DISEASES OF THE POTATO. 163 



mycelium of which penetrates the tissues of the leaves and 

 destroys them. In due course the mycelium develops 

 what are technically known as conidiophores, or tiny stems 

 which appear in the form of a mould on the surface. On 

 the conidiophores are borne conidia, which give birth to 

 zoospores. These, coming in contact with globules of 

 water, emit germ tubes that penetrate the epidermis of the 

 leaf or tuber, and eventually form the mycelium which 

 does so much mischief to the tissues. The mycelium will 

 often lie dormant in the tubers all the winter, and start 

 into activity when new growth begins in the soil. The 

 disease is mostly prevalent in rainy seasons. 



REMEDIES. First of all, let it be clearly understood that 

 it is quite useless applying remedies, once the foliage is 

 attacked by the blight. The mischief is done then. 

 There is only one course to pursue in such a case, and that 

 is to promptly cut off the diseased haulm and burn it. On 

 no account ought it to be permitted to remain on the land 

 to decay, otherwise the disease will attack crops in future 

 years. Nor is it advisable to give diseased tubers to pigs, 

 since the disease will be transported with the manure, 

 and reconveyed to the land, ready to attack the next crop 

 of potatoes grown thereon. Really, there should be no 

 hesitation about burning both diseased haulm and tubers, 

 as then the disease will be eradicated. Infested land 

 should be liberally dressed with quicklime, and no pota- 

 toes grown thereon for at least two or three years. 



SPRAYING WITH FUNGICIDES. Repeated experiments have 

 demonstrated that it is possible to prevent an attack of the 

 Potato Blight by one or more timely sprayings of the 

 foliage w r ith a fungicide. According to leaflet No. 14 

 issued by the Department of Agriculture and Technical 

 Instruction for Ireland, the results of spraying potato 

 crops have been of a most gratifying nature. Experiments 

 have been made for three years with the following results : 



M2 



