leO Journal of Aijr'tciiVture, Victoria. [10 March, 1916. 



favorable for further development. Wliile these stomata have the 

 power to open and close, they are probably never so closely shut that the 

 small germs could not enter. The moist conditions favorable for the 

 entry of the germ, or bacterium, through the stoma are also just the 

 conditions necessary for keeping this entrance open. 



Non-blighting of Late Blooming Trees. — The majority of the bearing 

 groves of California are at this time year 1908 seedling trees, differing 

 greatly in their blooming periods. The difference in time is frequently 

 from one to tvv^o months, and may be as much as three months between 

 the earliest and the late-^t French varieties. Such a wide range in time 

 of blooming gives considerable chance for difference in climatic condi- 

 tions. "We find that the early or medium blooming trees are in blossom 

 at a favorable period for the blight to develop, Avhile the late bloomer'^ 

 come into flower at a time when bacteriosis can make little headway. 

 Particular attention has been given to this phase of our investigation, in 

 the hope of finding a commercially profitable tree that blooms at a 

 season when conditions for the infection of the small nuts is at a 

 minimum. While this work is not yet completed, enough has been done 

 to show that nuts in such late trees are comparatively free from the 

 disease.* 



Immunity. — Certain trees are some times spoken of as being immune 

 to the blight, but while there is probably no such thing among walnuts 

 as absolute freedom from this disease, where conditions are favorable for 

 blight infection, yet some trees do show quite a marked resistance, and, 

 if otherwise desirable, are given precedence in new plantings on this 

 account (variety Eureka, for instance). It may be that in certain 

 localities there is no blight, but this probably is not due to any immunity 

 that the trees possess, but is rather the effect of climatic conditions, or 

 due to the fact that the specific organism has not yet reached this par- 

 ticular locality, t 



Snraving to Control Bacteriosis. — American experiments. — In the 

 spring of 1906, several large blocks of good-sized seedling trees were 

 selected for this purpose in the vicinity of Whittier, and spraying opera- 

 tions were commenced. The principle experiments w^ere made with 

 tbree different fungicides — Bordeaux mixture, lime-sulphur, and -^ 

 sulphur spray made by boiling together sulphur and caustic potash. The 

 work was done with a power sprayer, and was carried on more thoroughly 

 and carefully than any grower would be likely to do such spraying, and 

 without regard to expense. In one instance a large block of trees was 

 «prayed with Bordeaux mixture, using a 5.6.50 formula; in another, a 

 heavy lime-sulphur was used, the spray being prepared by boiling ; while 

 in the third the potash-sulphur spray mentioned above was used. It 

 was found in all this work that to spray large walnut trees thoroughly 

 is an extremely slow, difficult, and expensive operation. As a result of 

 this experience we were led very soon to lelieve that the general spraying 



* Probably this lateness in blooming is responsible where trees are found reasoDably free frc m 

 attack, and growing adjacent to those very susceptible. The majority of walnut trees in Victoria 

 originated from non-selected seedling trees, and start to bloom early, frcmthe latter end of Septembrr 

 and during October. Any trees found blooming towards the end of October and early November should 

 be comparatively free from this disease. If this lateness of blooming is an important factor such trees 

 should be kept under observation by the grower, and compared with the early bloomers. — Authoe. 



t No doubt these conditions are responsible for the immunity of trees growing in certain localities 

 in Victoria. — Aitthor. 



