问题 问答题 简答题

简述植物病害的防治方法。

答案

参考答案:

1、植物检疫:又称为法规防治,其目的是利用立法和行政措施防止或延缓有害生物的人为传播。植物检疫的基本属性是其强制性和预防性。

2、林业技术防治

(1)育苗技术中的防病措施

(2)造林技术中的防病措施:适地适树、造混交林

(3)林分抚育中的防病措施:生态治理的思路:区划、培育和经营有机结合,贯穿于林业生产的全过程。

3、选育抗病品种

4、生物防治是指利用有益生物防治植物病害的各种措施。迄今所利用的主要是有益微生物,有益微生物亦称拮抗微生物或生防菌。生物防治的机制主要是利用有益微生物对病原物的各种不利作用,来减少病原物的数量和削弱其致病性。有益微生物还能诱导或增强植物杭病性,通过改变植物与病原物的相互关系,抑制病害发生。有益微生物对病原物的不利作用主要有抗菌作用、溶菌作用、竞争作用、重寄生作用、捕食作用及交互保护作用等。

生物防治措施及其应用:植物病害的生物防治有两类基本措施:

1、是大量引进外源拮抗菌;

2、是调节环境条件,使已有的有益微生物群体增长并表现拮抗活性。

5、物理防治

6、化学防治

填空题
单项选择题

We once had a poster competition in our fifth grade art class.

"You could win prizes," our teacher told us as she wrote the poster information on the blackboard. She passed out sheets of construction paper while continuing. "The first prize is ten dollars. You just have to make sure that the words on the blackboard appear somewhere on your poster. "

We studied the board critically. Some of us looked with one eye and held up certain colors against the blackboard rocking the sheets to the right or left while we conjured up our designs. Others twisted their hair around their fingers or chewed their erasers while deep in thought. We had plans for that ten- dollar grand prize, each and every one of us. I’m going to spend mine on candies one hopeful would announce while another practiced looking serious wise and rich.

Everyone in the class made a poster. Some of us used parts of those fancy paper napkins, while others used nothing but colored construction paper. Some of us used big designs and some of us preferred to gather our art tidily down in one comer of our poster and let the space draw the viewer’s attention to it. Some of us would wander past the good students’ desks and then return to our own projects with a growing sense of hopelessness. It was yet another grown up trick of the sort they seemed especially fond of making all of us believe we had a fair chance and then always—always—rewarding the same old winners.

I believe I drew a sailboat, but I can’t say that with any certainty. I made it. I admired it. I determined it to be the very best of all of the posters I had seen and then I turned it in.

Minutes passed.

No one came along to give me the grand prize and then someone distracted me and I probably never would have thought about that poster again.

I was still sitting at my desk thinking, what poster When the teacher gave me an envelope with a ten-dollar bill in it and everyone in the class applauded for me.

We can infer from the passage that the author()

A.enjoyed grown up tricks very much

B.loved poster competitions very much

C.felt surprised to win the competition

D.became wise and rich after the competition