68 MAINE AGRICULTURAI, EXPERI-MENT STATION. ' T913. 



spring in large numbers, are carried to the leaves of the lower 

 branches of the trees, and there serve as centers of infection 

 as soon as they have germinated and have begun to produce a 

 diseased area. This period of ejection of the sac spores lasts 

 but for a comparatively short time and then the danger from 

 them is largely past. Consequently if a fungicidal spray is 

 applied to the trees when these spores are being matured and 

 .thrown off, or at least before they have germinated and infected 

 the leaves and parts of the young blossom buds, a large propor- 

 tion of the potential possibilities of scab infestation for the com- 

 ing season will be eliminated at the start. If, on the other hand, 

 the first application is too long delayed and infection has oc- 

 curred no amount of later spraying will absolutely control the 

 disease although it may do much to prevent its spread to unin- ' 

 fected fruit and leaves. 



That two applications of standard dilution lime-sulphur did 

 materially check the development of scab is plainly shown in 

 comparing plots C and E where the former gave 32 per cent 

 more perfect apples than the latter. On the other hand plot G, 

 sprayed three times, gave a like increase of over 70 per cent. 

 This much greater efficiency in disease control is very evidently 

 due to the prevention of the early spring infection from the sac 

 spores produced on the old leaves under the trees. 



Dilution of lime-sulphur. The fact that only two applications 

 were made to the different plots of which the different dilutions 

 of lime-sulphur were tested detracts from the value of the data 

 obtained. While too sweeping conclusions should not be drawn 

 from them, the results taken for their face value are fairly sug- 

 gestive. The "one-fifth stronger" dilution was decidedly more 

 efficient in scab control than was the "standard dilut'on" and 

 produced but little more russeting of the fruit. This did, as 

 has been previously noted, produce some slight leaf injury. 

 Judging from this season's experience and that of the year be- 

 fore it would seem that a 2"/° Baume lime-sulphur can be used 

 at the rate of two gallons to 48 of water with comparative 

 safety on varieties like the Ben Davis which are very susceptible 

 to spray injury. Judging from the results of the present season 

 alone this stronger dilution is much more efficient than the 

 standard dilution in scab control — possibly sufficientlv so to 



