3.2. Field experiments
Rust severity was high and uniform in inoculated and unprotected
plots, ranging from 55 to 65% (Table 4), whereas it was lower
than 7.6% in non-inoculated and fungicide protected plots. Rust
infection caused circa 22e26% yield reduction in 1999e2000 in cvs.
‘Baraca’ and ‘Amcor’, respectively, and 23 and 22% in 2000e2001.
Therewas a tendency for increase in the numbers of seed/plant and
in seed weight in disease protected plots, but these were not
significant.
All fungicides except mancozeb were effective, reducing faba
bean rust under field conditions when applied twice (Table 5).
Reduction in rust severity was significant but rather low, with
a maximum of 26% reduction resulting in a maximum of 14% yield
increase. Only treatments with triazoles and benzimidazole-triazole
mixtures provided significant yield increases (22.7e15.6%)
when applied twice. Efficacy increased with a third application
with 18.7e41.7% rust reduction resulting in 15.6e22.7% yield
increases. Three treatments of oxycarbosin or copper-mancozeb
were needed to provide a significant yield increase. Dithiocarbamates
(thiram, maneb or mancozeb) or chortalonil reduced rust
severity but did not provide a significant yield increase.