18 



dust form, one pound of arsenate of lead powder should 

 be thoroughly mixed dry with from ten to twenty 

 pounds of air slaked lime, or dry wood ashes, and dust- 

 ed thinly on the leaves of affected plants. If a spray 

 is preferred, use one pound of arsenate of lead powder 

 to 50 gallons of water, and apply with spray-pumj). 



No danger of poisoning. — The cabbage heads from 

 within outwards, not by a folding in of the outer leaves 

 as is occasionally supposed. There is no danger of. 

 poisoning therefore if the remedies here suggested are 

 used prior to the time the head is half-formed. Most 

 of the cabbage, especially throughout the northern i)art 

 of the country, is thus treated with arsenical jjoisons 

 for cabbage worm control. Chemical tests have shown 

 that it would be necessary to eat many hundred pounds 

 of cabbage at one time to convey a poisonous ([uantity 

 to a human being three weeks after the treatment is 

 given. 



The lutrleqnin cabbage bug, or "calico-back" (Miir- 

 gantia histvionica) . which sucks sap from the leaves 

 of cabbage and other cruciferous plants, cannot ])e 

 destroyed by the use of arsenical or stomach poisons. 

 They are also very resistant to kerosene enudsion. 

 Clean culture and hand-picking are imj)ortant measures 

 of control. This insect is more troublesome on the late 

 crops than on early cabbage. Mustard, planted early, 

 or in advance of the later crops, may be used as a trap- 

 crop. The bugs will first congregate on the nuistard 

 and deposit quantities of eggs thereon. The nuistard 

 may then be sprayed with pure kerosene, or covered 

 with straw and burned. 



Root-knot: — Roots attacked become knotty at irregu- 

 lar intervals. The trouble is caused l)y tiny worms 

 (nematodes) which are ])resent in old southern garden 

 soils, especially those which are light and sandy. Since 

 nematodes cannot live on the roots of all kinds of 

 plants, it is possible to ])artly starve them out by prac- 

 ticing rotation of croi)s. Some of the |)lants on which 

 nematodes do not live are corn, oats. Iron and Brab- 

 ham varieties of cow-peas, peanuts, velvet beans, and 

 crab-grass. 



Clnb-Root: — This disease is caused by the presence 

 of a myxomycete, Plasmodioj)hora brassirae, (a low 

 form of |)lant life) within tlie cells of the roots, and is. 



