. Agriculture for southern schools. Fig. 157.—A Peach Tree protectedAGAINST Leaf-curl by Spraying SOME DISEASES OF FRUITS 231 it may cause the little apples to fall. In ordinary seasonsthis disease is well controlled by spraying at intervals oftwo weeks with Bordeaux mixture. Bitter-rot of the apple. —As the name implies, an appleattacked by this disease has a bitter taste. Bitter-rot isworst in moist, warmweather. It begins asa small spot and rapidlyspreads from fruit tofruit. Later the affectedarea becomes flattenedor sunken. A few daysafter the rot has begun,there are little circles ofblack
. Agriculture for southern schools. Fig. 157.—A Peach Tree protectedAGAINST Leaf-curl by Spraying SOME DISEASES OF FRUITS 231 it may cause the little apples to fall. In ordinary seasonsthis disease is well controlled by spraying at intervals oftwo weeks with Bordeaux mixture. Bitter-rot of the apple. —As the name implies, an appleattacked by this disease has a bitter taste. Bitter-rot isworst in moist, warmweather. It begins asa small spot and rapidlyspreads from fruit tofruit. Later the affectedarea becomes flattenedor sunken. A few daysafter the rot has begun,there are little circles ofblack dots beginning toappear at the centerof the diseased little dots containthe spores which willspread the disease. Thisfungus also makes in-. juries, called cankers, Fig. 158.—Peach Tree not SprayedInjured by leaf-curl. on the branches of the apple tree. It is estimated that bitter-rot of apples has repeatedlycaused damage to the extent of ten million dollars a may be controlled by the use of Bordeaux mixture. Fire-blight of the pear and apple tree. — The commonblight of pear and apple trees, which kills and blackensthe leaves and sometimes kills the pear tree, is caused bygerms, called bacteria. This disease also kills the bios- 232 AGRICULTURE soms. The germ is usually carried by bees from adiseased tree to a healthy flower of pear or apple. Thefungus grows into the flower and on into the twigs. Thediseased twigs die. Pear-blight, unlike most diseases, doesleast harm to trees that are growing slowly and thus form-ing tough, short twigs. Hence, when a grown pear treeis attacked, cultivation may be stopped, and no fertilizerrich in nitrogen should then be used. Spraying is not a cure, but cutting in winter and t
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