16 



Walter H. Burkholder 



of the bacteria, and no 

 mechanical injury was 

 made in the plants, the 

 results were variable. 

 Environmental condi- 

 tions favorable for in- 

 fection under such cir- 

 cumstances are not yet 

 sufficiently understood. 



Cross inoculations 



Inoculation experi- 

 ments were conducted 

 on a number of legumes 

 which are listed in table 

 3 (page 77) . On the sieva 

 bean (Phaseolus lunatus 

 L.), the scarlet runner 

 bean (P. coccineus L.), 

 and the hyacinth bean 

 (Dolichos lablab L.), the 

 symptoms produced by 

 the disease were very 

 similar to those on the 

 common bean (P. vul- 

 garis L.) . Good infection 

 was obtained also on the 

 white-flowering lupine 

 (Lupinus polyphyllus 

 Lindl.). With this spe- 

 cies, inoculations were 

 made by pricking the 

 crown and introducing 

 the organism. A wilt of 

 the leaves and the petioles 

 resulted, and the patho- 

 gene was easily recov- 

 ered from the leaves. 

 Gardner (1924) reported Strophostyles helvola (L.) Britton as a host of 

 Phytomonas phaseoli, but this species was not used in these experiments. 

 In 1924 the writer reported some inoculation experiments on various 

 species of legumes grown in the garden with some varietal susceptibility 

 tests of P. vulgaris (Burkholder, 1924). In the light of the present series 

 of carefully conducted experiments in the greenhouse, the former inocula- 



FlGURE 2. WILT OF BEAN SEEDLING CAUSED BY PHYTO- 

 MONAS PHASEOLI 

 The seedling was artificially inoculated at the cotyledon node 



