The use of preemergence residual herbicide provides a foundation for season-long weed management, along with tillage and other chemical management practices. It’s recommended to use preemergence when temperatures are high enough for seeds to take water, but before any germination. In Central Arizona, the end of fall and beginning of spring are the optimum times to use preemergence herbicides. But again, it’s judgment based on the temperature and amount of rain in certain areas. If above normal rain occur during late summer/early fall, I would expect you have many emerged weeds in your property right now. If this is the case, and beside preemergence, you will also need to deal with these weeds using postemergence herbicides. Near the end of winter when it starts to warm up, and before any germination, you’ll need to apply preemergence again. Besides standard orange preemergence, there are dinitroaniline (DNA or “yellow”) products that are helpful in delay or avoid developing herbicide resistant weed populations. Most of herbicides can be found at some retailers like Bug and Weed Mart, and some agrochemical companies like Helena, Fertizona and Wilbur-Ellis. With some weed resistant to Roundup and other postemergence herbicides in central Arizona, it requires the use of a diverse chemicals for weed control tactics.
“When applying any chemical you must abide by its label. The label is law. Some chemicals require license and training to apply”.
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