598 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



fungus sent to me on Gooseberries has proved to be Microsphcera 

 Grossularue. I do not consider that there is any reason for thinking 

 that the fungus has been introduced into Russia from America. We 

 have a great many American fungi on wild and cultivated plants that 

 could not have been introduced in any way (e.g. Plasmopara cubensis, 

 Phytophthora Phaseoli, Exobasidium platy discus). It is very probable 

 that the fungus is to be found in many localities here, but we have so 

 few mycologists in Russia that there are few investigations on the sub- 

 ject, and our knowledge of the geographical distribution of fungi in 

 Russia is very incomplete." Prof. A. de Jaczewsky kindly sent me 

 beautiful specimens (now in the Kew Herbarium) of the Russian 

 examples of S. mors-uvcB. 



In August last a further communication was made to Gartenflora by 

 Dr. Hennings (2), who reported as follows : — " On July 15, 1902, Mr. N. 

 A. Mossolow wrote to me that the mildew had again appeared on all the 

 Gooseberry bushes in the private gardens at Michailowskoje, Podolsk, 

 district of Moscow ; and that not only was all the fruit completely 

 destroyed, but the fungus occurred also on the young shoots. On the 

 17th of the same month I heard from Prof. Buchholtz, at Riga, that he 

 had received a few days previously examples of the American Gooseberry- 

 mildew on diseased Gooseberry-branches from Port Kunda in Esthonia, 

 where the fungus had destroyed the whole crop of Gooseberries. In 

 Prof. Buchholtz 's opinion the disease appears to be spreading more and 

 more from East to West." Dr. Hennings concluded by pointing out that 

 it would seem from the existing evidence that the fungus is spreading 

 from the interior of Russia, and that there are no grounds for assuming, 

 as Prof. Magnus has done (3), that it has been imported on diseased 

 Gooseberry bushes from America. Dr. Hennings also points out that it is 

 very probable that the disease will appear in Germany, and remarks that 

 should this happen it is expedient that all the affected bushes should be 

 at once destroyed by fire on the spot, while all the non-infected bushes 

 should be well sprayed with Bordeaux mixture. It may be mentioned 

 here, however, that undoubtedly the best fungicide for combating the 

 present disease is potassium sulphide, as has been proved by numerous 

 careful experiments in the United States. (See vol. xxv. p. 141, and vol. 

 xxvi. p. 779, of this Journal.) 



De Wildeman, in the Prodrome de la Flore beige (Thallophytes, fasc. 2, 

 p. 219 ; 1898), has enumerated, on the authority of Prof. Em. Marchal, 

 S. mors-uvai among the Erysiphacc(6 of Belgium. Prof. Marchal writes 

 to me, however, that this record is erroneous and must be expunged. 



We see, therefore, that the present disease has, since its original out- 

 break in Europe in 1900, appeared in numerous fresh localities in 

 Ireland, and in two widely- separated districts in Russia. In every case 

 where the disease has appeared it has assumed a serious character, and 

 tends to recur annually in increasing severity ; and there is no doubt that 

 Gooseberry-growers in Europe are now face to face with a dangerous 

 enemy. 



There is reason also to fear that another fruit than the Gooseberry is 

 threatened by the present fungus. In a recent ' Bulletin ' of the New York 

 Agric. Exper. Station (4) the following statements occur : — " The 



