Studies of spray deposits. IV.—Polyvinyl acetate as a sticker for copper fungicides

AbstractThe influence of polyvinyl acetate (PVA) latex on the tenacity of cuprous oxide and Burgundy mixture on the upper surface of daffodil, potato and tomato leaves has been determined in laboratory tests. PVA improved the tenacity of the fungicides on the leaf surfaces : the optimum concentration of the supplement was 1% (v/v). PVA was also found to improve the dispersion of the cuprous oxide suspension. There was no evidence that PVA reduced the fungitoxicity of cuprous oxide when assayed in vitro against Alternaria tenuis.In field trials on potato foliage, although PVA improved the tenacity of the fungicide deposits, the effect was not sufficiently marked to recommend PVA as a practical spray supplement, and its use did not significantly improve the protection of the foliage against potato blight.