Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 13, 1997
Publication Date: N/A
Interpretive Summary: Agricultural adjuvants, mixed with pesticides, are commonly used in pecan orchards. Their use is without knowledge of any adverse side-effects on leaf physiology. Of 18 commonly used adjuvants, a few exhibited potential for substantially suppressing net photosynthesis and the conductance of water vapor from the leaves when used at label recommendations. This suppression was capable of lasting from 1 to 14 days, depending upon adjuvant type. Most of the commonly used adjuvants on pecan are likely safe when used at label recommendations; however, the organosilicone containing adjuvants are generally those that are most likely to result in adverse side-effects when used in orchard operations.
Technical Abstract: Adjuvants are commonly used in the cultivation of pecan [Carya illinoinensis (Wangenh) K. Koch] and most other tree-nut and temperate fruit crops. Their usage on pecan has been without knowledge of their influence on critical physiological processes, such as gas exchange, of orchard canopies. Of 18 commonly used adjuvants evaluated on orchard trees in the present study, a few exhibited potential for substantially suppressing net photosynthesis and the conductance of foliage to water vapor when used within their recommended concentration range; however, most provided no evidence of adversely influencing net photosynthesis or water vapor movement. Suppression of gas exchange by certain adjuvants persisted at least 14 days after a single application. The recently developed organosilicone based surfactants generally exhibited the greatest potential for suppression. These data indicate that orchard managers should consider the potential adverse influence of certain adjuvants when developing orchard management strategies.