Liming with dolomite reduces the efficacy of the biocontrol fungus Trichoderma koningiopsis against cabbage clubroot

Abstract

<p><span>Cabbage clubroot<em> </em>is a major constraint for the pro</span><span lang="EN-US">duction of cruciferous species. This research aimed to explore the effect of <em>Trichoderma koningiopsis </em>(as the wettable powder formulated product Tricotec®) and dolomite on the disease and crop growth of cabbage. This study was carried out in a field with a prolonged history of clubroot incidence. The trial was set up in a randomized complete block design with five repetitions. The following treatments were applied: 0) absolute control; 1 and 2) liming with dolomite at 1.0 and 2.1 t ha<sup>-1</sup>; 3) Tricotec® at 200 g ha<sup>-1</sup>; 4) combination of treatments 1 and 3; 5) combination of treatments 3 and 4. The treatment with just Tricotec® applications gave the lowest disease incidence and severity and the heaviest plant dry weight. Joint applications of Tricotec® and dolomite at 2.1 t ha<sup>-1</sup> reduced the crop growth variables and had the highest disease intensity. The <em>Trichoderma</em> concentration in the soil was increased by a factor of 10 in the plots that received just Tricotec®, but not in the limed plots. These results showed that <em>T. koningiopsis,</em> in a Tricotec® formulation, is a promising candidate for the control of cabbage clubroot and that its biological activity is affected by dolomite when applied jointly at 2.1 t ha<sup>-1</sup>.</span></p>