EFFECTS OF ADJUVANTS ON THE PERFORMANCE OF A NOVEL POWDERY MILDEW FUNGICIDE, 1-(4-CHLOROBENZYL)-4-PHENYLPIPERIDINE

The effects of adjuvants on the performance of a dispersible concentra te formulation (DCI) of a novel powdery mildew fungicide, 1-(4-chlorob enzyl)-4-phenylpiperidine (I) were investigated. The method involved a ssessment, under glasshouse conditions, of the therapeutic (curative) control of infections of powdery mildew (Erysiphe graminis DC f.sp. ho rdei Marchal) on barley (Hordeum vulgare, L.) eight to nine days after spray application to plants that had been inoculated one day prior to spraying. The results from the first trial showed that marked improve ments (similar to five-fold) in the performance of DCI could be obtain ed by the spray tank addition of some types of surfactant adjuvants an d a series of further trials investigating a wide range of adjuvants w as conducted. Nonylphenol, alkylamine and alcohol ethoxylates varying in mean ethylene oxide content between 5 and 20 moles were highly effe ctive. There were indications that optimum performance enhancements we re obtained with these surfactants containing between 5 and 10 moles e thylene oxide. Lower enhancements, sometimes only marginal, were obtai ned from trisiloxane, phosphate ester, propylene oxide, alkylamine-pro pylene oxide and castor oil ethoxylates and also alkyl polyglucoside b iosurfactants. Negligible adjuvant enhancements were observed with emu lsifiable paraffinic/naphthenic and rape seed oils, though slightly be tter enhancements were seen with an emulsifiable transmethylated rape seed oil and, interestingly, larger enhancements with an emulsifiable lipophilic alcohol. A final trial identified the alcohol ethoxylate, ' Dobanol' 91-6, as the most effective adjuvant and that its optimum app lication rate under glasshouse conditions was 250 g ha(-1). This infor mation will be used to guide the design of field trials.