DEPARTMENT REPORTS, 181 



The chewing insects arc certainly as well controlled by the dusting 

 of the trees as by the use of the spray. And, in ordinary seasons when 

 there is comparatively little injury from apple scab, it has been possible 

 to control it by means of dusting. However, in some sections where rain- 

 have been frequent and conditions have been favorable for the develops 

 ment of the apple scab, the results from the use of dust have not been 

 as satisfactory as those from spraying. 



It has been pretty well established that the effects of the dust are not 

 as lasting as those of liquid applications; and hence we may infer that to 

 secure equally good results it will be necessary to use the dust at more 

 frequent intervals. Especial care should also be taken to cover the trees 

 just before a storm. 



Thus far, although the dust apparently serves to hold the brown rot 

 and scab of stone fruits in check, it has not been conclusively shown that 

 the various leaf-spot diseases can be controlled with equal certainty. From 

 the fact that the dust may be used with safety upon the foliage of peaches 

 and Japanese plums, and since it serves so well to prevent the scab and 

 brown rot, it would seem that dusting machines certainly have their place 

 in peach orchards. They should also be of use in cherry orchards where it is 

 sometimes necessary to make use of a fungicide a few days before the 

 crop is ripe when a liquid application would be liable to spot the fruit. 



THE CONTROL OF PEACH LEAF CURL. 



The past spring had weather conditions which were very favorable 

 to the development of the disease which causes the leaves of peach trees 

 to thicken and roll and to which the name peach leaf-curl has been given. 

 As is generally understood, this is a fu^ngus disease for which a cold, wet 

 spring is especially favorable. When the weather is warm and dry little or 

 no harm results. Nearly thirty years ago the writer demonstrated that 

 the disease could be controlled by spraying; and, that to secure good 

 results it was necessary to make the application very early in the spring, even 

 before the buds have commenced to swell, and at least three weeks before 

 the trees blossom. Careful experiments also showed that the spraying 

 might be done in the fall with practically as good results, provided the 

 leaves had dropped so that all parts of the trees could be reached. Open 

 periods in the winter could also be utilized for spraying peach orchards, 

 except that care was required not to allow the water in the rigs to freeze. 

 Care also must be taken only to spray on days when the moisture would 

 evaporate before it has time to freeze. 



Either Bordeaux-mixture, copper sulphate solution at the I'ate of one 

 to two pounds in fifty gallons of water, or lime-sulphur solution (diluted ] 

 to 15) if applied at the proper time will prevent the development of this dis- 

 ease. The dormant strength of lime-sulphur solution as used for San 

 Jose scale would also be effectual against the peach leaf curl. 



Many of the best peach growers of Michigan who have usually kept 

 their trees free from leaf-curl suffered seriously from the disease in 1919. 

 They had planned to spray their trees and supposed there would be ample 

 time; but, during the month of March it was so wet in most orchards as to 

 make it practically impossible to get around with spray rigs. During the 

 last few days of the month, the weather was unusually warm for the season 

 which resulted in the swelling of the leaf-buds so that very little effect was 

 secured when the spraying was done during the first half of April. On the un- 



