POTATO 



POTATO 



523 



(10) The vigor. The variety and the strain se- 

 cured must be vigorous and not subject to second 

 growth of the tubers. 



(11) True to name. The variety should be what 

 it is purchased for. 



Many thousand varieties of potatoes have been 

 developed during the past hundred years. Among 

 prominent varieties of today may be mentioned : 



Fig. 750. Beginning of late blight on left. Eight spray good, 

 but showing a few holes made by flea-beetles. 



Earlies: Bliss Triumph, Early Ohio, Six Weeks 

 Market, Early Thoroughbred, Bovee, Reliance, Crown 

 Jewel, Noroton Beauty, Burpee Extra -Early, 

 Eureka, Early Rose (some strains). Second earlies: 

 Burpee Extra -Early, Eureka, Beauty of Hebron, 

 Polaris, Irish Cobbler, Early Rose (some strains), 

 Late : Carmen No. 3, Sir Walter Raleigh, Rural New 

 Yorker No. 2, Vermont Gold Coin, State of Maine, 

 Green Mountain, Freeman, Burbank. 



Potatoes sometimes sport or " mix " in the hill, 

 and these bud-sports may be treated as new varie- 

 ties. Practically all the new varieties of potatoes, 

 however, are produced from seed, for every seedling 

 is likely to be different from the parent. Seed-balls 

 are not produced abundantly on most varieties. If 

 it is desired to produce new kinds, the seed should be 

 saved and treated as tomato seed is treated, being 

 planted the following spring. The first year the 

 plants are small and slender, and the tubers will also 

 be very small. These tubers are saved and planted 

 the next year, when a crop of good-sized tubers may 

 be expected, showing their characteristics. If it is ' 

 desired to combine features of two varieties, the 

 flowers may be crossed ; and the resulting seed will 

 produce hybrids. 



Harvesting and storing. — Early potatoes are dug 

 as soon as large enough for sale. Late varieties 

 are left until the vines are dead ; should the vines 

 be killed by blight and it is intended to store the 

 tubers, the digging should be delayed, if possible, 

 until ten days after the date the vines died. The 

 grower should harvest when the land is dry, pick 

 up the tubers at once and keep them cool. In stor- 

 age the tubers should be held between 32° and 40° 

 Fahr., be well ventilated and kept dark. 



Potatoes may be stored in the open, in piles 

 covered with straw and earth, in cellars or rootN 

 houses according to the climatic conditions. In 

 the northern states the cellar is the most advan- 

 tageous, since the conditions can be more easily 

 controlled, and the crop may be inspected or sold 

 at any time. The cellar should be kept dark. With 

 sound tubers, the loss in weight in storage may 

 vary between 5 and 20 per cent in the five winter 

 months. Both temperature and the moisture con- 

 tent have an influence, a high temperature increas-j 

 ing and a high moisture content diminishing the 

 loss. Nobbe found that about 75 per cent of thei 

 depreciation is loss of the water content. 



Enemies. 



Diseases. — In the northern and north-central . 

 states the two most serious diseases are the early 

 and late blights. The early blight (Alternarid 

 solani) is a fungus which attacks the leaves, enter- 

 ing frequently through holes made by flea-beetles. 

 It comes on earlier in the season than the late 

 blight and does not cause rot of the tubers. The 

 late blight (Phytpphthora infestans, Figs. 750, 751, 

 752), another fungous disease, injures and often 

 destroys the leaves, stems and tubers,- and is prob- 

 ably familiar to most growers. These diseases 

 spread by means of spores which germinate on the 

 potato leaves and stems and produce the fungus: 

 that causes the diseased appearance. If the leaves 

 and stems be kept coated with some fungicide, as 

 Bordeaux mixture, it prevents the germination of 

 the spores and helps to check the spread of the 

 disease. 



Potato rosette attacks the stem, causing the 

 leaves to grow in clusters. It re- 

 duces the yield in many parts of 

 the country. The disease is caused, 

 in part at least, by Corticium 

 vagum solani (Rhizoetonia solani). 

 One form of this fungus develops 

 scale-like bodies on the tubers, 

 causing the "black scale" of 

 potatoes. 



Scab (Oospora scabies) is a fun- 

 gous disease which appears on 

 the tubers. For treatment, the 

 seed tubers should be immersed 

 for two hours in a solution of 

 formalin of the strength of one 

 pound of formalin to thirty gal- 

 lons of water. If the seed is not 

 planted at once, it should be 

 spread thinly to dry, and should 

 be planted on scab-free soil. 



Dry-rot (Fusarium oxysporum). 

 — This disease attacks all parts 

 of the plant below ground and 

 produces a gradual premature 

 death of the plants. Infected 

 tubers rot and shrivel. This fun- 

 gus causes more or less loss to the potato crop in 

 all sections of the United States. 



A good and rather long rotation of crops is of 

 value in combating all of these diseases. 



Fig. 751. 



Shoot kiUed by 



blight. 



