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Hort Notes 2019 Vol. 30:2

April 1

A monthly e-newsletter from UMass Extension for landscapers, arborists, and other Green Industry professionals.

To read individual sections of the message, click on the section headings below to expand the content:

Hot Topics

Deer tick questing Landscapers, arborists, tree wardens, lawn care professionals, grounds managers, and essentially any professionals working outdoors run the risk of encountering, being bitten by, and contracting a tick-associated disease from multiple tick species in Massachusetts. UMass Extension is presenting this conference to bring together speakers who will discuss what is currently known about tick and tick-associated diseases in Massachusetts and surrounding states, habitat and winter survival of ticks, personal protection, and the management of ticks in landscapes. 

Topics include:

  • Tick Surveillance - Dr. Stephen Rich, UMass Laboratory of Medical Zoology
  • Personal Protection and Ticks: How Industry Professionals Can Protect Themselves - Larry Dapsis, Cape Cod Cooperative Extension 
  • Habitat, Winter Survival of Ixodes scapularis and Amblyomma americanum and the Establishment of the Lone Star Tick in Connecticut - Kirby C. Stafford III, CT Agricultural Experiment Station
  • Disease Risk Assessment - Dr. Stephen Rich, UMass Laboratory of Medical Zoology
  • Management of Ticks in Landscapes: Mechanical and Chemical Management, Deer Exclusion, and other Research - Kirby C. Stafford III, CT Agricultural Experiment Station

Credits:
5 pesticide contact hours for all categories and Applicators License.
Association credits: 5 ISA, 5 CTSP, 2 MCA, 2 MCLP, and 1 MCH credits. SAF credit requested.

For more details and registration options, go https://ag.umass.edu/landscape/events/ticks-tick-associated-diseases-conference.

Questions & Answers

Q. I am concerned about viburnum leaf beetle, are certain species more susceptible?

Yes, unfortunately many of the more popular Viburnum species are susceptible to viburnum leaf beetle; however, there are servel great species with good resistantance. Also keep in mind that all species have more feeding damage when plants are grown in shade. The following lists the susceptibility of some of the most popular Viburnum species. 

Highly susceptible: first to be attacked, generally destroyed in the first 2-3 years following infestation
V. dentatum – arrowwood viburnum
V. nudum – smooth withered
V. opulus – European cranberrybush
V. opulus var. americana – American cranberry bush
V. propinquum – Chinese viburnum
V. rafinesquianum – downy arrowwood viburnum

Susceptible: eventually destroyed; not heavily fed upon until the most susceptible species are destroyed
V. acerfolium – mapleleaf viburnum
V. lantana – wayfaring tree
V. rufidulum – rusty blackhaw viburnum 
V. sargentii – sargent viburnum
V. wrightii – Wright viburnum

Moderately susceptible: varying degrees of susceptibility; usually not destroyed by the beetle
V. alnifolium or lantanoides - hobblebush
V. burkwoodii – burkwood viburnum
V. x carlcephalum – fragrant viburnum
V. cassinoides – witherod viburnum
V. dilatatum – linden viburnum
V. farreri  - fragrant viburnum
V. lentago – nannyberry viburnum
V. macrocephalum – Chinese snowball viburnum
V. x pragense – Pragense vibrunum
V. prunifolum – blackhaw viburnum
V. x rhytidophylloides – lantanaphyllum viburnum

Most resistant: Show little or no feeding damage, survive infestation fairly well
V. bodnantense – Bodnant viburnum
V. carlesii – Koreanspice viburnum
V. davidii – David viburnum
V. x juddii – Judd viburnum
V. plicatum – Japanese snowball viburnum
V. plicatum var. tomentosum – doublefile viburnum
V. rhytidophyllum – leatherleaf viburnum
V. setigerum – tea viburnum
V. sieboldii – siebold viburnum

Mandy Bayer, Extension Assistant Professor of Sustianable Landscape Horticulture

Trouble Maker of the Month

Cedar-Quince Rust

Cedar-Quince rust is one of many rust diseases in the landscape caused by the fungus Gymnosporangium. Like all species in this genus, G. clavipes attacks redcedar/juniper (Juniperus) and rosaceous hosts, particularly serviceberry (Amelanchier), quince (Cydonia) and hawthorn (Crataegus). In late April to early May, the signs of the disease will become visible on infected Juniperus in the landscape. Red-colored pads of fungal tissue will swell from infected stems and branches and once they become wet, they turn orange and gelatinous. These spores disperse to infect rosaceous hosts. On serviceberry, quince and hawthorn, stem distortion and cankering can occur, in addition to a fruit blight and leaf spots. On shrub serviceberries, significant canopy dieback can occur as a result of the stem cankering. Signs of the disease on rosaceous trees and shrubs do not appear until mid-summer. Most Juniperus are largely unaffected by the disease, but often serve as a perennial source of the pathogen in the landscape. Therefore, early season scouting should be performed to confirm the presence of the pathogen. See UMass Extension's Cedar-Quince Rust fact sheet for more information and photos.

Nicholas J. Brazee, UMass Extension Plant Pathologist 

Plant of the Month

Abeliophyllum distichum, white forsythia

All winter long, small black buds adorn the tips of slender, arching, leafless branches and stand in stark contrast to the pure white snow of winter. The arching stems cross over one another as if fighting for prominence at the top of the 4’-5’ tall framework of this deciduous shrub. In central Massachusetts, the air warms sufficiently around the middle of April, and the black buds begin to swell, eventually opening to reveal four-petaled white flowers which dangle elegantly in short axillary racemes along each branch. The flowers follow the same shape and form of their cousin, the common forsythia, though they are a bit smaller and clean white rather than garish yellow.  

White forsythia is not a true forsythia but, like Forsythia x intermedia, it is a member of the Oleaceae or olive family, a clan which also includes Lilacs (Syringa sp.), Privet (Ligustrum sp.), Fringetree (Chionanthus sp.) and the tender fragrant olive (Osmanthus sp.). Abeliophyllum is a monotypic genus containing just A. distichum. Its name is derived from ‘abelio’, referring to the genus Abelia, and ‘phyllum’ for leaf, together combining to indicate the resemblance of the leaves to those of Abelia. The specific epithet ‘distichum’ also refers to the leaves and indicates the paired, or two-ranked, arrangement of leaves. The leaves are simple, ovate and 2-3” long. They remain deep green in summer and rarely offer any fall color, though sometimes will show hints of red, yellow and burgundy before dropping. Like many of its cousins, it is pest and disease resistant. 

White forsythia flowers are about 1/3 of an inch across, though a quirky cross-pollination strategy has resulted in two types of flowers occuring on plants within this genus. The flowers types are very similar to one another, but differentiated by the placement of the reproductive parts and by a small difference in size. Those flowers with the style or female part extending beyond the male, pollen bearing stamens are called pin flowers. Those with the stamens forward – extending past the female style - are called thrum flowers. The placement of the parts makes pollination more likely when bees visit both types of flowers, transferring pollen from one plant to the other. This quirky occurrence, called heterostyly, also occurs in forsythia and jasmine, both members of the Oleaceae family, as well as in about 27 other families of plants. In Abeliophyllum, the thrum flowers are a bit larger than the pin flowers, but not so much so that you are likely to notice.    

In full sun or part shade, and given good growing conditions, the flowers will be borne in abundance. If temperatures remain moderate in the spring, they will provide a floral show for 10-15 days from mid to late April. As the flowers age, they gently fade to pink; some variants tend towards pink so frequently that they are often sold under the cultivar name ‘Roseum’ or as part of the Roseum Group. A sweet fragrance, likened to almond, accompanies the bloom, making this a lovely choice for a protected spot where the fragrance can be captured and enjoyed. Planting in front of a dark backdrop like an evergreen tree or shrub, or a dark structure, creates a pleasing contrast with the pristine flowers. Abeliophyllum will tolerate short periods of drought, but is best grown in a moist but well-drained garden soil. It is not particular as to pH, though would not perform well at extremely low or high pH conditions. It is stunning combined with the blue flowers of Siberian squill (Scilla siberica), glory of the snow (Chionodoxa forbesii), and windflowers (Anemone blanda ‘Blue Star’) with whom its bloom overlaps. Other early blooming companions include Iris ‘Harmony’, hellebores (Helleborus X hybridus), hyacinths (Hyacinthus orientalis), and Pigsqueak (Bergenia cordifolia). This unusual shrub is hardy to zone 5 (-10 to -20 degrees), though in fickle springs flowers may sustain damage from late frosts, particularly if they have gotten off to an early start. 

Though this is an undemanding shrub, one finds it variously described as a heap of twigs, a messy form, straggly or unkempt. These descriptions may well fit an untended plant that’s been left to its own devices, but a more acceptable and tidy shrub is easily formed with a bit of smart pruning. Shaping cuts and rejuvenation every few years will encourage new growth and a fuller, tidier plant as well as more prolific flowering. Prune immediately after flowering and shorten any excessively long stems which arch and root. It is altogether smaller and more manageable than its robust cousin, Forsythia x intermedia and deserves a place in the modern, often smaller garden. It can be easily propagated by layering a stem – that is, bending and pinning a stem to the ground, ensuring contact with soil. Roots will form in the axils and along the stem and the new plant can be separated from the parent plant once it’s well established. Semi-hard stem cutting can also be taken in summer.  

Growing this plant not only provides human enjoyment in a season where little else is making a show, it also helps pollinators in the very early shoulder of spring, and since this plant is so rare that it verges on extinction in its native range of central Korea (now found in only seven sites), including it in our landscapes can help ensure its future. 

white forsythia flower white forsythia shrub

 

 

 

 

 

 

Joann Vieira, Horticulturist

Upcoming Events


Get some hands-on experience scouting and identifying landscape diseases, insects, weeds, and abiotic problems. Join UMass Extension specialists for a walk through the landscape as they discuss and demonstrate how to put IPM practices to work effi ciently and examine some of the most common pest and cultural problems of woody ornamentals. Dress for walking; workshops held rain or shine. Bring a clipboard, pencil and hand lens if possible.

Landscape Pests and Problems Walkabout - Diseases, Weeds, Insects & Cultural Problems

Apil 29, 2019 - 4:00 to 6:00 pm
Location: UMass Amherst

Join Randy Prostak, Extension Weed Specialist; Nick Brazee, Extension Plant Pathologist; and Rick Harper, UMass Extension Professor of Urban and Community Forestry for this walkabout. 2 pesticide contact hours for categories 36 and Applicators License available; Association credits: 2 ISA, 1/2 MCLP, 1/2 MCA, and 1 MCH.

Landscape Pests and Problems Walkabout - Diseases and Weeds

May 10, 2019 - 4:00 to 6:00 pm
Location: Newton Cemetery

Join Randy Prostak, Extension Weed Specialist and Nick Brazee, Extension Plant Pathologist, for this walkabout. 2 pesticide contact hours for categories 36 and Applicators License available; Association credits: 2 ISA, 1/2 MCLP, 1/2 MCA, and 1 MCH.

Registration and Additional Information.


Other Upcoming Events:​

  • 4/9:  Developing an Invasive Plant Management Program (part B of the Invasive Plant Certification series), Milford, MA
  • 4/10: Webinar - 2018/2019 Tick Updates From the UMass Laboratory of Medical Zoology (LMZ)
  • 4/24: Ticks and Tick-Associated Diseases Conference, Milford, MA
  • 4/29: Landscape Pests and Problems Walkabout - Diseases, Weeds, Insects & Cultural Problems
  • 5/8: Webinar - American Dog Ticks and Lonestar Ticks and Associated Diseases
  • 5/10: Landscape Pests and Problems Walkabout - Diseases and Weeds
  • 6/2: Creating Pollinator Forage in the Landscape
  • 6/12: Ornamental Tree and Shrub ID and Insect Walk
  • 6/19: Weed Walkabout
  • 6/25: Landscape and Turf Weed Topics - You pick!

For more information and registration for any of these events, go to the UMass Extension Landscape, Nursery, and Urban Forestry Program Upcoming Events Page


Additional Resources

For detailed reports on growing conditions and pest activity – Check out the Landscape Message

For commercial growers of greenhouse crops and flowers - Check out the New England Greenhouse Update website

For professional turf managers - Check out Turf Management Updates

For home gardeners and garden retailers - Check out home lawn and garden resources. UMass Extension also has a Twitter feed that provides timely, daily gardening tips, sunrise and sunset times to home gardeners, see https://twitter.com/UMassGardenClip

Diagnostic Services

A UMass Laboratory Diagnoses Landscape and Turf Problems - The UMass Extension Plant Diagnostic Lab is available to serve commercial landscape contractors, turf managers, arborists, nurseries and other green industry professionals. It provides woody plant and turf disease analysis, woody plant and turf insect identification, turfgrass identification, weed identification, and offers a report of pest management strategies that are research based, economically sound and environmentally appropriate for the situation. Accurate diagnosis for a turf or landscape problem can often eliminate or reduce the need for pesticide use. For sampling procedures, detailed submission instructions and a list of fees, see Plant Diagnostics Laboratory

Soil and Plant Nutrient Testing - The University of Massachusetts Soil and Plant Nutrient Testing Laboratory is located on the campus of The University of Massachusetts at Amherst. Testing services are available to all. The function of the Soil and Plant Nutrient Testing Laboratory is to provide test results and recommendations that lead to the wise and economical use of soils and soil amendments. For complete information, visit the UMass Soil and Plant Nutrient Testing Laboratory web site.   Alternatively, call the lab at (413) 545-2311.