BULLETIN 231] 



WALNUT CULTURE IN CALIFORNIA. 



357 



positive, 10 of the 1J inch diameter nuts negative and 3 positive, and 

 3 of the 1J inch diameter nuts negative and 2 positive. August 1st, 

 however, showed all of the 26 nuts to be more or less diseased. The 

 smaller nuts were covered with many different points of infection, while 

 the larger nuts had a much smaller number of diseased places, usually 

 about twelve on each. 



8. The following table shows that there was very slight infection in 

 the afternoon, when the sun was shining brightly and the spray from 

 the atomizer evaporated rapidly. The influence of the bright sunlight 

 would also kill many of the organisms in the liquid atomized on the nuts. 

 The nuts that were infected from the afternoon atomizing had very few 

 places of infection as compared with those of the early forenoon. The 

 atomizing in the early forenoon produced a large number of infections 

 one month after inoculation; those atomized in the afternoon showed a 

 very small percentage of infection as well as few points of infection : 



INOCULATIONS ON OTHER SPECIES OF JUGLANS. 



Puncture inoculations were tried on the several species of Juglans that 

 were available. These trees were not of an age to produce nuts, so little 

 atomizing was done. Experiments were made on the eastern black, 

 Juglans nigra; on the northern California black, Juglans hindsii; on the 

 southern California black, Juglans calif ornica; on butternut, Juglans 

 cinerea; on Japanese walnuts, Juglans cordiformis and sieboldiana. Be- 

 sides these experiments, others were made on several hybrids. Paradox 

 hybrid, a cross between the English and the California black walnut ; the 

 Royal hybrid, a cross between the eastern and California black. 



Eastern Black. These were seedlings that had grown two years in our 

 nursery from Iowa, black walnuts. Last season 's growth had been cut 

 off in grafting and vigorous-growing sprouts had come up from the roots. 

 Inoculations were from pure cultures on these vigorous-growing sprouts. 

 No difficulty was found in producing the typical disease lesions. 



