Influence of number and timing of fungicide applications on the yield and quality of early and later-sown spring malting barley grown in the south-east of Ireland
Mj. Conry et B. Dunne, Influence of number and timing of fungicide applications on the yield and quality of early and later-sown spring malting barley grown in the south-east of Ireland, J AGR SCI, 136, 2001, pp. 159-167
Eighteen experiments were carried out over a B-year period (1989-94) on thr
ee different soil types to compare the effects of a broad-spectrum fungicid
e, applied as 1-, 2- or 3-spray programmes at different growth stages, to c
ontrol foliar diseases on early and later-sown Blenheim malting barley. Pow
dery mildew, caused by Erysiphe graminis (Blumeria graminis) f. sp. hordei,
was the dominant disease in all 6 years. Sowing date had a major effect on
grain yield and ex-farm quality of the malting barley. The earlier-sown tr
eatments gave significantly greater yield than the later-sown in 13 of the
experiments, and significantly lower grain N concentrations and screenings
(small grains < 2.2 mm) in 14 and 16 of them, respectively.
Early and more frequent fungicide applications improved grain yield and red
uced grain screenings but had no significant effect on grain N. Early-appli
ed fungicide (i.e. before GS 33) was generally the most effective in contro
lling disease, increasing yield and reducing screenings. The magnitude of t
he response depended on disease severity. In those years when disease was l
ow on the early-sown crops (1989, 1991 and 1994), the early-applied 1-spray
programme and 2-spray programmes increased grain yields by relatively smal
l amounts in both early and late-sown crops. In the other 3 years (1990, 19
92 and 1993), when disease severity was greater, the early-applied 1-spray
programme and 2-spray programmes gave much greater grain yield increments o
n both early and late sowings. The 3-spray fungicide programme gave the gre
atest yields in most of the experiments but they were not significantly gre
ater than the best of all the: other treatments. Grain screenings were redu
ced by fungicide applications in both early and late-sown crops, but the ea
rly-applied 1-spray programme and 2-spray programmes were generally the mos
t effective in reducing screenings.