UMass Extension's Landscape Message is an educational newsletter intended to inform and guide Green Industry professionals in the management of our collective landscape. Scouts compile and record environmental and phenological data for locations throughout Massachusetts to aid in the monitoring of plant and pest development, the planning of management strategies, and the creation of site-specific records for future reference. Detailed reports from Extension specialists on growing conditions, pest activity, and cultural practices for the management of woody ornamentals, trees, and turf are regular features. UMass Extension has updated the following issue to provide timely management information and the latest regional news and environmental data.
The Landscape Message will be updated weekly April through June. The next message will be available on April 15. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list.
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Scouting Information by Region
Regional Notes
Cape Cod Region (Barnstable)
General Conditions: Once again the Cape experienced both warm spring and cold winter weather over the past week! I’ve seen it jokingly referred to as the “Sprinter” season. From a high temperature of 64° F on March 31st to a morning low temperature of 18° F on April 6th in Marstons Mills, it has been an experience. Much of the time the Cape was also under a High Wind Advisory, leaving landscapes littered again with branches and debris. The mild weather from March 30 to April 2 was accompanied by rain. A cold front moved through overnight on April 3, bringing in sharply colder weather. Wet snow fell on the 3rd, then briefly changed to sleet and rain before exiting the Cape. Monday the 4th saw another round of wet snow and another bout of cold Canadian air, culminating with lows in the upper teens to low 20’s on the Cape. There has been some damage to newly emerging foliage on crabapple and ornamental pear. Star magnolia and ‘Leonard Messel’ magnolia blossoms that had opened are now brown. Upon examining unopened buds of star magnolia, they appear to be OK at this time. Partially opened buds had the outer layer of petals damaged but the interior looked OK at this time. Crabapple leaves were scorched and appeared wilted. Time will tell if there is more damage than is apparent at this time. Snow is still on the ground in shaded locations. Daffodils are blooming through the snow.
Pests/Problems: Larry Dapsis continues to monitor blueberry buds for the presence of winter moth. The cold weather may have delayed hatch, as none have been found to date. On a brighter note, Larry says that the fruit buds examined on the 6th appear healthy and uninjured by the cold temperatures. Several nurseries that I have visited were proactive in covering tender plant material before the seriously low temperatures arrived. Adult ticks will resume activity as the weather moderates. Bittercress (Cardamine hirsuta) is blooming.
Southeast Region (Hanson)
General Conditions: Hanson received 1.40 inches of rain this past week and 8 inches of snow. Soils continue to be very moist. I guess we could say, March went out more “like a lamb” with warm temperatures in the mid 60’s on March 30th and 31st, however, it was very windy with wind gusts up 50 mph. on Friday, March 31. April came in with warm temperatures on April 1 and high winds on April 2, plants were in bloom and peepers were peeping. After that, April 3rd came in “like a lion” with high winds, and 3 inches of snow, followed by 5 inches of snow on April 4th. Temperatures were below freezing overnight on April 3, 4, and 5, ranging from 17-22 degrees. Some areas of Plymouth County lost power due to high winds and falling trees on Sunday, April 3.
Prior to the freezing temperatures ofApril 3 - 4, Magnolia stellata (Star magnolia) and Magnolia ‘Wada’s’ memory were in full bloom and now their flowers are brown. M. x loebneri 'Leonard Messel' is in full bloom and some flowers were damaged by the cold but some look good and the unopened buds appear healthy. Forsythia was just about in full bloom before the cold and now the blossoms that were open look tired and some are brown. However, even before the freezing weather this past week, many of the Forsythia buds above the snow line were dead most likely due to the -4° and -9° degree weather over February 14-15. Other plants displaying various degrees of flower damage caused by the recent below-freezing April weather: Chaenomeles speciosa (Common Flowering Quince), Lonicera fragrantissima, Daphne mezereum (February Daphne), Lonicera fragrantissima (Winter honeysuckle, Omphalodes verna, Sanguinaria canadensis (Blood root) and Corydalis solida. H. foetidus and H. x hybridus (formerly orientalis) appear bedraggled but should recover. Cornus mas, Cornus officinalis, Pieris japonica, Pieris floribunda, Pieris 'Brouwer's Beauty', Salix sp. (pussy willow), Petasites japonicus, Scilla sibirica, hyacinths, Vinca minor, Chionodoxa luciliae are in full bloom. Rhododendron mucronulatum was in bloom the week of March 12th and a few flowers remain.Snow remains covering the ground in shady areas but is melting in sunny areas. Lawns not covered by snow, are green.
Pests/Problems: Winter moth caterpillars began to hatch in Hanson, MA, around April 1stt and 2nd at 47 GDD, base 50, and 217 GDD, base 40. However, on April 3rd, although there was silk (produced by the newly hatched winter moth caterpillars) observed on the oak tree trunk being monitored, there were few to no caterpillars observed during that cold stormy day. Also, on April 3rd, winter moth caterpillars were found in a few apple flower buds that were monitored. Of the 4 caterpillars found, 3 were dead. The newly hatched caterpillars on the tree trunk and in the apple tree buds probably died due to freezing overnight temperatures. (For more information on this, see Tawny Simisky’s Insect Section of the Landscape Message below) However, the winter moth eggs that did hatch are only a small portion of the eggs being monitored. Right now, there are still thousands of winter moth eggs yet to open which have the potential to impact trees. However, it is going to be an interesting and a tough season for predictions as buds have not yet begun to open on some trees, like oaks and Norway maples. And, if the weather warms up soon, and winter moth caterpillars continue to hatch and budburst is delayed, there is the potential that the some caterpillars could starve. Freezing weather, starvation, whatever it takes to possibly reduce the damage potential from this insect! Continue to monitor hemlocks for the white cottony egg masses of hemlock woolly adelgid. And continue to conduct tick checks frequently and use repellants. For tick information go to: http://ag.umass.edu/services/tick-borne-disease-diagnostics.
The high winds, at times this past this winter, and more recently, this past week, have brought down a number of trees and tree limbs, unfortunately and sadly, in some areas, with devastating and fatal results. Now is a good time, whether your clients are residential, municipal, or commercial, to check for dead trees, broken limbs, hazard trees, etc. and remove them, especially if they are in a public area or pose a threat to people, property, etc. Consider recommending, to your clients, a Massachusetts Certified Arborist to remove any large trees that may pose a threat and remember the old adage: Better to be safe than sorry. Bittercress continues to bloom but also continues to set seed.
North Shore Region (Beverly)
General Conditions: The weather in this past week was very odd. On Thursday March 31 and Friday April 1 temperatures were up into the low 70s and then they went down quickly to below freezing within 2 days. By Monday the temperature went down to 27 degrees and down to 19 degrees by the mornings of April 4th and and 5th. Snow was also reported on Sunday, April 3rd and Monday April 4th with an accumulation of 4 inches reported at Long Hill. By the morning there was still about 2 inches of snow on the ground. The low temperatures damaged the blooms of the plants that were in full bloom. The plants whose blooms were seriously affected by the freezing temperatures at Long Hill include Anise Magnolia (Magnolia salicifolia), Winter honeysuckle (Lonicera x purpusii) and February Daphne (Daphne mezereum). Plants whose blooms were not fully open such as Star Magnolia (Magnolia stellata) and Loebner Magnolia (Magnolia x loebneri) did show any damage. However we will be able to tell if there was damage when the flowers start to open. There was no damage observed on leaf buds and young developing leaves. However time will tell.
Pests/Problems: Tick activity has been slowed down by the cold temperatures. However they will resume activity when temperatures start to rise again. Fig buttercup (Ranunculus ficaria) is blooming on lawns not covered by snow at Long Hill.
East Region (Boston)
General Conditions: The unpredictable spring of 2016 continues. We ended the month of March with unseasonably warm temperatures reaching into the 70s before an arctic front moved in on the evening of the 2nd bringing high winds and winter weather and dropping an inch of snow. The storm’s energy continued into Monday (April 4th); high winds continued and snow accumulations totaled 4.5 inches as temperatures failed to reach 30° F. Conditions remained cold to finish out the week. Over the last seven days, temperatures have fluctuated by 50° F, ranging from 21° F to 71° F. We gained 21 GDDs on March 31st and April 1st combined, bringing us to 57 on the year. Snow cover has completely melted away in some areas, exposing green turf underneath, while in other areas, snow depth remains at 2 to 3 inches. Flowering plants which have handled the cold weather and continue to flower unscathed include: Dirca occidentalis (western leatherwood), D. palustris (eastern leatherwood), Pachysandra terminalis (Japanese pachysandra), Scilla siberica (Siberian squill), and Spiraea prunifolia (bridalwreath spirea). Despite the leafing out of some Syringa sp. (lilac), the buds appear undamaged by the cold temperatures. Prior to the arrival of snow, snapping turtles were observed migrating from the meadow to the neighboring ponds. Young great horned owls have been spotted on the grounds. Cercidiphyllum japonicum (katsura) is flowering despite the cold temperatures.
Pests/Problems: The erratic temperature fluctuations have damaged many early flowering plants: Anemone nemorosa (wood anemone), Chaenomeles sp. (flowering quince), Forsythia sp. (forsythia), Jeffersonia diphylla (twinleaf), Magnolia sp. (magnolia), Narcissus sp. (daffodil), and Prunus sp. (flowering cherry). Dandelion (Taraxacum sp.) remains in flower despite the weather, however the flowers of lesser celandine (Ficaria verna, formerly Ranunculus ficaria) are showing signs of cold damage. Winter moth has hatched despite cold temperatures; bud surveys have revealed that winter moth is alive but feeding appears to be minimal and retarded due to the cold temperatures. Many apples and crabapples (Malus sp.) which started to leaf out prior to cooling temperatures show damage to new leaf tissue; despite this damage, winter moth can be found sheltering deep within the flower buds.
Metro West (Acton)
General Conditions: What a crazy week that is has been! During this past one week reporting period, we’ve experienced three separate snow events if you count the heavy wet snow that we all woke up to on Sunday morning blanketing the landscape and later melting that same day by early afternoon, the squalls that quickly passed through the area later that afternoon and then the snow that wouldn’t quit on Monday. It didn’t amount to much more than 4” but it still remains in the landscape on tree limbs, the ground, where plows deposited it and rooftops. Magnolia and Forsythia blossoms that were in their glory just at the tail end of last week when temps were in the low 70s are now brown due to the recent cold temperatures. A low of 12.4° was recorded on the morning of the 6th. In bloom are the following plants: Acer rubrum (Red Maple), Acer saccharinum (Silver Maple), Cornus mas (Cornelian Cherry Dogwood), C. officinalis (Japanese Cornelian Cherry), Erica sp. (Heath), Forsythia spp. (Forsythia), Hamamelis × intermedia 'Arnold Promise' (Arnold Promise Witch hazel), H. × intermedia 'Diane' (Diane Witch hazel), Magnolia stellate (Star Magnolia), Lindera obtusiloba (Japanese Spicebush), Pieris japonica (Japanese Pieris) and Rhododendron mucronulatum (Korean Rhododendron). The following bulbs and herbaceous plants were seen in bloom: Caltha palustris (Marsh Marigold), Chionodoxa luciliae (Glory of the Snow), Crocus spp. (Crocus), Galanthus nivalis (Snowdrop), Helleborus niger (Christmas Rose), Narcissus spp. (Daffodil), Petasites japonicus (Japanese Butterbur), Pulmonaria rubra (Salmon colored Lungwort), Scilla siberica (Siberian Squill), Symplocarpus foetidus (Skunk Cabbage), and Vinca minor (Periwinkle).
Pests/Problems: The wind has been persistent and wind gusts were recorded up to 29 mph on March 31st and 26 mph on April 4thwhich has resulted in a number of whole tree blow downs and/or large limbs breaking and falling. Ticks are active. Draba verna (Spring Whitlow Grass) and Lamium purpureum (Purple Deadnettle), both winter annual weeds, as well as Taraxacum officinale (Dandelion) were observed in bloom.
Central Region (Boylston)
General Conditions: Snow and cold temperatures have slowed (and abruptly halted in some cases) the rush to bloom. 1.5” of snow was on the ground on the morning of April 3rd, and Monday, April 4th brought an additional 4” to Tower Hill, and as much as 6-7” elsewhere in the region. Temperatures dipped into the teens (between 13° and 19° F) on Monday and Tuesday evenings. Exposed petals were damaged by the cold on Magnolia, Forsythia and Abeliophyllum, but since only a few flowers had opened it appears that the damage will be slight. Spring-blooming bulbs like Narcissus, Scilla, Chionodoxa and Muscari appear to be fine though it remains to be seen whether or not the daffodil flowers will spring back to an upright position. The foliage of Hemerocallis, which was up 6-8”, appears to have been damaged by the cold, but the full extent of the damage is unknown at this point. The leaves of some trees and shrubs (Malus, Heptacodium, Spiraea, and Syringa) had begun to emerge, cold damage to flowers and foliage will become evident over the next few days and weeks. Also in bloom, and seemingly unfazed by the cold are some cultivars of Witch Hazel (Hamamelis x intermedia), American Elm (Ulmus americana), and Mountain Andromeda (Pieris floribunda), Fumewort (Corydalis solida), Windflower (Anemone blanda), Bloodroot (Sanguinaria canadensis), Lungwort (Pulmonaria cevennensis and P. rubra), and Henbane Bell (Scopolia carniolica) were in bloom but are now covered by snow.
Pests/Problems: Open flowers on Magnolia, Forsythia and Abeliophyllum were damaged by the cold. Ticks continue to be a problem, carpenter ants were active during the warm days last week.
Pioneer Valley Region (Amherst)
General Conditions: The big story in the valley this past reporting period, and across the northeast, was the abnormally frigid temperatures and the 4/4 snowstorm. In the valley, 2–7″ of snow was recorded with the highest accumulations in western Hampshire and Franklin Counties. The majority of this was melted by the warm April sun on Tuesday, 4/5 but remnants were still abundant days later in shaded settings. Low temperatures in the early hours of 4/5 ranged from 14° F in Greenfield and Deerfield, 18° F in Westfield and 21° F in Northampton and Springfield. On Wednesday, 4/6 lows were slightly warmer, with recorded temperatures of 19° F in Greenfield, 18° F in Deerfield and Westfield and 22° F in Northampton and Springfield. Backing up a bit, high temperatures in the valley peaked in the upper 60s to low 70s on Thursday 3/31 and Friday 4/1. But more importantly, the low temperatures during the early morning hours of 4/1 stayed consistently in the middle to upper 50s. This triggered many landscape plants to begin flushing new foliage. Winds were steady and strong during this time, most notably on Sunday, 4/3 when northwesterly winds gusted up to 47 mph at Barnes airport in Westfield. For some flowering trees and shrubs, bloom was cut very short by the cold temperatures. Many forsythias and star magnolias, in addition to some flowering cherries, were in full bloom in the Amherst area over the weekend. Their brightly-colored flowers are now brown, wilted masses drooping off the shoot tips. Numerous rosaceous plants that began flushing foliage for the season, such as crabapple, hawthorn and serviceberry, have been injured. It will take several more days to fully assess the damage, especially for fruit trees like apple, pear, sweet cherries and apricots. In some cases, only the leaf margins are likely be affected whereas other trees will have suffered a complete collapse of the current season’s foliage.
Pests/Problems: Incoming reports from UMass Extension fruit specialists are not encouraging. At the UMass Cold Spring Orchard in Belchertown, an estimated 50-75% of apple buds were killed by the cold weather. For sweet cherries, estimates are >75% mortality and swollen blueberry buds were also badly damaged. Continue to monitor for stems and branches killed by drought, cold injury or stem-cankering pathogens. With buds swelling on many trees, blighted shoots can be more readily detected. Bark on these killed plant parts may appear darker in color and small shoots can have a desiccated or shriveled appearance. Now is a good time to scout for the oystershell and white prunicola scales. At times, the white prunicola scale can be well camouflaged on branches and stems by its protective covering and lichens, making it easily overlooked without careful inspection. Its primary hosts include stone fruits (especially cherry), privet and lilac. The oystershell scale is more conspicuous with its elongate body that is tan to dark brown in color. It has a wider host range that includes dogwood, maple, lilac and aspen, among others. Scout blue spruce for signs of spruce needle rust. Immature pads of fungal tissue will be swelling under the surface of the needle and appear pale orange at this time. Once mature, in late April to early May, they rupture to release spores and may appear reddish-orange when fully developed. While more of an aesthetic problem, in conjunction with needle cast diseases, stem cankering and insect infestations, spruce needle rust can further the decline of stressed blue spruce.
Berkshire Region (Great Barrington)
General Conditions: It’s been an odd week with temperatures reaching into the low 70s on April 1st, followed by snow on April 3rd and 4th, and a record low temperature of 9° F on the morning of April 5th. Snowfall total was 8.5 inches which is equal to the total snowfall amount for the entire winter. Currently snow covers the ground throughout the county. The soil temperature reading was slightly higher in the shade than in the sun. This was the result of deeper snow in the shade area and thus more insulation of soil when the frigid 9° F drop occurred on April 5th. Forecasts are for continued below normal temperatures for most of the week ahead with a possibility for more snow.
Pests/Problems: The precipitous temperature damaged the blossoms of all the indicator plants on the phenology list except for Cornus mas, which remains in full bloom. Dissection of unopened buds of Magnolia stellata revealed that even the unopened flower buds were damaged. Likewise, some damage to unopened buds of lilac and quince was observed. While modern cultivars of forsythia were beginning to open, most old cultivars most likely will not open as their flower buds are less hardy. In general, flower buds of older type forsythias are killed at around -15° F and below. Such low temperatures occurred in February in this region. Likewise, tree fruit growers have reported that the flower buds of peach and nectarines have been killed, again probably due to the frigid temperatures in February. There is a possibility that other fruit trees, i.e. apples and cherries may also have been affected. Cold damage to plants will become more evident over the next several days to weeks and bears monitoring. At this point, no pests other than deer ticks and animal browsing are at issue. One landscape gardener in this area reported having had 21 tick bites thus far this year. Despite the recent cold spell, ticks will be a very serious problem in the months ahead and all precautions should be taken to protect oneself.
Environmental Data
The following growing-degree-day (GDD) and precipitation data was collected for an approximately two week period, March 31 through April 6. Soil temperatures and phenological indicators were observed on or about April 6. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via our instruments for the 2016 calendar year. This information is intended for use as a guide for monitoring the developmental stages of pests in your location and planning management strategies accordingly.
|
Region/Location |
GDD |
Soil Temp |
Precipitation |
Time/Date of Readings |
||
|
1-Week Gain |
2016 Total |
Sun |
Shade |
|||
|
Cape Cod |
13 |
48 |
44 |
35 |
1.50 |
10:00 AM 4/6 |
|
Southeast |
15 |
47 |
42 |
35 |
1.40 |
3:00 PM 4/6 |
|
North Shore |
19 |
48 |
36 |
34 |
0.20 |
10:00 AM 4/6 |
|
East |
21 |
57 |
40 |
36 |
1.51 |
3:30 PM 4/6 |
|
Metro West |
17 |
35.5 |
34 |
33 |
0.55 |
5:45 AM 4/6 |
|
Central |
21 |
54 |
35 |
33 |
0.47 |
4:00 PM 4/6 |
|
Pioneer Valley |
17 |
41 |
42 |
40 |
0.25 |
2:00 PM 4/6 |
|
Berkshires |
16 |
37 |
35 |
37 |
0.80 |
9:30 AM 4/6 |
|
AVERAGE |
17 |
46 |
39 |
35 |
0.84 |
- |
|
n/a = information not available |
||||||
Phenology
Phenological indicators are a visual tool for correlating plant development with pest development. The following are indicator plants and the stages of bloom observed for this period:
| Indicator Plants - Stages of Flowering (BEGIN, BEGIN/FULL, FULL, FULL/END, END) | ||||||||
|---|---|---|---|---|---|---|---|---|
| PLANT NAME (Botanic/ Common) | CAPE | S.E. | N.S. | EAST | METRO W. | CENT. | P.V. | BERK. |
| Forsythia x intermedia (Border Forsythia) | Begin | Begin/full | Begin | Full | Begin | Begin | Begin/Full | Begin |
| Rhododendron mucronulatum (Korean Rhododendron) | Begin | Full/End | * | Begin/Full | Begin | Begin | * | * |
| Magnolia stellata (Star Magnolia) | Begin | Full | Begin | Begin/Full | Begin | Begin | Begin/Full | Begin |
| Pieris japonica (Japanese Pieris) | Begin | Full | Begin/Full | Full | Begin | * | Full | Begin |
| Cornus mas (Corneliancherry Dogwood) | Full | Full | Full/End | End | Full/ End | Full | Full/End | Full |
| Acer rubrum (Red Maple) | Full/End | Full/End | End | End | Full/ End | Full/End | Full/End | Full |
| Acer saccharinum (Silver Maple) | End | End | Full/End | End | Full/ End | Full/End | Full/End | Full/End |
| * = no activity to report/information not available | ||||||||
- CAPE COD REGION - Roberta Clark, UMass Extension Horticulturist for Barnstable County - Retired, reporting from Barnstable.
- SOUTHEAST REGION - Deborah Swanson, UMass Extension Horticulturist for Plymouth County - Retired, reporting from Hanson.
- NORTH SHORE REGION - Geoffrey Njue, Green Industry Specialist, UMass Extension, reporting from the Long Hill Reservation, Beverly.
- EAST REGION - Kit Ganshaw & Sue Pfeiffer, Horticulturists, reporting from the Arnold Arboretum, Jamaica Plain.
- METRO WEST REGION – Julie Coop, Forester, Massachusetts Department of Conservation & Recreation, reporting from Acton.
- CENTRAL REGION - Joann Vieira, Superintendent of Horticulture, reporting from the Tower Hill Botanic Garden, Boylston.
- PIONEER VALLEY REGION - Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, reporting from UMass Amherst.
- BERKSHIRE REGION - Ron Kujawski, Horticultural Consultant, reporting from Great Barrington.
Woody Ornamentals
Diseases
Recent pathogens of interest seen in the UMass Extension Plant Diagnostic Lab:
Bifusella needle cast of eastern white pine (Pinus strobus). Samples collected from trees at three different sites, ranging in age from 15- to 30-years-old. Brown needle tips with long, black-colored pads of fungal tissue present. In late spring to early summer, these oily pads swell and rupture to release large volumes of clear spores. Trees can be generally characterized as low vigor with significant needle shedding observed. All are in mass plantings or pruned screening rows. Bifusella is one of several fungal pathogens associated with white pine needle cast in recent years.
Spruce bud scale (Physokermes piceae) on dwarf Alberta spruce (Picea glauca ‘Conica’). Tree is approximately 10-years-old and began showing symptoms of decline last year. Premature needle shedding was observed along with blackened stems from sooty mold fungi. This non-native pest is most often found on Alberta spruce in our area but can also infest Norway and blue spruce. Mature females cluster at the base of shoots and are easily overlooked without careful scouting. White spruce is also very susceptible to needle cast by Rhizosphaera.
Severe infestation of the San Jose scale (Quadraspidiotus perniciosus) and stem cankering caused by Phomopsis on domestic apple (Malus domestica). Tree is 40-years-old and growing in a sunny location with well-drained soils. Currently, the tree is exhibiting extensive dieback throughout the canopy that was first observed three years ago. The San Jose scale can be a devastating pest when populations are high and the feeding likely facilitated invasion and spread of the opportunistic Phomopsis.
Needle tip blight of white fir (Abies concolor) caused by establishment stress and Rhizosphaera. Tree is 15-years-old and was planted at the site last autumn. Over the winter, needle tips became yellow to brown. Research at the UMass Plant Diagnostic Laboratory has revealed there are as many as nine species of Rhizosphaera in our region, which may explain why symptoms on white fir differ from what is normally observed on spruces. Interestingly, a minor infestation of the black pineleaf scale (BPLS; Nuculaspis californica) was also detected from the sample. A pest of hard pines in western North America, the BPLS has been reported on white fir as a secondary host
For more detailed management information for woody plant diseases in the landscape, refer to UMass Extension's Professional Management Guide for Diseases of Trees and Shrubs.
Report by Nick Brazee, Plant Pathologist, UMass Extension Plant Diagnostic Lab, UMass Amherst.
Insects
Woody ornamental insect and non-insect arthropod pests to consider, a selected few:
- Eastern Tent Caterpillar: (Continued monitoring) Look to the first Landscape Message of 2016 for more detailed information about this insect. Eastern tent caterpillar larvae will begin to hatch across the state between 50-400 GDD’s, base 50°F. Once the snow melts so they are visible, we should be pruning and removing any remaining egg masses that have not hatched yet and removing any small webs found in the crotches of branches over young larvae.
- Forest Tent Caterpillar: (Continued monitoring) Look to the first Landscape Message of 2016 for more detailed information about this insect. We have more time remaining to look for forest tent caterpillar egg masses and remove them (prior to hatch) than we do for eastern tent. Forest tent caterpillar egg hatch will occur between 192-400 GDD’s, base 50°F. While removing any unhatched eastern tent egg masses, take care of forest tent egg masses as well.
- Gypsy Moth: (Continued monitoring) Look to the first Landscape Message of 2016 for more detailed information about this insect. We still have time to remove egg masses mechanically when small in number and they can be reached safely. Gypsy moth eggs will hatch between 90-731 GDD’s, base 50°F. Although this cold weather has stalled growing degree day accumulation this week to some extent, as temperatures warm we should be looking to manage young caterpillars once 90 GDD’s are reached. Some areas in the central and eastern portions of the state saw an increase in gypsy moth populations in 2015, so keep an eye on this insect.
- Hemlock Eriophyid Mite: Nalepella tsugifoliae (also known as the hemlock rust mite) is active between 7-400 GDD’s, base 50°F, and therefore may already be feeding openly on the needles of hemlock (a particular pest on eastern hemlock in Massachusetts) but has also been found on spruce, fir, yew (Taxus), golden larch (Pseudolarix), and Torreya. This mite will suck juices from the hemlock needle, causing off-color foliage (sometimes with a blueish hue before yellowing) and can lead to needle drop. This pest can sometimes go undetected for a period of time until damage is very apparent. Most of the damage will occur in the spring, but the mite can be active into the summer. These are not spider mites, and look very different. They can be identified by their pale yellow color, wedge-shape, 4 legs, and very small size (barely visible to the unaided eye). When temperatures rise again and remain above freezing for 24-48 hours, horticultural oils may be used to manage hemlock eriophyid mite if they are found when inspecting the needle surfaces of eastern hemlock.
- Lily Leaf Beetle: Lilioceris lilii is a beetle in the family Chrysomelidae that is originally native to Europe. This insect was discovered in Canada in 1945 and more recently in Massachusetts in 1992. Adult beetles will be active soon, as the adult stage over-winters and will begin to feed on the plants as soon as lilies break through the ground. They can feed on true lilies such as Turk’s cap, tiger, Easter, Asiatic, and Oriental and also fritillaria. They may also feed lightly on lily of the valley, solomon’s seal, bittersweet (Solanum spp.), potato, hollyhock, and hostas. The most destructive damage is done to the lilies. Adults are about ½ inch long with a very bright red body but with black legs, head, antennae, and underside. Adults will begin to lay tan colored eggs in rows on the undersides of leaves. Eggs will turn orange and then a deep red color prior to hatch. Larvae are slug-like with soft, orange/brown/yellow/ or green bodies with black heads. To deter predators, the larvae will cover themselves with their own excrement (a caution if you intend to hand-pick them off plants). The larvae are the most damaging feeding stage, but adults will feed on plant tissues as well. Pupation occurs in the soil and adults overwinter in soil, plant debris, or other sheltered areas. Management can be achieved by hand-picking and removing adults and larvae. Some chemical management options are available for this insect, but if caught early mechanical management may be effective.
- Southern Pine Beetle: Dendroctonus frontalis has been detected in traps in Massachusetts.
- Viburnum Leaf Beetle: Pyrrhalta virburni is another beetle in the family Chrysomelidae that is native to Europe, but was found in Massachusetts in 2004. This beetle feeds exclusively on many different species of viburnum. This insect will overwinter on the twigs of the host plant as eggs, which will hatch soon after budbreak. Larvae will feed in groups, skeletonizing the lower leaf surface. Adult feeding will lead to oblong holes on the inside of leaves. Now is the time to inspect susceptible plants (viburnum) for over-wintering eggs on stems toward branch tips. Removal and destruction of infested stems, if small in number, can be effective. If management this way is not possible, larvae may be treated with a product containing spinosad once they appear soon after budbreak.
- White Pine Weevil: Pissodes strobi is a beetle native to the northern United States and southern Canada. It can be found on hosts such as white pine and spruce (Colorado blue, Norway, Serbian). Other pines such as Scots, red, pitch, jack, and Austrian pines can also serve as hosts. Adult females are active between 7-58 GDD’s, base 50°F, and may have been apparent in the past couple of weeks. They will lay eggs on the terminal growth of their host plants, which will hatch in 1-2 weeks when young larvae will tunnel into stems. More damage may become apparent in June and July. Trees in sunny locations are more prone to attack. Some chemical management options are available; however, this insect rarely kills trees on its own. It can cause the development of multiple leaders, however. If tree resin is seen dripping from terminal leaders on these plants, it may signal the time to treat for this pest. Distorted terminal growth or “shepherd’s crooks” found on hosts due to this insect should be pruned and destroyed when possible.
- Winter Moth: (Continued monitoring) As mentioned in last week’s Landscape Message, the eggs of Operophtera brumata have been observed turning blue and hatching in eastern Massachusetts. So what does this mean for winter moth in the face of the cold temperatures and snowfall we have experienced this week? Dr. Elkinton and his graduate student Hannah Broadley have data from 2015 for winter moth eggs that are orange (not yet ready to hatch), blue (nearly ready to hatch), and young caterpillars and their ability to tolerate cold temperatures. Like many insects that become active this early in the season, they have a fair degree of tolerance for cold temperatures. The Elkinton lab reports that eggs that remain orange at this time may be able to tolerate temperatures around -22° F prior to freezing. Eggs that have matured to the blue stage, just prior to hatch, are less tolerant but may still remain viable until temperatures reach -13° F and below. Any of the caterpillars that hatched last week are the most vulnerable stage and have been observed freezing between 14° F and -4° F. These observations indicate exposure to acute or immediate temperatures required for freezing at these stages (and thus mortality), however extended periods of cold seen this week may contribute to mortality, particularly of the young caterpillars, even at temperatures slightly above 14° F. Dr. Elkinton and his lab are planning to sample winter moth larvae at this time and assess mortality due to these cold temperatures. Look to the Landscape Message in the coming weeks for reports on what they find. Winter moth eggs have been observed turning blue in Mattapoisett on 4/6/16. For more information about winter moth egg hatch in your area, look to the Regional Reports in this message. For green industry professionals looking to manage winter moth in the landscape this season, we will need to wait until foliage is fully expanded at this point to treat young caterpillars with spinosad products or pyrethroid products (if necessary). This will not prevent the early feeding done by the smallest caterpillars in the buds, but will allow for better coverage of the leaf surface so caterpillars do not need to damage more leaf surface before ingesting the pesticide. Apples, crabapples, and other flowering plants should not be sprayed with these products while in bloom to avoid unintended impacts to pollinators.
A note about Deer Tick Awareness: deer ticks (Ixodes scapularis), the American dog tick (Dermacentor variabilis), and the lone star tick (Amblyomma americanum) are all found throughout Massachusetts. Each can carry their own complement of diseases. Adults and nymphs can be active when temperatures are above freezing and anyone working in tick habitats (wood-line areas, forested areas, and landscaped areas with ground cover) should check themselves regularly for ticks while practicing preventative measures. Look to the following resources from Larry Dapsis, Entomologist and Deer Tick Project Coordinator with Cape Cod Cooperative Extension for more information. Have a tick and need it tested? Visit the web page of the Laboratory of Medical Zoology (www.tickdiseases.org) and click on the red 'Test a Tick' button for more information.
Report by Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program
Management Practices
Spring Frost Injury, Cold Damage, and Spring Salt Applications
The cold temperatures early this week have resulted in cold temperature damage to many of the early blooming and leafing plants. Some of the most noticeable impacts have been the flowers Magnolia stellata (star magnolia), the new leaves of Malus spp. (crapbapples and apples), and the newly emerging leaves of Syringa vulgaris (common lilac). Symptoms of spring freeze damage include brown or black foliage, shoot dieback in conifers, and curling or shriveling of leaves. Some leaves may appear water-soaked as a result of cell damage due to ice formation within the leaf cells. The damage on some plants may not be apparent for days or weeks until growth resumes.
The extent of damage will vary depending on the degree of emergence from dormancy, the sensitivity of the plant, the plant genetics, the location of the plant in the landscape, and the local microclimate. Often time the plants will drop the damaged flowers, leaves, or buds. Leaves and leaf buds will likely be replaced with new ones. If possible it is best to wait to prune damaged plant material as it is best to see where new growth begins.
Also keep in mind as the snow melts to pay attention to the path of the salt laden melt water. Plants are more sensitive to salt damage during this time of year due to greater activity and water uptake. Leaching of salts from the soil may be necessary in areas that may have salt buildup or that are known to be in the path of melt water from salt laden snow piles.
Plant of the Week: Magnolia stellata
The star magnolia is a small tree to large shrub growing 15-20’ tall spreading 10-15’ wide. White fragrant 3-4” flowers emerge in early spring. As demonstrated this week, spring freezes can severely damage the strap-like petals. Protected southern facing locations should be avoided to avoid early bloom. Flowers best in full sun, but can deal with part shade. Dark green oblong leaves turn yellow-bronze in fall.
Garden Retailers
Monitor the weather forecast and avoid moving cold tolerant annuals and herbaceous perennials outdoors if a hard frost (colder than 28° F) is predicted within at least three nights of when plants would be put outside. Avoid placing plants in low-lying areas because frost will more likely settle in these areas. Be prepared to cover plants or bring them into a protected area if temperatures go below 28° F.
The best scenario is to move plants outdoors on an overcast day, with moderate temperatures (40’s+), little wind (very important), and no severe cold (freezing temperatures) or heavy rain forecasted for (at least) the next 24 hours.
Annuals and perennials need to be acclimated before moving them to outdoor yards, by growing them at cool temperatures for at least week (45-55° F).
Begin with just a few plants and experiment with cultivars, making adjustments as needed. Some varieties of the same type of plant have varying degrees of cold hardiness. Learning which plants perform best will take some experimenting. Some cool tolerant annuals include pansy, annual phlox, alyssum, osteospermum, nemesia, verbena, diascia, bidens, antirrhinum (snapdragon), mimulus, lobelia, calibrachoa and petunias.
Note that extended periods cold, rainy weather will increase risk for diseases such as botrytis blight and root rots and nutrient deficiency.
Moving Cool Tolerant Plants Outdoors: Risks and Benefits: https://ag.umass.edu/fact-sheets/moving-cool-tolerant-plants-outdoors-risks-benefits
Additional Resources
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For a complete listing of upcoming events, see our Upcoming Educational Events page.
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.
Ticks are active at this time! Remember to take appropriate precautions when working and playing outdoors, and conduct daily tick checks. UMass tests ticks for the presence of Lyme disease and other disease pathogens. Learn more
