Compatibility of herbicides used in olive orchards with a Metarhizium brunneum strain used for the control of preimaginal stages of tephritids in the soil

摘要

In vitro and in vivo studies were developed to evaluate the compatibility of the six most common herbicides applied to the soil of olive orchards with the Metarhizium brunneum strain EAMa 01/58-Su for controlling Ceratitis capitata preimaginals. The fungus demonstrated high in vitro compatibility with the six active ingredients in malt agar medium, with growth rates (a) ranging between 2.5 mm d(-1) (glyphosate + terbuthylazine) and 3.3 mm d(-1) (oxyfluorfen). This compatibility was also revealed in vivo by assaying the fungus (1.0 x 10(8) conidia g soil(-1)) toward medfly prepupariating larvae in soil containing herbicides. Even if there was a decrease in the M. brunneum level in the soil up to 10(4)-10(5) conidia g soil(-1) 15 days after inoculation, mortality rates, which ranged between 70-80 %, did not differ significantly from the control, except the ones observed in soils that contained glyphosate and its herbicide combinations, in which a significant 50 % reduction of virulence was detected. These results reveal a general compatibility of M. brunneum with the most common herbicides applied to the soil of olive orchards, but a mixture of the fungus in the atomizer tank for simultaneous treatment beneath the tree canopy is recommended for all active ingredients except glyphosate.