Managing Late-Planted Cotton

KEY POINTS

  • Delayed planting reduces the time and heat units available for the production and maturation of cotton bolls.
  • Starting with a healthy stand helps to provide a strong start for a shortened growing season.
  • Protecting early-set bolls is a high priority for late-planted cotton.

What to Consider

Late planting that delays the cotton growing season by a week or more can lead to weeks of waiting for top bolls to mature later in the season. Late-season boll maturity can be further delayed as daily heat unit accumulation declines in the fall. A late-planted cotton crop can still produce a successful and productive crop. It is imperative that growers with late-planted cotton thoroughly follow established management practices to encourage early fruit retention. Focusing on setting and protecting early first position bolls is critical for optimum yield potential in late-planted cotton. A good stand helps to decrease susceptibility to pest damage and provide a strong start for the shortened growing season.

Early-Season Management

Planting Population. Avoid low populations, particularly in the northern tier of the Cotton Belt where heat unit accumulation may be limited. Higher populations encourage more first position bolls which set with a lower heat unit interval, than second and third position bolls.1 When heat unit accumulation is reduced, first position bolls are more likely to mature than bolls set further out on fruiting branches.

Avoid Excess Nitrogen. Late-planted cotton should only receive about two thirds of the full-season rate of nitrogen (N) and should be applied prior to first square.1 Excessive N application will not help speed up plant growth, and can lead to unnecessary vegetative growth and delay maturity. Growers should consider soil types and past experience as they evaluate the need for additional N on late-planted cotton.

Variety Selection. Select earlier-maturing varieties that are more determinant in growth.

Seed Treatment. Include a seed treatment to help control insects, diseases, and nematodes that may be more established in the field at a later planting date.

Insect Management. Thrips damage to the growing point or terminal bud of cotton seedlings (Figure 1) can delay plant growth. Some insecticide seed treatments can help control thrips for up to three weeks after planting. Late-planted cotton can be more susceptible to damage from plant bugs, stink bugs, and several caterpillar pests throughout the season.1 For more information refer to the Agronomic Spotlight - Managing Early Season Insects in Cotton.

Weed Management. Plant into a weed-free seedbed and apply effective preemergence herbicides to help keep weeds suppressed. Use of residual herbicides is highly recommended, and timing application shortly prior to precipitation or irrigation can help increase herbicide efficacy.1

Irrigation. Apply irrigation or plant into moisture to help establish a uniform and vigorous stand.2

Mid-Season Management

Plant Growth Regulators. Proactively apply plant growth regulators (PGRs) to help control rapid vegetative growth as a result of more available heat units per day. PGR application can also promote fruit retention and development. For fields with adequate precipitation or irrigation, apply multiple low-rate applications at matchhead square. In fields with low soil moisture, delay application until flowering can help reduce the risk of excessively reduced vegetative growth in the event of a drought.3 PGR rates and application timing should be adjusted according to variety selection and environmental conditions. For more information refer to the Agronomic Spotlight - Cotton Growth Management.

Insect Management.Fruit loss due to insect damage can stimulate vegetative growth, delay maturity, and eventually reduce yield potential. Early and frequent scouting is necessary for identifying potential insect infestations and making timely insecticide applications. Keep insect pests below threshold levels to help maintain early-season fruit retention above the target of 80%, which can reduce excessive vegetative growth, and increase the potential for a productive early crop.3

Weed Management. The same heat units that stimulate rapid growth in late-planted cotton can stimulate weed germination and growth. Continue weed suppression by following up with timely postemergence (POST) weed control. Late over-the-top herbicide applications and poor POST applications can cause boll loss, delayed maturity, and loss of yield potential.3

Late-Season Management

Timely Cutout. The goal of managing late-planted cotton should be to reach cutout before the season runs out of sufficient heat units to mature the crop. One risk of late-planted cotton is reaching the last effective bloom date (based on historic heat unit accumulation) before the crop has reached cutout. Cutout is the end of the boll loading period and occurs when at least 50% of the plants in a field have reached five nodes above white flower. With late-planted cotton, it is possible that the crop may not reach cutout prior to the last effective bloom date.1 With late-set bolls and bolls set in the upper part of the plant less likely to contribute to overall yield potential, growers should carefully evaluate the potential for late-set bolls to mature.

Apply a defoliant according to harvest planning and air temperature. Defoliants require temperatures of above 60 °F to be effective. Include an ethephon-based harvest aid to help increase the amount of bolls ready for harvest.3,4 Late-maturing bolls open slowly due to cooler temperatures, so delaying defoliation in the hopes of allowing late-set bolls to mature could result in reduced yield potential and reduced fiber quality. For more information refer to the Agronomic Spotlight - Cotton Defoliation and Application Timing​.

13;10;
Figure 1

Figure 1. Crinkled leaves due to thrips damage

​​​​