Monday, May 18, 2015

Getting an Early Take on Growth of Cotton Crop

Even though we’re only a month into the cotton season, this is a crucial time for the crop.
The first 30 to 40 days after planting determines the potential for the cotton crop by harvest time. Everything that takes place after the cotton plant stand is established will either maintain or decrease yields, according to UC IPM.
That’s why field scout Carlos Silva is taking a census of cotton fields. The exercise is called determining stand establishment. Simply put, he’s helping growers see how well the crop is growing.

Carlos follows a formula that compares the plant population per foot with the seedling rate per foot. The results will indicate if the stand is weak, ideal or growing too vigorously.
These are steps UC IPM says growers should follow to estimate the plant population:
  • Take at least four measurements from several representative areas of the field and average them.  
  • Use the table below to find the length of row that represents 1/1000th of an acre for various row widths.
  • In your field, count the total number of plants in the 1/1000th acre area and multiply by 1,000.
Valley cotton stands are generally falling in the optimal range.
The optimal rate is 40,000 to 60,000 plants per acre (PPA). The stand is considered weak if the rate is below 30,000 PPA. Excessive growth is anything over 60,000 PPA.

The best density rate also can depend on the variety and conditions. Higher densities may be better for plants growing in “low vigor situations.”

For weak stands, growers need to look for any seedling diseases or insects that could be causing the problem. Replanting should be considered for poor stands, including those with many adjacent rows without plants.

Pests can be one cause for poor stand development.
Excessive stands require thinning. UC IPM notes: “Dense plant populations, combined with conditions of adequate moisture and nutrients, can lead to rank growth, making the crop more vulnerable to insects and diseases. Depending on the cotton variety, a plant stand in excess of 60,000 plants per acre may require thinning.”

Right now, Carlos says most of his scouted fields fall in the optimal range. The plant populations fall within the 30,000 to 40,000 PPA range. “They’re in the ballpark.”
We’re sure growers are looking for a home run yield by fall.

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