Foliar Distribution of Seed-Applied Fluxapyroxad in Barley

Seed-applied fungicides play a crucial role in early-season
disease
management in cereals; however, their plant distribution and its
effect on disease control remain poorly understood. This study examines
the distribution of fluxapyroxad in seed-treated barley and its relationship
with protection against Pyrenophora teres f. maculata. Using liquid chromatography–high-resolution
mass spectrometry, fluxapyroxad concentrations were quantified at
multiple growth stages in seed-treated barley. A progressive decrease
in fungicide concentration was observed from the early emerging leaves
to the younger ones. In older leaves, a pronounced base-to-tip enrichment
pattern was detected, and this gradient was reflected in differential
suppression of P. teres f. maculata, with the greatest protection occurring at leaf
tips, where fungicide levels were up to 50-fold higher. These findings
provide insights into how seed-applied fungicides, such as fluxapyroxad,
behave in planta, supporting more strategic approaches
to fungicide use that optimize crop protection, enhance input efficiency,
and improve growers' outcomes.