| Data Sources |
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This calculator sources observations and forecasts from National Oceanic and Atmospheric Administration's
National Weather Service. |
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Long-term historical averages are sourced from the National Climate Data Center.
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Data Display |
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Data are displayed for two browser types:
• the Personal Computer version for complete data,
• the Mobile Version, limited to the past 7 and next 7 days. |
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Both versions have the same underlying data and same calculations, with the mobile device version abbreviated to fit the small display screen of
a cell phone or other mobile device. |
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Access the mobile device version at www.CottonHeatUnits.com/mobile |
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In practice, the personal computer version should be used for a comprehensive understanding of heat units being accumulated and forecast for
the next seven days. |
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The mobile device version can be utilized to refresh your memory or when access to a personal computer is not convenient, such as decision-making
in the field. |
Your Location |
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Select the Weather Station nearest your cotton fields. Long-term averages are available for more that 60 weather stations in cotton
producing areas. |
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Observations and forecasts for this season are compared to the long-term averages to assist your understanding of how this growing season compares
to the past seasonal averages. |
Your Date of Planting |
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Select the Date of Planting of your cotton. Accumulation of Heat Units is based on your planting date, providing more accurate measures
than weekly averages. |
Heat Unit Calculations |
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The calculation for heat units for cotton is Degree Day 60 (DD-60), based on the premise that cotton growth is proportional to daily
temperatures above a threshold of 60 degrees. |
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The calculator uses the formula ( (High + Low) / 2 ) – 60 |
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Minimum value is 0, respecting the 60 degree low temperature threshold. |
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Maximum value is not limted at this time. However, cotton producers and consultants in Arizona are invited to offer suggestions for calculations
in areas with very high temperatures. |
Nitrogen Fertilizer |
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Decisions regarding the amount and timing of nitrogen fertilizer can be enhanced with the knowledge of how fast the cotton is growing based
on recent heat units and the forecast for the next several days. |
Growth Management |
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Products containing mepiquat, or other growth regulating chemicals, typically recommend the application rate and timing based on the
pace of cotton growth, plus the anticipated growth following product application. |
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Decisions regarding the selection among alternative products, along with the best rate and best timing, can be enhanced with the knowledge of
past and forecast temperatures. |
Insect Control |
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Decisions regarding the selection of an insecticide, along with the best rate and best timing of application, can be enhanced with the knowledge
of past and forecast heat units, since insect growth is also related to temperature. |
Boll Ripening and Opening |
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Products containing ethepon, or other boll ripening chemicals, typically recommend the application rate and timing be respective of the pace
of cotton growth, plus the anticipated growth following product application. |
Leaf Defoliation |
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Products used to defoliate the cotton plant, recommend the application rate and timing be respective of the pace of cotton growth, plus the
anticipated growth following product application. |
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Decisions regarding the selection among alternative products, along with the best rate and proper timing, can be enhanced with the knowledge
of past and forecast temperature.
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