258 THE MONTHLY BULLETIN. 



experimental spraying for several years. The general conclusion that 

 ]\Ir. Pierce and other workers arrived at was that the number of 

 blighted nuts could be reduced about 50 per cent. In 1905 the 

 University of California, at the Whittier Laboratory, tried out Bor- 

 deaux 5-6-50, also lime-sulphur spray, and a sulphur spray made by 

 boiling together sulphur and caustic potash. From careful observa- 

 tions made during the summer no difference could be detected between 

 the sprayed and unsprayed trees. Last year spraying experiments were 

 in progress at Goleta and are being continued this year. As Mr. Nixon 

 is to consider this topic later in the meeting, the results will be but 

 slightly referred to at this time. Last year M^as unfavorable for the 

 development of walnut blight and no difference in the amount of 

 disease could be detected between the sprayed and unsprayed trees. 

 This year the work was again repeated, using Ortho lime-sulphur made 

 according to the following formula : 5 gallons Ortho lime-sulphur, 

 25 pounds quicklime to 100 gallons of water. The trees were 

 thoroughly coated with the spray when in a dormant condition. 



Early in May observations were made on the spraying work of 

 this season at Goleta. This year is quite favorable for the development 

 of the walnut blight as shown in untreated groves. In the plot 

 sprayed for the first time this year with this lime-sulphur, there was 

 considerable blight on many of the sprayed trees. From this fact 

 it might be concluded that the spray was not entirely effective. The 

 general appearance of the trees is indeed striking. They are so 

 clean and vigorous in growth that they can be easily distinguished 

 from the unsprayed ones. In observing the experimental plots that 

 were treated last year and this year Avith lime-sulphur there appears 

 to be a marked reduction of blight. This same fact was noted in 

 the spraying work at Whittier, the effect seeming to show the second 

 year after using the lime-sulphur spray. The expense of spraying 

 with the modern ecpiipment has been reduced to approximately 50 

 cents a tree. This includes labor and materials. There is little doubt 

 that spraying year after year would have a cumulative effect in 

 reducing the amount of walnut blight. 



It is exceedingly difficult to check up spraying experiments on seed- 

 lings, even though they may be seedlings of the same tree. This differ- 

 ence in individual trees has been repeatedly observed by walnut 

 growers and indicated a probable immunity or strong resistance to 

 the disease. A natural immunity to walnut blight is a valuable 

 characteristic for a tree to have, although there are other equally or 

 more important ones. One of the chief reasons for the immunity 

 may be the time that the tree comes into blossom. The later blooming 

 trees are, as a rule, much more free from blight, possibly because 

 of the different climatic conditions. Varieties may appear to have 

 immunity in one place and yet when grown under different con- 

 ditions may show the blight. Freedom from blight in any locality 

 does not necessarily mean immunity, for the blight may not be present. 

 A tree, however, that shows freedom from blight for several years 

 when surrounding trees are badly affected, must have at least an 

 element of immunity. It is not my purpose to discuss in detail the 

 different varieties. Dr. Fitzgerald, in his address, will consider these 

 and also, doubtless, the question of immunity. 



