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How Much Water Should Be Used When Chemigating Kerb on Lettuce (August 21, 2013)

Unlike Prefar and Balan, Kerb does not adhere strongly to soil. Balan and Prefar adhere very stongly to the soil and Balan should be mechanically incorporated and Prefar needs to have a lot of water put over the top of it to be adequately incorporated. Kerb is the opposite. It will move below the germinating weeds if too much water is applied. We conducted a few trials several years ago to get an idea how long it should take to run Kerb through the sprinklers when chemigating and how much water to put on after it is applied. The results are in the following graphs but every field and every year can be different. These trials give us a general idea however.

These graphs illustrate the number of weeds left uncontrolled from each treatment. The injection times were 30, 60 and 90 minutes and the amount of water applied after injection was 0, 4, 8, and 12 hours. It was apparent from the first graph that 30 minutes was too fast to inject the Kerb. 60 minutes was better and 90 minutes was best. Sprinklers are surprisingly variable in how they distribute the water. This variability is evened out by running them for longer rather than for shorter periods of time. The longer it takes to chemigate the herbicide, the more evenly it will be distributed in the field. The second graph illustrates that the herbicide began to leach too deep after applying 8 hours of water continuously after injection and much of it was gone after 12 hours.



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