1200 KESISTAXT PLANTS 



3) All the individuals of the 7 kinds of P. multiflorus studied were 

 exempt, with the exception of 2 belonging to 2 different kinds, in which the 

 Author was each time able to find a single leaf slightly attacked. 



Therefore these results confirm those obtained in the preceding re- 

 searches, and it is concluded consequently^ that P. multiflorus is practically 

 resistant to bean rust. Cases nevertheless occur where this species is likewise 

 attacked by Uromyccs, but they are so rare as to be without importance in 

 practical phytopathology. 



These experiments proved that there are differences in regard to rust- 

 resistant powers not only between P. vulgaris and P. multiflorus, but also 

 between the different varieties of P. vulgaris. Consequently the resist- 

 ance of the different kinds should be determined by cultivation experi- 

 ments continvied over several years. In the literature unfortunately little 

 information is given on this point. 



It was not possible to determine the cause of the immunity of P. mul- 

 tiflorus. It is well known that rust appears most frequently at the end of 

 summer, that is, at a time when the plant is already partly exhausted. It 

 was concluded from this fact, that resistance to rvist is connected with the 

 time at which the exhaustion of the plant takes place. This hypothesis 

 appeared particularly plausible when it was considered that P. multiflorus 

 lives longer than P. vulgaris. Closer examination however demonstrated 

 that this assumption is without foundation. It was shown that plants of 

 P. vulgaris which, owing to their very late plantation, were still in full 

 vigour and provided with young fresh foliage at the end of summer, already 

 contracted rust at this stage of development. Nevertheless, this question 

 should be still further studied by experiments in which the time of ex- 

 haustion is. accelerated by artificial means. 



Phaseolus multiflorus not only resists rust better than P. vulgaris but 

 is also more resistant to other diseases, above all bean anthracnosis which 

 appears on the pods and is caused by Gloeosporium Lindemuthianum Sacc. 

 and Magn. P. multiflorus therefore represents a species highly resistant to 

 certain fungal diseases. It therefore deserves to be more extensively grown, 

 the more so as the seed it produces is very good. 



934 - The Selection of Types of Tobacco Resistant to Thielavia basi'cola, in Amer- 

 ica. — Johnson James, in P/;y''o/'n^/;o/"^y, Vol. (->, No. 2, pp. 1 67-1 Si. Fig. 6. Baltimore, 

 M(l.,i9i6. 



Root rot in tobacco is caused by the fungus Thielavia basicola Zopf , which 

 attacks the roots only. Affected plants are characteristically stunted and 

 thus the yield is considerably reduced. Complete destruction of the plant is 

 rare. 



The disease remained unknown for a long time, and to the present day it 

 escapes notice in many cases, because the symptoms accompan^nng it 

 (retarded growth, yellowing of the lower leaves) are in the majority of cases 

 attributed to the advancement of the season or the unfavourable chemical or 

 physical properties of the soil. 



All kinds of tobacco are not equally liable to contract the disease 

 (see Table page 1201). 



