Resistance to brown leaf spot caused by Pyrenophora bromi (Died.) 

 Drechsl. is one of the objectives of bromegrass breeding at this Station. 

 The strains in this test appeared to be uniformly susceptible to this or- 

 ganism. Natural infection is normally heavy at this location, with a pri- 

 mary infection in the spring, followed by heavy secondary infections in 

 Julv and again in the fall. Incidence of disease was highly influenced by 

 weather. Severe infection occurred in periods of high rainfall and humidi- 

 ty, hut relatively light infection occurred during the late summer drought 

 in 1956 and 1957. 



MacKav (3) conducted a detailed study of these strains, the parental 

 clones, and their progenies. In general, it appeared that selection for re- 

 sistance to brown leafspot and better aftermath yields should be quite 

 feasible in bromegrass. 



Regional results for this test were published elsewhere (4). 



Data from bromegrass test :/£ 2 are given in Table 2. The germination 

 of Fischer and Manchar was relatively low in the August 27 seeding, and 

 unsatisfactory stands were obtained for these varieties. Another seeding 

 was made with good seed of these varieties on September 17, and yields were 

 consequently low in 1958, probably because the plants were not yet well 

 established. However, these varieties produced comparatively good yields 

 i'l 1959 and 1960. Best total and aftermath yields were obtained from 

 Saiatoga bromegrass. although two of the synthetics, Syn B and F, also 

 produced relatively high total and aftermath yields. 



Table 2. 



Forage Yields and Reaction to Brown Leafspot for 8 Bromegrass Strains, 



(tons per acre at 12 percent moisture) 



* Based on a scoring system of 1 = no leafspot to 5 = highly susceptible. 

 Number of ratings per strain for 1958-1960 varied from eight to sixteen. 



Synthetic B was selected for susceptibility to brown leafspot, and was 

 extremely susceptible in this experiment. It is being used primarily as a 

 source of inoculum for other strains. These results indicate that the dis- 

 ease is very abundant at this location. Some of the synthetics such as A 

 and F, appear to have relatively good resistance to this disease, and seem 



