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E. S. Salmon 309 



in my garden here. My garden records show that these clones did not 

 do very well, and that at present only three plants of Number 7 A 

 remain. These, however, are all pistillate plants and have regularly 

 borne a few clusters of hops. You can see therefore that I am quite at 

 a loss to account for your staminate plants under Number 7 A." 



The only references that I have been able to find on the subject of 

 the resistance to mildew shown by diffeient varieties of hops in the 

 United States are the statements made by Prof. F. M. Blodgett. In 

 1913 this author wrote(5): "Thus it happens that the disease may not 

 appear on the Cluster hop — the leaves of which appear to be more 

 resistant than do those of the Canada, or red-vine, variety — until 

 flowering time, when the mildew often spreads rapidly through the 

 yards of Cluster hops, attacking the young flowers and later the hops." 

 In 1915, Prof. Blodgett wrote («): "Different varieties and even different 

 leaves on the same plant vary in susceptibility. Named in order of 

 susceptibility beginning with the most susceptible, the New York varieties 

 would be arranged as follows: Canada red vine, English clu.ster, Hum- 

 phrey and native red vine. No serious injury has been noticed, so far, 

 on the native red vine variety though planted near badly infested yards 

 and, in some instances, scattered through yards of a susceptible variety. 

 It is said to be a light yielder, however." In a letter, dated Feb. 4, 1918, 

 Prof. Blodgett wrote to me as follows: "I have found in the vicinity of 

 Milford, Cooperstown, and East Springfield, in New York State, one 

 variety of hops, the so-called ' Native Red Vines,' which appear almost 

 entirely immune to the mildew. I have frequently seen yards in which 

 this variety was mixed with very susceptible varieties, where the vines 

 intertwine in many places, and still the Native Red Vine hops remained 

 immune. Unfortunately, however, this hop is not a very desirable variety 

 being a rather light yielder and has not appealed on that account to the 

 growers. In 1914 a fellow in this department attempted making crosses 

 between this and the more desirable commercial varieties in order to 

 secure a good variety that was immune to the malady, but unfortunately 

 this work was discontinued and was never completed." 



Summary. 



1. Several forms of H. Lupulus with yellowish-green ("golden") 

 leaves exist. One form ( ?) has proved persistently immune to mildew 

 both in the greenhouse and in the open. A second form ( 9) has proved 

 slightly susceptible when grown in the greenhouse. A third form (o) 



21—2 



