Air-blast Sprayer

Evaluating the Use of an Air-blast Sprayer with Variable-Rate Technology for High Coverage Trunk Applications in Multi-row Blocks of Field and Pot-in-Pot Nursery Production. Karl McKim, Lauren Fessler Mathews, Wesley C. Wright, Xiaocun Sun, Heping Zhu, and Amy Fulcher. Journal of Environmental Horticulture 43(3):173–187

In order to protect tree crops from trunk-boring insects such as flatheaded borers (Chrysobothris spp.), most nursery producers rely on either systemic insecticides applied to the root system or contact insecticides directly applied to trunks with an air-blast sprayer. Due to increasing concern about non-target effects of systemic insecticides, in particular to pollinators, we

Abstract

Topramezone was evaluated in an outdoor container experiment for tolerance of multiple conifer species in Windsor, CT and for postemergence weed control and Fraser × balsam hybrid fir tolerance on a Christmas tree farm in Enfield, CT in 2022 and 2023. In both experiments, topramezone was applied to actively growing Christmas trees at 49 g ai·ha⁻¹ (0.04 lb ai·A⁻¹), 98 g ai·ha⁻¹ (0.09 lb ai·A⁻¹), or 196 g ai·ha⁻¹ (0.17 lb ai·A⁻¹). Balsam fir [Abies balsamea (L.) Mill. var. balsamea], canaan fir [Abies balsamea (L.) Mill. var. phanerolepis Fernald], Fraser fir [Abies fraseri (Pursh) Poir], Nordman fir [Abies nordmanniana (L.)], Norway spruce [Picea abies (L.)] Karst), and white pine [Pinus strobus (L.)] in the container experiment and Fraser × balsam hybrid fir [Abies fraseri (Pursh) Poir] × [Abies balsamea (L.) Mill. var. balsamea] in the field experiment were not injured from topramezone rates ranging from 49 g ai·ha⁻¹ (0.04 lb ai·A⁻¹) to 196 g ai·ha⁻¹ (0.17 lb ai·A⁻¹). Colorado blue spruce [Picea pungens (Engelm)] in 2022 and 2023 and Douglas fir [Pseudotsuga menzeisii (Mirb.) Franco] in 2023 showed temporary bleaching/yellowing of the new growth with topramezone at 196 g ai·ha⁻¹ (0.17 lb ai·A⁻¹). The highest injury was observed at 3 weeks after treatment and ranged from 9% in Colorado blue spruce to 23% in Douglas fir. Common ragweed [Ambrosia artemisiifolia (L.) var. artemisiifolia], horseweed [Conyza canadensis (L.) Cronquist], fall panicum [Panicum dichotomiflorum (L.)], large crabgrass [Digitaria sangunalis (L.) Scop.], and yellow foxtail [Setaria pumila (Poir.) Roem. & Schult. ssp. Pumila] were controlled 61 to 91%, 66 to 98%, and 45 to 99% by 4, 8, and 12 weeks after treatment, respectively, depending upon topramezone rate. Weed density 12 weeks after treatment showed a 58 to 100% reduction depending upon topramezone rate applied and weed species tested. Overall, these results suggest that postemergence topramezone at the labelled rate (98 g ai·ha⁻¹ or 0.09 lb ai·A⁻¹) can be safely used for effective weed control in Christmas trees. Further research is needed to evaluate postemergence topramezone in conjunction with preemergence and other postemergence herbicides for enhanced crop safety and weed control.

Herbicides used in this study: topramezone (Frequency), 4-[3-(4,5-dihydro-1,2-oxazol-3-yl)-2-methyl-4-methylsulfonylbenzoyl]-2-methyl-1H-pyrazol-3-one.

Christmas tree species used in this study: balsam fir [Abies balsamea (L.) Mill. var. balsamea], canaan fir [Abies balsamea (L.) Mill. var. phanerolepis Fernald], Colorado blue spruce [Picea pungens (Engelm)], Douglas fir [Pseudotsuga menzeisii (Mirb.) Franco], Fraser fir [Abies fraseri (Pursh) Poir], Fraser × balsam hybrid fir [Abies fraseri (Pursh) Poir] × [Abies balsamea (L.) Mill. var. balsamea], Nordman fir [Abies nordmanniana (L.)], Norway spruce [Picea abies (L.) Karst], and white pine [Pinus strobus (L.)].

Weed Species used in this study: common ragweed [Ambrosia artemisiifolia (L.) var. artemisiifolia], fall panicum [Panicum dichotomiflorum (L.)], horseweed [Conyza canadensis (L.) Cronquist], large crabgrass [Digitaria sangunalis (L.) Scop.], and yellow foxtail [Setaria pumila (Poir.) Roem. & Schult. ssp. Pumila].

Abstract

Pycnanthemum is a relatively new market introduction. Due to a lack of existing production procedures, growers may hesitate to work with the genus. Determining optimal plant growth regulator concentrations could make the plant more accessible. In the study, P. virginianum were drenched with 0, 0.5, 1, 2, 4, 8, and 16 mg a.i./pot of paclobutrazol (Bonzi®), while P. flexuosum were drenched with 0, 6, and 8 mg a.i./pot. The height, growth index, shoot dry weight, density, and inflorescence count were measured to compare growth between treatments. The height was controlled in all treatments except P. virginianum treated with 0.5 mg a.i./pot. The inflorescence count and growth index of P. virginianum increased at lower concentrations, while the shoot dry weight decreased at higher concentrations. Pycnanthemum virginianum plants treated with 8 mg a.i./pot had increased density (mg·cm⁻³) . The height, inflorescence count, and growth index of P. flexuosum decreased when treated with paclobutrazol. Treating P. flexuosum with 6 mg a.i./pot decreased shoot dry weight compared to nontreated plants, although the shoot dry weight was numerically higher when treated with 8 mg a.i./pot compared to 6 mg a.i./pot . Plant introductions can be daunting for growers if plants have no previous protocols for care. Providing information about Pycnanthemum production will enable more efficient production and faster distribution.

Species used in this study: Virginia mountain mint, Pycnanthemum virginianum (L.); Appalachian mountain mint, Pycnanthemum flexuosum (Walt.).

Chemicals used in this study: paclobutrazol (Bonzi®).

Abstract

While only a small portion of introduced species naturalize, and even fewer become invasive, those that do may alter ecosystems and disrupt natural plant communities. Recognizing that many non-native landscape plants are valuable commodities that provide important ecosystem services, enhance property values, and improve our quality of life, there is strong justification for developing cultivars with low reproductive fertility to prevent further distribution. This report reviews approaches for developing and evaluating low-fertility landscape cultivars to minimize self-sowing, weediness, range expansion, and potential invasiveness with recommended approaches, guidelines, and policy. Specific conclusions and recommendations include:

Selecting and developing cultivars with reduced fertility is a viable approach for maintaining economic, environmental, and aesthetic benefits of important landscape crops while minimizing potential invasiveness.
A ≥ 98% reduction in fertility, compared to fertile controls, is an achievable and practical criterion for accepting low-fertility cultivars as alternatives to potentially invasive, sexually reproducing plants.
Regulations of potentially invasive plants should include exclusions and provisions to allow for the continued production of cultivars with documented low reproductive fertility.

Significance to the Horticulture Industry

Air-blast Sprayer

Christmas Tree Tolerance and Weed Control with Postemergence Topramezone

Abstract

The Effects of Paclobutrazol on the Vegetative and Reproductive Traits of Pycnanthemum¹

Abstract

Development and Evaluation of Landscape Plant Cultivars with Reduced Fertility to Minimize Potential Invasiveness¹

Abstract

Impact of Rice Hull Mulch Depth on Emergence of Multiple Weed Species at Varying Growth Stages in Nursery Containers

Abstract

Evaluating the Use of an Air-blast Sprayer with Variable-Rate Technology for High Coverage Trunk Applications in Multi-row Blocks of Field and Pot-in-Pot Nursery Production¹

Abstract

Christmas Tree Tolerance and Weed Control with Postemergence Topramezone

The Effects of Paclobutrazol on the Vegetative and Reproductive Traits of Pycnanthemum¹

Evaluating the Use of an Air-blast Sprayer with Variable-Rate Technology for High Coverage Trunk Applications in Multi-row Blocks of Field and Pot-in-Pot Nursery Production¹

Impact of Rice Hull Mulch Depth on Emergence of Multiple Weed Species at Varying Growth Stages in Nursery Containers

Development and Evaluation of Landscape Plant Cultivars with Reduced Fertility to Minimize Potential Invasiveness¹

Susceptibility of Calathea Species and Cultivars to Bipolaris setariae

Identification of Red-Fruited Pears by Fourth Derivative Spectroscopy of Intact Lamina

Effect of Soil Compaction and Oxygen Content on Vertical and Horizontal Root Distribution

Available Water and Root Development Within the Micropores of Pine Bark Particles

A Comparison of Light Acclimatization Methods for Reduction of Interior Leaf Drop in Ficus spp.