Diseases of economic plants (1921) Diseases of economic plants diseasesofecon00stev Year: 1921 204 Diseases of Economic Plants in this country, in Europe, and in Bermuda. In the latter place it was so injurious that the legislature applied to the mother country for investigation and )i aid. The first reference to it in the I , United States was in 1872, It is now 1 / reported from coast to coast. B / The blight was described fully by Thaxter in 1889, again by Whetzel in 1904, during which latter year it was particularly destructive in New York, causing a loss of half the yield, even more in
Diseases of economic plants (1921) Diseases of economic plants diseasesofecon00stev Year: 1921 204 Diseases of Economic Plants in this country, in Europe, and in Bermuda. In the latter place it was so injurious that the legislature applied to the mother country for investigation and )i aid. The first reference to it in the I , United States was in 1872, It is now 1 / reported from coast to coast. B / The blight was described fully by Thaxter in 1889, again by Whetzel in 1904, during which latter year it was particularly destructive in New York, causing a loss of half the yield, even more in some instances. The attack in the field occurs first upon a few plants during warm, damp weather. Examined while the dew is still present, these plants, seen from considerable distance, display a peculiar violet tint especially easy to discern through the dewy covering. Close ex- amination shows the affected part to be covered with a fuzzy coating. On the second day these parts lose their green color, turn pale, or even yellow. On the third or fourth day the plant is entirely collapsed. The diseased spots in the field may each cover an area of only a few feet in diameter, enlarging slowly. If the weather favors the fungus, the disease may sweep rajiidly across the whole field. Affected plants, under suitable weather conditions, brilliant, dry atmo- sphere, recover slowly, putting out new leaves. Subsequent attacks may occur if the weather favors the growth of the fungus. The injury from this disease is through the loss of leaf surface, thus re- ducing the growing power of the plant. Usually little or Fig. 108. — Onion plant illustrating manner of death of leaves affected with downy-mil- dew. After Whet- zel.
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