I 



ABSTRACTS OF PLBLICATIOXS OF THE \r,RlC!lTrR\L EXPERIMFNT STATIONS IN 



THE IMTEII SFATES. 



Alabama College Station. Bulletin No. 36. March, 1892 (pp. 32). 



Some lkaf blights of cotton, G. F. Atkinson. I'n. li. (plates 

 2). — Tliis inclinle.s articles on the yt'llow and red leaf hli^dit.s of cotton. 



YdUnc Irtif hll;/lit (pp. L'-.'51 ). — L'mh'i- this iiaiin' invest iy:atioii.s on the 

 disca.se coniniuidy known as lihick iiist are reported. In vi«'\v of the 

 confnsion exi.stinj; in rejjard to tlie ap]»Ii<ation of the term "mst" to 

 di.seases of cotton, the anthor nrj;es the adoption of the name yelh)W 

 leaf bli^rhi for the parlicnlar disease dcscrilx-d in this Itnllrtin. In a 

 jneliminary report on investiuations of thi.s disea.se in llnMetni No. 27 

 of the station (see Experiment Station l{«'cord, \ol. in. p. 7) it was 

 stated that several sjiecies of t'uugi '' i>Iay an impintant jtart in thedis- 

 ea.se." Later investi^^itions have shown tlnit whih' these or;:anisms 

 agjjravate the disease they do not cansc it. Yellow leaf ltli<;ht is fonnd 

 to be a ]>liysiol(i;;ical disca>;c dnc to impcrtcct nutrition »)r assimilation. 



TIk- ollVct of tills ili-lii-i(«ii<-y, citlicr in iiiitritii)ii or iisMiinil.-ttion. is hIiowii in a par- 

 tial iliHorj^anizatiun of flio ('hl<>ni|i|iyll or ;ircfii Niiltstanco wliich (•.•inscs it to heounie 

 yellow in ri>l(ir. At lirst this chan^f in «t>I(»r is (piitf inilistiiit-t, bnt ;;ra<lnally 

 beconu's more iiiaikt'<l. nut il it is ]tlainly soon. WIhto this taki-s plaoo it jjivos to the 

 leaf achoi'ki-roil ap))oaranr<'. the cells ah>u^ the eliannels in the veinlots whioli hound 

 the yellowish areas reinaininj^ quite jjreen for some time. Sunietinies the diHCJise 

 progresses more rapidly so that the smaller voins are also yellow and it is only along 

 quite close to the larger veins and thi'ir hranehe.s that the green cidor is present. In 

 thefnrtlu-r jtrogre.ss of thedisease. if the woathereontinues (piitedry, the leaf after 

 a while will gradually dry, herome shriveled, and fall off. If rain and hot weather 

 succeed each other, semiparasitic timgi grow in the leaf, absorbing the living sub- 

 Btan<ofor their own growth. •• « • 



We are not at jjresent in n position to say with « crt.tinty whether it is intluced 

 by the lack of sonic nutritive clement in the soil or whether the i>hysieal condition 

 of the soil h.is become dcr.aiiged either by hmg cuiti v:ition, by washing away of the 

 surface soil, or in some cases by an original detrimental jihysical con<lition of the soil, 

 when the disea.se is said to apjiear any \ ear under .'ill cunditions. It is certainly not 

 exclusively line to an impo\«"rish<'d condition of tin- soil, for it appears in some of 

 the richest lands of the State. It may be that both of these couditituis are nmre or 

 less responsible for the trouble. 



