Potato Tuber attacked by Winter Rot. 

 (Much reduced.) 



434 The Profitable Culture of Vegetables. 



formalin to each 1,000 cubic feet of air-space. Spread the perman- 

 ganate evenly in a pan or bucket and pour the formalin over it. 

 Leave the room at once and keep it closed for two days. 

 In any case be careful not to bring disinfected seed in contact with 

 diseased tubers, or with the bags or hampers which have contained them. 



POTATO WINTER ROT (Nectria solani). This fungus is very common 

 amongst potatoes which have been stored through the winter, and some- 

 times reaches the proportions of an epidemic after a hot dry season. Such 

 conditions favour the development and spread of the fungus in the field ; 



the tubers are attacked when they are 

 quite young, but the disease is not, as 

 a rule, noticeable when they are lifted. 

 If they are stored when perfectly dry and 

 under dry airy conditions no further 

 development takes place, but if they are 

 badly stored that is, before being per- 

 fectly dry, in large badly ventilated 

 clamps sweating takes place, the tem- 

 perature rises, and the fungus begins to develop. 



Treatment : When the disease is common apply kainit as a top-dressing 

 before the final earthing. Use it at the rate of 3 to 5 cwts. per acre, and 

 work it into the ground round the plants. 



When an attack has been severe, the ground which has produced the 

 diseased crop should not be planted with 

 potatoes for several seasons afterwards. 



The potatoes should be quite dry before 

 clamping, and the clamp only of moderate 

 size, with a dry base, and provided with 

 ample ventilation. 



Where this disease is common it is gener- 

 ally an indication of a deficiency of lime in 

 the soil. 



SCLEROTIUM DISEASE (Sclerotinia 

 sclerotiorum ; Botrytis cinerea). Most 

 cultivated plants and many weeds are liable 

 to be attacked by this disease. The Botrytis 

 or summer form of the fungus produces a 

 white velvetty growth on the stem, leaf or 

 fruit attacked. Although it usually attacks 

 the stem or leaves just above the ground 

 its operations are often conducted at a 

 higher point, as in the case of tomatoes in 

 the open-air, which are attacked at the 

 point where fruit and stem join, a great 

 amount of loss being often occasioned in 



Sclerotium Disease. 



1. Portion of a potato haulm with 

 the Botrytis form starting from the 

 ground line. 



2. Portion of a potato haulm split 

 open showing black sclerotia inside. 



3. Onion with sclerotia of S. bnl- 

 borum on the scales. (All reduced.) 



