238 Early Studies in Bacterial Plant Diseases 



he wrote of his work in the San Joaquin and Sacramento valleys, 

 and referred to his " nearly 1000 acres of raisin grapes in the 

 Lucerne Vineyard" at Hanford where he had spent some seven 

 weeks in very warm weather. " I made 10 new crosses among 

 the raisin grapes during my stay there," he reported, 



which involved the emasculation of something like 16,000 to 20,000 grape 

 flowers. . . . But if we can only grow the vines from them I shall feel 

 abundantly repaid for this hard work. . . . The crossing of the raisin 

 grapes is a line of work very important to this portion of the world and 

 to all vine growing or rather raisin producing countries. . . . The whole 

 world does not contain more than 12 to 15 good raisin varieties, while 

 the good wine grapes may be numbered by the hundreds if not thousands — ■ 

 and the table varieties are not far behind in number. This shows you the 

 newness of the field so far as raisin grapes are concerned, and I know of 

 no good reason why California should not be the birthplace of hundreds 

 of good raisin grapes especially adapted to its climate so as to hold their 

 fruit and be comparatively free from other troubles. As I have started 

 this line of work I think I will keep it up each spring. The field is 

 certainly a most fertile one and wholly unoccupied so far as I am aware. 

 The chances are all favorable to the production of most valuable grapes 

 for this region. The work has in direct view the prevention of Coulure 

 by the production of a hardy variety which will resist the unfavorable 

 climatic conditions as the Malaga now does. 



Pierce had not conquered the California vine disease, although 

 Galloway reported in 1893 that during the " past season . . . the 

 disease [had] lost much of its virulence." ^^ He took its study into 

 his indoor laboratory, and, along with microscopical examinations 

 of Plasfuodiophora brassicae, persisted with this research which 

 he recognized to be on '"the very frontier of vegetable pathology." 

 He had no doubt that what he characterized as " constitutional 

 effects were physiological effects." He asked Galloway in a letter 

 of October 17, 1893, 



Why are not the peculiar characters of this trouble showing in that 

 valley of 40,000 to 50,000 acres of Muscats and a large extent of wine 

 vineyards.^ Why does a perfectly ripened cutting from a diseased vine 

 produce a diseased vine in a region where this disease was never seen 

 before.? 160 acres of Muscat cuttings died with this disease in Arizona, 

 and still Arizona vines do not die with this disease so far as I am able to 

 learn. 



If the disease was wholly a physiological trouble, he could not 



" 1893 report, supra, 274. 



