By Bill Robertson, Cotton Agronomist
Date: May 3, 2020
Recommendation: We are currently on the tail end of a good planting window. Outlook for planting beginning Monday May 3 through Thursday May 7 is very poor. Forecast improves greatly beginning Friday May 8.
Predicted Heat Units Tuesday through Sunday ranges from 0 to 2.5 with three days in a row with 0 DD60s. If planting is warranted, significant pressure will be placed on seed treatments and seed quality to achieve desired stands, vigor, and pest control. It is also common to experience loss in yield potential with a rocky start. If planting during this timeframe, avoid fields with cold natured soils and use best quality seed as discussed below.
Oftentimes we feel the need to plant as early as possible. Our data shows that we can still optimize yields with delays in planting. Our optimum planting window in southeast Arkansas historically includes dates ranging from April 20 to April 30 (Table 1). Locations at and north of I-40 see their optimum window shifting back as late as May 9. Weather varies from year to year. However, the most important thing is to do it right the first time.
Optimum conditions for planting include a mid-morning 68-degree soil temperature at 2 inches for 3 consecutive days, and favorable 5-day forecast. Heat unit accumulation (DD60s) the five days after planting is an excellent guide to evaluate planting conditions (Table 2). Park the planter if DD60 accumulation 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.
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 after planting increases.
Although dependent on growing conditions, a delay in planting early in the planting window can have little impact on the date of flowering as cotton planted under optimum conditions will often catch up to earlier planted cotton that struggled with cool temperatures. Adequate soil temperature for vigorous plant growth is critical. Make sure adequate soil moisture is available for optimum results and that seedbeds are firm to ensure good seed-to-soil contact.
There are many signals or signs that people use to indicate the right time to plant. Getting off to a good, quick start will pay dividends season long if we do it right the first time.