172 MAINE AGRICULTURAL EXPERIMENT STATION. 1916. 



All the other applications were made to all of the plots on the 

 same day. The first was made on May 14 just as the blossom 

 buds were showing pink, the second -on June 3, immediately 

 after the petals fell, and the third on June 21. 



The dormant strength lime-sulphur was prepared on the 

 basis of a 1 to 8 dilution of a 33° B. concentrate, the summer 

 strength on the basis of a 1 to 40 dilution of the same material. 



Effect of the Different Sprays on the Foliage and 

 Fruit During the Summer. 



The development of scab. As will be shown later in the tab- 

 ulated results obtained from sorting the fruit, scab was not 

 severe even on the unsprayed trees. Undoubtedly early cultiva- 

 tion of the orchards last season materially assisted in reducing 

 the amount of early spring infection. On May 3, the date of the 

 late application of the dormant spray, a considerable number of 

 scab infested leaves of the season before were gathered from 

 under the trees and were taken to Orono for examination. At 

 this time only immature asci or spore sacs could be found. 

 These leaves were moistened, and then placed in covered, 

 porous flower pot saucers, the latter being partly sunk in the 

 soil out of doors to prevent drying out and to keep the leaves 

 as near under natural conditions as possible. Under these 

 conditions the spores in the asci were still immature at the 

 time of the first application of the fungicidal spray on May 14, 

 and did not reach maturity till 4 or 5 days thereafter. The or- 

 chards had been quite thoroughly plowed, and the fallen leaves 

 of the season before turned under before May 14, so that it 

 was impossible to secure fresh material at that time to deter- 

 mine what the actual conditions were in the field. However, 

 since the temperatures at Orono during this time averaged 

 higher than at the farm, it is not probable that the spores 

 developed any more rapidly there. Hence it would seem that 

 the early plowing whereby the leaves were turned under the 

 soil before the ascospores of the scab fungus were mature and 

 were able to bring about the first spring infection may partly 

 account for the small amount of scab on the unsprayed plot. 



Although frequent examinations were made, usually once 

 a week, up to about August 1, no scab was observed on the 

 leaves till July 28 when a small amount was found on both 



