Efficacy of bio-surfactants and spray volume on performance of fenoxaprop-p-ethyl against Avena sterilis subsp. ludoviciana

Whether fenoxaprop-p-ethyl activity could be affected by the carrier volume and whether this relationship can be affected by two types of bio-surfactants, rhamnolipid and surfactin, was assessed under greenhouse conditions. Treatments consisted of herbicide dose (۰, ۱۸.۷۵, ۳۷.۵, ۵۶.۲۵, ۷۵, and ۹۳.۷۵ g ha-۱), spray volume (۶۰, ۱۲۰, ۲۴۰, and ۴۸۰ L ha-۱), surfactant type above, and surfactant concentration (۰, ۰.۱۲۵, ۰.۲۵, ۰.۵, ۱, ۲, ۴, and ۸x critical micelle concentration (CMC). The dry matter of sterile oat was regressed over the doses of fenoxaprop-p-ethyl to obtain a dose causing ۵۰% sterile oat control (ED۵۰). Without surfactant, a ۳۸% increase in the ED۵۰ with increasing the spray volumes from ۶۰ to ۴۸۰ L ha-۱ (۴۴.۷ and ۷۲.۱ g ha-۱, respectively) revealed a negative relationship between fenoxaprop-p-ethyl activity and spray volume. In other words, a low-volume spray solution, creating smaller, more concentrated spray droplets, is necessary to get the optimal action of fenoxaprop-p-ethyl. This relationship could also be observed when both surfactants were used at ۰.۱۲۵ to ۱x CMC. At ۲ to ۸x CMC, the relationship mode changed from negative to neutral for rhamnolipid, while it did not change for surfactin. This study shows that, unlike surfactin, rhamnolipid worked better at a low concentration in a low-volume spray solution to get the optimal action of fenoxaprop-p-ethyl.

کلیدواژه ها:

adjuvant ، herbicide ، nozzle size