This is the VOA Special English Agriculture Report.

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.
藜草蔓延很快，能长到两米多高。这种杂草会压倒棉花等作物的生长。它来自苋科大家庭，也被称为帕尔默苋菜或帕尔默的藜。

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.
一个培育版的苋菜在非洲和亚洲被作为粮食和医药。在美国，有些人买苋菜作为一种无麸质小麦面粉的替代品。但是，野生藜草在南方的棉花种植州是一个大问题，而且这种植物现在已经蔓延到了美国中西部地区。

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.
在许多情况下，藜草会杀死转基因棉花和大豆。多年来，农民曾可以通过喷洒孟山都公司生产的农达或草甘膦来控制它们。

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.
但是，宾夕法尼亚州立大学的杂草科学家William Curran称，在过去三四年中，藜草已经能够抵抗草甘膦。现在，一些地区的农民不再单独依赖这些常用除草剂来对付藜草。

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."
WILLIAM CURRAN：“当一种杂草产生抗药性，或者是除草剂已经完全没有效果，你知道的，或者是它可能有一定效果，但通常不足以杀死它。”

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.
他说，农民可以尝试其它除草剂。或者，他们可以在日常喷洒中将毒滴混剂与其它除草剂混合使用。

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."
WILLIAM CURRAN：“现实情况是，即使有这样一种具有抗药性的杂草，还有很多其它杂草可以被毒滴混剂杀死。”

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.
美国东北部的农民面临另一种杂草日益严重的威胁。科学家称其为加拿大蓬(北美植物)，农民称其为尾巴草。像藜草一样，这种植物也对草甘膦具有抗药性。

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.
Curran教授发现这种情况的一个主要原因。农民过多依赖单一品种，在采用不同策略来管理杂草方面做得不够。
 
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.
他说，问题是如何更好地使用虫害综合管理系统（简称IPM）来控制杂草。例如，虫害综合管理系统要求农民在同一块土地上，轮种不同作物，而不每年都直种同一种作物。

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.
Curran教授说，农民也应考虑种植覆盖作物，这类作物可以临时生长以保护土壤。例如，在秋季种植黑麦草可以抑制加拿大蓬生长。

WILLIAM CURRAN:  "If you have winter rye out there occupying that space, it is very competitive and the horseweed is less successful in establishing."
WILLIAM CURRAN：“如果你在地里种植冬季黑麦草把空间都占了，这种草极具竞争力，加拿大蓬就不太可能生长。”

In the next two or three years, several companies expect to have new herbicides, along with crops that can survive spraying with those chemicals.
在未来两三年内，有几家公司有望推出新的除草剂，作物可以在喷洒这些化学品的情况下生存下去。