622 



SWEET-POTATO 



SWEET-POTATO 



disturbing of the potatoes in the bin results in 

 their destruction. It is necessary, therefore, when 

 a bin is once opened to keep shipping continuously, 

 say two or three times a week, otherwise the exposed 

 potatoes may begin to decay. 



A large part' of the sweet-potato crop is shipped 

 in three-bushel barrels, the same size as the apple 

 or flour barrel. Occasionally "snide" or irregular- 

 sized barrels are used, but these do not ordinarily 

 pay the shipper. On the other hand, potatoes may 

 be shipped in sugar barrels and large packages of 

 any kind when they are sold by weight. In New 

 Jersey, Delaware and Maryland a one and one-half- 

 bushel basket made or fashioned after the Delaware 

 peach basket has come into use. Some of these hold 

 a bushel' and some one and one-fourth bushels. 



In shipping in winter it is necessary to use con- 

 siderable care to avoid having.the stock frozen, 

 though it will stand considerable cold if not too 

 long exposed. On the other hand, sweet-potatoes 

 frequently suffer from the heat. The disturbance 

 of sorting and barreling causes them to sweat. If 

 they are shipped in open-head truck barrels under a 

 burlap cover, the cover should be removed on their 

 arrival on the market. In warm weather it is often 

 better to bore several ventilating holes an inch in 

 diameter or with a hatchet to remove a chip from 

 several parts of the barrel. 



The Yellow Jersey type of potato is usually pre- 

 ferred by northern markets. On the approach of 

 warm weather, however, in March and April, this 

 sweet-potato ordinarily loses quality and becomes 

 slightly out of season. Of late years the trade in 

 the so-called yam or sticky sweet type of potato 

 has increased, especially for the spring and early 

 summer trade. Southern people usually prefer the 

 yam type of sweet-potato at all seasons. Some of 

 the yams keep better, or actually improve in quality 

 in the spring of the year, and these yams may be 

 kept through to June or July, when sweet-potatoes 

 from Florida and the Gulf coast begin to arrive. 

 The result is that the market is continually sup- 

 plied with this vegetable throughout the year. As 

 a rule, growers of the Yellow Jersey close out their 

 stock in March. April is the season for bedding, so 

 that attention is then given to the seed bins. 



Enemies. 



The crop of sweet-potatoes grown in the field is 

 generally remarkably healthy and free from both 

 fungous diseases and insect enemies. However, 

 there are some pests on the foliage and some very 

 serious diseases on the roots. 



Black-rot (Ceratoeystis fimbriata). — This disease is 

 more troublesome in the storage house and hotbed 

 than it is on the crop in the field. It is a pronounced 

 fungous disease and usually appears as large, irreg- 

 ular black spots, slightly sunken in the skin of the 

 potato. On cutting or breaking them open, these 

 spots are found to be deep, usually extending 

 through the skin and sometimes into the central 

 part of the potato. They are of a peculiar blue- 

 black tint, ordinarily distinguishable from ordinary 

 rots or other fungous diseases. Even though sweet- 

 potatoes may be apparently free from disease when 



placed in the storage house in the fall, this rot 

 often develops badly. The infected potatoes are 

 rendered bitter and worthless, and are unsalable 

 when the spots are bad. Black-rot is particularly 

 objectionable in the seed-roots, as when these are 

 bedded the disease is started in the hotbed producing 

 the so-called "black shank" or black-rot of the 

 plants. The failure of black-rot-infected plants is 

 more pronounced during the cool, moist weather 

 than during a hot spell. In fact, on a vigorous 

 variety the disease is largely outgrown during 

 favorable hot weather. 



The best remedy for black-rot is the use of slip- 

 seed. It is advisable to grow the crop of vine 

 cuttings on new land which is not infested, or on 

 land which has never grown sweet-potatoes or has 

 not been in sweet-potatoes for several years, thus 

 making an absolutely clean start, even though the 

 vine cuttings are taken from an infected crop. 

 Another remedy is to clean and sweep the storage 

 house both overhead and underneath before putting 

 in the potatoes, and whitewash the entire interior 

 of the house with a spray pump. The addition of 

 boiled lime and sulfur to the whitewash would 

 undoubtedly be an improvement. The whitewash 

 would then consist of the ordinary lime-sulfur wash 

 thickened with lime. The hotbed should have all 

 the old soil removed, and the boards and (in the 

 case of a fire hotbed) the floor thoroughly white- 

 washed with freshly slaked lime before new earth 

 is put in. The new soil should be from ground that 

 has never been in sweet-potatoes. Early bedding 

 and early planting out in the field are objectionable, 

 as they put the crop at a disadvantage. In the same 

 way, digging late in the fall encourages black-rot, ■ 

 while early digging just before the first frost, when 

 the weather is still warm, seems to be particularly 

 desirable. The black-rot is the worst of the dis- 

 eases of the sweet-potatoes. 



Soil rot {Acrocystis Batatas) is injurious to young 

 roots in dry seasons. The diseased part ceases to 

 grow. Crop rotation and the application of kainit 

 or sulfur at the rate of 300 pounds per acre are 

 suggested remedies. Soft rot (Bhizopus nigricans) 

 occurs in the storage house during the curing pro- 

 cess. If the potatoes are dry before storing it is 

 not likely to be troublesome. Affected potatoes 

 should be destroyed. Other diseases of little im- 

 portance are white rust, white rot, stem rot, dry 

 rot, scab and leaf spot. 



Among insects, sweet-potatoes are attacked by 

 the weevil, plume moth, tortoise beetles, sawflies, 

 cutworms, flea-beetles, crickets and tobacco worms 

 [See Index]. The weevil (Cylas formicarius) is a 

 small bluish black insect that deposits its eggs in 

 recesses at the base of the vine or at the upper 

 end of the root. The white grubs burrow in the 

 vine and down into the roots, which they destroy. 

 The remedy is to feed or completely destroy all 

 infested vines and roots. The plume moth (Ptero- 

 phorus monodactylus) is a silver-brown insect bear- 

 ing black lines on the forewings. It is the larva 

 of this that is destructive to sweet-potatoes by 

 feeding on the leaves. The use of arsenical sprays 

 (one pound to twenty-five gallons of water) will 



