The nodulation and other adaptations of certain summer legumes

Data are summarized for a number of summer legumes on promptness with which each became inoculated and on their relative earliness, luxuriance of growth, palatability, and extent of injury by Mexican bean beetle and nematodes. Those found especially prompt in the spontaneous development of root nodules included Brabham cowpea, Laredo soybean, velvet bean, Common, Tennessee 76, and Kobe lespedezas, five species of Phaseolus from India, P. calcaratus, Strophostyles helvola, Crotalaria striata, and C. sericea. Somewhat slower in nodulation but also naturally well supplied ultimately with root tubercles were Runner peanut, beggarweed, hyacinth bean (Dolichos lablah.), mung bean, and wild sensitive plant (Chamaecrista nictitans). There was complete or nearly complete failure to form nodules spontaneously by navy bean, tepary bean, bush lima bean, Dolicholus minimus, Acuan, Daubentonia, Dalea, Sesbania macrocarpa, and S. vesicaria. The apparent anomalies involved in the contrasting nodules behavior of various species of Phaseolus, of two species of annual lespedeza, and of the Spanish and Runner varieties of peanuts suggest the probable need for extending the usually accepted list of races of bacteria symbiotic with leguminous plants. The list of legumes making most luxuriant growth included velvet bean, kudzu, Crotalaria striata, C. sericea, and Sesbania macrocarpa. Silage from Crotalaria sericea, guar, and sword bean, all surrounded for months in the silo by sorghum silage, was eaten with fair relish by cattle, but the fresh forage from each of these three species was wholly rejected. Uninjured by common pests were the following: (1) By the Mexican bean beetle, Crotalaria, Sesbania, guar, sword bean, Dolicholus minimus, Chamaecrista nictitans, annual lespedezas, and peanut; (2) by nematodes, beggar weed, Brabham cowpea, Laredo soybean, Crotalaria striata, guar, and Dolicholus minimus. Guar and Korean lespedeza were especially susceptible to a soil rootrot. Mung and urd beans were among the species most severely injured by leaf diseases. Only Kobe and Tennessee 76 lespedezas proved to be superior on the whole to comparable legumes now in general use. However, sufficiently promising for further experimentation seemed Crotalaria, Sesbania macrocarpa, beggar weed, the late acclimatized form of Phaseolits calcaratus, moth bean, and possibly Strophostyles helvola.