Effects of certain cations on the formation and infectivity of Phytophthora zoospores. 1. Effects of calcium, magnesium, potassium, and iron ions

Abstract

The effects of four cations, Ca2+, Mg2+, K+, and Fe3+, upon the production of zoosporangia by isolates of four species of Phytophthora in axenic culture have been investigated. A response surface design was used to examine main effects and possible interactions. Responses to Ca2+ and Fe3+ were strongly quadratic with the higher concentrations inhibiting sporangial production in P. cinnamomi and P. drechsleri isolates. Responses to Mg2+ and K+ were weaker and, in the case of magnesium, were linear rather than quadratic. There was no significant interaction between cations except in the case of P. cambivora where the interaction between Mg2+ and K+ was significant at the 5% level. For each cation, the optimum concentration for zoosporangial production was calculated. The processes of zoospore release and infection of plant material by P. drechsleri showed a strong linear and weak quadratic response to Ca2+, higher concentrations of Ca2+ favouring these processes. A strong quadratic response was obtained to Mg2+, K+, and Fe3+. Interaction between Ca2+ and Mg2+ was evident for all three host materials used; Mg2+ and K+ showed an interaction when Pinus radiata was used as the host material. The implications and limitations of these results are discussed.

Calcium fertilizers induce soil suppressiveness to Phytophthora cinnamomi root rot of Quercus ilex

“…However, our results suggest than the high ability of CaO to inhibit P. cinnamomi mycelial growth is probably due to the marked increase of pH rather than to the direct effect of the Ca 2+ fertilizer itself. These results agree with studies carried out by Halsall and Forrester (1977), Duvenhage and Kotzé (1991) and Duvenhage et al (1992).…”

Effects of Two Salts Compounds on Mycelial Growth, Sporulation, and Spore Germination of Six Isolates ofBotrytis cinereain the Western North of Algeria

“…Similarly, a minimum concentration of calcium is necessary for the production of zoosporangia or zoospore release by Phytophthora spp. [48–50]. …”

A Forest Soil Suppressive to Phytophthora cinnamomi and Conducive to Phytophthora cryptogea. I. Survival, Germination and Infectivity of Mycelium and Chlamydospores.

“…Zoosporangia were produced in axenic solution by the method of Halsall and Forrester (1977). The mineral salts solution used to wash the mycelial mats for induction of zoosporangial formation was varied according to the fungal species being treated.…”

“…Counts of zoosporangia and chlamydospores were made by the method described in Halsall and Forrester (1977). Each field counted had an area of 12.5 mm2.…”