SOYBEAN MOSAIC ' 



By Max W. Gardner, Associate in Botany, and James B. Kendrick, Assistant in 

 Botany, Purdue University Agricultural Experiment Station 



In a small field of Hollybrook soybeans in West La Fayette a typical 

 mosaic disease was found August 25, 1920. A rather low percentage of 

 the plants were affected, and the disease was more or less confined to 

 one quarter of the field adjacent to which were several rows of garden 

 beans affected with mosaic to a considerable degree. In another larger 

 field of soybeans in the same locality no mosaic was found. Leafhoppers 

 were very prevalent on the soybeans. The impression was gained that 

 the disease might have spread from the garden beans to the soybeans, 

 but as yet no evidence to support such a theory has been obtained. 



Clinton^ found soybean mosaic in 19 15 at Mount Carmel, Conn., and 

 under the name of chlorosis or crinkling has given an excellent account 

 of the leaf symptoms along with a good illustration. He found the 

 disease on the varieties Medium Green, Wilson, Swan, Kentucky, Wing's 

 Mikado, and Hollybrook, and states that the Hollybrook showed the 

 most marked symptoms. He found the chlorosis without the crinkling 

 on the varieties O'Kute, Ito San, and Manhattan. C. R. Orton ^ has 

 reported the occurrence of mosaic in a field of Ito San soybeans at 

 Girard, Pa., July 30, 1920. 



SYMPTOMS 



The mosaic symptoms on the soybeans were conspicuous and unmis- 

 takable, resembling those characteristic of mosaic diseases in general. 

 Affected plants were stunted, and petioles and intemodes were shortened 

 to some extent. The leaflets were stunted, greatly misshapen, and puck- 

 ered with dark-green puffy areas along the veins (PI. 18, A, C, D, B). 

 Between these puffy areas the leaf tissue was etiolated. Affected leaflets 

 tended to be asymmetrical, twisted, and curled downward about the 

 margins (PI. 18, D, E). As in other mosaic diseases, the young, rapidly 

 growing leaves showed the most severe effects, and in some cases whole 

 leaflets or portions thereof were extremely stunted or killed outright by 

 the disease (PI. 18, B). The mosaic symptoms were readily distinguish- 

 able from a uniform crinkling of the leaflets which was rather common 

 in this field and apparently attributable to insect injury. 



The pods on mosaic plants were stunted and flattened, less pubescent, 

 and more acutely curved than those on normal plants (PI. 19, C, D). 



' Contribution from the Botanical Department of Purdue University Agricultural Experiment Station, 

 I^a Fayette, Ind. 



2 Clinton, G. P. notes on plant diseases of Connecticut. In Conn. State Agr. Exp. Sta. Ann, 

 Rpt., 1915, p. 446-447, pi. 23a. 1916. 



3 Fromme, F. D. diseases of cereal and forage crops in the united states in 1920. In U. S. 

 Dept. Agr. Bur. Plant Indus. Plant Disease Bui., Sup. is, p. 173- 1921- Mimeographed. 



Journal of Agricultural Research, Vol. XXII, No. a 



Washington, D. C. Oct. 8, 1921 



zu Key No. Ind. -10 



(III). 



