470 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



end of June — on the young fruits, sometimes on the young shoots as well, 

 is to be referred to external infection, either (1) from hibernated perithecia 

 on the same or neighbouring bushes, or (2) from berries or shoots already 

 covered with the white powder consisting of the spores. 



The summer outbreak — at Stockholm from the middle to the end 

 of July — (1) on young newly planted bushes is not caused only by 

 external infection with the white powder from diseased bushes growing 

 in another place ; in many cases I believe that an invisible germ of disease 

 already exists within the young bushes themselves at the planting time. 

 Nor is the summer outbreak (2) on older bushes, previously seriously 

 attacked and heavily pruned, to be explained in all cases only by means 

 of external infection from other diseased bushes ; here, too, we must 

 suppose an invisible germ of disease incorporated within the bush during 

 the previous year of disease. 



The autumn outbreak, August-October, is principally to be referred 

 to external infection caused by other diseased bushes. 



7. The Spread of the Disease during the period of Vegetation takes 

 place principally through the carrying of the spores on solid objects, living 

 or dead, and also, through shorter distances, by means of the wind. The 

 spread is often capricious, being sometimes of greater, sometimes of less, 

 extent than we have had reason to expect. 



8. The Spraying with Fungicides generally Insufficient. — This 

 treatment helps only for the moment. The success of the spraying 

 depends not only on the power of the ' fungicide to kill the spores or 

 the threads of the fungus, but also on the manner of growth of the 

 plant sprinkled. Now the continuous putting out of new shoots and the 

 folded foliage of its tops, make the gooseberry bush difficult of access for 

 the purpose of spraying. Spraying is therefore needless trouble and 

 useless expense. 



9. The Pruning of Diseased Young Shoots. — Such a pruning during 

 the summer can be effective only in rare cases where the bush is but 

 slightly affected ; that is to say, if the diseased shoot is immediately 

 observed and removed, and if, neither before nor during the process, 

 nor after the removal of the diseased part, the contagion is carried to 

 other shoots of the same bush. It being impossible, however, to estimate 

 these chances beforehand, we can by no means rely on the shoot-pruning 

 process during the summer as being a sure means of combating the 

 disease, or on its being a method advisable in practice. Such a pruning 

 may become the best ally of the enemy. 



The pruning of diseased shoots late in the autumn, October- 

 November, is capable of diminishing the strength of the next spring 

 outbreak on the same bush and its nearest neighbours ; but, as a rule, 

 it does not prevent the outbreak of the disease in the following summer, 

 and besides, it cannot be carried out with thoroughness, as far as the 

 pruning of seriously diseased older bushes is concerned. The autumn 

 pruning, therefore, would be a dangerous weapon in the enemy's hand. 



10. The Gutting Down of Diseased Bushes late in the Autumn. — 

 Kven when diseased bushes have been cut down to the ground, all cuttings 

 burnt, and the ground sprayed and limed — two years consecutively — this 

 proceeding has, so far as I know, in no case been able to eradicate the 



