. Manual of gardening; a practical guide to the making of home grounds and the growing of flowers, fruits, and vegetables for home use. Gardening. 180 MANUAL OF GARDENING >5>. Leaves and fruits injured by fungi, chiefly apple- scab. attack is commonly not so much in the individual leaves as in the stems, the sources of food supply being thereby cut off from the foliage. The symptoms of this class of diseases are general weakening of plant when the disease affects the plant as a whole or when it attacks large branches; or sometimes the leaves shrivel and die about the edges or in large ir
. Manual of gardening; a practical guide to the making of home grounds and the growing of flowers, fruits, and vegetables for home use. Gardening. 180 MANUAL OF GARDENING >5>. Leaves and fruits injured by fungi, chiefly apple- scab. attack is commonly not so much in the individual leaves as in the stems, the sources of food supply being thereby cut off from the foliage. The symptoms of this class of diseases are general weakening of plant when the disease affects the plant as a whole or when it attacks large branches; or sometimes the leaves shrivel and die about the edges or in large irregu- lar discolored spots, but without the dis- tinct pustular marks of the parasitic fungi. There is a gen- 214. era] tendency for the foliage on plants affected with such diseases to shrivel and to hang on the stem for a time. One of the best illus- trations of this type of disease is the pear-blight. Sometimes the plant gives rise to abnormal growths, as in the " willow shoots" of peaches affected with yellows (Fig. 215). Another class of diseases are the root-galls. They are of various kinds. The root-gall of raspberries, crown-gall of peaches, apples, and other trees, is the most popularly recognized of this class of troubles (Fig. 216). It has long been known as a disease of nursery stock. Many states have laws against the sale of trees showing this disease. Its cause was unknown, until in 1907 Smith and Townsend, of the Bureau of Plant Industry, United States Department of Agriculture, undertook an investigation. They proved that it is a bacterial disease (caused by Bacterium tumefaciens); but just how the bacteria gain entrance to the root is not known. The same bacterium may cause galls on the stems of other plants, as, for example, on certain of the daisies. The "hairy-root" of apples, and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these
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