With Cotton Planting just getting underway, planting date and seeding rate are just some of the important things that growers need to consider. Here are some comments from UGA Extension Agronomists Guy Collins and Jared Whitaker about planting date and seeding rate considerations for the 2013 cotton crop:
Planting Dates – Planting in optimal soil conditions is very important in achieving optimal germination and vigorous early-season growth. Although seed companies generally only bring high quality seed to the market, temperature and moisture play significant role in the establishment of the crop. We are currently coming out of a short mild cool spell. Many growers have probably planted in conditions similar to these in the past, without observing any adverse effects on germination or seedling vigor, especially when planting into well-drained and/or bedded soils. Despite its perennial and indeterminate nature, cotton is a very weak plant when it is young. Cotton seed and seedlings are very susceptible to injury resulting from both biotic and abiotic stresses, one of which is cool, wet conditions within a few days of planting. This is generally not a problem for most of our planting season, yet we are sometimes faced with cooler temperatures towards the early end of our planting window. The first five to seven days after seed imbibe water is generally the period when cotton is sensitive to cool temperatures, with the greatest sensitivity occurring during the first two to three days after imbibition. If we anticipate potential problems with germination and vigor, it is very important to avoid planting when cool, wet conditions occur or are expected soon after planting, and to adjust seeding rates to account for potential losses. Even though we may experience some high daytime temperatures, we must not forget the impact that low nighttime temperatures could have on germination and emergence. In general, cotton should be planted when soil temperatures are 65°F or greater and 30 to 50 DD60’s are expected to accumulate within five days of planting. However, the risk of poor germination and vigor increases when planting in soil temperatures less than 65°F. Growers are currently at the beginning of their planting season, therefore waiting a short time for suitable planting conditions is an option. The urge to plant into moisture in dryland fields often takes precedence over waiting for optimal soil temperatures for some growers. Close observation of expected rain events and high/low temperatures within five days of the anticipated planting date can aid growers in making these decisions. In addition, observing soil temperatures at the 2, 4, and 8-inch depths (www.georgiaweather.net), and any changes in soil temperatures that occur over several days, can provide useful information in determining when it is safe to plant. Temperatures at the 4 and 8-inch depths could also be an indicator of the warming capacity of the soil, or the likeliness of rapid cooling, when encountering a short-lived cool spell. Hopefully, the recent mildly cool spell will be the last.
Seeding Rates – Utilizing optimal seeding rates and planting depths are also very important in establishing a good stand. For cotton planted on 36 to 38-inch rows, planting at a rate of 2.5 seed per linear row foot, or a hill-dropped system consisting of 2 seed per hill with hills spaced 9 to 10 inches apart, is generally our standard planting rate (for 30-inch rows, this would equate to approximately 2.1 seed per linear row foot). This rate generally allows for optimal plant stands, growth, canopy architecture, maturity, and yield. Reducing seeding rates below this standard could lead to poor stands, delayed maturity, erratic and inconsistent plant growth, and possibly reduced yields, even if planting larger-seeded varieties (which can result in more consistent stands and higher vigor), and/or if planting conditions are favorable. If planting conditions are unfavorable, this rate could be slightly increased. Some growers may also want to utilize or capture available soil moisture by deep planting. Cotton in Georgia should be planted at depths between 0.75 and 1 inch but not greater than 1 inch. Planting on the shallower end of this spectrum is advised when encountering unfavorable soil or environmental conditions, or if surface crusting is likely. Deep planting in unfavorable soil temperatures, or in soils that tend to crust, could lead to germination and emergence problems. Planting at depths closer to 1 inch is only appropriate when planting in good soil moisture, warm soil temperatures, and in well-drained soils without the potential for crusting. One way in which growers can combat soil crusting is to run a rotary hoe over the seed bed after germination and before (or at) the point in which the plants emerge. This method is extremely effective in reducing potential stand losses due to soil crusting, but special considerations should be made to ensure this practice does not injure emerging plants (which may in fact reduce overall stands).