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Alfalfa
> Year-Round IPM Program > Summer > Weed
Survey
Alfalfa
 Weed
Survey, Established Stands—Summer
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.
Weed identification
The most dangerous summer
annual is yellow starthistle. Identify common summer
annual weeds and perennial
weeds.
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."
- Check
fencerows, ditch banks, field edges, and wet spots
as these may be problem areas for weed growth.
- Check areas around the field
edges as these areas could be potential sources
for wind-disseminated seeds.
- Pay particular attention to perennial weeds; record the
dominant species.
- Sketch a map of the
field and mark areas with major weed infestations.
- Record results on an established
stands weed survey form .
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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