REPORT OF COMMITTEE ON PUBLICATION 121 



Dusting and Spraying Experiments in 1911. 



In 1911 the writers began a series of experiments with sulphur as a 

 possible control for powdery mildew. Bordeaux, while very effective in hold- 

 ing the disease in check in its early period (August 1st), does not protect 

 late unless other applications are made. Late applications are undesirable, 

 as they stain the fruit, if the rainfall is deficient, and thus render it open 

 to the suspicion of the consumer. In certain seasons one application of 

 Bordeaux has so persisted that the pedicels and peduncles have been practi- 

 cally free from mildew at harvest time. It was for the purpose of controll- 

 ing the disease during the ripening period, and up to the harvest without the 

 staining attendant upon late applications of Bordeaux, that the tests were 

 carried out. 



A vineyard consisting of Concord, Worden and Lindley was selected for 

 the early tests. The presence of Lindley in considerable numbers made this 

 vineyard particularly desirable, as this variety is very subject to powdery 

 mildew. The fifteen rows of vines included in the experiment were all 

 sprayed in the dormant state on April 27, 1911, with commercial lime- 

 sulphur solution at the dilution of 1 part of solution to 11 parts of water. 

 Rows 1, 4, 8, 10 and 11 were sprayed July 1st, July 21st and July 31st with 

 Atomic sulphur^ 2 pounds and arsenate of lead 2 pounds to 50 gallons of 

 water. Rows 2, 5, 9 and 14 were dusted with flowers of sulphur with a 

 knapsack duster on July 14th and 31st. Row 13 was given one application 

 of Atomic sulphur and arsenate of lead July 21st. Rows 3, 6, 7, 12 and 15 

 were left as controls. The dust applications were made on warm days as 

 far as possible. Comparison of the various treatments a short time before 

 harvest, showed that neither the dormant spraying nor the spraying with 

 Atomic sulphur had controlled the mildew satisfactorily. Marked differences 

 were plainly seen between the rows that were sulphur dusted and the con- 

 trols. The leaves of the latter were fairly white with mildew and the 

 peduncles and pedicels were but slightly less affected. The dusted foliage was 

 green and with a minimum of mildew and the berries were practically free 

 from mildew. No injury to leaf, fruit nor wood was shown at this time nor 

 did later observations disclose any such. 



Sulphuring in 1912. 



In 1912 the same vineyard was again used for dusting but no dormant 

 or summer sprayings were given. This year the experiment was limited 

 to 6 rows of Lindley of 22 vines each. The dusted rows alternated with the 

 controls, there being three that were treated and three left as controls. The 

 first dusting was done July llth, and this application as well as the later 

 ones were made with a traction duster. The weather on this date was warm, 

 cloudy and humid. The second application of dust was made July 29th, the 

 weather being humid and cloudy. The third application was made on 

 August 12th. The forenoon of this day was humid and cloudy, changing to 

 clear in the afternoon with fresh winds. 



Just previous to the picking of these rows careful counts were made 

 of the affected and unaffected clusters, and the presence of mildew on the 



'Trade name for an exceedingly fine sulphur sold in paste form by 

 Thomsen Chemical Company. 



