Effect of Dactylaria higginsii on interference of Cyperus rotundus with L-esculentum

Greenhouse experiments were conducted to evaluate the effect of the fungus Dactylaria higginsii on the interference of Cyperus rotundus (purple nutsed ge) with Lycopersicon esculentum (tomato 'Agroset'). Cyperus rotundus plant s established from tubers were planted at initial densities equivalent to 4 0, 80, 160, and 320 tubers m(-2) with L. esculentum in 35-cm-diam pots. Cyp erus rotundus plants were inoculated by spraying with a spore suspension of D. higginsii containing 0.5% Metamucil as a carrier. The treatments were M etamucil only, 10(4) conidia ml(-1) + Metamucil, or 10(6) conidia ml(-1) Metamucil. In the absence of D, higginsii, C. rotundus at densities of 80, 160, and 320 tubers m-2 reduced L. esculentum yield by 14, 68, and 70%, res pectively. In contrast, yield L. esculentum treated with D. higginsii at 10 (6) conidia ml(-1) was equal to that in the weed-free control. The race of disease increase (r(G)) was higher In treatments with 10(6) conidia ml(-1) (r(G) = 0.126 to 0.136) compared to 10(4) conidia ml(-1) (r(G) = 0.046 to 0 .050). At 10(6) conidia ml(-1), D. higginsii reduced the interference from C. rotundus, controlled C. rotundus better, and increased L. esculentum yie ld compared to the weedy checks.