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Alfalfa
> Year-Round IPM Program > Planting > Weed
Survey
Alfalfa
 Weed
Survey—Seedling to Stand Establishment
In the Central Valley most winter annual weeds
start to germinate in late September or October and continue
to germinate until
late January, whenever soil moisture and temperature conditions
permit. When the alfalfa crop germinates, survey the
field for newly emerged weeds.
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
winter annuals to livestock are fiddlenecks and common
groundsel. Identify common winter
annual weeds, perennial
weeds,
and summer
annuals.
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.
- Sketch a map of the
field and mark areas with major weed infestations.
- Indicate the growth stage of the weed (seedling
or mature).
- Record results on a seedling
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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