7. Reliable Protection for Plants

Farmers world over are concerned with problems of protecting food resources from numerous insects, animals, pathogenic agents and weeds. Plant protection in conditions of all-round agricultural intensification is an important reserve for increasing yields of farm produce. If no regular struggle on pests, p1ant diseases and weeds takes place, 20-30 per cent of harvest can be lost. Or, in other words, each fifth hectare of arable land would not be producing anything. That's why effective and bio1ogically safe methods of plant protection have become a world problem.

The protection of plants from pests, diseases and weeds has become one of the most important elements of plant growing processes and of increasing agricultural produce.

The protection of harvest and environment should based on a firm scientific foundation. A combination of methods – agrotechnical, biological, mechanical, chemica1 and quarantine contro1 – is being developed, which makes possible the protection of particular crops not from one, but from all types of pests, diseases and weeds. First of all non-chemical methods are used, chemical means being used only when extremely necessary.

The selection methods of harvest protection are most rational. There are, for example, disease and pest resistant types of cotton, potatoes, winter wheat. This method gives also great economy: every rouble spent on developing a new species is repaid 300 times over.

There are quite a few useful insects in nature. It is very important to preserve useful fauna and to increase the number of useful insects. For example, in some zones the increased sowing of grasses, especially, 1eguminous grasses, the sowing of nectar-bearing plants rapidly enrich the agricultural landscapes with usefu1 insects. Of great importance is international cooperation on exchange of useful species and forms of organisms.

The essence of the microbiological method is that plants have diseases. Re-searchers in many countries are now looking for agents causing diseases of pests – fungi, viruses and bacteria – and methods of propagating them. Bacterial preparations were developed and are now being used in agriculture and forestry. Virus preparations are now being tested.

Chemical methods of harvest protection are likewise being improved. The tactics of using pesticides has been changed. The selectivity of chemicals, i. a. their ability to act only against definite types of organisms, has also increased. Moistening powders, concentrated emulsions which po11ute the air to a lesser extent are used more often. The contro1 over the safety of using pesticides should be of constant concern.

8. Rain-Making

Clouds in the air, even those big ans full of water vapour, do not help the farmers whose fields need rain, or the city people whose reservoirs are running low. To be of use, the clouds must become rain. Scientists think that clouds can be turned into rain if provided with more particles around which the rain drops can form.

All kinds of particles have been tried for artificial rain-making. One kind that seems to work is a chemical called silver iodide. Small particles of this chemical can be scattered from an airplane. They can spread very well among the particles of water vapour, so that only a small amount of this harmless chemical can help a large cloud to form rain drops.

Besides, dry ice can be used. Clouds can be cooled and possibly “dusted” by scattering bits of these crystals from a plane. The dry ice breaks up into cold crystals around which water vapour can cool and condense.

Of course, artificial rain-making will not work on every cloud. It seems to work only on clouds that need a little push, that are almost cool enough ot that have almost enough dust. But further experiments are being tried all the time, and some day it will be possible to have rainfall from any cloud, whenever we need it.

Dry ice can be used to start a chain reaction that will release a great deal of energy from hurricane clouds and so control the farm centres. Perhaps it will be able to force rain by cloud seeding at an early stage in the life of a hurricane and thus prevent the formation of the storm.

Although some scientists are very enthusiastic about cloud seeding with dry ice and a chemical known as silver iodide, others say such actions do not really change the weather. Some farmers consider that new methods of increasing rain are not producing the results needed. Cloud seeding holds great promise. So, there is good reason to believe that man may some day prevent hail and storms which produce crop damage, as well as increase rain supply to certain areas.