PLATE 21. 



Walnut disease. 



Bacterial black spot of the Persian walnut (Jualans rrgia), more commonly known as the English walnut. Half-developed green fruit* from an 

 orchard in California, showing the badly spotted epicarp ; spots due to Bacterium juglandis (Pieice). Leaves and shoots are also subject to this 

 disease, which has become serious in Southern California, where large quantities of these nuts are grown for market. The attacked parts are 

 conspicuously blackened as if charred. The numerous small white spots show the location of group* of stomata. Infection takes place readily 

 through unbroken tissues. 



