W. A. (IIITIIN. - Tlll': DKVKLOI'.MK.NT OF DISKASK HKSISTANT VAIUEIIKS «il' ITAMS. ->:,'.) 



UniletI Slales, where il is in gênerai cullivalion l'or green manuring, for forage 

 and for iiiiman foocl. The wiit diseasc duc to Fiisarium (raclteijj/iiluni Erw. 

 Sni. oceiirs more or less on sandy soil from Virginia to Florida and Texas. 

 Il is :ery similar in character lo llie collon wilt, bul owing to liie dilference in 

 Ihe slrucliire and physiology of llie planis, liie cowpea does not exliijjil llic 

 sudden wilting characleristic of liie collon. Itiil a graduai casling of Ihe leaves 

 précèdes dealh. 



In Ihe sanie dislricls tliere is widespread itil'eslaliuii by liie roulknol neina- 

 tode {lleteroilera radkicola ((Jreef.) Miil.), lo wliicli (lie cowpea is very suscep- 

 tible. Hundreds of other wild and cullivaled plants are altacked by H. radki- 

 rola ', but Ihe univcrsal use of Ihe cowpea as a forage crop and for green 

 manuring niakes ils susceplibilily of greal économie importance, since ils 

 culture on infecled fields resnlls in still grealer loss lo subseipicnl collon 

 crops. 



Our tcsis of cowpea varielies did not show Ihe occurence of exceplionally 

 résistant planls as liad bcen Ihe case in collon. AU of Ihe numerous soris in 

 gênerai cullivalion proved quile susceptible lo wiil as well as to roolknol, 

 excepl one variely, named Iroii, wliicli was discovered lo be practically imnuine 

 lo bolh diseases '-. 



AI the lime of ils discovery, Ihe Iroii C.nwpea was in cullivalion only in a 

 limited area in ceniral South Carolina. Ils origin is unknown. bul as wilt is 

 prévalent lliere, il niay be presumed lo be of chaiicc origin and lo hâve been 

 preserved by nalural seleclion. During Ihe pasi cleven years il has been 

 widely disiribiiled by the U. S. Deparlmenl of Agriculture and is now much 

 grown. Il has proved to be very valuable, especially where other sorls are killed 

 by disease. IL has preserved ils vigor and résistance perfectly, and has fur- 

 thermore proved lo be résistant to Rusl (Uromycen appcndivulalus (Pers.) Link.) 

 and lo leaf spot (Cercospora cruenta). Il is inleresling to note thaï il is suscep- 

 tible to Iwo olher fungi, Leaf-spot {Amerosjwrium oeconotnkum) and Mildew 

 {Eri/sijt/ii- jiohjgoni) both of wliich are forlunalely of lillle économie imporlance. 



The Iron Cowpea is of vigorous growlh and consequenlly désirable l'or 

 forage and green manuring, but is less fruilful Ihan many olhers. Il was 

 consequenlly desired lo produce a heavier yielding strain, and lo tliis end crosses 

 were made wilh olher varielies named Hiark. L'nknown, Whippoorwill and 

 ("alifornia Blaekeye. 



The crosses were made in Ihe Deparlmental greenhouses in wiiiler. The 

 first génération, grown iii Soulli Carolina, was uniform in chaiaclcr, ami 

 disease résistant. (Hesislance dominant). The second génération presenled the 

 greatesl possible varialion. A ç(jnsiderable number of Ihe planls were large and 

 vigorous, but produced no seeds. The necessily of securing strains Ihal were 

 at the same lime résistant lo bolh will and rool-knol ami of uniform seed color 

 and babil of growlh prolonged Ihe breeding <oiisiderably ; liul liiru llic wmk 



AyiiiuUuie. liureau of J'ianl liuluslnj. — WiiMjr \V. 1'. . Tlie llistdiv of llio Cow|ieii ami ils liiln.ihic - 

 lion inlo AiÈicric:i, ['. >S'. Dejuirlmeiil of Aijvindliiie, Hiirciiu of l'Iaiil Indusiri/. UuW. 102, Pai'l VI. 



1. IÎE>fEï (Dr. Knisl A.i. Roolkiiot U'. S. Deparlmenl of .l,/ririillMi-e. Iliaenu of l'hiiil liirliislr,/, 

 Bull. 217, l'.lll. 



2. Wiiuuiiii li.-.l.,. .ind (liiTuN (W.-A.;. Soirio lliscases ni llio (;..\v|ie:i : 



I. ïlio Will lliscasc ul llie Cowpc.-i ami Ils C roi. \V.-.\. Orliiii. 



II. A r,..\v|)ca UesisUnl lo Hool IvmoI Ihhr.idein ntrh',i,ol„. II.-,!., \\i.]M:hi! ajj<l W.-A. Oiim.v. /;»- 

 iroo of l'buil Iiidiislnj, Bull. 17. 



