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Arizona Cotton Comments

Flexible Management in a Late Planting Season

by Jeffrey C. Silvertooth,
Extension Agronomist - Cotton

The 1998 cotton season is progressing very slowly in Arizona and throughout the desert Southwest. Many growers have been trying to plant and some have been forced to replant considerable acreages already. As a couple of friends of mine commented last week "a lot of people have been practicing planting". In terms of heat unit (HU, 86/55° F thresholds) accumulations since 1 January, we are generally about two weeks behind normal in most areas. Therefore, although we are definitely behind by calendar standards, we still have some room (time) to work with regarding planting windows from a HU standpoint. It is also very likely that the planting windows will end up being compressed into rather short periods of time if the weather changes rapidly and turns very hot, very quickly.

With the difficulties we have encountered thus far in 1998, it is important to consider the three stages at the very beginning of the season as being very critical periods in determining cotton crop potential. These three stages are outlined in Figure 1, and consist of the following:

  • Stage 1: stand establishment - planting, germination, and emergence;
  • Stage 2: foundation development - early root system development, early vegetative growth, and conversion from vegetative to reproductive or fruiting development (formation of the first fruiting branch and pinhead square); and
  • Stage 3: PRIME TIME - from pinhead square (PHS) to peak bloom.

Planting management is critical. We often recommend an "early / optimum" date of planting for optimal yield potential. However, it is important to qualify an early planting as occurring prior to an accumulation of about 700 heat units after January 1 (HU/Jan. 1). It is important not only to have a stand, but also to have a healthy, vigorous stand. Crops that are compromised by enduring substantial early season stress in Stage 1 will often develop slowly in Stage 2, and experience reduced potentials in Stage 3. Therefore, as we have seen in the past few months, considering weather forecasts can be constructive to planting management.

In the process of reformulating management plans for the 1998 crop, it is important to consider the fundamentals associated with any strategy (see Ten Point Plan below). In Arizona, good crop development and final yields often depend a lot on the crop development through the early parts of the primary fruiting cycle (Stage 3 = Prime Time). We still have a good probability of experiencing a period of hot and dry weather in late May, June, and early July, before the onset of the monsoon (our next weather nemesis). It is possible, under proper conditions, to set a significant boll load very quickly. The period from mid-June to mid-July in 1997 serves as a reminder and testimony to that. Accordingly, the 1998 crop still has potential if we can take advantage of opportunities that may occur later in the season. In some cases for example, it may require switching to medium or shorter maturity varieties in a delayed or replant situation. Setting the crop up for having strong vigor and being able to gain rapid fruit retention in the first fruiting cycle will be important for this season.

Cotton Management Strategies – Fundamental Ten Point Plan

  1. proper variety selection (fit production strategy and planting date)
  2. early/optimum planting
  3. manage for early fruiting
  4. protection of early fruit
  5. good scouting for (all) cotton pests + timely control of damaging pests
  6. manage for high fruit retention
  7. monitoring crop development (vigor, fruit retention, stage of growth)
    • split fertilizer N applications (PHS to peak bloom)p>
    • use plant growth regulator (i.e. PIXtm) according to crop vigor and fruit retention
  8. good irrigation management (eliminate water stress)
  9. effective defoliation
  10. timely harvest
Figure 1.  Graph of the first three stages of cotton crop development in Arizona. (1 from February to mid April, 2 from mid April to mid-late May, 3 from mid-late May to mid July)


Full Disclaimers

Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director Cooperative Extension, College of Agriculture and Life Sciences, The University of Arizona.

The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

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Information provided by Jeffrey C. Silvertooth,
Extension Agronomist - Cotton, College of Agriculture, The University of Arizona.
Material written 16 April 1998.

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