The influence of soil-pH on the saprophytic growth in soil of the take-all fungus Gaeumannomyces graminis var tritici

Experiments were conducted firstly, to determine whether there was a difference in saprophytic growth response of the pathogen to pH in soil from that on agar. Secondly, we examined whether the response to liming involved a sensitivity of the fungus to the concentration of hydrogen (H+) or calcium ions (Ca2+). The saprophytic growth of the take-all fungus showed that, although it is sensitive to soil pH, each strain behaves differently, and this behaviour cannot be predicted from agar studies. It seems unlikely, therefore, that the observed disease response to soil pH resulted from direct effects on the saprophytic phase of the fungus. There was no indication that increase in the Ca2+ in soil played any part in the growth response of the fungus. The potential for other indirect effects of pH on nutrient availability to the plant and to other stages in the disease cycle is discussed.