Text B. Why herbicides don't always work

1. Chemical weed control is important in growing many crops to get high yields, but herbicides don't always work. There are some reasons for this.

2. Weed control with chemicals is affected by things that can be arranged into three groups: selection, application and environment¹.

3. Selecting the proper chemical to control the weeds that are present is probably one of the most important things. To do this properly one should know specific weed species that are found or are likely to be found in the crop grown. Then one should choose the herbicide or a mixture of herbicides, to control those weeds.

4. Improper application is another common reason for herbicide failure². Properly working machines for the application of the herbicides, the right rate per acre and good timing are the things that must be paid attention to minimize the possibility of failure.

5. A pre-emergence herbicide must be placed evenly³ on the surface of the soil. For the chemical to move into the germination zone of the weeds, rainfall is required within seven to ten days after application.

6. Some herbicides are volatile⁴. They must be incorporated⁵ into the soil just after spraying. If this is not done the herbicide effectiveness will be reduced.

7. Post-emergence herbicides should be applied after the weeds come up.

8. Growers should carefully prepare the machines for the application of the herbicides. If they use some herbicides at a time⁶, the chemicals must be mixed thoroughly.

9. The right rate of chemical application per acre is also very important. Applying too low rates of the chemical may allow weeds to grow. Too high rates can cause the injury⁷ of the growing crop.

10. Timing of the application is another factor of herbicide effectiveness. Some must be applied about ten weeks before planting, while others should be applied two weeks before planting.

11. Environmental conditions affecting herbicide effectiveness cannot usually be controlled, but information about them can be helpful.

12. As has already been said rainfall is necessary for the action of pre-emergence surface-applied herbicides.

13. Strong winds may cause uneven herbicide spraying. With volatile herbicides winds and high temperatures may cause a loss of the chemical.

14. Soil structure, moisture and organic matter content also affect the effectiveness of the herbicides.

15. Weed species, stage of growth and life cycle must also be taken into consideration in applying the herbicides. Young weeds, for instance, are easier to control than old ones. Biennial weeds are easier controlled in the rosette stage⁸ than in the seed-formation stage while perennial weeds are usually controlled in the seedling stage before the extensive root system is developed.

Notes and commentaries:

¹environment – навколишнє середовище

²failure – неуспіх, невдача

³evenly – рівномірно

⁴volatile – летючий

⁵to incorporate – вносити (добрива)

⁶at a time -одночасно, за один раз

⁷injury – шкода, пошкодження

⁸rosette stage – стадія розетки (розпластане прикореневе листя)

 

3.2. Annotate Text C in writing:

 

Text C. WEEDS

Weeds are found on every farm and in every field. It is impossible to find land completely free from weeds. There are many ways in which weeds may be spread. They are mostly transported by seed, by water, by wind and the animals. Many weed seeds can live in the soil for some years, making the control much more difficult. Weeds reduce growth and yields of cultivated crops as they take away their food water. The best time to kill most weeds is before they can be seen and the best way to kill them is by means of cultivation. Good plowing is the basis of weed control. Rotation of crops is another method. Each type of crop is associated with certain weeds, so if the same crop is grown for many years, this will increase the number of weeds. By crop rotation many weeds are controlled. Chemical weed control is a rather efficient method, too. Spraying machines are used to apply different weedkillers. There exist weedkillers that kill only certain plants or groups of plants. They are called selective weedkillers and can be used to kill weeds growing in many crops. Nowadays hormone weedkillers are produced which kill the weeds by stopping their growth. Hormones can kill underground parts of weeds, and sometimes they remain in the soil for some time after spraying. At present hormones which can kill many kinds of weeds are being developed.

 

 

3.3. TEST-5

Choose the proper definition for each term:

1. fertilizer	a) the process of killing unwanted plants
2. uniform fertility	b) surrounding nature
3. weed control	c) a matter added to the soil to increase cropping
4. pre-emergence herbicides	d) ability of soil to produce the same yield in every part of the field
5. environment	e) chemicals used to kill weeds before their germination

Complete the sentences with the necessary words:

6. … is typical of almost anything in nature.

a) excess

b) variability

c) ground

7. All soils vary in ….

a) fertilizer

b) fertility

c) wheat

8. How many approaches to fertilization are used?

a) one

b) two

c) three

9. An … of nitrogen can result in an undesirably high level of protein in wheat.

a) excess

b) lack

c) absence

10. Which system of fertilization results in maximum possible crop production?

a) fertilize at a high rate

b) fertilize at a low rate

c) neither

11. To select the proper chemical for … one should know specific weed species.

a) rainfall

b) planting

c) weed control

12. To apply herbicides correctly one should know weed species, stage of growth and ….

a) life cycle

b) food water

c) hormone

13. If several herbicides are used at a time, they must be … thoroughly.

a) caused

b) affected

c) mixed

14. … may affect herbicide spraying.

a) volatile herbicide

b) organic matter

c) strong wind

15. Weeds … growth and yields of cultivated crops.

a) assist

b) reduce

c) develop

16. Planting potatoes can be … any time during April and May depending on the soil condition.

a) do

b) did

c) done

17. … triticale as well as wheat grown mainly for pasture?

a) does

b) is

c) has

18. Triticale is usually … with wheat in quality, yield and other aspects.

a) compare

b) compared

c) comparing

19. In upland areas, planting … be done at such a time so that young plants are not damaged by late frost.

a) is

b) has

c) must

20. Best quality tubers …obtained when seed potatoes was harvested in late autumn.

a) were

b) are

c) have

21. Potato tubers will keep better if they are … to remain on the ground after digging for 1 or 2 hours.

a) allow

b) allowed

c) allowing

22. There are herbicides that should not … placed on the surface of the soil.

a) be

b) are

c) to be

23. At what stage … better?

a) weeds are controlled

b) are weeds controlled

c) are controlled weeds

24. No herbicides are effective unless they … applied in proper rates.

a) are

b) was

c) had

25. Under no-plough system a greater amount of chemicals … needed to control weeds.

a) will have

b) will be

c) will do

 

 

Unit 6

1. Agrochemistry and soil science 2. Job titles 3. Modal verbs

 

LABORATORY WORK