Disease management (see Chapter 24) with fungicides involves the dual responses of disease control and the enhancement of seed yields by maintaining green leaf area during seed filling.

Stem rust (Puccinia graminis subsp. graminicola Urban) probably is the most common disease in tall fescue seed production. Epidemics of stem rust can occur in ryegrass without tall fescue being infected; thus, it is reasonable to postulate that different races of stem rust are involved. In Oregon, it has been found that inoculum from perennial ryegrass caused only limited infection (low incidence and/or small pustules) of tall fescue, whereas the inoculum from tall fescue had a host range that included perennial ryegrass (Pfender, 2001). Hare (1992) reported seed yield increases when propiconazole {(2RS,4RS;2RS,4SR)-1-[2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-ylmethyl]-1H-1,2,4-triazole} was applied to control stem rust (Fig. 23-3), whereas Rolston and Archie (2001) reported no stem rust and no seed yield response to a range of fungicides applied to ‘Kentucky 31' tall fescue.


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Fig. 23-3. Stem rust control with Tilt (250 g propiconazole/ha) on tall fescue in New Zealand (Hare, 1992). (EE = ear emergence or heading).




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