SWEET POTATO PESTS 



1955 



Black Shank. See Black Rot, this 

 section. 



Dry Bot 

 Phoma 'batatae Ell. & Hals. 



Occurs on underground parts, causing 

 wrinkled and pimply appearance. In- 

 side of potatoes turn brown and become 

 dry and powdery. Rotate crops. Gather 

 and burn diseased potatoes. Plant clean 

 stock. 



Soil Eot 

 Acrocystis "batatas Ell. & Hals. 



Soil rot is a serious disease of the 

 sweet potato for which the following 

 treatment has proved successful. 



Bake a mixture of six parts earth to 

 one part flowers of sulphur and drop in 

 handfuls where the plants are to be set 

 and set the plants through this mixture. 



Literature 



New Jersey Experiment Station Bulle- 

 tin 126. 

 Soft Rot. See Bin Rot, this section. 



Stem Kot or Yellow Bot 



Nectria ipomoeae Hals. 



Appears as dark streak on stems and 

 upper ends of potatoes at or near sur- 

 face of ground, causing vines to die and 

 extending downward into roots, causing 

 potatoes to rot. 



It is necessary to have clean seed, the 

 hotbed surrounding must be free from 

 the organisms, and the plants must be 

 set in soil which is free from disease. 



Rotation so as to bring sweet potatoes 

 onto the same soil not oftener than three 

 years is advised. 



SWEET POTATO PESTS 

 Cutworms 



*Under some conditions and in some 

 seasons cutworms do considerable mis- 

 chief in sweet potato fields, and their in- 

 jury is always clean-cut and readily rec- 

 ognizable. The plants are cut off close 

 to the surface and the heart is chewed out 



Remedial Measures 



If by some misfortune a field is found 

 infested after it is set with plants, the 

 cutworms can be cleaned out by using 



*New Jersey Experiment Station Bulletin 229. 



poisoned bran. For some reason bran is 

 very attractive to these insects, and they 

 will take it in preference to even succu- 

 lent plant-food. Mix one pound white 

 arsenic or Paris green with fifty pounds 

 of bran and five pounds of powdered 

 sugar; add water enough to moisten 

 thoroughly, so that it can be ladled out 

 without dripping. The sugar will hold 

 it together and a spoonful to a hill of 

 plants will attract every cutworm in a 

 field in two or three nights, absolutely 

 cleaning them out. No one who has not 

 tried this method carefully can realize 

 how complete is the remedy. 



The Gold Bugs or Tortoise Beetles 



The leaves of the newly-set plants are 

 apt to be eaten into irregularly, and some- 

 times altogether devoured before they get 

 a fair start at growth; and even in the 

 forcing bed such eating may appear to 

 some extent. The authors of this injury 

 are called "tortoise beetles" from their 

 shape, which is a somewhat squared oval, 

 very flat beneath, and not very convex 

 above, or "gold bugs," from their beauti- 

 ful color, some of them looking like drops 

 of molten gold. There are four distinct 

 species of these beetles — two-striped 

 sweet potato beetle, golden tortoise 

 beetle, black-legged tortoise beetle, and 

 mottled tortoise beetle — ^but their habits 

 are so much alike that, for convenience, 

 they may first be considered together. 



Gfeueral Life History 



The insects live through the winter in 

 the adult or beetle stage in crevices, 

 under bark, and in similar dry places 

 wherever they can find shelter. They 

 make their appearance in May, when 

 warm weather has fairly set in, and feed 

 on any Convolvulus plant that is avail- 

 able, favoring sweet potato in every in- 

 stance. At first they favor the under 

 side of the leaf, eating round or oval 

 holes until the tissue is so much eaten 

 that they take it as they can get it, and 

 leave only the larger veins and leaf 

 stalks. They continue feeding until after 

 the middle of June, but usually disappear 

 before the end of the month. 



