PLANTS NOT AFFECTED BY KOOT-KNOT. 

 Table I. — List of plants susceptible to root-knot — Continued. 



21 



Name of plant. 



{Cissus 



* Vigna unguiculata (L.) Walp. ( Vigna catjang, 



Dolichos catjang). Covvpea. 



* Viola odorata L. Violet 



Vitis aestivalis Michx. Grape 



Vitis labrusca L. Grape 



Vitis serianaefolia (Bunge) Maxim 



aconitifolia) . 



* Vitis vinifera L. Old World grape 



*Washingtonia filifera microsperma ' Beccari. 



California fan palm. 



*Washingtonia gracilis ' Parish 



Wilbtghbaea scandens (L.) Kuntze. (Mikania 



scandens) . 



*Zamia floridana DC 



^Zea mays L. Maize or Indian corn 



Name of observer. 



Neal. 



Halsted. 



Neal 



Licopoli. 

 Cornu . . . 



Neal. 



Neal. 



Neal. 



Date of 



observa- 

 tion. 



1889 



1891 



1889 



1877 



1879-2 



1899 



1899 



1889 



Charac- 

 ter of 

 Injury. 



a 

 a 



a 

 b 



1 Seed received under this name from Dr. O. Beccari. 

 PLANTS NOT AFFECTED BY ROOT-KNOT. 



Among the plants grown by the writer in infected land without 

 their becoming infected witli root-knot in the slightest degree were sev- 

 eral species of Stizolobiiim, the genus to which the velvet bean belongs, 

 viz, StizoloUum lyoni, S. pruriens, S. hir.mtum, and the velvet bean and 

 one or more other unidentified species of this genus.* Many of the 

 grasses seem to be resistant. Thus the writer has failed to find the 

 nematode on crab-grass (Syntherisma sanguinalis), redtop (Agrostis 

 alba), Johnson grass (Andropogon halepensis) , some varieties of oats 

 {Avena sativa)— hut some are susceptible— Bromus schraden, Eusta- 

 chys petraea, some varieties of barley (Hordeum vulgare), Lolium 

 perenne, J apsiuese barnyard millet (Echinochloa frumeniacea) , broom- 

 corn millet, or proso (Panicum miliaceum), pearl millet (Pennisetum 

 sp.), timothy (Phleum pratense), rye (Secale cereale), the various fomis 

 of sorghums, milos, Kafir corn, etc. {Andropogon sorghum), wheat 

 (Triticum aestivum), but see list of susceptible plants. The same is 

 true of com (maize, Zea mays) as of wheat. Euchlaena luxurians 

 was also free. Several Compositae seem to be free from the trouble 

 even where the nematodes are very abundant in the soil. Thus, 

 Bidens leucantha and B. hipinnata always were found free. Ona- 

 phalium, pur jmreum, Helenium tenui folium, species of Solidago, Zinnia, 

 etc., were also free. The absence of nematodes in the plants above 

 enumerated is far less significant than their presence in other plants, 

 for conditions may have been unfavorable, and yet under other con- 



1 Rolfs, however, 1898, reports root-knot on the velvet bean, and recently Prof. C. V. Piper has found It In 

 abundance on plants of Stizohbium pruriens, S. P. I. 215C0, grown in a greenhouse in Washington, D. C. 

 Evidently under certain conditions some strains may be susceptible, but as a rule It is immune. 

 217 



