Monday, April 2, 2018

Cotton Planting a Matter of Degrees for Valley Growers

We’ve turned the page on another month. Welcome April.

To cotton growers, that means getting their crop planted. Field scout Damien Jelen reports growers were busy working their fields in the past week, redoing beds pounded by the recent rain storms.
Cotton fields are ready for planting across the Central Valley.
“Cotton season is ready to roll,” Damien says. Some growers even worked over the weekend to prepare for another year. Planting, he adds, “depends on the soil temperatures.” Plus, growers will need for the ground to dry enough to get their equipment out in the field.

It’s a matter of degree days to decide the right time to plant.

Since early March, growers have been keeping track of the temperature readings in their fields. UC IPM provides daily temperature readings on its “Cotton Planting Forecast” online site.

Good stand establishment requires sufficiently warm air (measured in heat units) and suitable field soil temperatures,” UC IPM says. “Cotton seed requires approximately 50 degree-days to accumulate in order to emerge when planted at an optimum planting depth. It is also important that temperatures be consistently warm and don't drop during the first five days after planting.”

In the Valley, the first day growers officially can plant their cotton is March 10, which represents the end of the 90-day host-free period for the pink bollworm control program. Of course, there usually aren’t any early birds that start on the 10th


UC IPM offers these guidelines for interpreting its five-day forecast for determining field soil temperature readings:

  • 10 degree-days or less are unfavorable for planting.
  • 11 to 15 degree-days are marginally acceptable for planting.
  • 16 to 20 degree-days are adequate for planting.
  • Greater than 20 degree-days are ideal for planting.
  • Be cautious about planting if cooling temperatures are forecast over the course of the 5-day period.
“Couple the five-day forecast with soil temperature readings from a number of locations in your field. A soil temperature reading of 58 degrees to 60 degrees taken at 8 a.m. is considered the minimum temperature required for good stand establishment, as long as the five-day forecast predicts favorable conditions for the next four days,” UC IPM says

Take soil temperatures in six separate field locations.
Farm advisors say measurements should be taken in six different locations to get the average field temperatures. A soil thermometer probe should go down to planting depth to take a reading.

After the crop is planted, cotton seedlings should emerge from the ground within 10 days. That indicates good germination.

Damien expects planting conditions to be ripe this week, meaning a flurry of activity in the cotton fields.

Meanwhile, Damien also anticipates alfalfa growers to do the first cutting of the season this week. The dry weather and 80-degree temperatures in recent days – after heavy rains to start the spring – has dried the crop enough for the first harvest to take place. As long as there’s plenty of water and nature cooperates, look for the alfalfa season to stretch into the early fall.

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