximize cotton production, and are expanding concepts of traditional cotton production practices. New cotton traits provide powerful insect control and herbicide tolerance to help maximize yield potential. Early-maturing and fast fruiting varieties will typically have the best fit in double-cropping situations.

 

Conventional vs. Double-Crop Cotton

Insect Protection: In a wheat and cotton double-crop system, the late-planted cotton crop will need increased protection from late-season insect pests. Genuity® Bollgard II® cotton provides the most powerful built-in worm control, protecting against leaf- and boll-feeding worm species including budworm, bollworm, armyworm, loopers, plus saltmarsh caterpillars and cotton leaf perforators. Genuity Bollgard II cotton can reduce or even eliminate the need for spraying for worm infestations, which otherwise could occur during harvest of other crops. It is especially important to intensively scout late-planted cotton fields for insect infestations as younger plants may be more attractive and easily damaged by pests. Insecticides should be applied at economic threshold levels.

Weed Control: In a double-crop system, after the wheat crop is harvested, fields should either be burned or a burndown herbicide application with residual activity should be applied to plant cotton into a clean field. Double-crop cotton can benefit from Genuity® Roundup Ready® Flex cotton technology by providing easy and efficient weed control. Due to late planting and plant development, the need to spray late-season weed flushes may coincide with other farm work. Genuity Roundup Ready Flex cotton increases flexibility and creates a wider herbicide application window, which allows for management around other crops or unfavorable weather conditions. Roundup® brand agricultural herbicides can be applied to Genuity Roundup Ready Flex cotton up to 7 days prior to harvest for broad-spectrum weed control.

Management Recommendations

Moisture Management: One very important factor for raising a successful cotton crop after wheat is maintaining adequate moisture. Mississippi State University and University of Arkansas Cooperative Extension Services recommend that double-crop cotton is only planted on irrigated fields to supply adequate water. A winter wheat crop is harvested in late May through early June, which is typically when rainfall can become less frequent. After wheat harvest, planting preparation for the second crop can deplete soil moisture. The burning of wheat stubble and tillage can dramatically dry out soil. No-till planting into existing wheat stubble is an option; however, the practice can be difficult to perfect and additional planter attachments are needed.

 

Performance vs. Early-Maturing Stacked Competitors

Variety Selection: The proper cotton varieties and maturities must be selected to help achieve a successful double-crop cotton harvest. Due to a compressed season, double-crop trials have shown that earlier maturing varieties show more promise than late-maturing varieties. When selecting an earlier-maturing variety, moisture management is very critical during the fruiting and maturation phases. Any lack of moisture during these phases can result in dramatically lower yields. Double-cropping cotton with early-maturing varieties is ideal in irrigated fields.

Managing for Earliness: Double-crop cotton should be managed for maximum earliness due to a shorter season and limited heat units.2

  • Pest Management - It is important for late-planted cotton to maintain early fruit (first 5-7 nodes of fruiting). Close scouting of fields for Lygus spp. or other fruit-feeding insects can help keep fruit retention high.
  • Manage Vegetative Growth - Plant vegetative growth should also be kept in check as it is important for the plant to focus energy into boll production. Plant growth regulator (PGR) treatments may be needed for the crop to reach cutout. Prior to cotton bloom, a locally tested method should be used to determine the need for growth regulator application.
  • Do Not Over Fertilize - It is also important not to over fertilize a field prior to planting double crop cotton. Applying too much nitrogen (N) can result in excessive vegetative growth, which may be at the expense of reproductive growth. Petiole testing during bloom may be used to determine the need for a late sidedress or foliar applications.
  • Irrigation Management - Irrigating double-crop cotton can be another tricky management area. Irrigation should be timed for only limited stresses throughout the growing season. This should keep the crop producing new nodes and avoid going into pre-mature cutout. As the crop approaches cutout, begin to slow down on irrigations so that the vegetative development slows and cutout (NAWF=5) will occur in a timely manner and before the last effective bloom date in your area.
  • Manage Cutout - Double-crop cotton must reach cutout before the season runs out of heat units to mature the crop. By tracking the nodes above white flower (NAWF) from early bloom when it should peak at near 9 to cutout of 5, a grower can adjust his inputs to result in a timely cutout.

Double-Crop Cotton Trials

Application Rates and Dates for PGR Regimes
In 2007, a study was established at the Monsanto Learning Center in Leland, MS to compare yield potential of cotton and wheat in a double-crop system versus conventionally planted cotton. The study evaluated six high-yielding cotton varieties with early, early-mid, mid-full and full maturity. Two early-mid and mid-full maturity products were selected and yields were averaged. Cotton was planted on April 27, 2007 for the conventional cotton plots and June 15, 2007 for the double-crop plots. For double-crop plots, cotton was planted into 8- to 10-inch tall wheat stubble. Planting into the wheat stubble resulted in poor stand as the stubble caused the planter to ride up and in some instances plant seeds on the soil surface. Cotton varieties planted in the conventional system out-yielded all double-crop plots (Figure 1). Lint yields in the double-crop plots varied among varieties from the highest at 934 lbs lint/acre and the lowest at 287 lbs lint/acre. An economic analysis of the study was prepared to compare gross income and net return above variable cost of the different maturities selected in the doublecrop trial (Table 1). Commodity prices and production expenses are based on Mississippi State University Agricultural Economics Cotton 2011 Planning Budget.3 Comparisons were made for yield results from the early and full maturity cotton products. Within the analysis, each double-crop plot produced 70 bu/acre of wheat for a gross income of $305/acre at $4.35/bu. According to the Cotton 2011 Planning Budget, cotton pricing was calculated at $0.84 per lb lint.

 

Yield of Common Varieties

Total variable cost, as set by the Cotton 2011 Planning Budget, was subtracted from the total gross income to provide the net return above variable costs. Results from the economic analysis show profit can be made from a wheat and cotton double-crop with proper variety selection. Data collected from this study infers that when planting cotton late, cultivar selection may play an integral part in maximizing lint yield.

Three years of cotton variety tests conducted across a range of planting dates were analyzed to determine relative yield potential for each variety by planting date. Six popular cotton varieties were selected for the trials (DP 0912B2RF, FM 1740B2RF, PHY 367 WRF, PHY 375 WRF, ST 4288B2RF and ST 4498B2RF). Results from the study can be valuable to growers considering double-crop cotton as the yield potential of DP 0912B2RF stood out among other varieties for the later planting dates. For the May 21 to 31 planting date, 113 comparisons were made and DP 0912B2RF won 79 of the comparisons (69.91% wins) with an average yield of 1,139 lbs lint/acre (Table 2). For the June 1 to 15 planting date, 16 comparisons were made and DP 0912B2RF won nine of the comparisons (56.25% wins) with an average yield of 1,117 lbs lint/acre. Results from planting date trials show the DP 0912B2RF has high yield potential when compared to other cotton products available to growers for late planting scenarios.

Effect of Population and PGR Regime

In 2011, a demonstration trial was established at the Monsanto Learning Center in Scott, MS to evaluate the effect of PGR application, planting density, and variety selection on the success of double-cropped cotton behind wheat. Six Deltapine® varieties were planted on May 31, 2011, at 42,000 and 52,000 seeds per acre. Three PGR regimes were evaluated: untreated check (UTC), passive, and aggressive (Figure 2). Several varieties showed promise of very high yield in this system including DP 0912B2RF, DP 1133B2RF, and possibly DP 1044B2RF (Figure 3). At lower populations, the less aggressively PGR managed plots yielded more than the more aggressively managed plots (Figure 4). At higher populations, aggressively managed plots yielded more than passively managed plots and were able to generate yield in excess of 2 bales despite being planted on May 31. When considering double-cropping cotton following wheat, aggressive management will likely be necessary. Higher populations should allow the field to generate equivalent or higher yield potential in shorter amounts of time versus lower planting densities which can force the plants to generate fruiting positions further up and out on the plant. However, higher densities demand more aggressive PGR applications to increase the odds for success. Cotton growth is heat driven. When accumulating heat quickly, as a late- planted crop would, PGRs are diluted faster so applying them early (beginning at early squaring), more often and in higher doses can be helpful managing the crop for higher yield potential.

​Risks associated with weather and insects are likely to be higher when planting late. Additionally, any delay in planting double-crop cotton will likely result in yield reductions. Variety selection becomes even more important as planting dates are delayed. Careful management can help to mitigate some of the risks associated with delayed planting, and help to produce a profitable cotton crop.