EFFECT OF PLANT MOISTURE STRESS AND APPLICATION SURFACE ON UPTAKE ANDTRANSLOCATION OF TRICLOPYR WITH ORGANOSILICONE SURFACTANT IN RED MAPLE SEEDLINGS

This study investigated the effect of plant moisture stress and surfac e of application on the absorption, translocation, and ''rainfastness' ' (short-term ability to retain herbicide) of organosilicone-adjuvated (adjuvant added) [C-14]triclopyr amine on greenhouse-grown, 4-month-o ld red maple (Acer rubrum L.) seedlings. Xylem water potentials were - 1.6 and -0.9 MPa and leaf conductances were 0.07 and 0.13 cm . s(-1) f or the stressed and control seedlings, respectively At 2 h, rainfastne ss was 13% less for stressed seedlings. Uptake increased with time, an d by 72 h no effect of moisture stress treatment was apparent. Abaxial absorption into living leaf tissue was 57% greater at 72 h than was a daxial absorption, but application surface did not significantly affec t translocation. Plant moisture stress did, however, reduce translocat ion of herbicide into the shoots and roots. Organosilicone surfactants may enhance long-term triclopyr uptake in water-stressed seedlings, b ut do not appear to facilitate translocation in stressed seedlings. Pl ant moisture status, therefore, should continue to be a concern when s cheduling herbicide applications.