Effect of Dactylaria higginsii on purple nutsedge (Cyperus rotundus) interference with pepper (Capsicum annuum L)

摘要

Greenhouse studies were conducted to evaluate the effect of the fungal pathogen, Dactylaria higginsii, on purple nutsedge interference with 'Capistrano' pepper (Capsicum annuum). Purple nutsedge plants established from tubers were planted at initialdensities of 40, 80,160, and 320 plants m~(-2) with pepper in 35-cm diam pots with a commercial potting medium under nonlimiting fertilization and irrigation conditions. Three to four-leaf-stage purple nutsedge and four-leaf-stage pepper plants were inoculated by spraying D. higginsii in 0.5 percent Metamucil, a carrier; the treatments were carrier only, 10~4 conidia ml~(-1) + carrier, or 10~6 conidia conidia ml~(-1) + carrier. Purple nutsedge at all tuber densities significantly reduced pepper yield in the absence of D. higginsii. Percentage yield loss of pepper was greater in treatment with 10~4 conidia ml~(-1). However, percentage yield loss of pepper was negligible in treatments with D. higginsii at 10~6 conidia ml~(-1) when compared to the non-weedy control. The disease progress rate was significantly faster in treatments with 10~6 conidia ml~(-1) (r_G = 0.113 - O.123) compared to 10~4 conidia ml~(-1) (r_G = 0.049 - 0.050). At 10~6 conidia ml~(-1), D. higginsii reduced nutsedge interference, provided greater nutsedge control, and increase pepper yield compared to weedy checks.