Investigation of Diseased Plants. 85 



The following suggestions, if acted upon as far as practicable, 

 would materially assist in reducing the number of such dis- 

 appointments. 



In selecting material, endeavour to illustrate every phase of 

 the disease from the earliest indication of its presence up to the 

 death of the part affected. In the case of an epidemic among 

 herbaceous plants, cereals, &c, one or several entire plants 

 should be sent. Detached leaves alone are as a rule useless. 

 The root, after the soil has been shaken off, should be sent if 

 practicable, as in many instances the primary cause of trouble 

 is located there ; the stem and leaves as a result of this root- 

 disease, become limp and very susceptible to the attacks of 

 fungi. Now it is obvious that examination of leaves or stem in 

 a case like the one just described, would fail to indicate the 

 primary cause of disease in the plant. 



Material for transmission through the post should be care- 

 fully packed in a box and wrapped up in waterproof paper. 

 Never use cotton-wool for packing. Specimens sent in letters 

 or paper parcels usually arrive dried up and useless. 



Information as to the conditions of life of diseased plants is 

 of value. If grown out of doors, the nature of the soil, drainage, 

 aspect and surrounding vegetation should be noted. When 

 grown under glass, state average temperature, humidity, method 

 of watering, kind of fertiliser used ; also whether an apparently 

 similar kind of disease had been previously observed. 



In addition to the living material as indicated above, it is 

 always of advantage to receive characteristic examples of the 

 disease in various stages, preserved in methylated spirit. 



Yellow Spots on Black Currant Buds and Leaves. 

 The Board are sometimes asked whether the small yellow 

 spots, visible on the buds and leaves of the black currant, have 

 any connection with the Black Currant Mite (Eriosyphes ribis). 

 Although at one time there was supposed to be such a connec- 

 tion, further investigation has shown that these " galls " are not 

 due to the mite, but are "glands " or organs secreting a pungent 

 oil, and are in fact not diseased, but healthy structures natural 

 to the younger parts of the black currant plant itself. 



