the VOA Special English Development Report.
in Africa call the striga plant by the name witchweed. It grows a pleasant
looking purple flower. But it attacks many crops in the grass family. Witchweed
is among the few flowering weeds that act as parasites on other plants.
year it causes six to seven billion dollars in damage to African grain sorghum.
Sorghum is important to the local food supply. The witchweed steals water and
nutrients from the roots and attacks the sorghum with a poisonous substance.
scientists say they have produced seeds that can protect sorghum crops from
Al-Katib is a weed expert at Kansas State University in the United States.
Mitch Tuinstra is a genetics and plant-breeding expert formerly at Kansas State
but now at Purdue University in Indiana.
with witchweed, they developed special sorghum-seed genes. These genes can
accept carefully chosen chemical herbicides without being harmed. The
researchers placed the herbicides on the sorghum seeds. Kassim al-Katib said
the seeds kill the witchweed as the sorghum grows.
Tuinstra directed greenhouse tests of the seeds in the Netherlands in two
thousand five and two thousand six. Similar studies took place in field trials
in Mali and Niger. These studies showed the treatment to be highly successful.
Tuinstra recently returned from Africa, where he met with agriculture experts.
They are working to develop local kinds of sorghum that employ the genes. The
project is a collective research program under the United States Agency for
has another unusual quality. It requires chemical signals from sorghum seeds to
grow. If no sorghum seeds are present, the witchweed seeds can lie under the
soil for years. The seeds begin to grow only when they receive the needed
seed capsules can hold four hundred to five hundred seeds. Winds and rain
spread the parasite. The plant can reduce a farmer's crop. Or it can completely
destroy many hectares of grain. Witchweed is very difficult to remove after it
invades an area.
from the parasite is worst in dry soil with low fertility. It often strikes
farmers who work the poorest land. This can mean disaster for people who
already do not have enough to eat.
that's the VOA Special English Development Report, written by Jerilyn Watson.