This study investigated the effect of plant moisture stress and surface of application on the absorption, translocation, and "rainfastness" (short-term ability to retain herbicide) of organosilicone-adjuvated (adjuvant added) [14C]triclopyr amine on greenhouse-grown, 4-month-old red maple (Acerrubrum L.) seedlings. Xylem water potentials were −1.6 and −0.9 MPa and leaf conductances were 0.07 and 0.13 cm s−1 for the stressed and control seedlings, respectively. At 2 h, rainfastness was 13% less for stressed seedlings. Uptake increased with time, and 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 adaxial absorption, but application surface did not significantly affect translocation. Plant moisture stress did, however, reduce translocation of herbicide into the shoots and roots. Organosilicone surfactants may enhance long-term triclopyr uptake in water-stressed seedlings, but do not appear to facilitate translocation in stressed seedlings. Plant moisture status, therefore, should continue to be a concern when scheduling herbicide applications.

No abstract

Release and fertilization treatments were applied to two 10-yr-old yellow-poplar (Liriodendron tulipifera L.) stands of natural origin in southwest Virginia. Seven growing seasons after the first treatment, the released trees had an absolute dbh growth response of 47.4%. Fertilization did not affect any of the growth variables studied, but resulted in a significant interaction with the release treatment for absolute height growth, which was significantly increased. Initially, height growth was slower with the released trees, but they increased their growth in the later years and had significantly greater live crown ratios than the unreleased trees, 53% compared to 46%. The released trees had 311% absolute response in crown volume, significant at the 0.001 level. Release treatments like this may be advantageous in maintaining yellow-poplar on intermediate sites, which may become an important landowner objective, since a component of gypsy moth-immune yellow-poplar can reduce overall stand vulnerability. South. J. Appl. For. 21(4):175-179.

Although the risk of exposure during various methods of herbicide application is generally quite low, eliminating the potential of worker exposure by encapsulating herbicides may be desirable. Therefore, three methods of injecting encapsulated herbicides - the FIC™, the Wee-Do™, and the Gelcap™ - were compared to a standard hack-andsquirt technique on two common weedy hardwood species using picloram and triclopyr. Both chemicals showed similar trends over the four injection methods, however, picloram was the more efficacious across all treatments. Mortality rates were highest for the hack-and-squirt technique, with 100% mortality using picloram and 89% mortality using triclopyr. Picloram mortality rates were 81 and 67% for the Wee-Do and FIC methods, respectively, and below 50% when formulated with triclopyr. The Gelcap never exceeded 10% mortality for either chemical. Current relative costs for materials and labor are 1:23:9:27forthe hack-and-squirt, FIC, Wee-Do and Gelcap methods, respectively. The Gelcap proved to be the easiest and most efficient alternative method of injection, however, it unfortunately had the lowest mortality rates. The FIC proved to be the most cumbersome and unreliable injection technique due to both equipment failures and engineering problems. Although the Wee-Do had some minor equipment failures, we found this tool to be the most effective alternative injection technique when considering ease of use, cost and efficacy.