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Aerial spraying of phreatophytes with antitranspirant
Author(s) -
Davenport D. C.,
Martin P. E.,
Hagan R. M.
Publication year - 1976
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr012i005p00991
Subject(s) - transpiration , canopy , willow , environmental science , wax , interception , horticulture , hydrology (agriculture) , botany , biology , materials science , ecology , geology , composite material , photosynthesis , geotechnical engineering
An antitranspirant (AT) can retard excessive groundwater consumption by phreatophytes without eradicating them. To determine whether aerial spraying (the only realistic application method for most sites) of a 6% (vol/vol) wax‐based AT emulsion would provide adequate spray coverage and reduce transpiration, multiple passes were made with (1) a fixed wing plane on salt cedar, cottonwood, and willow and (2) a helicopter on salt cedar. Spray coverage on the ground was 30–100% in the open (depending on the number of passes and wind drift) and 10–90% under the canopies (depending on vegetation density). Average coverage on tags ranged from 13% in the lower canopy to 75% in the upper (depending on species and application rate) after spraying by the fixed wing plane and 47 to 98% after spraying by the helicopter. Coverage in the center of dense bushes was 0–20%, but transpiration is only minimal there. Scanning electron microscope photomicrographs showed considerable AT on foliage in the upper canopy and lesser amounts in the lower; the film was detected even 24 days after spraying. Aerially applied AT increased resistance to leaf water vapor diffusion by 150% during the first few days and by 80% thereafter. Transpiration of outer foliage of salt cedar was reduced 50% initially and 20% after two weeks without phytotoxicity.