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Vegetable IPM Updates Archive
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Injury from the Movement of Glyphosate and Paraquat with Wind Blown Soil is Unlikely (September 18, 2013)

Glyphosate and Gramoxone are commonly used at this time of year for ground preparation for vegetable crops. These are both broad spectrum, non selective herbicides that can cause injury to many crops and off target movement to fields where crops have already been established is a concern. Both of these herbicides can move on air and cause off-target injury but they are unlikely to cause problems after they have reached the soil. Many herbicides can move after they have been deposited on the soil but this is unlikely with these .They both adhere strongly to clay and silt soils and are inactivated by the soil. It is not uncommon for Paraquat and Glyphosate to be inactivated when dirty and high PH water is used and ammonium sulfate or a water conditioner should be used prior to adding the herbicide when this type of water is used. The injury symptoms that result when off target movement does occur prior to soil deposition are very different for both of these. Paraquat is a fast acting contact herbicide that causes necrosis to any part of the plant that it contacts within 12 hours. Glyphosate is a much slower acting systemic herbicide that causes chlorosis and discoloration over a period of 2 days to weeks.

Note: We have begun to run lettuce samples for Benefin (Balan), Promamide(Kerb) and Bensulide(Prefar). We hope to gain experience with the equipment and techniques this season and to confirm the accuracy of our results. We will be glad to run samples free of charge if you want to bring them in. We will need soil from good and bad areas of the field and a total of 1 lb. collected from the top inch in at least 10 spots in each (a total of 1lb. from the 10 spots). Please call either myself (928-580-9902), Octavio Lopez (928-919-8736) or Marco Pena (928-782-5871) to let us know you are bringing samples and we will tell you where to leave them.


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For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.

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