H. WuRMALD o7 



celeste and lime-sulphur, were almost useless in this respect since, as a 

 rule, they failed even to wet the pustules. They became more effective 

 however when prepared so as to contain 1 ]ier cent, soft soap^ for then 

 the pustules were wetted and the surface layer of conidia was killed. 

 Ammonium sulphide with soft soap, as recommended by Eyre and 

 Salmon (r), c) for use against the oidium sta<i;e of the Erysiphaceae, was 

 also tried with similar result. The pustules were thus prevented from 

 shedding conidia for some time but they were not killed and during a 

 period of wet weather the pustules evinced a tendency to grow out 

 through the superficial barren layer and once more become powdery. 

 Under favourable dry atmospheric conditions therefore such fungicides, 

 when used with soap to reduce their surface tension and increase their 

 wetting properties, would tend to check the spread of the disease if 

 applied just before the flower buds open, to render the pustules non- 

 infective during the flowering period, and again when the fruit has set 

 to prevent the dispersion of the conidia while the fruit is growing. They 

 are not to be relied on however from the fact that the pustules themselves 

 remain alive and re-develop, producing fresh crops of conidia, during 

 periods of moist weather. 



Better results were obtained with a solution consisting of 1 per cent, 

 caustic soda and 1 per cent, soft soap, the pustules remaining dark brown 

 for fully three weeks after the appUcation of the mixture; this solution 

 would in practice be used as a " winter- wash " as its caustic properties 

 would cause serious damage to growing shoots. Experiments with this 

 spray-fluid have not been carried out in the open on plum trees, but 

 results of trials on apple trees bearing similar pustules of the "Blossom 

 Wilt" Monilia were not such as to warrant its recommendation. 



V. SUMMARY AND CONCLUSIONS. 



1. In the summer of 1916 many plum trees in Kent were affected 

 with a disease which caused the wilting and death of the tips of young 

 twigs. 



2. On each diseased shoot one or two leaves became infected and 

 the disease extended into the tissues of the shoot causing the wilting and 

 death of that portion distal to the node bearing the withered leaf. 



3. Such twigs bore pustules of Monilia cinerea Bon. during the 

 following winter and spring. 



^ It was found that soft soap could be succossfully mixed with oarh of the sprays 

 mentioned except Hme-sulphur. 



