WALNUT— WALNUT DISEASES 



2007 



little trouble, as the buds in starting will 

 break through a light covering of wax. 

 During warm weather it is a good plan 

 after waxing to tie a piece of paper 

 or paper sack split down the side over 

 the bud to protect it from the sun. If 

 the trees stand closely in the rows, and 

 have sufficient foliage to shade the 

 trunks, this will not be necessary. In 

 about ten days after waxing the bud will 

 have sufficiently united with the stock so 

 that the wax and paper may be removed, 

 and about a week later the raffia should 

 be cut and removed. Care should be exer- 

 cised, however, in the last regard in that 

 if the stock is growing very rapidly the 

 raffia is apt to girdle it. In such a case 

 the raffia should be cut sooner, or if the 

 bud is not sufficiently united, retie more 

 loosely. 



Starting the Bud Into Growth 



If the budding has been done in June 

 or earlier and the buds are to be started 

 into growth the same year, the trees 

 should be headed off at the time the raf- 

 fia is removed — about 15 days after the 

 budding. Cut off the stock about one and 

 a half to two inches above the bud, al- 

 lowing the top CO remain attached at one 

 side by a small piece of wood or bark. 

 These tops should then be broken over 

 and laid overlapping each other in the 

 row, thus providing shade to the buds 

 and aiding in the carrying off of excess 

 sap and preventing to a considerable ex- 

 tent an excessive sprouting from the root. 

 In about two weeks the scion bud will 

 have started into active growth. The 

 top of the stock should then be removed 

 entirely, close to the bud. In sections 

 subject to high winds, the young shoots 

 should be staked. See that all buds and 

 shoots from the stock are taken off, as 

 they are a material drain on the reserve 

 food supply in the stock. 



If the budding has been done late in 

 the season so that the trees can not be 

 headed back before August 1. such head- 

 ing back had best be deferred until the 

 following spring, just about the time that 

 growth starts. There is some danger of 

 the buds being killed during the winter, 

 or injured by excessive wet weather. It 



is therefore preferable in such cases to 

 put the buds somewhat higher on the 

 stock than when the trees are to be 

 headed back in June or July. Trees com- 

 ing from stock headed back about the 

 middle of June to the first week in July 

 will make from 14 to 20 inches growth 

 the same season, and usually mature 

 thoroughly, so that there is no danger of 

 killing back during the winter. Such 

 young trees could be put on the market 

 the winter following the budding. Trees 

 from stock which has been headed back 

 in the spring will make a straight growth 

 of five to seven feet during the season. 

 E. J. Kraus, 

 Oregon Experiment Station. 



WALNUT DISEASES 



Black Sap. See Sun Burn, this section. 



Walnut Bligbt or Bacteriosis 



Pseudomonas juglandis 

 This disease is the most important one 

 affecting the English walnut as grown in 

 the United States. It has been known 

 in California for over 20 years, being first 

 mentioned in scientific literature in 1893* 

 Since then the disease has spread until at 

 present it is well distributed through the 

 walnut-growing sections of California, 

 and also is to be found at other points on 

 the Pacific coast. In foreign countries the 

 disease has been reported from New Zea- 

 land, and California walnut growers who 

 have visited France report having seen 

 the disease there. These observations 

 have been confirmed by those of Professor 

 R. E. Smith, who, during a recent visit to 

 France, saw there typical cases of walnut 

 blight on nuts, twigs and nursery stock. 

 The disease was undoubtedly brought to 

 California on nursery stock and scions im- 

 ported from France. ** 



Hosts 



The natural occurrence of the disease is 

 probably confined to the English walnut 

 and its hybrids with the black walnut. 

 Blighted nuts have been found on a Par- 

 adox walnut tree (a hybrid of English 

 and California black) and in one instance 



• Report of Secretary of Agriculture. Divi- 

 sion of V'ecetable PatlioloEy, IKn."!, p. 27."!. 



••California Cultivator, Vol. CI. No 12, 

 September IS, iniS. 



