356 



UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



by using a solution of water and diseased nuts. May 21st six nuts were 

 attached and four of these were diseased, each on one to four places. 

 Other nuts on the tree were free from blight. 



6. Atomizing at Various Hours of the Day. June 8, 1907, small nuts 

 were atomized at different periods, 9 to 10 a. m., 5 to 6 p. m. The 

 results are tabulated in the following table : 



The results from experiment 6 show no difference in the infecting 

 power of the organism for the different hours of the day. The day was 

 bright, sunny and warm. Another interesting fact was that the orchard 

 was being irrigated at the time the atomizing inoculations were made. 

 The ground continued to be wet for about a week after the experiment 

 was made, and the results were exceptionally fine, as all the inoculations 

 showed many points of infection. The nuts treated, with hardly an ex- 

 ception, were all badly blighted with hundreds of points of infection. 

 The extreme virulence of the infections are probably because of favor- 

 able external conditions, due without doubt to the additional moisture 

 in the air from the evaporation of the irrigation water. On this tree, 

 as well as on trees in orchard not treated, no additional development of 

 blight occurred, and it is not probable that irrigation in any way in- 

 creases the amount of blight in an orchard, as at the time walnut 

 orchards are irrigated the conditions necessary for carrying the germs 

 from the sources of infection are usually lacking. From our field obser- 

 vations we have never associated in any way an increase of blight with 

 orchard irrigation. 



7. July 2 and 3, 1907. Atomized twenty-six nuts of different sizes, 

 as follows: 5 nuts 1J inch diameter, 13 nuts 1J inch diameter, 8 nuts 

 If inch diameter. The weather at this time was very bright and hot, as 

 it was for several days following. The temperature was about 100 F. 

 during the middle of the day. The atomizing was, however, done be- 

 tween 5 and 5 :30 p. m., when it was somewhat cooler. The results on 

 July 16th showed' 5 of the If inch diameter nuts to be negative and 3 



