DISEASES DUE TO FUNGI. - RESISTANT PLANTS I707 



tions similar results were obtained from wintering experiments at Rocky 

 Ford, Colorado and IMadison, Wisconsin. 



2) Climatic conditions and the development of the leaf spot can only 

 be correlated when all records are taken at the same relative positions, 

 as shown b}^ comparison of the Weather Bureau records and the records 

 taken among the plants and 5 feet above the field. 



3) The maximum temperature earh' in the season is much higher 

 near the ground than it is 5 feet above, but the difference diminishes as 

 the season advances. 



4) Throughout the season the ma.ximura humidity was higher among 

 the leaves than 5 feet above the field. Earh' in the season while the plants 

 were small the humidity remained above 60 longer each da}^ at 5 feet above 

 the field than among the plants near the ground; but after the plants 

 attained a good size this condition was reversed. Because of this difference 

 onl}' records collected among the leaves should be considered in correla- 

 ting climatic conditions and conidial production and infection. 



5) The eft'ect of rainfall and irrigation on the increase of relative 

 humidit}' and its duration is apparently much the same. 



6) Thermal tests with artificial cultures showed that: 



a) exposure to constant temperatures of 35° and 36^ C. is fatal to 

 to the growth of the fungus; 



b) growth occurred when cultures after exposure for 3 da^^s to 

 either of these temperatiires, were changed to 30.8", and also when they 

 were held at either for 8 hours and then at 20° for 16 hours; 



c) a temperature of 40.5° was fatal in all combinations tested. 



7) Temperature and relative humidity' influence the production 

 of conidia and infection in much the same way. A temperature of 80° to 

 90° F., with a night minimum preferably not below 60°, is most favour- 

 able to conidial production, while it is checked by a temperature of 100° 

 or more, and is greatly checked by a range from below 50" to 80°. A maximum 

 humidity ranging above 60 for not less than 15 to 18 hours each day in- 

 duces a good growth of the fungus. 



8) Because of the greater degree of moisture on the lower than on 

 the upper side of the leaf the conidia are generalh" more abundant on the 

 lower surface of the spots, but because of the action of rain and wind they 

 disappear more rapidly from the upper surface. 



1227 - The Susceptibility of Phaseolus vulgaris to Haricot Rust (t/romyces resistant 



appendiculatus) (i). — Jordi, v.., in Zcitschrilt fiir Pllanzcnkrankhcitcn,\ol. 26, PLANTS 



Nos. 6-7, pp. 374-o75. Stuttgart, Sept. 16, iqi6. 



In 1915 the writer cultivated 5 varieties of Phaseolus vulgaris (Ohne 

 Gleichen, Blaue vSpeck, Sans Viacre, Phanomen, Klosterfrauen). The three 

 first were grown in one field, and the other two together with the first 

 one, in a second field. 



The second field, 98 ^-ards long by 27 yards wide, was divided into three 



(i) See B. August 1916, n. 933. {Ed. 



