A typographical error has recently been discovered on the current Princep herbicide label in regards
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
A typographical error has recently been discovered on the current Princep herbicide label in regards to the Pre-Harvest Interval (PHI) for apples. In the apple section of the label, there is a restriction that the PHI for Princep alone on apples is 150 days. Farther down the label under the tank mixing section, there is a footnote that the PHI for Princep tank mixed with Roundup or Touchdown is 14 days. Syngenta will correct this on future labels. The intent of the current Princep label is that the PHI for apples is 150 days regardless of whether Princep is applied alone or in tank mixture with Touchdown or Roundup. Therefore, all applications of Princep have a 150 day PHI restriction for use on apples.
Princep (simazine) is most effective when applied to weed-free soil in late fall or in early spring before weeds begin to grow. Addition of Roundup improves kill of early-emerging weeds, especially perennials and horseweed. Simazine is not very effective when applied this late in the year, so this change in the Princep label should not cause major changes in weed control practices.
If growers need another preemergence herbicide application in May or June, Matrix is available. It gives better weed control than simazine, and preemergence weed control will be maintained for about two months. A foliar active herbicide such as glyphosate, paraquat, or glufosinate should be included in the tank mix.
Several new herbicides are in the process of being registered for apple and other tree fruit, which will help extend weed control late into the summer and the harvest season.