Halo-blight of oats (Google eBook)

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Government Printing Office, 1920 - Halo-blight
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Page 140 - Foster (/o)1 for similar lesions of the wildfire disease of tobacco, and the spots do not fall out of the leaves. Exudate does not occur in connection with the lesions. When several lesions occur on the same leaf they often coalesce and produce a general yellowing followed by a breaking across of leaf blades (PI. C) or a shriveling and drying of tips and margins. During periods of warm, dry weather yellow haloed leaf tissue loses its turgidity and color and forms oval, gray-brown dead spots which...
Page 167 - The primary yellowing sooner or later changes to a mottled red or brown. In another place he says: The preliminary effects of this disease is a yellowing, beginning either as small, round lesions on the blade, or as long, streak lesions extending throughout the blade or even the whole length of the culm and blade. Occasionally it begins at the tips and works back into the culm; again the upper leaves often break down through a weakened condition of the plant from defoliation below. When lesions work...
Page 153 - CHART. Indorsed by the society for general use at the annual meeting Dec. 31. 1914. Prepared by the committee on revision of chart identification of bacterial species. power is moderate; gelatin is liquefied slowly, beginning in 2 days and not complete in 60 days; reduction of litmus occurs in milk, and the casein is digested without curdling; milk curdles in 5 days, and peptonization is completed in 5 weeks. No acid is produced in milk. Oxidations of proteins are incomplete; ammonia is produced;...
Page 167 - In the early stages of the disease there is "a yellowing, beginning either as small round lesions on the blade, or as long, streak lesions extending throughout the blade or even the whole length of the culm and blades. In the advanced stages, the affected blades take on a mottled to almost red color, which has been called 'rust
Page 140 - ... diameter, evident on both sides of the leaf blade. The halolike margin spreads rapidly, becoming uniformly lighter green to yellow or showing concentric markings (PI. 26) of different shades of green and yellow. Occasionally these halolike margins are prolonged at one end into points (PI. C) from i to several centimeters long. They may extend as yellow streaks through the center or along the margin to the tip of the leaf, but ordinarily they appear as oval spots, measuring i cm. or more in diameter....
Page 139 - ... carried on at the University of Wisconsin during 1917 and 1918 under the direction of Prof. LR Jones and was continued in the Pathological Laboratory of the United States Department of Agriculture during 1918 and 1819 under the direction of Dr. Erwin F. Smith. The writer also wishes to acknowledge the courtesy of the Boston Branch of the Association of Collegiate Alumnae whose research fellowship she held during the college year of 1917-18. Journal of Agricultural Research, Washington.
Page 166 - Manns carried on his investigations during the seasons of 1908-9 at the Ohio Experiment Station. WORK OF THOMAS F. MANNS, 1906-1909 Manns (j) states that— the disease manifests its presence by changes in color varying from a light yellowing, which apparently checks but little the growth of the oats, to a pronounced reddening, which in severe cases kills the blades, leaving only the younger leaves and the central axes alive.
Page 157 - These were uni-' formly inoculated from broth cultures and kept at 24° C. In 24 hours there was clouding in all except + 20 and +25. At the end of 3 days there was clouding in all except + 25. The clouding in + 20 wd% slight.
Page 141 - One-fourth of the fields showed only scattered lesions on the lower leaves—an infection of 1 per cent or less. About one-half of the fields showed a general spotting of the lower leaves on from 60 to 100 per cent of the plants. In some cases the infection was in patches from 2 to 6 feet in diameter, where every plant had all but the last one or two leaves badly spotted.
Page 165 - Stained sections of haloed leaf tissue also show bacteria only in the center of the lesion. The bacteria at first are intercellular, but later they destroy the cell walls and cause the collapse of the tissue. The collapsed tissue is evident as the dead brown centers of lesions. (See...

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