E. S. Salmon 181 



any peritheciujii. In several cases the perithecia had apparently never 

 reached full development, since the ascus was not the normal size ; 

 in those cases where a full-sized ascus was present, it was without excep- 

 tion shrunken and obviously dead, and the ascospores, which contained 

 oil drops, were evidently undergoing a process of degeneration. 



On May 4 a commercial gooseberry plantation of " Berry's Early " 

 near Rodmersham, Kent, was visited at a time when the American 

 gooseberry-mildew was just beginning to appear for the first time this 

 season. A number of bushes were found with the (conidial) " summer- 

 stage " of the mildew developing — mostly on the young, green berries. 

 In a considerable number of cases — perhaps in the majority of cases — 

 the aft'ected berries were in close proximity to portions of last year's 

 shoots which were badly infested with the (" over wintered ") perithecial 

 stage. On microscopical examination, however, of nine of these shoots 

 — i.e. where mildewed berries occurred close to the winter-stage formed 

 in 1913 — all the perithecia appeared to be dead, the ascus being either 

 shrivelled or empty, or when containing ascospores the ascus was not 

 turgid, and the spores were full of oily degeneration-products. The 

 perithecium on being pressed open usually exuded drops of some oily 

 substance. 



On other branches of the bushes which bore the mildewed berries, 

 and also on other adjoining bushes where no mildew occurred yet, the 

 perithecial stage of 1913 could be found not uncommonly on some of 

 the young shoots (although all the bushes had been " gone over " 

 twice in the process of " tipping "). As in the above-noted cases, the 

 perithecial stage consisted of the dark brown persistent mycelium, often 

 considerably worn away by " weathering," and hundreds of closely 

 aggregated perithecia. Thirty-two of these shoots with the perithecial 

 stage were examined and not one perithecium could be found with a 

 living ascus. The experiment was made of incubating some of this 

 material at 27° C. but no change resulted. 



On May 6 a commercial plantation of " Cousin's Seedling," near 

 Sandwich, Kent, was visited. This plantation was so virulently attacked 

 by the mildew in 1913 that practically all the young shoots on every 

 bush became infested with the perithecial stage, and this also was 

 developed on nearly every berry — the whole crop was lost, not a single 

 berry being fit to pick. An examination on May 6 showed that the 

 disease was just re-starting for the season ; from 40 % to 50 % of the 

 bushes (250 in number) bore a few berries with small patches of the 

 (conidial) " summer-stage " on them. In a few cases young shoots 

 more or less plentifully infested with the perithecial stage of 1913 were 



