By Bill Robertson, Extension Cotton Agronomist
This time last year a good number of cotton acres had been planted. There have been reports of a few producers planting cotton. Conditions have not gotten to where they really need to be for cotton. The pressure will mount greatly in the coming days to get cotton planters rolling. In doing so, it is good to review recommendations and guidelines in order to help increase the potential for success in less than optimum conditions.
Soil and air temperatures should be at optimum levels when planting. A mid-morning soil temperature of 68˚F at the planting depth for three consecutive days and a favorable five-day forecast following planting is best, but not always realistic for early planting (Table 1). Soil temperatures below 50˚F have been associated with chilling injury of pre-emerged seedlings (Fig. 1). A favorable five-day forecast will help avoid potential chilling injury getting the seedling off to a good start which can pay dividends at the end of the season (Fig. 2).
Table 1. Actual heat unit accumulation (DD60’s) for the five day period after planting today, April 23, based on extended weather forecast information from a smartphone app.
Figure 1. Impact of heat unit accumulation during the first five days after planting.
Figure 2. Sensitivity to chilling injury in relationship to days after planting (NCC, 1996).
The first step toward a successful season is establishing a healthy stand. Cotton does not tolerate difficulties encountered during its first weeks of growth nearly as well as most of our insect pests and weeds. Variety selection and seed quality have a lasting effect on the crop’s early-season vigor and on overall plant health which is critical in establishing high yield potentials.
Optimum conditions for planting include a mid-morning 68-degree soil temperature at 2 inches for 3 consecutive days, and favorable five-day forecast. It is important to start with the best quality seed to increase the chances of getting a good uniform stand if conditions are less than optimum. Remember that as seed size decreases the importance of having good soil temperatures increases.
Many place more emphasis on the five-day forecast as it is often difficult to achieve the optimum soil temps. Even with marginal soil temps at planting, a favorable five-day forecast will lend confidence that soil temps will improve. Heat unit accumulation calculations are shown in Table 2 from planting cotton today (April 23, 2018). If it were dry enough to plant today, we would only capture 3.5 DD60’s in the five days after planting putting us in the very poor category for planting.
Regardless of the calendar date, park the planter if heat unit accumulation (DD60s) is predicted to be 15 or less for the 5-day period after planting. Good results are often seen with 25 or more heat units being accumulated during the 5-day period after planting.
There are many signals or signs that people use to indicate the right time to plant. Regardless of your method, it is important to remember that planting early does not ensure earliness. Getting off to a good, quick start will pay dividends season long if we do it right the first time.