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Field maintenance is the first step to proper cotton production. OSU's Department of Plant and Soil Sciences offers educational resources for field irrigation, fertility, sprayer calibration, and weed control and resistance management.



Cotton water use, also known as evapotranspiration (ET), can be defined as the sum of evaporation and transpiration, and is both crop-species and growth-stage dependent. Evaporation is water loss from plant and soil surfaces. Transpiration means water taken up by roots and is transpired through the stomata in leaves. From planting to square initiation (about 40 days), ET is generally less than 0.1 inch per day. 




The Soil, Water and Forage Analytical Laboratory (SWFAL) was established by the Oklahoma Cooperative Extension Service to provide soil testing, plant, animal waste and water analyses for the State of Oklahoma and anyone who needs agricultural testing services. Each year over 60,000 various samples are submitted for analyses by thousands of farmers, ranchers, homeowners, consultants, governmental agencies and researchers. Interpretations and recommendations are made based on many years' field calibrations conducted in Oklahoma.



Sprayer Calibration

Although technology has taken a lot of the headache out of accurate application, not all of our operations are of the scale to justify the latest technology. A fair percentage of pesticide applications still do not include automatic flow control valves and
computer monitors. Bottom line, regardless of what type of sprayer you operate, maintaining efficiency includes an understanding of how to make accurate pesticide applications. The most effective way to maintain accurate calibration is to know the facts



Weed Control

Contact herbicides kill primarily by contact with plant tissue. Two requirements for successful contact herbicide use are good plant coverage and an adequate rate (often based on the temperature on the day of application). Many labels on contact herbicide containers will suggest that the chemical be applied on a day when the temperature is above a certain minimum and a higher volume of water be used than would be required for most other herbicides.



Weed Resistance Management

Resistance occurs when a genetic change allows a population of weeds to survive a herbicide treatment to which the original population was susceptible. Individual plants of weed species that are resistant to a particular herbicide are typically  present  in  untreated  populations  at  very  low  frequencies. 


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