Summer annual weeds, especially grasses, start to germinate in late February and early March and can continue to germinate through midsummer with irrigations.
Recording weed survey results assists in weed management decisions, including herbicide choice and cultivation practices. Information collected over a period of years tells you how weed populations are changing and how effective your management operations have been.
How to survey
Walk through each field in a random pattern, rating the degree of infestation for each weed species. Use either a numeric scale from 1 to 5 (1 being the lightest, 5 being the heaviest), or rate as "light," "medium," or "heavy."
The need for treatment depends on weed species, their competitiveness, the potential market for the alfalfa, and toxicity to livestock. In addition, vigor of the alfalfa stand is a complicating factor; weakened stands will require treatment when denser ones won't.
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