|Manthey, Frank - PLNT SCI, NDSU, FARGO, ND|
Submitted to: Pesticide Formulations and Application Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 24, 1998
Publication Date: N/A
Interpretive Summary: Surfactants are added to pesticide sprays to help them stick to plant leaves. Unfortunately, some surfactants can damage plants and prevent the pesticide from working. Experiments on barley were done in the greenhouse and laboratory to determine the damage caused by different surfactants. The amount of leaf damage depended on the surfactant chemistry, and increased surfactant concentration. The amount the spray droplets spread on the leaf surface was not related to the amount of leaf damage. Surfactants had little or no effect on water movement out of the plant leaves. The amount of surfactant damage to cells in the laboratory could not be used to predict the amount of damage to leaves in the greenhouse. This lack of relationship suggests that factors associated with the leaf cuticle are regulating leaf damage by surfactants.
Technical Abstract: Surfactants are used in pesticide and spray adjuvant formulations. unfortunately, some surfactants are phytotoxic and can inhibit pesticide efficacy. Experiments were conducted in the greenhouse and laboratory to determine the phytotoxicity of surfactants that differed in lipophilic chemistry and/or hydrophilic:lipophilic balance (HLB). Barley (Hordeum vulgare L.) was bioassay species. Foliar injury generally was greater with low than high HLB surfactants when surfactants were applied based on weight/volume but not when applied based on molar concentration. Lipophilic chemistry, HLB, and concentration influenced the surfactant effect on droplet spread, plant transpiration, and proton extrusion from barley calli. Surfactants did not affect or reduced transpiration 1 h after application. Transpiration recovered to original levels 24 h after application, if no foliar injury occurred. Most surfactants at 0.01 mM reduced proton extrusion from barley calli. Simple relationships were not observed between foliar injury and droplet spread; foliar injury and transpiration; droplet spread and transpiration; or foliar injury and proton extrusion.