120 INTERNATIONAL CONGRESS OF VITICULTURE 



Spraying. 



Since the Chautauqua grower can use a spray with profit in fighting the 

 root-worm, some of the first efforts in mildew control were to combine a 

 fungicide with the poison. Bordeaux mixture has been used commonly 

 where any spraying has been done and, in fact, some of the men who use 

 the mixture believe that it is a part of the insect poison. The amount of 

 mildew in Bordeaux-sprayed vineyards is considerably reduced even though 

 the applications are made a month or more before the first appearance of 

 the disease. Extensive spraying experiments were performed, the entomo- 

 logical features of which have been published in detail by Hartzell.4 As a 

 general summary of those experiments it may be said that the degree of 

 mildew control obtained by making applications at the time when the Fidia 

 beetles could be killed barely warranted the use of a fungicide. Bordeaux 

 mixture gave best results where the foliage was sparse and where it was 

 possible to cover the clusters thoroughly. In cases where the foliage was 

 very dense any of the sulphur sprays proved superior. The mildew fungus 

 did not grow where there was a film of Bordeaux mixture but if a leaf 

 received a coarse sprinkling of the mixture the fungus grew between the 

 individual spots. With any of the sulphur sprays the leaves remained 

 entirely free from the fungus until all the sulphur had been washed away. 



In one of the experiments, which was followed up a second year by the 

 owner of the vineyard, it developed that the sulphur sprays positively injured 

 the set of fruit for the next year; in one instance the crop was reduced one- 

 third on that account. HartzelH states that a lime-sulphur spray cannot be 

 used on grapes. He also finds that Bordeaux mixture interferes with effec- 

 tive spraying for the root-worm when molasses is used with the poison. It 

 appeared, therefore, that if mildew was to be controlled at all, the applica- 

 tions should be specifically for that trouble and at the most opportune times 

 and in view of the general apathy of growers with respect to mildew, it 

 seemed that if any treatment were made at all it must be one quickly, easily 

 and cheaply applied. 



Dusting. 



Even before the trouble with sulphur sprays and with Bordeaux had 

 developed, some preliminary experiments were performed (in 1909) by Dr. 

 F. M. Blodgett, with sulphur dusted over the vines with a French "puffer". 

 These experiments were continued in a desultory manner by the writers 

 but some work has been done every year since 1909. Dusting sulphur over 

 the vines late in the season proved effective in controlling the disease. Even 

 when the fungus was well established it could be killed by the use of sulphur, 

 although more satisfactory results were secured if an application was made 

 at the time when the first traces of the disease were evident, and was fol- 

 fowed by another application in the course of two weeks or more, depending 

 on meteorologic conditions. 



4 Hartzell, F. Z. A preliminary report on grape insects. New York, 

 (Geneva) Agr. Exp. Sta. Bui. 331:579-581. 



