Cotton Planting Decisions

We are in the fourth year of determining the ideal planting date and need for replanting. Replant decisions are some of the toughest decisions to make in cotton production. A wrong decision can be so costly.

Our planting decision trial is divided into three parts: planting date, plant density and leaf removal. Plots are planted one week apart in late April, throughout May and in June. In 2001 there was a twenty-one pound drop in lint yield as the season progressed. In 2002 it did not matter when the crop was planted. The planting dates after the major rain and cold spell in mid May damaged the older stands enough that the May 23 planting did as well as the earlier dates. In 2003 the yields were stable until May 13 and then the yields dropped dramatically. May 13 yield was 1018 pounds and June 2 was 346 pounds. The date study illustrates the amount of yield that may be lost if a crop is replanted in late May and emphasizes the need for planting in late April or early May.

Four plant populations being evaluated are four per foot of row, two per foot, one per foot and one per eighteen inches. To our surprise the yields have been very similar with the spacing of one per eighteen inches being the highest in 2001. In 2003 the two plants per foot was the earliest maturing and highest yielding. It must be taken in consideration that these are very healthy plants that remain and not unhealthy plants as may be present in some situations.

Hail can remove many leaves in a plant stand and it may be difficult to determine the extent of the damage. Five degrees of damage were evaluated by hand removing leaves at the four true leaf stage. The damage rates tested were one, two, three and four true leaves per plant being removed. Also in another treatment the terminals were removed. The treatments did not take into account stem damage that may occur in a real situation. None of the treatments reduced lint yields more than one third. Usually the loss is not more than twenty percent. Loss of the terminal resulted in yield losses similar to more than two lost leaves.

We are developing techniques using a digital camera in making replant decisions. We are able to predict the death of some plants. This is done by using PhotoShop and changing the colors, especially the greens and yellows so that the greens will show as a bright red. This red color shows the healthy tissue that is likely to survive.

Our thanks to Cotton, Inc. and the Southern Cotton Ginners for funding these projects.