EESEAROHE.S AT WISLEY. 



169 



some overhanging hazel bushes teeming with " big-bud " ; bunches of 

 diseased hazel buds were also tied on to the shoots of the currant bushes. 

 These experiments have now been going on for three seasons, and as yet 

 no infection in either direction has been observed ; in other words, the 

 originally healthy hazels have not been infected by the diseased " Baldwins," 

 neither have the healthy " Baldwins " been infected by the diseased hazels 



Fig. 40.— Healthy Hazels and Diseased Black Ccrkants at Wisley 



(fig. 40). It is not suggested that these experiments furnish absolute 

 proof that no infection of the nature suggested can take place, but as far 

 as it goes the experiment is reassuring. 



Vine Leaf Mite. 



During certain seasons the leaves of outdoor vines are disfigured by 

 the presence of numerous blotches on the under surface. These blotches 

 are at first pure w^hite in colour, gradually changing to a dark, rusty 

 brown, and are due to the presence of a mite closely allied to those 

 forming " big-buds " on black currants and hazels. This disease, known 

 as erinosis, has occurred on the leaves of one of the vines growing in the 

 field at Wisley, and requires to be investigated. 



Tomato Bactebiosis. 



A bacterial disease of tomatoes often proves very destructive to the 

 crop in the central and northern parts of France. The fruit of a single 

 tomato plant grown at Wisley showed this disease, but prompt removal 

 prevented its spread. Infection takes place when the plant is in 

 flower, the bacteria being conveyed by insects and deposited on the 

 stigma. Some time after an infected fruit is set a small black speck 

 appears at that point of the fruit occupied by the stigma ; this speck 

 gradually increases in size until by the time the tomato is fully grown it 

 is almost entirely black both externally and internally, and soon 

 deliquesces into a pulpy mass teeming with bacteria (fig. 41). 



