432 The Profitable Culture of Vegetables. 



depend more or less upon (1) the soundness of the seed, (2) the suitability 

 of the soil, (3) the space between the plants, (4) the climatic conditions, 

 and (5) the timeliness, frequency, and efficiency of any protective spraying 

 the crop may receive. 



It is of the greatest importance that tubers kept for planting or any seed 

 purchased should be saved from a perfectly sound crop ; any showing the 

 slightest taint should be at once rejected. 



Potatoes should never be planted on low-lying wet land; crops on a 

 water-logged soil are almost sure to be attacked by disease." 



The seed should be set at such distances apart as will allow the sun and 

 air free play amongst the plants. In an overcrowded crop the haulm grows 

 in a close mass which prevents free access of light or air ; thus the growth 

 is soft, and beneath the surface of the foliage there is a damp stagnant 

 atmosphere in which the disease runs riot immediately it finds a lodgment. 

 Although the first three of the points enumerated above are all excellent 

 and necessary steps towards securing a sound crop, they alone cannot be 

 depended upon to ward off disease in an unfavourable season, and to secure 

 comparative immunity these measures should be accompanied by timely 

 sprayings with Bordeaux mixture first about the end of June and again 

 three weeks later. This work should be done, when possible, in fine dry 

 weather ; if it is persistently wet the mixture must be applied more fre- 

 quently and at greater strength. The underside of the leaves must receive 

 particular attention, because it is here that the disease first appears. 



Should spraying have been neglected and the disease appear, the opera- 

 tion will then be comparatively useless, and the only safe course is to at 



once cut off the diseased haulm and burn it. 

 Land which has borne a diseased crop 

 should be dressed with gaslime, and kept 

 free from potatoes for the next two or three 

 years. 



The rows of potatoes should always be 

 well earthed up, because the spores of the 

 fungus which fall to the ground from 

 diseased leaves are washed through the soil 

 by rain, and when the young potatoes lie 

 near the surface they thus become readily 

 infected ; a good covering of soil over the 

 tubers affords a measure of protection. 



POTATO LEAF CURL (Macrosporium 

 solani). Frequently in rows of potatoes 

 some plants will be found which are stunted 

 in growth, the leaves being small and curled 

 and blackish patches being present on 

 leaves and stem. The tubers are generally 

 infected before planting, though infection 

 Potato Leaf Curl. (Reduced.) may take place after planting from spores 



