-6- 



Host Disease RPD No. 



Apple, crabapple Scab 803 



Bluegrass Helminthosporium leaf spot 405 



Corn Moldy stored grain 206 



Anthracnose . 



Sun scald 



Hail damage 



Oats Bacterial stripe blight and halo blight . . . 106 



Yellow dwarf (Red leaf) 101 



Septoria leaf spot Ill 



Plum Plum pockets 805 



Rhubarb Leaf spot 



Soybean Pythium x Phytophthora root rots 504 



Rhizoctonia root rot 504 



Hail damage ........ 



Phyllosticta leaf blight 



Strawberry Red stele 701 



Leaf blight 702 



Leaf scorch 702 



Raspberry Leaf curl and mosaic. 710 



Tomato 2,4-D injury 



Wheat Scab 103 



Septoria glume blotch 105 



PLANT DISEASES 



OATS 



Halo blight is caused by the bacterium Pseudomonas aoronafaoiens . Mature leaf spots 

 are oval to oblong and may be pointed at one end. The margin of the gray-brown le- 

 sion is outlined by a wide, pale-green, halo-like border that later turns yellow to 

 brown. 



Bacterial stripe blight is caused by Pseudomonas striafaciens. Lesions first ap- 

 pear as sunken, water- soaked areas. These later enlarge (coalesce) and may extend 

 the entire length of the leaf. Halo- like borders do not form, as they do with halo 

 blight. In moist weather, a bacterial ooze may form and later dry, leaving crystal- 

 line scales along the leaf. 



Halo blight and bacterial blight are usually not sufficiently destructive to warrant 

 specific control measures. 



BARLEY DISEASES 



Barley yellow dwarf (a virus-caused disease) is prevalent in many late-planted oat 

 fields this spring. Aphids which are the ONLY source of transmission, feed on young- | 

 er, late-planted seedlings and deposit the virus. Symptoms first appear as yellowish- 

 green blotches near the leaf tip. These blotches fuse and turn red, brown, or yellow- 

 orange. Infected leaves often die. Blasting of florets also occurs. Kernels may 



