. Farm friends and farm foes : a text-book of agricultural science . Agricultural pests; Beneficial insects; Insect pests. THE DOWNY MILDEWS 221. the stalk to the forming tuber below. Wherever they go, they cause the death of the cells of living tissue, breaking them up, turning them brown, and causing a foul odor to be given off. In the case of the stalks and tubers the result appears as a sort of rot. The prosperous, healthy plant is thus stricken with a sudden sickness that may well be called a blight. The tubers are no longer able to increase in size through the addition of starch cells. A
. Farm friends and farm foes : a text-book of agricultural science . Agricultural pests; Beneficial insects; Insect pests. THE DOWNY MILDEWS 221. the stalk to the forming tuber below. Wherever they go, they cause the death of the cells of living tissue, breaking them up, turning them brown, and causing a foul odor to be given off. In the case of the stalks and tubers the result appears as a sort of rot. The prosperous, healthy plant is thus stricken with a sudden sickness that may well be called a blight. The tubers are no longer able to increase in size through the addition of starch cells. A field thus blighted is a sight that may well bring dismay to the owner who had hoped for a bountiful harvest. But the paraisite is not yet done with its stricken host. AU this growth of mycelium has been but a preparation for the development of the reproductive spores, just as the growth of the mushroom myce- lium beneath the soil surface is but a preparation for the sending up of the spore-bearing mushroom. The mycelium in the leaves sends out to the surface vertical branches that bear upon their tips the tiny summer spores. These mature quickly and are readily carried away by the slightest breeze. Thus the disease is able to spread rapidly by means of the bil- lions of spores produced. This development of summer spores begins soon after the mycelium gets well started, often before the whole leaf is affected. Many of these spores are Ukely to be washed through the soil till they reach the "tubers, and they may develop there, causing a characteristic brown discoloration. This fimgus commonly passes the winter by means of Spores on Leaf. Magni- fied: a, spore; i, spore germinating; <;, spore with germinating tube entering breathing pore. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Weed, Clarence
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbenefic, bookyear1910
