The Importance of Early Season Crop Management

by Jeffrey C. Silvertooth,
Extension Agronomist - Cotton

Realizing the greatest amount of yield from the first or primary fruiting cycle serves as a logical goal or objective for cotton fields in any part of Arizona, irrespective of the length of the season or whether or not a top-crop is part of the plan. Research concerning many aspects of cotton growth and development in Arizona has shown that the early stages of the fruiting cycle are very important in realizing a large amount of the potential for crop yield. In fact, I would suggest that we consider three important stages at the very beginning of the season as the most critical periods for 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.

We are just now entering into stage 1 with planting. Planting date management is critical. Many farms have a lot of acres to cover and it is difficult to find a perfect time or set of conditions for every field. But it is important to recognize the importance associated with planting date management. 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). Early planting will also be dependent upon legal planting date of course, but also minimum soil temperatures at least > 55 ^oF at the depth of planting. Optimum conditions should also take into account a 5-day weather forecast. Weather forecasts are not always perfect, but they can often warn us of an approaching cold front, which may also carry the potential for rain. The period immediately following planting, as germination proceeds, is very critical. Therefore, if a storm is on its way, if at all possible, it is good to consider adjusting planting schedules until more favorable conditions are present.

As planting dates are delayed, for whatever reason, beyond the optimal range of about 400 to 700 HU/Jan. 1, yield potentials for most varieties will begin to decline (Figure 2). This is particularly true for full season or indeterminate varieties. Medium or short season (determinate) varieties may not have as high a yield potential as a full season variety with an early planting date, but they maintain better yield potentials with later plantings (i.e. STV 474, Figure 2). Thus, if planting is delayed or if replanting is necessary, it is important to consider not only the calendar date, but how far the planting season has progressed. This can be assessed by reviewing HU/Jan. 1 accumulations, which are listed each week in the weekly cotton advisories that are distributed by University of Arizona Cooperative Extension offices. Adjusting varieties planted to more determinate types with delayed plantings may be advisable.

Events that take place in stage 1 can have a profound influence on crop growth, health, and further development in stages 2 and 3. Therefore, try to manage the planting season with some degree of flexibility and try to be prepared for the various challenges that can be thrown at us this planting season.

We are just now entering into stage 1 with planting. Planting date management is critical. Many farms have a lot of acres to cover and it is difficult to find a perfect time or set of conditions for every field. But it is important to recognize the importance associated with planting date management. 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). Early planting will also be dependent upon legal planting date of course, but also minimum soil temperatures at least > 55 ^oF at the depth of planting. Optimum conditions should also take into account a 5-day weather forecast. Weather forecasts are not always perfect, but they can often warn us of an approaching cold front, which may also carry the potential for rain. The period immediately following planting, as germination proceeds, is very critical. Therefore, if a storm is on its way, if at all possible, it is good to consider adjusting planting schedules until more favorable conditions are present.

As planting dates are delayed, for whatever reason, beyond the optimal range of about 400 to 700 HU/Jan. 1, yield potentials for most varieties will begin to decline (Figure 2). This is particularly true for full season or indeterminate varieties. Medium or short season (determinate) varieties may not have as high a yield potential as a full season variety with an early planting date, but they maintain better yield potentials with later plantings (i.e. STV 474, Figure 2). Thus, if planting is delayed or if replanting is necessary, it is important to consider not only the calendar date, but how far the planting season has progressed. This can be assessed by reviewing HU/Jan. 1 accumulations, which are listed each week in the weekly cotton advisories that are distributed by University of Arizona Cooperative Extension offices. Adjusting varieties planted to more determinate types with delayed plantings may be advisable.

Events that take place in stage 1 can have a profound influence on crop growth, health, and further development in stages 2 and 3. Therefore, try to manage the planting season with some degree of flexibility and try to be prepared for the various challenges that can be thrown at us this planting season.

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.

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