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- Author or Editor: Richard Zollinger x
The authors investigated salinity tolerance of four intermountain western United States native (Penstemon palmeri, Mirabilis multiflora, Geranium viscosissimum, and Eriogonum jamesii) and four common (Echinacea purpurea, Lavandula angustifolia, Leucanthemum ×superbum ‘Alaska’, and ×Penstemon mexicali ‘Red Rocks’) ornamental herbaceous perennials. Each was irrigated with a solution containing 2 CaCl2 : 1 NaCl (m ratio) at salinity levels of 0 (control), 1000, 3000, and 5000 mg·L−1 during two 8-week experiments. They measured weekly visual quality and gas exchange and final shoot and root dry weights. Mirabilis multiflora, L. ×superbum, and L. angustifolia maintained high visual quality and 100% survival across salinity levels. However, dry weights for L. ×superbum decreased at salt levels ≥ 3000 mg·L−1 in both experiments and for L. angustifolia in one experiment. Mortality rates of 12% to 100% were observed for the remaining five species irrigated with 3000 and 5000-mg·L−1 solutions. Visual quality of P. palmeri, G. viscosissimum, and E. purpurea varied with time of year the experiment was conducted, with low visual quality associated with high temperatures and light intensities, whereas dry matter and gas exchange responses to salinity were similar between the two experiments. Penstemon ×mexicali and E. jamesii exhibited high mortality, low visual quality, and low gas exchange in the case of E. jamesii at high salinity treatments regardless of when experiments were conducted. Based on visual quality responses, M. multiflora, L. ×superbum, and L. angustifolia are relatively more salt tolerant, and P. ×mexicali and E. jamesii are relatively more intolerant, than the three other species. Penstemon palmeri, G. viscosissimum, and E. purpurea exhibited intermediate tolerance to salinity with acceptable quality during periods of cool temperatures and lower light intensities.
Three 2-year field studies were conducted to evaluate 1-naphthaleneacetic acid (NAA) as a suppressant of suckers in European hazelnut (Corylus avellana L.). Treatments were basal-directed applications of NAA at 5, 10, and 20 g·L−1 a.i. applied once per season, and two sequential applications of NAA 10 g·L−1 a.i., 28 days apart, compared with 2,4-D (3.8 g·L−1 acid equivalent), and a nontreated control. Treatments were applied early in spring and repeated the following year. Both NAA and 2,4-D delayed sucker growth by 1.2- to 3.0-fold compared with the nontreated control, and response varied with experimental site and year. Sequential treatments of NAA significantly reduced sucker height and fresh weight 120 days after treatment. NAA applied in sequential treatments increased tree trunk cross-sectional area and canopy volume in two of the three experimental sites. Yield of hazelnuts increased when suckers were removed with NAA or 2,4-D compared with nontreated. Results indicate that NAA is an effective option to control suckers in hazelnuts and can help reduce herbicide and labor in sucker control.
Field trials using sublethal doses of glyphosate, dicamba, or mixtures of both herbicides on dry edible pea (Pisum sativum), dry edible bean (Phaseolus vulgaris), and potato (Solanum tuberosum) were conducted at six locations to determine the injury potential if spray drift were to occur. All studies used three increasing sublethal doses of glyphosate and dicamba, which were labeled as low, medium, and high. The doses for each herbicide varied for the three crops because of expected sensitivity differences. Herbicide doses were targeted for the reproductive stage 1 with dry edible pea and dry edible bean, and at tuber initiation for potato. Visible injury 20 days after the treatment ranged from 0% to 13% for dry edible pea, 0% to 53% for dry edible bean, and 0% to 50% for potato. Compared with the nontreated, yield was least when doses included dicamba, regardless of the crop. Dry edible bean was the most sensitive crop to sublethal doses of dicamba, followed by dry edible pea and potato. Results from these six studies suggested that drift injury potential to dry edible pea, dry edible bean, and potato will be greater if a dicamba-resistant soybean (Glycine max) crop is adjacent and upwind compared with a glyphosate-resistant crop. Results also reinforce the need for diligence in the application of these herbicides in proximity to susceptible crops and the need to thoroughly clean sprayers before spraying a sensitive crop.