ACAEINA OR MITES. 



135 



Some varieties, such as Balvvins and Black Naples, are especially 

 prone to it ; others, as Boskoop Giant, seem to resist it. Hand- 

 picking will keep the disease in check. It also attacks red 

 and white currants. 



The Pear Leaf Blister Mite (JS. pijri) is found in winter 

 sheltering under the bud scales. As the buds open the mites 

 crawl out and enter the leaves through the stomata on the 

 under sides. They then live and breed in the leaves, and 



Fio. 60.— 1, Black Cuerant Mite (much magnified) erecting itself upon its terminal 

 suckers (after B. J. Lewis). 2, Twig of Black Currant in which an uninjured bud 

 has opened. Two lower buds are hindered by presence of mites, while the lowest buds 

 are swollen by them. 



produce pale or sometimes red (on young leaves) areas or galls, 

 which later turn black. They even attack the young fruitlets 

 and ruin them. As the leaves harden off they crawl back to 

 the buds. This Leaf Gall Mite is also found in America and 

 South Africa and Australia. It may be kept in check by 

 winter spraying with lime and sulphur, and spring spraying 

 with paraffin jelly. 



