This is the VOA Special English Agriculture Report, from
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When is a plant
considered a weed? Experts at Penn State University have a simple answer: When
its undesirable qualities outweigh its good qualities.Consider the fact that
crops generally produce several hundred seeds from each plant. But each weed
plant can produce tens or even hundreds of thousands of seeds. And some buried
seeds can survive up to 40 years -- or even longer.Eradicating weeds means that
you have to remove all the seeds and roots so the plants will not grow back. But
birds or the wind can reintroduce them to the land. A more common way to deal
with weeds is to control them enough so that the land can be used for planting.
Experts advise using two or more control methods to deal with weeds. Chemical
weed killers or natural treatments like corn gluten can suppress weed growth.
Dense planting of a crop can also act as a natural control. Bill Curran is a
professor of weed science at Penn State, in University Park, Pennsylvania. He
says one of the most common methods for suppressing weeds is dense planting.He
says a dense, competitive crop that quickly shades the soil will help suppress
many weeds. The seeds need light to grow, so blocking the sun will reduce weed
growth. Other controls include turning over the soil, pulling the weeds or
covering them with mulch made of shredded wood, garden waste or other material.
But even mulch has its limits. Natural resource specialists point out that weeds
can be transported in mulch. This is also true of soil, grain, hay and animals.
Yet animals like sheep or goats eat weeds, so they can provide a biological
control. Insects and other organisms can also act as biological controls.
Preventing the spread of weeds is an important part of weed management. Farm
vehicles should be kept out of areas with weeds. If that is not possible, then
clean off the equipment and your shoes when leaving. Some people burn weeds or
bury them deeply or make them into mulch. Professor Curran says another way to
make use of weeds is to compost them. Heat is produced in the process of making
organically rich compost to improve soil. The heat will kill many, though not
all, weed seeds. The same is true for seeds that pass through animals that graze
on weeds. Tell us about your own fight against weeds. Share your stories at
voaspecialenglish.com. For VOA Special English, I'm Carolyn Presutti.(Adapted
from a radio program broadcast 19Jun2012)
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