Iowa State University Extension has worked with iOS app developer Rade | Eccles to develop the Pesticide and Field Records iPad app to help farmers and agriculture businesses record and maintain pesticide application information. The free iPad app allows users to link information to specific field locations using satellite mapping and document pesticide application information needed to comply with state and federal record-keeping requirements.
The app also features a product search option that lists Environmental Protection Agency (EPA) product registration numbers and identifies restricted use products, says Kristine Schaefer. She is a program specialist in the Department of Entomology at Iowa State University and can be reached at 515-294-4286 or [email protected].
Development of the app was funded by the ISU Extension Pest Management and the Environment program and a grant from the EPA under assistance of the Iowa Department of Agriculture and Land Stewardship's pesticide bureau.
UAN liquid nitrogen and herbicides—can this mix be applied to emerged corn?
Here's a question ISU Extension agronomists have been getting this week: Can UAN liquid nitrogen and herbicides be mixed and apply to emerged corn? ISU's Bob Hartzler, an Extension weed management specialist, and ISU Extension soil fertility specialist John Sawyer, provide the following answer.
Urea Ammonium Nitrate, or UAN, a nitrogen fertilizer widely known as UAN, and pre-emergence herbicide products can be applied to emerged corn, but using UAN as a herbicide carrier may result in foliar damage.
Prolonged wet periods often disrupt the normal sequence of field operations. Some fields may be planted before nitrogen and/or preemergence herbicides are applied. While UAN (urea-ammonium nitrate) and many preemergence products can be applied to emerged corn, using UAN as a herbicide carrier enhances the foliar activity of products and may result in foliar damage. Check herbicide labels for restrictions on use of UAN as a carrier.
Combination of herbicides with UAN poses a threat of severely injuring corn
UAN alone can be applied to emerged corn, and the risk of injury to the corn is dependent upon UAN rate, corn stage and weather conditions. Conservative suggestions are to limit postemergence applications of UAN to 90 pounds of N per acre when corn is at the V3 to V4 growth stage and to 60 pounds of N per acre at the V7 stage. Applications beyond the V7 stage are not recommended, and the risk of injury increases during hot, dry conditions.
The combination of herbicides with UAN greatly enhances the foliar activity of these products and poses a real threat of killing all emerged tissue contacted by the spray.
Some farmers might try to rationalize this combination if the corn is at the VE-V1 stage since the growing point is still underground. While corn often can recover quickly from loss of the shoot at this growth stage, the herbicide may influence the plant's ability to recover and therefore result in uneven plant size and yield loss.