Arizona Agricultural Experiment Station 613 



Fire blight caused by Bacillus amylovorus, from Ara- 

 vaipi Valley, St. David, Nogales. 



Crown gall caused by Bacterium tumefaciens, from 

 Dewey. 



Peach. 



Bacterial leaf spot caused by Bacterium pruni, from 

 Tucson and Douglas. 



Crown gall caused by Bacterium tumefaciens, from Casa 

 Grande, Yuma, Winkelman, Tucson. 



Frost injury, from Tucson and Willcox. 



Pear. 



Black mold caused by AlterTiaria sp., from Tempe. 

 Fire blight caused by Bacillus amylovorus, from Oracle, 

 Phoenix, St. David. 



Orange. 



Die-back, from Yuma. 



Date. 



Leaf spot caused by Macrosporium and Alterruiria, from 



Yuma and Tempe. 



SMALL FRUITS 



Gooseberry. 



Powdery mildew caused by Sphaerotheca mors-uvae, 

 from Navajo County. 

 Grape. 



Mildew caused by Plasmopara viticola, from Inspiration. 

 Grape rot, cause unknown, first reported last year. Un- 

 ripe fruits of white varieties become spotted with soft, broviTi- 

 ish, semi-translucent areas. Shrivelling and rotting begin 

 and the spots become bronzed, later turning to purple. Dry- 

 ing proceeds more rapidly on one side than the other so that 

 the outline of the seeds shows. Often the berry remains nor- 

 mally greon excepting for one sunken spot. The appearance 

 of the tissues in histological preparations strongly suggests 

 a parasite, but cultures made from surface-sterilized fruit 

 usually show no growth. A few have given a species of 

 Gloeosporium with spores much larger than those of any 

 species hitherto reported on the grape. 



Crown gall caused by Bacterium tumefaciens, from sev- 

 eral localities. __ 



