- Author: Peter B Goodell
Cotton planting season for cotton is already upon us. Planting cotton into the most favorable temperature conditions results in good stands and vigorous plants. The 5-day forecast of degree-days (heat units) is provided to help California's San Joaquin Valley and Sacramento Valley cotton growers determine suitable weather to plant cotton and avoid chilling injury to emerging cotton seedlings. Healthy, vigorous plants are a good foundation of an IPM Program.
UC Cooperative Extension, UC IPM Program has been providing cotton planting forecast to cotton growers and PCAs for over 20 years. The system is now available for the 2012 season. This forecast, with the planting guidelines, should be used in conjunction with soil temperatures (at seed depth) above 58°F for timely, vigorous seedling establishment.
The degree-day forecasts are based on the best available weather forecast from National Weather Service. However, local conditions may cause some variation. Use your judgment if your local temperatures are different. If your min/max temperatures are above those reported, then your degree-days will be higher; if your min/max temperatures are below those reported, then your degree-days will be less.
|Forecast Degree-Days||Planting Conditions|
|16 - 20||Adequate|
|11 - 15||Marginal|
|< = 10||Unfavorable|
The degree-day accumulations are calculated using the single-triangle method and a lower threshold of 60°F with no upper threshold. Forecast temperatures were accessed from the National Weather Service Web sites for Hanford and Sacramento.
In 2004, an evaluation of the accuracy of UC cotton planting forecasts for 1998 through 2002, for Bakersfield and Fresno was published in California Agrculture and showed:
- In March, planting only on days with ideal category forecasts (which occurred on 25% of March days), can likely avoid the need to replant due to incorrect forecasts predicting favorable planting conditions.
- In April, following the forecast is quite safe, since it failed to predict unfavorable planting conditions (which occurred on 29% of April days) on average only 1 day out of 30 April days.
See the article for details.