8Q 



Treatment should consist of cuttiug out the worst diseased canes and 

 spraying. Beginning in spring, the first application may he the copper 

 suljihate solution (1 pound in 2.j gallons of water) before the leaf buds open. 

 The second, soon after the foliage is out, with Bordeaux mixture. A third 

 sjiraying with the Bordeaux should follow the harvesting of the crop. Start 

 new plantations from healthy canes or from root cuttings in case of red 

 raspberry and blackberry. — Michigan Bulletin, Xo. 25. 



Irish Blight, or L.\te Blight of Potatoes (Pliiiloiihthora iiifrxtans). 



Symptoms. 



The first indication of this disease is to be seen on the leaf in the shape 

 of a slight reduction in the intensity of the colouring-matter of the leaf. This 

 is rapidly followed by the apijearauce of small brownish blotches, commencing 

 generally at the edge of the leaf. These spots soon increase in size and the 

 tis.sues die, turning dark brown or nearly black. In dry weather these 

 patches do not increase much, but in humid weather they spread over the 

 leaves with immense rapidity. After destroying the leaves, the disease 

 travels down the haulms, and in severe cases the whole of the aerial portion 

 of the [lotato plant may within a few hours become a blackish mass of rotten 

 plant-debris, which emits a characteristic and unpleasant odour. If the under- 

 surface of the leaves be examined with a pocket-lens, there will generally be 

 seen around the margin of each spot a more or less distinct border of whitish 

 mould, looking somewhat as if fine Hour had been sprinkled on the leaves. 

 This white mould is the fruiting portion of the fungus causing the disease, 

 and as myriads of spores are quickly formed on each leaf, it is easy to 

 understand how it can be spread so rapidly. 



This potato-disease is practically wholly propagated and carried on from 

 sea.son to season in the tubers themselves. It is, therefore, of the first 

 importance that none but perfectly sound potatoes should be used for seed. 



The appearance of diseased tubers is very characteristic. Numerous 

 sunken, dead, brown patches are developed on the surface of tlie tubers. 

 These may remain firm and hard for some time, but generally they become 

 soft, and the whole tuber rapidly rots. This rot is accompanied with a partic- 

 ularly foetid odour, quite distinct from the rots caused by bacteria, fusarium, 

 etc. — New Zealand, 13th Report. 



Seed iiotatoes should be stored in a perfectly dry and well-ventilated shed. 

 They should be examined at intervals, and any tubers showing signs of disease 

 should be at once destroyed. 



The dipping of seed potatoes in Bordeaux mixture, using the 4-4-40 form- 

 ula, or, if the skin is well hardened, the C-4-40 formula, is to be recommended. 

 A large barrel should be used, and the potatoes placed in a basket made of 

 wire-netting, or some such material, and the potatoes totally immersed for a 

 few minutes, then la.v them out in a warm place to dry before storing. It 

 must be remembered that this dipping kills only the spores and those portions 

 of the fungus that are on the surface of the potato, and is quite ineffectual in 

 destroying the part which winters in the tissues of the tubers themselves. 



