This is the VOA Special English Agriculture Report.
breeders and genetic engineers keep working to give crops the strength to resist
threats like insects, diseases, droughts or floods.
before you can resist a threat, you need to understand it.
told you last week about a newly completed genetic map of the organism that
causes late blight. That disease led to starvation in Ireland from potato
shortages in the middle of the eighteen hundreds. The new genome could lead to better
ways to protect potatoes, tomatoes and other crops.
Science may supply a stronger crop. Yet that
does not always guarantee demand.
Nik Grunwald from the United States Agriculture
Department worked on the international team that completed the genome. He says
it is possible to grow potatoes that resist late blight. But these may not look
like Russet potatoes. And most American farmers grow Russets because, as Nik
Grunwald puts it, "that is where the demand is."
Another example of scientific progress involves a
natural bacterium known as Bt. Bt is used as a pesticide to fight cotton
bollworms, corn borers and other pests. Scientists have found a way to grow
cotton plants that contain a Bt gene, reducing the need for pesticides. But
sometimes, when one problem gets solved, another one appears.
In China, some farmers and researchers blame a decrease
in pesticide use for an increase in pests unaffected by Bt. Also, there are
concerns that some organisms could begin to resist the plants designed to
scientists are reporting this week on what they call the "indirect
costs" of a virus-resistance gene in Cucurbita. This is the species of
squash that includes pumpkins and gourds. The scientists say virus-resistant
transgenic squash are grown throughout the United States and much of Mexico.
genetically engineered squash are usually larger and healthier than wild
squash. But a three-year study showed that beetles like to feed more on the transgenic
plants, increasing cases of wilt disease. The
report by a team from the United States and China appears in the Proceedings of
the National Academy of Sciences.
researchers point out that gene flow between crops and their wild relatives is
common and difficult to contain. They note concerns that wild plants could, as
a result, gain genetically engineered resistances. And these could affect the
natural balance in their environment.
that's the VOA Special English Agriculture Report, written by Jerilyn Watson. I'm Bob Doughty.