70 



THE BLACK CURRANT MITE. 



(Eriophyes ribis, Nalepa.) 



The disease known as " big bud " in Black Currants caused 

 by the Black Currant Mite, was first recorded in these islands 

 in the year 1869, but according to Miss Orinerod it had been 

 responsible for losses in the district of Blantyre, N.B., for 20 

 years previously. Similarly Theobald* states that about the 

 same period it was known to the Maidstone growers. * The 

 original home of the mite, however, is uncertain. It has now 

 spread throughout Great Britain and Ireland, and occurs in 

 most of the countries of Western Europe. It has also been 

 introduced into Canada. 



It has been scheduled as a destructive pest by the Depart- 

 ment of Agriculture for Ireland, where attempts are being 

 made to stamp it out, but this end does not yet appear to have 

 been attained. 



The Black Currant Mite is undoubtedly the most serious 

 animal pest of the Black Currant, and its attacks have caused 

 a marked reduction in the area devoted to this fruit. In spite 

 of much careful research by numerous investigators, no really 

 satisfactory methods of control have yet been discovered, and 

 there is need for still further investigation. It is only necessary 

 here to describe the nature of the attack and to indicate the 

 lines of the treatment which have given the more hopeful 

 results. 



Plants Attacked Nature of Injury. The plant which 

 suffers most seriously from the mite is the Black Currant, 

 but Red and White Currants and the Gooseberry are also 

 attacked. Owing to the difficulty in carrying out the necessary 

 experiments, it does not appear to have been proved that the 

 mites can pass from one species of host plant to another, but 

 it is highly probable that they can do so. The point is 

 obviously one of great practical importance. 



The nature of the injury in the case of the chief host plants 

 is briefly as follows: 



Black Currant. The developing buds are attacked and swell 

 until they are almost globular in shape and are about twice 

 the size of the normal buds thus giving rise to the term 

 " big bud." Buds, if slightly attacked, may produce small 

 stunted and crumpled leaves, but as a rule they dry up and 

 die in early summer. 



The natural result of this loss of buds is a progressive 

 decrease in the crop which may ultimately fail altogether. 

 In the case of certain old bushes, however, it has been noticed 

 that the number of " big buds " produced each year has 



* Theobald, " Ingect Pests of Fruit," p. 232. 



