The Mechanism of Phosphonic (Phosphorous) Acid Action in Phytophthora.

Grant, Bruce; Dunstan, R. Hugh; Griffith, Julia M.; Niere, Julie O.; Smillie, R.H.

doi:10.1071/app9900115

Cited by 48 publications

(23 citation statements)

References 34 publications

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“…In addition, the degree to which the mycelium density was affected by phosphite differed between the isolates. Grant et al . (1990) found that isolates grown on solid medium were generally inhibited at a lower concentration of phosphite than isolates grown in liquid culture.…”

Section: Discussionmentioning

confidence: 99%

“…It is important to determine whether in vitro phosphite sensitivity of an isolate is an appropriate method to determine phosphite sensitivity in planta . In planta , it is thought that phosphite affects Phytophthora by inducing it to overproduce elicitins, or by inhibiting the production of suppressors, which increases the ability of the plant to recognize the pathogen and leads to the induction of a more rapid defence response ( Guest et al ., 1989 ; Dunstan et al ., 1990 ; Grant et al ., 1990 ; Saindrenan et al ., 1990 ). This response by phosphite‐treated plants to Phytophthora indicates that isolates that are more inhibited by phosphite in vitro may also be recognized more rapidly by host‐defence systems in planta .…”

Section: Discussionmentioning

confidence: 99%

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Variation in sensitivity of Western Australian isolates of Phytophthora cinnamomi to phosphite in vitro

Wilkinson

Shearer²,

Jackson

et al. 2001

Plant Pathology

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Seventy-one Australian isolates of Phytophthora cinnamomi (68 from Western Australia) were tested for sensitivity to phosphite on Ribeiro's modified medium. Isolates formed a continuum in their response to phosphite, but could be divided into sensitive (9% of isolates), intermediate (82%) and tolerant (9%) groups. Sensitivity varied between isolates, with EC 50 values ranging from 4 to 148 mg phosphite mL 21. Phytophthora cinnamomi A1 mating-type isolates were at the upper end of the range of tolerance shown by the A2 mating-type isolates.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Variation in sensitivity of Western Australian isolates of Phytophthora cinnamomi to phosphite in vitro

Wilkinson

Shearer²,

Jackson

et al. 2001

Plant Pathology

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“…Phosphonates have complex modes of action ranging from direct toxicity against the invading pathogen to indirect effects such as activation of host defence responses (Grant et al, 1990;Guest & Bompeix, 1990;Griffith et al, 1993). They are also known to interfere with uptake of phosphate in the mycelium and induce structural and metabolic changes in Phytophthora spp.…”

Section: Effect Of Ag3 Phosphonate On Phytophthora Blight Of Bell Pepmentioning

confidence: 99%

Effectiveness of AG3 phosphonate formulation in suppressing phytophthora blight in cucumber and bell pepper plants under growth room conditions

Abbasi

Lazarovits

Weselowski

2011

Canadian Journal of Plant Pathology

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Phytophthora blight or crown or root rot (Phytophthora capsici Leonian) is an important disease of a wide range of plant species including peppers, tomatoes, cucumbers and other cucurbits in Canada and worldwide. We have previously demonstrated the effectiveness of a new liquid formulation of AG3 phosphonate (Calirus 150, Bromine Compounds Ltd., Beer Sheva, Israel) in suppressing pythium damping-off of cucumbers and clubroot of bok choy and cabbage. In this study, the effectiveness of AG3 phosphonate formulation to suppress phytophthora damping-off and root rot of cucumber (Cucumis sativus L.) seedlings or phytophthora blight of bell pepper (Capsicum annuum L.) plants was determined in a peat-based mix or sandy-loam soil artificially infested with soil inoculum of P. capsici under growth room conditions. In an infested peat-based mix, AG3 phosphonate preplanting amendment or postplanting drench treatments (0.05%, 0.1% and 0.2% a.i.) and a 10-min seed-soak treatment (10.45% a.i.) significantly increased the percentage of healthy cucumber seedlings and reduced damping-off and root rot severity. The seed-soak and 0.2% treatments were the most effective treatments that consistently suppressed damping-off and root rot of cucumber even in a peat-based mix infested with high inoculum levels of P. capsici. Disease severity on cucumber plants was also significantly less in the AG3 phosphonate treatments. The single drench applications of AG3 phosphonate (0.05%, 0.1% and 0.2% a.i.) significantly reduced the incidence and severity of phytophthora blight of bell pepper plants in an infested peat-based mix or a sandy-loam soil compared with the control plants receiving no treatment. The best control of phytophthora blight of bell pepper was achieved with the higher rate (0.2% a.i.) in both peat-based mix and soil with 90% of the plants remaining healthy compared with none in the control. The disease protection increased with increasing concentrations of AG3 phosphonate in both bell peppers and cucumbers without any phytotoxicity.Résumé: La brûlure phytophtoréenne, ou pourriture phytophtoréenne des tiges et du collet (Phytophthora capsici Leonian), est une grave maladie qui, au Canada comme partout dans le monde, touche une grande variété d'espèces dont les poivrons, les tomates, les concombres et d'autres cucurbitacées. Nous avons auparavant démontré l'efficacité d'une nouvelle formulation liquide de phosphonate AG3 (Calirus 150, Bromine Compounds Ltd., Beer Sheva, Israël) quant à l'inhibition de la fonte des semis chez le concombre et de la hernie chez le chou et le pak-choï. Dans cette étude, l'efficacité de la formulation de phosphonate AG3 quant à l'inhibition de la fonte phytophtoréenne des semis et de la pourriture des tiges et du collet chez les jeunes plants de concombre (Cucumis sativus), ou de la pourriture des fruits chez le poivron (Capsicum annuum L.), a été démontrée, en chambre de culture, dans un mélange à base de tourbe ou dans un terreau sableux infectés artificiellement avec un inoculum de P. capsici. Dans ...

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“…by fosetyl-Al and phosphorous acid (Fenn & Coffey, 1984Coffey & Joseph, 1985 ;Cohen & Coffey, 1986), but with fosetyl-Al supposedly being absorbed less than phosphorous acid and having lower activity. The mechanisms of action of fosetylAl and phosphonate (or phosphorous acid) in the plant and the possible complicating effects of aluminium on uptake and activity are not understood fully (Cohen & Coffey, 1986 ;Coffey & Ouimette, 1989 ;Grant, 1990 ;Grant et al, 1990).…”

Section: mentioning

confidence: 99%

The effect of fungicides on vesicular–arbuscular mycorrhizal symbiosis. III. The influence of VA mycorrhiza on phytotoxic effects following application of fosetyl‐Al and phosphonate

et al. 1998

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This study compares the effects of the fungicide Aliette2 (fosetyl-Al) on non-mycorrhizal and mycorrhizal onion (Allium cepa L.) with effects of the degradation products, aluminium (applied as aluminium chloride) and phosphonate (applied as dimethyl phosphonate). We sought to determine the extent to which the plants absorb and accumulate phosphonate and ascertain why, as shown previously, toxic effects of fosetyl-Al on mycorrhizal plants are less severe than effects on equivalent non-mycorrhizal plants.Fosetyl-Al markedly reduced growth, especially of roots, and also inhibited mycorrhizal colonization. Dimethyl phosphonate caused smaller effects on growth and did not decrease colonization. Aluminium chloride did not affect growth of non-mycorrhizal or mycorrhizal plants, or mycorrhizal colonization. In all cases, mycorrhizal plants grew better than equivalent non-mycorrhizal plants (with no added soil phosphate), and non-mycorrhizal plants given supplementary soil phosphate grew best.Concentrations and contents of total P in shoots were increased by dimethyl phosphonate and more so by fosetyl-Al. Concentrations of P were also increased in roots. $"P nuclear magnetic resonance (NMR) spectroscopy was used to determine relative concentrations of phosphonate and phosphate. Application of fosetyl-Al led to accumulation of more phosphonate than did application of dimethyl phosphonate, and non-mycorrhizal plants treated with fosetyl-Al accumulated much more phosphonate than did equivalent mycorrhizal plants (both with no added soil phosphate). Internal phosphate concentrations increased, especially in mycorrhizal plants, following application of both dimethyl phosphonate and fosetyl-Al. Non-mycorrhizal plants given supplementary soil phosphate also showed restricted growth when treated with fosetyl-Al even though they accumulated phosphate in relatively high amounts and had lower ratios of phosphonate to phosphate, particularly in shoots. In general, high internal concentrations of phosphonate were correlated with large reductions in plant growth among treatments.Possible causes of these effects include conversion of phosphonate to phosphate in the tissues (especially in mycorrhizal plants), enhanced uptake of phosphate via mycorrhizal fungi and additional accumulation of P in plants with restricted growth. Competition for uptake between phosphate and phosphonate is also discussed.

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The Mechanism of Phosphonic (Phosphorous) Acid Action in Phytophthora.

Cited by 48 publications

References 34 publications

Variation in sensitivity of Western Australian isolates of Phytophthora cinnamomi to phosphite in vitro

Variation in sensitivity of Western Australian isolates of Phytophthora cinnamomi to phosphite in vitro

Effectiveness of AG3 phosphonate formulation in suppressing phytophthora blight in cucumber and bell pepper plants under growth room conditions

The effect of fungicides on vesicular–arbuscular mycorrhizal symbiosis. III. The influence of VA mycorrhiza on phytotoxic effects following application of fosetyl‐Al and phosphonate

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