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
Massachuetts Pollinator Protection Plan
The Massachusetts Department of Agricultural Resources has developed a Massachusetts Pollinator Protection Plan. It is a set of voluntary guidelines that discuss best management practices for stakeholders seeking to promote the health of the European honey bee and other pollinators. This document includes information for beekeepers, pesticide applicators, land managers and farmers, nurseries and landscapers, and homeowners and gardeners. Please locate the MA Pollinator Protection Plan for more information here: http://www.mass.gov/eea/docs/agr/farmproducts/apiary/pollinator-plan.pdf .
Lily Leaf Beetle Project
The University of Rhode Island Biological Control Lab is researching ways to find a natural method to combat lily leaf beetle. Small parasitic insects have been established in lily plots in Cumberland, RI and Wellesley, MA in hopes that these insects will disperse naturally to reduce the effects of the lily leaf beetle.
In an attempt to track these parasitic insects, URI would like to collect the larvae found on your lilies (they can be identified as the brown blobs, since they cover themselves in their excrement). The larvae will be dissected to identify the parasitic insects.
If you have larvae in your yard (or customers), please send to URI, following the instructions on the URI Biocontrol Lab website.
Questions & Answers
Q: When will gypsy moth egg masses begin hatching? What plants will they affect?
A: Gypsy moth (Lymantria dispar) egg masses begin hatching between 90-100 growing degree-days, using a developmental threshold of 50°F. For more information about using growing degree-days to predict insect development, please visit the "Growing Degree Days for Management of Insect Pests in the Landscape" fact sheet. Typically, this occurs around the first week in May in Massachusetts, or when serviceberry (Amelanchier) are blooming. Gypsy moth will feed on the leaves of and defoliate oak (preferred), maple, birch, poplar, willow, apple, and other deciduous plants. When their preferred hosts have been defoliated and gypsy moth populations are high, they will eat the needles of eastern white pine, spruce, and hemlock. (The 2016 population of gypsy moth did feed on conifers in certain areas.)
Q: How long will the gypsy moth caterpillars feed?
A:Gypsy moth caterpillars, following hatch in the 1st week of May will continue to feed and grow throughout roughly the 3rd week of June at which time caterpillars typically form the cocoons within which they pupate. Following pupation, adult gypsy moth males and females will emerge around the end of June, early-July. Adult males are brown and can be seen flying to find and mate with white colored, flightless (although winged) females. The females will lay the egg masses (that they coat with the fuzzy, brownish-tan hairs from their bodies) that can contain 500-1000 eggs and will overwinter in that stage. The caterpillars are the only stage of the gypsy moth that feed.
Q: What can I do to manage gypsy moth on ornamental plants?
A: A common management strategy for gypsy moth on valued, ornamental landscape trees and shrubs would be to apply Bacillus thuringiensis Kurstaki (Btk) on the foliage of the host plants when young gypsy moth caterpillars are actively feeding (shortly after egg hatch, when caterpillars are roughly between ¼ and ¾ inch in length). Older caterpillars are not as susceptible to Btk. Btk is practically non-toxic to birds, fish, and other aquatic organisms. It is non-toxic to people and pets. Btk is also practically non-toxic to non-target insects including pollinators such as honeybees. This particular strain of Bacillus thuringiensis is toxic only to the Lepidoptera (moths and butterflies). It is a naturally occurring, soil-dwelling bacterium that must be ingested by the caterpillars to be effective. It eventually destroys their gut and causes the caterpillars to stop feeding and they die. Btk products have been listed as suitable products for organic food production.
Another active ingredient, spinosad, may also be used against gypsy moth caterpillars. This is also derived from naturally occurring, soil-dwelling bacterium. Spinosad is toxic to gypsy moth through both contact and ingestion, and can be effective against slightly older caterpillars. It will cause the death of the insect in 1-2 days (roughly) due to improper nerve functioning. Spinosad should not be applied to flowering host plants, as it is highly toxic to pollinators, such as bees, before it dries. Once it dries, it is practically non-toxic to these non-target organisms.
Insecticides containing other active ingredients are also labelled for their use against gypsy moth caterpillars, but the different risks associated with these active ingredients should be fully understood and taken into consideration prior to using products that contain them. Always completely read and understand the insecticide label. These active ingredients include but are not limited to acephate, acetamiprid, azadirachtin, Bacillus thuringiensis subsp. Aizawai, carbaryl, emamectin benzoate, insecticidal soaps, permethrin, and tebufenozide. Some of the products associated with some of those active ingredients are restricted use products. Homeowners looking for assistance in managing gypsy moth caterpillars should contact a Massachusetts licensed pesticide applicator and arborist for help.
Non-chemical options include banding trees for gypsy moth caterpillars and removing egg masses prior to hatch. Banding trees for gypsy moth caterpillars will not be 100% effective and may not yield the desired results. While the sticky band may catch some caterpillars, many others may still make it to the canopy of the tree to feed as they crawl up the tree trunk. Young, newly hatched caterpillars can also disperse through ballooning, or using a silken thread to catch the wind and blow to a new location. This can allow young caterpillars to move from tree canopy to tree canopy of hosts and never encounter the tree bands, early on in their life cycle. Scraping the brownish-tan, fuzzy gypsy moth egg masses into a can of soapy water can be labor intensive and time consuming, and not all egg masses will be found or able to be reached. Some may be hidden from view or on the undersides of branches that are out of the reach of the homeowner.
Another option for gypsy moth management is to do nothing and wait for the population to collapse. (See: Are there other organisms that will affect gypsy moth populations?) This might not provide the best protection for valued ornamental plants, but may be a feasible management option to choose in largely forested areas. Ornamental plants suffering from multiple, consecutive years of gypsy moth defoliation may become weakened and more susceptible to secondary invaders or other organisms such as wood boring beetles and decay fungi that are attracted to otherwise weakened hosts. Add drought stress to that equation and such plants may be even further compromised.
Q: Are there other organisms that will affect gypsy moth populations?
A: Yes. Small mammals such as mice can have a large impact on gypsy moth populations when they are low. Certain species of native birds and insects may also act as predators of gypsy moth. Previously introduced parasitoids in the fight against gypsy moth including Ooencyrtus kuvanae, Cotesia melanoscelus, and Compsilura concinnata can attack certain percentages of the gypsy moth population, but even together their impact is not significant enough to reduce an outbreak.
The most effective organisms at regulating gypsy moth outbreaks are two pathogens- the fungus, Entomophaga maimaiga and the NPV virus. E. maimaiga is an insect killing fungus native to Japan that kills gypsy moth caterpillars. A first attempt to introduce it into North America was made in 1910 and 1911 for gypsy moth control, but it was thought that the attempt at that time failed. In 1989, the fungus was found to be killing large numbers of gypsy moth caterpillars in North America, perhaps from a separate introduction. Since 1989, E. maimaiga has been particularly successful in keeping gypsy moth populations out of an outbreak situation. Prior to that time, gypsy moth outbreaks occurred approximately every 10 years. The issues in Massachusetts seen in 2015 and 2016 are thought to be because of the very dry springs we have been experiencing, particularly in May and June. The fungus needs ample moisture at the right time in its lifecycle in order to effectively infect gypsy moth caterpillars. If enough rainfall is received, E. maimaiga is a density independent pathogen- meaning that typically, even in low populations of gypsy moth, this pathogen can be lethal to the caterpillars. The NPV virus, however, is density dependent, meaning that it requires a large population of gypsy moth in order to effectively infect and therefore reduce the population. The NPV virus tends to kill high populations of older caterpillars typically after they have done their feeding damage.
Q: Where did gypsy moth come from?
A:Gypsy moth was brought to Medford, Massachusetts around 1868 or 1869 by Etienne Leopold Trouvelot. Trouvelot was an artist, amateur entomologist, and eventually an award-winning astronomer. He purposefully brought gypsy moth from France to his home in Medford for the purpose of studying them in hopes of using gypsy moth for silk production. Some of the larvae escaped and Trouvelot tried to notify the authorities, as he understood the potential degree of this accident. By 1889, the gypsy moth problem had spread and the local efforts to manage this insect began. Gypsy moth is a non-native, invasive insect in North America.
Q: Where can I find more information?
A:Look to the Landscape Message for seasonal updates about gypsy moth and other insect pest activity throughout 2017. Information about egg hatch and defoliation seen in Massachusetts by this invasive pest will be shared under the Woody Ornamentals and Insects section. Further information about gypsy moth can be found in the UMass Extension Gypsy Moth Fact Sheet.
Tawny Simisky,UMass Extension Entomology Specialist
Trouble Maker of the Month
Winter Kill and Summer Patch
It’s finally spring, and lawns have begun to green up beautifully in response to the warmer temperatures. This is the time when any areas of dead turf will become evident. If sections of your lawn do not appear to recover in the next couple of weeks, the problem may be winter kill. “Winter kill” is not caused by a pathogen, but is the result of unfavorable conditions over the winter. There are several potential causes: very low temperatures, ice cover, desiccation, and/or a period of warm temperatures followed by a cold snap. Road salt and snow plowing can also result in turf damage. Snow mold may contribute to the problem. Turf that is weak going into the winter is especially vulnerable, as was the case in many areas hard hit by last year’s drought. Winter kill can be repaired by laying new sod or by overseeding. Use cultural practices such as adequate irrigation, proper fertility, and correct mowing height to encourage the deep rooting that turf will need to endure the summer heat.
Spring is also the time when the summer patch fungus (Magnaporthe poae) becomes active. M. poae begins to infect turf roots when temperatures reach the mid-60s. For lawns with a history of summer patch, it may be helpful to have the soil pH tested now. Summer patch can be more severe when soil pH is >6. An acidifying fertilizer can be used to bring the pH down to the 5.5-6.0 range. If overseeding, consider using less susceptible varieties of Kentucky bluegrass and including some perennial ryegrass in the mix. Summer patch can be managed with good cultural practices; however, if fungicides are to be used, they must be applied in spring in order to be effective.
Angela Maderias, Plant Pathologist, UMass Extension Plant Diagnostic Lab
Plant of the Month
Cornus florida, flowering dogwood
Flowering dogwood is a beautiful low-branched deciduous small tree native to the eastern United States. It typically grows to 15-30 feet tall and wide with a rounded to flat topped crown. Plants have an attractive horizontal, tiered branching habit. Cornus florida has lovely 3-4 inch diameter flowers (bracts) in spring. The true flowers of dogwood are insignificant tiny yellow or greenish button like clusters. The tiny clusters are surrounded by showy petal like bracts that give the appearance of four-petaled flowers. The flowers are generally white, but cultivars can have pink or red flowers. The leaves of flowering dogwood are dark green, 3-4 inches long and turn to beautiful red to reddish purple fall color. The fruits are bright red, ripening in late September to October and persisting into winter. Fruits are not edible to humans but are frequently eaten by birds. Bark on the stem and older branches develop an alligator hide appearance that is very attractive in the winter landscape.
Flowering dogwood prefers acidic, well-drained soil that is high in organic matter. It does not tolerate poorly drained soil. The tree should be mulched to keep the soil moist and cool. It performs best in partial shade but can be planted in full sun. When planted in full sun flowering dogwood tends to be bushier and produce more flowers. Cornus florida is not tolerant to stresses such as heat drought or salt. When stressed they become susceptible to a number of diseases most severe being dogwood anthracnose (Discula destructiva). Stressed trees are also susceptible to powdery mildew, leaf spots and are vulnerable to dogwood borers.
There are several cultivars to choose from including:
- ‘Cloud 9’ – Hardy. Reaches a height of 15 feet and may have a spread of up to 20 feet. Produces many white flowers (bracts) at an early age.
- ‘Cherokee Princes’ – Produces large white flowers (bracts)
- ‘Cherokee Chief’ – Produces deep red flowers (bracts)
- ‘Rubra’ – Produces pink flowers (bracts)
- ‘First Lady’ – Variegated yellow green foliage and white flowers (bracts)
- ‘Pluribracteata’ – Produces double white flowers (bracts)
Geoffrey Njue, UMass Extension Green Industry Sustainability Specialist
Upcoming Events
Featured Event:Landscape Pests and Problems Walkabout - Insects, Diseases, and Weeds
Get some hands-on experience scouting and identifying landscape diseases, insects, weeds, and abiotic problems. Join Randy Prostak, Extension Weed Specialist; Nick Brazee, Extension Plant Pathologist, and Tawny Simisky, Extension Entomologist, for a walk through the landscape as they discuss and demonstrate how to put IPM practices to work efficiently and examine some of the most common pest and cultural problems of woody ornamentals
Event Location: Stanley Park, Westfield, MA
Other Upcoming Events:
- 5/10: Spring Blooming Tree and Shrub ID Walk
- 5/18: Landscape Pests and Problems Walkabout - Insects, Diseases and Weeds
- 6/8: Weed Walkabout
- 6/15: Landscape Pests and Problems Walkabout - Insects, Weeds and Cultural Problems
- 7/26: UMass Turf Research Field Day
For more information and registration for any of these events visit 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.
