156 THE MONTHLY BULLETIN. 



A tainted soil is as sure to result in fungous affection as affected seed. 

 Such poisoned soils are not quick to lose the toxic germs. It is believed 

 that six years, possibly eight, are required to rid tainted soil of the 

 fungous germs or the presence of nematodes. This explains why a long 

 rotation of crops, six or eight years^ so desirable in general agriculture, 

 is imperative in growing potatoes. The crops included in the rotation 

 should be such as would not favor the potato fungi. In Europe some 

 cereal occupies the last two or three years of the rotation. I need not 

 say that rich, well aerated soil, like that of a well kept garden, good 

 cultivation and abundant water are desirable in potato culture. It 

 pays richly to fertilize heavily. A generous supply of stable fertilizer, 

 nitrates, and phosphates in good ciuantity will pay well. I know a 

 potato grower who applied $50 w^orth of fertilizer per acre last year 

 and sold his potatoes for $150 per acre more than he received for those 

 grown in like soil not fertilized. In Great Britain and Germany whole 

 potatoes are planted, as a cut surface favors fungous attack; small 

 potatoes are also planted, but only from selected hills which had yielded 

 a large product of the best quality. Also in Europe rather immature 

 seed is favored, and time is gained by sprouting the tubers before 

 planting. 



EELWORM AND TUBER MOTH. 



This nematode and insect are also both enemies of the potato. Neither 

 is as serious as is Fusarium wilt or Rhizoctonia. The eelworm is more 

 harmful than the moth and is widely distributed, while the moth is not 

 found except in California and to a limited extent in three or four 

 other states. The nematode has attracted attention in California for 

 only a few years, but the moth has been known for more than twenty 

 years. Eelworms live for years and so are comparable to Fusarium wilt 

 and Rhizoctonia as destructive soil agencies. They cause an uneven 

 or mammillated surface on the tubers and darken the fleshy part, espe- 

 cially close to the peel. The roughened surface quickly reveals this affec- 

 tion, and eelworm potatoes should never be planted. The tuber moth 

 bores through the tubers and blackens the tissue. Keeping the potatoes 

 well covered during the entire growing season and removing all, even 

 the smallest, from the field as soon as dry after digging should never 

 be neglected. The potatoes should be placed at once in moth-tight sacks, 

 as the moths continue to work after the potatoes are stored and thus it 

 is imperative to carefully guard against their presence in the sacks, 

 pits, bins, boxes or cellars where the potatoes are stored. The solution 

 of the tuber moth problem only requires great caution. 



In order of damage from these several potato enemies we give the 

 following: Fusarium wilt, Rhizoctonia — a close second, eelworm, tuber 

 moth and potato scab. 



SUMMARY. 



1. Plant only on disease-free soil. 



2. Plant none but clean, sound seed. 



(a) That from hills of great production of best quality of tubers. 

 (6) That from hills where the vines were green and vigorous to 



maturity. 

 (c) That which is entirely smooth and perfect, showing no disease 



when cut. 



