Tolerance of Greenhouse-grown Strawberries to Terbacil as Influenced by Cultivar, Plant Growth Stage, Application Rate, Application Site and Simulated Postapplication Irrigation

Abstract

Terbacil at 0, 0.8, 1.6, 3.2, and 6.4 oz/acre (0, 0.06, 0.11, 0.22, and 0.45 kg·ha-1) a.i. was applied immediately after planting, at the thee-leaf stage and at the six-leaf stage to greenhouse grown strawberry (Fragaria × ananassa) cultivars Jewel, Mira, and Allstar. Strawberry was most tolerant of terbacil when the herbicide was applied before leaf emergence. `Mira' was more tolerant of terbacil than was `Jewel'. `Jewel' and `Allstar' exhibited similar levels of tolerance. In a second experiment terbacil at 4.8 oz/acre (0.34 kg·ha-1) was applied to the soil, to the foliage, and to the foliage followed by a water rinse. Injury was greatest when terbacil was applied directly to the strawberry foliage rather than to the soil, but was minimal when foliage was rinsed after application. In a final experiment terbacil at 4.8 oz/acre was applied to greenhouse-grown `Jewel' strawberries at the thee-leaf stage followed by a water rinse 0.5, 1, 2, or 4 hours after application. Rinsing the foliage of strawberry plants after application significantly reduced leaf injury. Delaying the rinse up to 4 hours did not lead to increased injury. Over all, the results from our study indicate the potential for using terbacil as an effective herbicide on newly established strawberries, especially if the compound is rinsed from leaves (if present) after treatment.