. California plant diseases. Plant diseases. 1128 UNIVERSITY OF CALIFORNIA—EXPERIMENT STATION. time. It has even been found that the most healthy, green leaves, if picked from the tree and placed in a moist chamber, soon become cov- ered with this wither-tip fungus. Trees suffering from gum disease, gophers, drouth or any other influence which causes them to lose their vitality and begin to weaken and die back in the branches soon develop an abundance of this organism. It is also likely that citrus insects, like the red spider and any other which punctures or injures the fruit, may promote the
. California plant diseases. Plant diseases. 1128 UNIVERSITY OF CALIFORNIA—EXPERIMENT STATION. time. It has even been found that the most healthy, green leaves, if picked from the tree and placed in a moist chamber, soon become cov- ered with this wither-tip fungus. Trees suffering from gum disease, gophers, drouth or any other influence which causes them to lose their vitality and begin to weaken and die back in the branches soon develop an abundance of this organism. It is also likely that citrus insects, like the red spider and any other which punctures or injures the fruit, may promote the development of this fungus. All in all, our conclusion has been that it is extremely doubtful whether the wither-tip fungus ever in California attacks sound, unin-. Fig. 56.—Effect of wither-tip fungus on sickly lemon leaf and twig (Col- letotrichum gloeosporioides). jured, vigorous foliage, twigs or fruit, or develops at all, save in a secondary manner or following some other injury. The subject is still receiving careful investigation and will be made the subject of a future bulletin. "Within the last two or three years considerable spraying has been done in lemon groves in southern California with the idea of combating the supposed effects of this fungus. Such work has been done with Bordeaux mixture and also with various sulphur sprays made by com- bining sulphur with lime, soda or potash. Some growers have believed that they saw good results following such spraying, while others were unable to see such benefits. "We are following the results of such 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 Smith, Ralph E. (Ralph Eliot), 1874-1953; Smith, Elizabeth H. (Elizabeth Hight), 1877-1933. Berkeley, Cal. : Agricultural Experiment Station
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