Efficacy of Several Herbicides on Yellow Archangel (Lamiastrum galeobdolon)

Yellow archangel is a twining perennial species that produces a dense evergreen canopy and may negatively affect forest floor vegetation. Because it is spreading rapidly in the Pacific Northwest (PNW), greenhouse and field trials were conducted on yellow archangel to determine its relative sensitivity to several herbicides. Products that slowed or prevented yellow archangel regrowth at 9 mo after treatment (MAT) in one or both iterations of the greenhouse trial were aminopyralid, diclobenil, glufosinate, imazapyr, isoxaben, metsulfuron, sulfometuron, triclopyr amine, and triclopyr ester + 2,4-D ester. In the field trial at 10 MAT, triclopyr and imazapyr were controlling 81 and 78% of treated yellow archangel, respectively, similar to aminopyralid, glyphosate, and metsulfuron (61 to 65%). Two applications of 20% acetic acid or 20% clove oil were controlling 53% at the same timing. At 13 MAT, only imazapyr and glyphosate were still providing good control of yellow archangel (81 and 80%, respectively), while all other products were controlling the weed at 53% or less. By 7 or 8 MAT after a second application, only imazapyr and glyphosate provided effective control of yellow archangel (86 to 94%).

Evaluation of Plantable Containers for Groundcover Plant Production and Their Establishment in a Landscape

The demand for groundcover plants for landscape use is increasing. Plantable containers are becoming available in sizes appropriate for groundcover plants. Landscapers are seeking ways to decrease the time required to prepare and plant groundcover beds. Studies were conducted in 2011 and 2012 to evaluate plantable containers for a variety of groundcover plants. The study has shown that ‘Bronze Beauty’ ajuga (Ajuga reptans), ‘Herman’s Pride’ lamiastrum (Lamiastrum galeobdolon), ‘Beacon Silver’ lamium (Lamium maculatum), ‘Immergrunchen sedum (Sedum hybridum), ‘Red Carpet Stonecrop’ sedum (Sedum spurium), and ‘Vera Jameson’ sedum (Sedum telephium) were grown to a marketable size from 1.5-inch plugs in 8 weeks in Lexington, KY, when transplanted in May through August. ‘Big Blue’ liriope (Liriope muscari) from bare root bibs required 12 weeks. Plant growth in a 90-mm paper container and 80-mm bioplastic container was similar to that of plants grown in standard 3-inch rigid plastic containers and required 20% less time to transplant into the landscape and grew rapidly after transplanting in the field. Peat containers in this production system yielded smaller plants and slower ground coverage after transplanting in the field than plants grown in the other containers.

Evaluation of Herbaceous Perennials as Weed Suppressive Groundcovers for Use Along Roadsides or in Landscapes

Fifteen herbaceous perennials were evaluated in field experiments in two New York State locations to determine their utility in roadside and landscape areas as weed suppressive groundcovers. Four species, Alchemilla mollis, Nepeta x faassenii, Phlox subulata, and Solidago sphacelata were strongly weed suppressive in both managed (weeds removed) plots and unmanaged (weeds not removed) plots. Weed suppressivity of perennial groundcovers was significantly increased in year two in both locations when perennials were well established. The most suppressive perennials showed several similar characteristics likely associated with their successful establishment. Successful groundcovers possessed dense foliage which strongly reduced light transmittance at the soil surface and emerged relatively early in spring. Lamiastrum galeobdolon and Thymus praecox proved to be more successful over a 2-year period when managed by weed removal in early spring. Although Leymus arenarius, a relatively tall monocot, also inhibited weed growth, this species demonstrated invasive characteristics due to its spread outside plots by fast-growing rhizomes.

Comparative Analysis of the Composition of Flower Volatiles from Lamium L. Species and Lamiastrum galeobdolon Heist. ex Fabr.

The volatiles of fresh flowers from nine natural populations of four Lamium species and Lamiastrum galeobdolon were analyzed by GC/MS. 49 compounds, 43 of them new for Lamium and Lamiastrum, were identified. The studied samples showed similarity of the volatile profiles and dependence of the oil-composition on the collection site. Significant amounts of squalene were found in all samples. The presence of homological series of straight chain alkanes from C12 to C31 was shown. Phenethyl alcohol was found only in L. maculatum f. alba.

Compost and Rubber Tire Chips as Peat Substitutes in Nursery Container Media: Growth Effects

This research investigated the feasibility of using composted yard wastes, composted municipal solid waste and shredded rubber tire chips in nursery container media. Containerized Physocarpus opulifolius ‘Dart's Gold’, Forsythia × ‘Meadowlark’, Spiraea × billiardii, Juniperus chinensis ‘Seagreen’, J. sabina ‘Mini Arcade’, J. horizontalis ‘Hughes’, and Lamiastrum galeobdolon were grown in media amended with five recycled waste materials used as peat substitutes in a standard container medium of composted woodchips, peat, and sand (3:2:1 by vol). Waste materials used included three yard waste composts, one municipal solid waste compost and shredded rubber tire chips. Fifty or 100% of the peat in the standard growing medium was replaced with each amendment. Ten treatments (five amendments, each at 50% and 100% peat replacement) and a control (standard medium) were used for all seven plant species. Visual ratings, height and width measurements (crown volume), number of growing points and plant dry weights indicated that media in which 50% of the peat was replaced by an amendment produced larger plants of superior quality compared to the control. Rubber tire chips were acceptable as a 50% peat substitute for plants that prefer well-drained conditions, while 100% peat substitution with tire chips was detrimental to plant growth and performance. Use of immature compost in container media negatively influenced plant growth.

Compost and Rubber Tire Chips as Peat Substitutes in Nursery Container Media: Effects on Chemical and Physical Media Properties

Physocarpus opulifolius ‘Dart's Gold’, Forsythia x ‘Meadowlark’, Spiraea x billiardii, Juniperus chinensis ‘Seagreen’, J. sabina ‘Mini Arcade’, J. horizontalis ‘Hughes’, and Lamiastrum galeobdolon were grown in container media amended with three yard waste (YW) composts, one municipal solid waste (MSW) compost and shredded rubber tire chips. Each of the five amendments was used to replace 50% or 100% of the sphagnum peat in a standard container medium resulting in eleven media treatments. Effects of peat replacement with compost or tire chips were compared relative to chemical and physical media characteristics. Amendments evaluated had limited long term nutritional value. Initial pH was increased when peat was replaced with compost or rubber tire chips; the increase in pH was proportional to the amount of peat replaced (50 or 100%). Over time, pH of all media equilibrated with irrigation water pH. Soluble salts were reduced for media amended with rubber tire chips while peat replacement with compost had variable effects on soluble salt levels based on compost source. Media amended with compost exhibited increased bulk density and decreased porosity, water infiltration capacity and water holding capacity compared to the standard, peat-based control medium. Peat replacement with rubber tire chips increased bulk density and porosity and decreased water holding capacity compared to the standard control medium. Water infiltration capacity was greatly increased and water holding capacity decreased when peat was replaced 100% with rubber tire chips.