Agriculture Reference
In-Depth Information
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contaminating the product at harvest
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harboring pest insects, mites, vertebrates, or plant disease agents
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releasing toxins in the soil which inhibit growth of desirable plants.
Weeds may become pests in water by:
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hindering fish growth and reproduction
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promoting mosquito production
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hindering boating, fishing, and swimming
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clogging irrigation ditches, drainage ditches, and channels.
Weeds can harm grazing animals by:
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poisoning
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causing an "off-flavor" in milk and meat
Weeds are undesirable in rights-of-way because they:
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obscure vision, signs, guideposts, crossroads, etc.
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increase mowing costs
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hinder travel
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provide cover for rodents and other pest animals
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clog drainage areas.
In cultivated crops, the weeds that are favored by the crop production prac-
tices do best. The size and kind of weed problem often depends more on the
crop production method, especially the use or nonuse of cultivation, than on
the crop species involved. In noncrop areas, the weed problem may be affected
by factors such as:
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weed control programs used in the past
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frequency of mowing or other traffic in the area
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susceptibility to herbicides.
A.
DEVELOPMENT STAGES
All plants have four stages of development:
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seedling—small, vulnerable plantlets
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vegetative—rapid growth: production of stems, roots, and foliage.
Uptake and the movement of water and nutrients is rapid and thor-
ough
