在线词典,在线翻译

农民认识到除草剂的局限性

所属:听力板块 来源:voa 阅读:2171 次 评论:0 条 [我要评论]  [+我要收藏]

小编摘要:藜草蔓延极快,能长到两米多高。这类杂草会压制棉花等作物的生长。藜草来自苋菜科,也被称为帕尔默苋菜或帕尔默藜。

Farmers Learning Limits of Popular Herbicide

 

Pigweed spreads fast and grows as tall as two meters. This weed can overpower cotton and other crops. It comes from the amaranth family and is also known as Palmer amaranth or Palmer's pigweed.

A cultivated version of amaranth is grown for food and medicine in Africa and Asia. In the United States, some people buy amaranth as a gluten-free substitute for wheat flour. But wild pigweed is a big problem in cotton-growing states in the South. And now the plant is spreading into the Midwest.

In many cases the pigweed is killing genetically modified cotton and soybeans. For years farmers could control it by spraying with Roundup or glyphosate made by Monsanto.

But weed scientist William Curran at Pennsylvania State University says over the past three or four years, pigweed has become resistant to glyphosate. Now, farmers in some areas can no longer depend on that popular herbicide alone to defend against pigweed.

WILLIAM CURRAN: "When a weed is resistant, either the herbicide that it is resistant to has no effect at all or, you know, it might have some effect, but usually not enough to kill it."

He says farmers can try other herbicides. Or they can mix another herbicide with Roundup and use the mixture when they would normally spray their fields.

WILLIAM CURRAN: "The reality is even though have this weed, this one one weed that is resistant, there's still a lot of other weeds that Roundup still kills."

Farmers in the American Northeast face a growing threat from another weed. Scientists call it horseweed; farmers call it mare's tail. Like pigweed, this plant has also developed the ability to resist glyphosate.

Professor Curran sees one major reason for this. Farmers are depending too much on individual products and not enough on different strategies to manage weeds.

The question, he says, is how best to use a system of integrated pest management to control weeds. For example, IPM calls for farmers to rotate their crops instead of planting the same ones in the same soil year after year.

Professor Curran says farmers should also consider planting cover crops. These crops are grown temporarily to protect the soil. For instance, planting rye in the fall can suppress horseweed.

WILLIAM CURRAN: "If you have winter rye out there occupying that space, it is very competitive and the horseweed is less successful in establishing."

In the next two or three years, several companies expect to have new herbicides, along with crops that can survive spraying with those chemicals.

标签:voa special
0
2012-01-27 00:12 编辑:pliny
分享到:
关注海词微博:
发表评论:
表达一些您的想法吧!已有0条评论>>
登录,再发表评论
文明上网,理性发言!
您可能还感兴趣的文章:
  • [听力板块]为什么说精准农业是一项好投资?

    精准农业是谋划如何提高产量,以及从现有资源中获取更多回报的一种途径。它通常涉及到技术的运用。计算机制导的拖拉机就是富裕国家常见的一个例子。
  • [听力板块]补充每天所需维生素

    维生素(vitamin)是人和动物为维持正常的生理功能而必需从食物中获得的一类微量有机物质,在人体生长、代谢、发育过程中发挥着重要的作用。