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hand due to its more active chemical nature, tends to break 

 down arsenical compounds forming new combinations in- 

 jurious to foliage and fruit. One compound, arsenate o£ 

 lead, has proven quite satisfactory with lime-sulfur, giving 

 but little injury even under exceptional conditions. Not 

 only must the combination of the fungicide with the insecti- 

 cide prove non-injurious to the host plant but the efficiency 

 of neither against the fungus and insect pest must suffer. 

 There is abundant evidence in the results of experiments and 

 in the general experience of growers to warrant the con- 

 clusion that neither the fungicidal value of lime-sulfur nor 

 the insecticidal efficiency of arsenate of lead are injured by 

 the combination. In fact Dr. Wallace was able to show that 

 the fungicidal efficiency of the combination was greater than 

 that of the lime-sulfur alone. 



Having set forth the nature and requirements of a good 

 fungicide and having shown wherein lime-sulfur is superior 

 to bordeaux let us consider the matter of time of application. 

 To be effective the fungicide must be applied before the ar- 

 rival or at least before the germination of the fungus spore 

 upon the leaf or fruit to be protected. We have seen that 

 the first scab spores to reach the young leaves and blossoms 

 in the spring come from the old leaves upon the ground at 

 the time when the blossom buds just begin to show pink. 

 The ascospores are not mature and so not discharged before 

 this time. We have also seen that the fungus does not win- 

 ter on the twigs. It must be evident to all of you, there- 

 fore, that dormant spraying can be of no value for apple 

 scab. This is borne out by experiments and experience. 

 The first application therefore for scab is to be made as 

 shortly before blossoms open as possible. The next period 

 for infection is usually just after blossoms fall. Evidently 

 the time for the second application is as soon after the blos- 

 soms begin to fall as possible, say when two-thirds are off. 

 A third infection depending on weather may call for a third 

 application, within ten days to three weeks after the blos- 

 soms fall, but this is not usual with us in New York. An 



