458 Forms of the Hop Resistant to Mildew 



With regard to the nine seedhngs of the "wild hop" from Italy, 

 the seed was kindly sent to me by Prof. P. A. Saccardo in 1913, labelled 

 "Semina H. Lwpuli, Oct. 1913. Vittorio (Treviso), ad sepes, omnino 

 sponte. In Italia Hmmdus non colitur." Subsequently, however, 

 I was informed, in 1915, by Dr M. Corvi, of the R. Instituto Superiore 

 Agrario, of Perugia, that in the years 1860-70 the hop was cultivated 

 near Bologna "with good results," and that experiments with its culture 

 were now being conducted in Umbria ; thus the certainty of hop-seed 

 obtained from Italy being that of the truly wild H. Lwpulus appeared 

 to be called in question. The following information, however, supplied 

 by Prof. P. A. Saccardo in April, 1916, makes it practically certain 

 that the parent plant of the resistant seedlings was the wild species:— 

 "Apres investigations chez mes collegues Mittirolo, Peglion, Beguinot, 

 &c. je peux vous assurer, — Vhouhlon n'a ete jamais cultive dans la 

 province de Treviso d'oii je vous I'ai expedie et ou il se trouve sauvage 

 partout abondammenf , surtout sur les haies. M. le prof. Peglion qui va 

 publier dans ce moment un Monografia del luppolo in Italia m'ecrit de 

 Bologna que en toute Italic on cultive: 3 hectares de houblon dan? la 

 plaine d'Orvieto et dans I'haute-plaine de Alfina (Ombria), | hectare a 

 Pedavena (Feltre). Comme vous le voyez vous pouvez etre sur, tres sur, 

 que les exemples que je vous ai expedies sont absolument sponfanes et 

 sauvages." 



Some of the KeedUngs of the same Italian parentage which have been 

 planted out in the hop-garden have proved to be extremely susceptible 

 to the mildew, far more so than any of the numerous cultivated varieties 

 planted round them. 



It is clear, then, that the species H. Lupulus in its wild state comprises 

 forms which may be either very susceptible or very resistant to the 

 attacks of S. Humuli. Whether these forms are identical morphologi- 

 cally or not, cannot be determined until a detailed comparison of the 

 mature plants becomes possible. 



With regard to the form with yellow leaves, Messrs Bide inform me 

 that they bought the plant from M. G. Benard, of Orleans, France. 

 I have not been able to obtain the history of its origin. 



Neger, in 1902, pointed out the possibihty of the existence of 

 "immune races" among mildew-susceptible host-species, and de- 

 scribed (ii) instances where individual plants of Spiraea Ulmaria and 

 Epilobium nwntanmn resisted all infection from the conidia of the 

 Sphaerolheca {S. Humnli) on the same host-species respectively. In 

 another case a plant of Ranunctdiis repens proved immune under 



