Humans have struggled against weeds since the beginnings of agriculture. Marring our gardens is one of the milder effects of weeds - any plants that thrive where they are unwanted. They clog waterways, destroy wildlife habitats, and impede farming. Their spread eliminates grazing areas and accounts for one-third of all crop loss. They compete for sunlight, nutrients, and water with useful plants.

   The global need for weed control had been answered mainly by the chemical industry. Its herbicides are effective and sometimes necessary, but some pose serious problems, particularly if misused.

   Toxic compounds threaten animal and public health when they accumulate in food plants, groundwater, and drinking water. They also harm workers who apply them.

   In recent years, the chemical industry has introduced several herbicides that are more ecologically sound. Yet new chemicals alone cannot solve the world's weed problems. Hence, scientists are exploring the innate weed-killing powers of living organisms, primarily insects and microorganisms. The biological agents now in use are environmentally benign and are harmless to humans. They can be chosen for their ability to attack selected targets and leave crops and other plants untouched. In contrast, some of the most effective chemicals kill virtually all the plants they come in contact with, sparing only those that are naturally resistant or have been genetically modified for resistance. Furthermore, a number of biological agents can be administered only once, after which no added applications are needed. Chemicals typically must be used several times per growing season.

Which of the following statements about the use of chemical agents as herbicides would the author most likely agree?

Câu hỏi liên quan

• According to the passage, what is implied about tea harvesting?

• These changes in the Amercan home may ______________

• According to the passage, we can infer that .........

ZUNIA12

• The latter half of the last sentence in paragraph 3, “or one tourist for every person living in Spain” means .........

• The word “vary” in paragraph 6 can be best replaced by ___________.

• According to the passage, a fair division of labour is that ...................

• What does the author mean by staring that, "At interpersonal levels, tone may reflect ideas and feelings over and above the words chosen" in lines 8- 9?

• The passage is organized by .....

• The word “employment” in line 4 refers to the ......

• The word “proliferated” is closest in meaning to ......

• What happened when the writer's father came?

• The pronoun “they” in the second paragraph refers to_____.

• In the second paragraph, the word "stored" is closest in meaning to ............

• This reading would most probably be assigned in which of the following courses?

• According to the passage, the way to stop water pollution is ...........

• According to the passage, one benefit of diagrams is ...............

• Using the information in paragraph 2 as a guide, it can be inferred that ...............

• Which of the following is NOT true, according to the passage?

• Did the town people believe the story of the five men about their meeting with Bigfoot?

• Growing up by the sea, the writer felt ............