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Show Iarm Topics PLANT DISEASE EASILY SPREAD Insects Are Found to Be Chief Carrier Agents. B C. W. HUNGERFORD How are plant diseases spread? There is little mystery in the answer an-swer to that question, though plant scientists, entomologists, and others are constantly adding to our knowledge knowl-edge of the subject. Man, domestic animals, rodents, slugs, snails, birds, insects, wind and water are among the more common agencies that spread plant diseases. Insects are the most important spreaders of certain types of diseases, according accord-ing to the results of tests conducted at the Idaho college of agriculture. Perhaps you have wondered just what causes plant diseases. Plant diseases have about the same causes as diseases of animals and humans. Fungi and bacteria cause many plant diseases. Others are caused by a group of organisms known as viruses, which are too small to be detected with the most powerful microscope. Wind and rain act as agencies for spreading many plant diseases. In some of the winter wheat growing grow-ing areas of the country the spores of the stinking ant are blown in such quantities - that "smut showers" show-ers" occur and many thousands of spores fall on every square foot of ground. Birds may also carry fungus fun-gus spores. In one case a single downy woodpecker was found to be carrying over 750,000 spores of the chestnut blight fungus. The secret of control for many virus diseases lies in the control of insects, which are the principal means of spreading these diseases In the field. Much can be done to prevent the spread of plant diseases In general by seed treatment and by general sanitary practices around the farm. Burning of diseased dis-eased plants and disinfection of pruning tools and various containers contain-ers are examples of proper sanitary sani-tary practices. Silting Rate Increases In Historic York River This historic York river of Virginia Vir-ginia is an example of the way in which too much lana in clean cultivated culti-vated crops, and land worn out and abandoned because of too much row cropping, may increase sedimentation sedi-mentation in a stream. Sediment has been accumulating in the York river during the last 27 years at a rate five times as great as during dur-ing the preceding 57-year period, the soil conservation service finds. Carl Brown, geologist in charge of the studies, says this sedimentation is the result of increased erosion on the slopes draining into the headwaters head-waters of the river slopes on which in recent years there has been an increase in land either in clean-cultivated clean-cultivated crops or abandoned because be-cause of too much row-crop farming. A comparison of navigation charts prepared by the coast and geodetic survey indicating water depths on the stream in 1857 and 1911 shows that during that 54-year period approximately ap-proximately 5,600 acre-feet of the soil from the watershed settled as sediment in the York river estuary. Sediment accumulated at the rate of more than 100 acre-feet a year. From 1911 to 1938, when scientists of the service made soundings to determine the extent of accumulation, accumula-tion, 15,293 acre-feet 566 acre-feet a year lodged in the river bed. In determining the amount and rate of accumulation, the surveyors took water depths at the same points along the river at which measurements measure-ments were made in 1911. Low Advertising Costs Of all commodities retailed in the United States, agricultural equipment equip-ment bears the lowest advertising expense. In other words, when a farmer buys farm machinery less of his money goes to defray the cost of advertising that commodity than it does in the purchase of many other advertised products. This is the finding of the Twentieth Century fund. An advertising analysis recently conducted by the fund discloses that i out of each dollar spent on farm machinery but 1.6 cents goes to advertising. ad-vertising. This compared to 8.2 cents by tobacco manufacturers; 6.7 cents for confectionery and bottled goods; 6.2 cents for groceries; 6.1 for furniture; 4 cents for automobiles; automo-biles; 3.7 for clothing; approximately approximate-ly 3 cents for home furnishings; and 2.2 for hardware. Agricultural News 4 Close observers of conditions in the farm implement industry now believe that sales for the year will probably run about 10 per cent under un-der the 1938 dollar totals. The oldest horse of which England has any record died at the age of 60 years. In this country, so far as we know at the moment, the oldest horse lived to be 52 years old. |