REPORT OF COMMITTEE ON PUBLICATION 125 



least in part, for the injury. As has been stated previously a relatively long 

 period of high temperatures followed the sulphuring and there was little 

 precipitation. It is possible that sulphur particles became heated sufficiently 

 to cause a mechanical burning, aside from any chemical reaction with the 

 leaf tissues. The heat concentrated on the leaf surfaces may have resulted 

 in excessive transpiration, which could not be met by the roots owing to 

 the drought at the time. One of the writersG has been studying a leaf affec- 

 tion of the grape, that is apparently dependent upon the amount of moisture 

 in the soil at critical periods. Examination of the injured dusted vineyards 

 showed the leaves affected in much the same manner as with the leaf 

 trouble due to a lack of moisture. In fact it was only after several observa- 

 tions that this writer was led to believe that the sulphur was a contributor 

 to the injury present. That four of the vineyards were uninjured may be 

 due to the availability of a greater amount of soil moisture, or to the fact 

 that demands of the growing wood, leaf and fruit were not so great, due 

 to less fruiting wood having been retained at the winter pruning. 



This unexpected turn of affairs leaves the practical control of mildew 

 where it was years ago. It is possible that much smaller quantities of 

 sulphur may be used per acre. It is equally possible that such a combina- 

 tion of circumstances may not exist again in many years. At any rate the 

 desirability of dusting the vineyards of the Chautauqua belt is such that 

 renewed experiments on a small scale will be continued in 1915. 



Prof. Bioletti remarked that the paper showed that the control of this 

 disease in the eastern portions of the United States is very different from 

 its control in California. They sulphur many times during the summer, 

 while in California the sulphur should be applied principally during the 

 spring. 



President Alwood: "If someone here has had experience with Oidium, 

 he may state that experience." 



Mr. Henry: "It has been very hard to control mildew in the San Joaquin 

 Valley. It has been very bad this season. Sulphur prevents mildew just as 

 long as it lasts on the vines, but no longer." 



Prof. Bioletti. "In regard to the mildew in the San Joaquin Valley this 

 year, I went through a large part of Fresno, Tulare and Kern counties and 

 I was told that there was a great deal of mildew in these sections. I visited 

 forty or fifty vineyards and did not find a single indication of mildew. In 

 every case it was something else. It was alkali, or some other trouble of 

 the vine. I have never seen so little at this time. There is a great deal of 

 worrying in this region about something that is not mildew at all. Many 

 growers haven't learned to recognize it when they see it." 



Mr. Henry: "When you go into a vineyard one day, and two days after- 

 ward you go back and find the vines are gray, I think it is plain that it is 

 mildew." 



Mr. P. F. Lint, Los Gatos, Cal.: "I want to say a word about sulphuring. 

 The great secret is to sulphur just as soon as the leaves come out." 



Prof. Flossfeder asked Mr. Henry if the vines were totally covered with 

 leaves or not when he found what he says was mildew. 



Mr. Henry: "There were bunches of grapes on the Thompson Seedless 

 vines right out in the open. We often find mildew on the second crop and 

 not on the first crop." 



6Gladwin, F. E. Phytopathology 5:. 1915. 



