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【Getting a Firm Grip on Weed Control】
TEXT:This is the VOA Special English Agriculture Report.
这里是美国之音慢速英语农业报道。
When is a plant considered a weed? Experts at Penn State University have a simple answer: When the undesirable qualities outweigh the good qualities.
什么时候植物会被当成杂草？宾夕法尼亚州立大学的专家们给出了一个简单的答案：当其不良品质超过优良品质时。
Consider the fact that crops generally produce several hundred seeds from each plant. By comparison, each weed plant can produce tens or even hundreds of thousands of seeds. And some buried seeds can survive up to forty years -- or even longer.
考虑到每株农作物通常产生几百颗种子。而相比之下，每株杂草能产生数万甚至数十万颗种子。而且，一些被埋在地里的种子可以存活40年乃至更久。
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.
根除野草意味着必须除掉所有的种子，并且将植株连根拔起，以免其重生。但是鸟或风会将种子重新带回土地。
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.
一种更常见的对付杂草的方式是严格控制其生长，这样土地才能种植作物。专家建议使用两种或两种以上的方式来对付杂草。
Chemical weed killers or natural treatments like corn gluten can suppress weed growth. But so can dense planting. Bill Curran is a professor of weed science at Penn State. He says a dense, competitive crop that quickly shades the soil from the sun will help reduce weed growth.
化学除草剂或玉米蛋白粉一类的自然控制手段可以抑制杂草的生长。作物密集种植也行之有效。Bill Curran是宾夕法尼亚州立大学的杂草科学教授。他表示，经过密植的竞争性作物会很快遮蔽阳光，这将有助于抑制杂草生长。
Other controls include turning over the soil, pulling the weeds or covering them with mulch made of wood, garden waste or other material.
其它控制手段包括翻土、拔草或用地膜覆盖杂草。地膜一般由木屑、园林废弃物或其他材料制成。
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.
但是，即使地膜也有其局限性。自然资源专家指出，杂草可以通过地膜传播，还可以通过土壤，谷物，干草和动物传播。
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.
然而，像绵羊或山羊之类的动物以杂草为食，因此它们能够提供一种生物控制手段。昆虫和其他生物也可以起到生物控制作用。
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.
控制杂草的传播是杂草管理的重要部分。农田机器应该远离长满杂草的地方。如果不可能的话，离开的时候要清洁机器和鞋子。
Some people burn weeds or bury them deep in the ground or make them into mulch.
有人将杂草烧掉，或者将其深埋，或者将他们转化成地膜。
Professor Curran says another way to make use of weeds is to compost them. The process of making organically rich compost produces heat. This heat kills many, though not all, weed seeds. The same is true for seeds that pass through animals that graze on weeds.
Curran教授说，用杂草制作堆制肥料是对杂草加以利用的好方法。制作有机堆肥的过程会产生热量。热量会杀死许多杂草种子。农田生物拒绝杂草的过程道理也是一样的。
