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    Author(s): Mark A. Fenn; M.D. Coffey
    Date: 1984
    Source: Phytopathology 74:606-611
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (967 KB)


    In a low-phosphate medium fosetyl-Al showed a much higher activity in vitro against Phytophthora than previously reported in the literature. Both fosetyl-Al, and more particularly phosphorous acid (H3PO3), were highly inhibitory in vitro against several species of Phytophthora. Phosphorous acid was much less inhibitory in vitro against Pythium and had only low activity against a selection of non-oomycetous fungi. The EC50 values for an isolate of Phytophthora cinnamomi, cultured on a low phosphate medium, were 0.05 PO3 meq of H3PO3 (4 μg/mi) and 0.45 PO3 meq of fosetyl-Al per liter (54 μg/ml). An increase in the level of phosphate reduced the inhibition of mycelial growth due to fosetyl-Na, but there was little or no effect of phosphate on the inhibition caused by H3PO3. In vivo, either 12.7 PO3 meq of H3PO3 (1.0 g/L) or 12.7 PO3 meq of fosetyl-Al per liter (1.5 g a.i./L), applied as a foliar spray or soil drench, gave equivalent control of root rot caused in seedlings of Persea indica by Phytophthora cinnamomi. Compared to fosetyl-Al, H3PO3 had a similar, though generally higher efficacy, in reducing stem infection of Persea indica seedlings by Phytophthora citricola. The EC50 values for inhibition of stem infection were 0.09 PO3 meq of H3PO3 (8 μg/ml) and 0.22 PO3 meq of fosetyl-Al per liter (26 μg a.i./ml).

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    Fenn, Mark A.; Coffey, M.D. 1984. Studies on the in vitro and in vivo antifungal activity of fosetyl-al and phosphorous acid. Phytopathology 74:606-611


    Aluminum tris-O-ethyl phosphonate, sodium ethyl phosphonate

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