Barley Yield-Loss Due to Net Blotch and Leaf Rust in Bale Highlands

Abstract

A yield loss study on barley due to net blotch and leaf rust was conducted in ‘meher’ (August-December) seasonfrom 1996-1997 and in ‘belg ’ (March-July) season in 1997 and 1998. Sprayed (broad spectrum-systemic fungicide) and unsprayed treatments were used
in nine farmers' fields in each experimental year. Fungicides were applied two to three times at 15-25 days intervals starting from on-set of disease symptoms. The difference in disease severity between fungicide sprayed and unsprayed treatments for both leaf rust
and net blotch was significant. Losses in grain yield, straw yield and thousand-grain weight were calculated as the difference between sprayed and unsprayed treatments .Grain yield loss ranged from 20 to 35% in meher season with the mean of 28% and from 25 to
33% in belg season with an average of 29%. The total straw yield loss varied from 19- 40% in meher season and from 13-31 % in belg season. Likewise, straw for direct animal feed (total straw yield - loss in field) was reduced by 19-40% in meher season and by 13
-31 % in belg season with corresponding average of 29% and 22%. Similarly, 11 % and 2-14% loss of thousand-grain weight was observed in belg and meher seasons, respectively. The magnitude of grain, straw and thousand kernel weight losses recorded
under farmers' circumstances confirmed that net blotch and leaf rust are important barley diseases in the bimodal rainfall areas of Bale highlands. Fungicide application has provided a marginal rate of return of 50.9% in meher season. However, regardless of
effective disease control and yield advantage gained from cultivar Arusso, grain yield remained low under both seasons. Thus, developing resistant and high yielding cultivars and effective means of control against net blotch and leaf rust needs emphasis in Bale highlands.