Source: http://ag.umass.edu/landscape/landscape-message-apr-27-2018
Timestamp: 2019-04-24 13:55:06+00:00

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The Landscape Message will be updated weekly in April, May and June. The next message will be posted on May 4. To receive immediate notification when the next Landscape Message update is posted, be sure to join our e-mail list.
The following data was collected on or about April 25, 2018. Total accumulated growing degree days (GDD) represent the heating units above a 50° F baseline temperature collected via our instruments for the 2018 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.
General Conditions: The average temperature over the last week was 46°F with a high of 59°F on April 24 and a low of 32°F on April 22. Some local areas experienced frost on April 20, 22, and 23. Less than an inch of precipitation has fallen, primarily falling on April 19 & 25. Topsoil and subsoil moisture conditions remain adequate. Lawns are continuing to green-up; however, mowing is not yet necessary for most lawns. Plant development is still very slow. Garden centers have been cautious with shipments of plant material. At one location, annual vegetable transplants were observed with obvious frost damage.
General Conditions: Overnight lows for the past week have been averaging 34 degrees with daytime temperatures finally starting to warm up into the low 60’s on April 23 and 24. The warmer temperatures have resulted in increased plant development and we are finally starting to see color in the landscape; spring is slowly arriving. Hanson received 1.5 inches of rain over the past week.
Magnolia x loebneri ‘Leonard Messel’, Magnolia ‘Wada’s Memory’, Pussywillow, Forsythia, Lonicera fragrantissima (winter honeysuckle), Cornus officinalis, Cornus mas (Cornelian cherry Dogwood), Corylopsis spicata, Stachyurus praecox, Pieris japonica, Pieris floribunda, Pieris 'Brouwer's Beauty', Omphalodes verna, Waldsteinia ternata, Petasites japonicus (Japanese butterbur), Helleborus foetidus, H. x hybridus, Corydalis solida, Trillium, early daffodils, Chionodoxa luciliae, Hyacinths, Scilla, Sanguinaria canadensis, Pachysandra terminalis and Pulmonaria rubra (Red Lungwort) are in full bloom. 'PJM' rhododendron is in full bloom in a few areas, just beginning bloom in other areas.
Magnolia stellata, Prunus subhirtella var. pendula (Weeping Higan Cherry), Epimedium sp., Brunnera macrophylla, Vinca, Dicentra cucullaria (Dutchman’s breeches), violets and early tulips are beginning bloom. Magnolia soulangiana (Saucer magnolia) buds are fat and look ready to burst open as soon as we get some warm weather! Abeliophyllum distichum (White Forsythia) has ended bloom. Spring cleanups, including removing numerous fallen trees, continue. Lawns continue to green up and may require mowing in some areas next week. Hanson has recorded 153 GDD at base 40.
Pests/Problems: Insect development remains behind, but once the weather warms up, insect and plant development should both increase dramatically! For reports of winter moth hatch in Hanson, MA, please see the Insect section of the Landscape Message for more information. Norway maple flower buds are swollen but unopened and dissecting some buds showed no sign of winter moth caterpillars. Oak and wild blueberry buds are still tight. They were also examined for signs of winter moth caterpillars with no results. Winter moth caterpillar numbers should be way down this year and difficult to find, but continue to monitor susceptible plants like oak, blueberry, maples, birch, crabapple, apple, American beech, etc. and if found, manage as needed.
Lily, Lilium sp., foliage is up, and usually by this time, the bright red Lily leaf beetles would be seen feeding on the newly emerging foliage. To date, no beetles were observed even on the warm sunny days. However, continue to monitor lilies for lily leaf beetle and manage if found. Lily leaf beetle and larvae cause significant damage to lilies if not managed. Monitor pines, especially hard-needled pines like Mugo pine, for European pine sawfly larvae which usually cause significant damage to pine foliage if not managed early. The larvae of European pine sawfly are not lepidopteran caterpillars and Bacillus thuringiensis (Bt) will not work on sawfly larvae. Continue to monitor hemlocks, fir and spruce for elongate hemlock scale (Fiorina externa) and continue to monitor eastern and Canadian hemlocks for the white, cottony egg masses of hemlock woolly adelgid (HWA). Monitor spruce, fir, hemlock, arborvitae, etc. for spruce spider mite. Black flies are active and numerous.
Honey bees are active and were observed on the flowers of hellebores and Cornus mas.
Continue to check for deer ticks and take necessary precautions to avoid being bitten. See the Insect section of the Landscape Message for more information.
Ranunculus ficaria, a pernicious weed, is in full bloom.Bittercress remains in bloom and some plants are setting seeds. Dandelion is beginning bloom. Deer continue to browse daylilies, hosta, tulips and other ornamentals. Turkeys, chipmunks and voles are also active and aggravating.
Remind clients that hummingbirds will be returning shortly and to remember to put out their hummingbird feeders, if they are so inclined. Clients may also want to plant some hummingbird-attracting plants this season. According to a 2018 hummingbird migration map, hummingbirds were seen on April 24 in Harwich, MA and N. Andover, MA. In 2017, Hummingbirds were back at the Hanson, MA feeders on April 28.
General Conditions: Finally, it feels and looks like spring. The temperatures are starting to be more seasonable for this time of the year. Many early spring flowering bulbs are in full bloom and grass is greening up. We experienced seasonable temperatures over the previous seven days adding 11 growing degree-days for a total of 37 growing degree-days. We received minimal precipitation. Approximately 0.19 inches of rainfall was received at Long Hill during this reporting period with most of the rain coming down on Thursday, April 19th. Woody plants in full bloom include: Winter honeysuckle (Lonicera fragrantissima), Fragrant viburnum (Viburnum farreri), Red Maple (Acer rubrum), Cornelian Cherry Dogwood (Cornus mas), Anise Magnolia (Magnolia salicifolia), Star Magnolia (Magnolia stellata), Merrill Magnolia (Magnolia loebneri) and Winter hazel (Corylopsis winterthur). Weeping Higan cherry (Prunus subhirtella) is beginning to bloom. Spring flowering herbaceous plants in full bloom include: Daffodils (Narcissus spp.), Bloodroot (Sanguinaria canadensis), Glory of the Snow (Chionodoxa luciliae), Crocus (Crocus spp.), Puschkinia (Puschkinia libanotica), Siberian Squill (Scilla siberica) and Christmas Rose Hellebores (Helleborus x hybridus).
Pests/Problems: Spring clean-up and pruning of broken branches from March storms continued on some landscapes. Annual weed seeds continue to germinate. Yellow buttercup weed (Ranunculus ficaria) is in full bloom with yellow flowers. Fungal leaf spots of mountain laurel seem to be severe under shaded areas. Rake and remove fallen leaves from the vicinity of the shrubs in the fall to reduce the number of spores available to infect in the spring. Ticks are active and people should be careful to protect themselves when working outdoors.
General Conditions: What a difference sunny conditions make: it is starting to look and feel like spring! Average temperatures this week were similar to last week: low temperatures were one degree cooler, averaging 35°F and highs were four degrees warmer, averaging 57°F. The warmest temperature was 68.5°F, the same as the previous week. We are at 46 GDDs (base 50) after accumulating 4.5 GDDs compared to 8.0 GDDs last week. (We are at 245.5 GDDs base 40.) Overall, conditions were similar to last week, except for the amount of sunshine. There has been considerable plant development: grass is greening up throughout the landscape and buds are swelling and opening. If you look closely, a green halo can be seen on many shrubs and some trees. Lilac (Syringa spp.) buds have opened, leaving flower buds visible. Following a tough winter and a snowy March, the greening of the landscape is a welcome sight. The message would not be complete without the mention of snow, which we did receive on the morning of the 19th, along with sleet, hail and rain. By the afternoon, the sun had melted away all traces of this winter weather. Sunny conditions pushed many plants into bloom including: Anemone nemorosa (wood anemone), Asarum europaeum (European ginger), Cercidiphyllum japonicum (katsura), Corylopsis glandulifera (fragrant winter hazel), C. sinensis (Chinese winterhazel), Dicentra eximia (fringed bleeding heart), Forsythia suspensa ‘Decipiens’ (weeping forsythia), Lindera benzoin (common spicebush), Lonicera standishii (Standish honeysuckle), Lonicera x purpusii (Purpus honeysuckle), Petasites hybridus (butterbur), P. japonicus var. giganteus (fuki), Prunus apetala (clove cherry), P. cyclamina (cyclamen cherry), P. incisa forma serrata (Fuji cherry), P. sargentii (Sargent cherry), P. subhirtella ‘Pendula’ (weeping Higan cherry), P. x yedoensis (Yoshino cherry) and its cultivar ‘Shidare Yoshino’ and P. cultivars ‘Accolade’, ‘Karl Sax’, and ‘Okame’, Rhododendron mucronulatum ‘Cornell Pink’ (Korean rhododendron), Spiraea prunifolia var. simpliciflora (bridalwreath spirea), S. x arguta (garland spirea), Vinca minor (common periwinkle), and Xanthorhiza simplicissima (yellowroot).
Pests/Problems: Sunny conditions pushed Ficaria verna (lesser celandine) into bloom, making it visible throughout the landscape. Now is the time to treat this winter ephemeral while it is in bloom. Glechoma hederacea (ground ivy) is flowering. The winter annual Cardamine hirsuta (hairy bittercress) remains in full bloom. Alliaria petiolata (garlic mustard) is just beginning to germinate and one-year-old plants continue to develop rosettes.
General Conditions: Happy belated Earth Day and Happy Arbor Day! Spring is exploding with the recent and long awaited spell of spring-like temperatures. Lawns are turning green; turtles are bathing in the sun; and buds are swelling. Days have been warm but the evening and early morning temperatures have been cool enough to cause frost to cover car windows in the mornings on the 22nd, 23rd, and 24th. Even with the warm daytime temperatures, this area has only gained 0.5 growing degree-days for this recording period because of the cool nights. The average rainfall total for the month of April is 4.16” and I have recorded 3.42” of rain in this area for this month so far. Observed in bloom this past week were the following woody plants: Acer rubrum (red maple), Cornus mas (Cornelian cherry dogwood), C. officinalis (Japanese Cornelian cherry), Forsythia spp. (Forsythia), Magnolia stellata (star magnolia), Magnolia x loebneri 'Merrill', (Merrill magnolia), Pieris japonica (Japanese pieris), and Rhododendron mucronulatum (Korean rhododendron). The following bulbs and herbaceous plants were seen in bloom: Anemone nemorosa (wood anemone), Asarum europaeum (European ginger), Chionodoxa luciliae (glory of the snow), Crocus spp. (crocus), Helleborus niger (Christmas rose), Hepatica spp. (liver leaf), Hyacinthus spp. (hyacinth), Mertensia virginica (Virginia bluebells), Muscari sp. (grape hyacinth), Narcissus spp. (daffodil), Omphalodes verna (blue-eyed Mary), Pachysandra procumbens (Allegheny spurge), Petasites japonicus (Japanese butterbur), Primula spp. (primrose), Pulmonaria longifolia (lungwort), P. rubra (salmon-colored lungwort), Puschkinia libanotica (striped squill), Sanguinaria canadensis (bloodroot), Scilla siberica (Siberian squill), Symplocarpus foetidus (skunk cabbage), Tulipa spp. (tulip), Vinca minor (periwinkle) and Viola spp. (violet).
Pests/Problems: Seen flourishing everywhere, along streambeds, in the woodland understory, along roadsides and in abandoned lots, is the basal foliage of Alliaria petiolata (garlic mustard), an invasive, biennial weed.
General Conditions: The temperatures have finally started to feel more seasonable and the plants are responding in kind. This week's report shows what a difference a week can make. The majority of the snow drops (Galanthus nivalis) are finally finishing, along with white forsythia (Abeliophyllum distichum) and crocus. Still going strong are glory of the snow (Chionodoxa luciliae), Siberian squill (Scilla siberica), and red maple (Acer rubrum). Cornell pink rhododendron (Rhododendron ‘Cornell Pink’), striped squill (Puschkinia scilloides), daffodils (Narcissus cultivars), N. ‘Rip Van Winkle’, bloodroot (Sanguinaria canadensis), windflower (Anemone blanda), Loebner magnolia (Magnolia x loebneri ‘Merrill’), and Dutchman's breeches (Dicentra cucullaria) are all coming into bloom and looking great!
Pests/Problems: Nothing new to note. Ticks are still high in numbers.
General Conditions: After a cool start to April, conditions improved dramatically over the past week with plentiful sun and steadily warming temperatures. The Northeast Regional Climate Center reported that during the first half of April, temperatures in the Pioneer Valley were 4–8°F cooler than average (http://www.nrcc.cornell.edu/services/blog/2018/04/17/index.html). Since our last report, high temperatures have progressively climbed towards the threshold of respectable spring weather, with the mercury peaking just above 70°F on 4/23 and 4/24. The cool weather in March and the first half of April was beneficial in buffering against a damaging spring frost or freeze event, similar to the early April freeze of 2016. Two years ago, flowers (magnolia and forsythia), tender foliage (crabapple and serviceberry) and even stems and branches (for cherries) suffered freeze damage when low temperatures dropped below 20°F on 4/5 and 4/6. Because trees and shrubs are very slowly leafing out this year, there are minimal succulent parts that could be damaged by frost or freeze temperatures as we approach the month of May. At the time of writing, the valley is receiving some additional rainfall with moderate accumulations forecasted. With the spring winds in the valley, surface soils in exposed settings were drying out once again, despite the soaking rain the region received on Patriot’s Day. Red flag warnings, indicating ideal conditions for wildland fire development and spread, were issued during the recent dry stretch. Subsurface soils are still moist and conditions are prime for new plantings right now. Lawn grasses continue to green and grow and mowing has begun on the UMass campus. Full sun soil temperatures at the UMass reporting site are now over 50°F while the shade reading is still lingering in the mid-40s. Aside from larch, which have needles expanding at this time, most conifers are not flushing new growth just yet. But, Norway spruce and eastern hemlock buds have broken and hard pine candles are starting to expand, so closely monitor conifers requiring treatment for needle cast so that appropriate materials can be applied at the right time. For eastern hemlocks injured by cold weather this past winter, avoid pruning or shearing to shape the trees in 2018. Provide supplemental irrigation during extended dry periods and prune dead shoots and branches to avoid secondary pests and pathogens. Create or enlarge mulch rings to avoid competition between roots and nearby turfgrasses, keeping in mind that hemlock roots are shallow and can be easily damaged.
Pests/Problems: According to reports from the UMass Cold Spring Orchard, the rainfall on 4/25 initiated the season’s first significant apple scab infection. Boxwood spider mite injury has been abundant on samples submitted to the diagnostic lab the past several years. Now is a good time to scout for damage and plan a treatment regime if the pest is present. From afar, leaves appear off-color, pale green to yellowish-green. Upon closer inspection, flecking symptoms will be evident on the upper leaf surface. The flecking appears as short lines that have been scratched into the leaf surface. The cool start to spring means that most fungal pathogens are not yet active, but will be soon as new growth emerges. Continue to prune blighted plant parts from shrubs and trees to reduce overwintering inoculum that serves to initiate new infections.
General Conditions: Spring-like weather finally arrived over the weekend of April 21, but not before a 2-inch snowfall on Thursday (April 19) morning; by afternoon, the snow had melted. Temperatures on April 23 and 24 reached into the low 70s. Except for the morning of Wednesday, April 25, sub-freezing temperatures were the norm through the scouting period. However, the trend in the near future is toward normal temperatures for this time of year. The warmth did spur leaf bud opening on woody species, mostly shrubbery, especially invasive and likely invasive species such as the bush honeysuckles (Lonicera spp.) i.e. amur honeysuckle, Morrow’s honeysuckle and Tatarian honeysuckle. The blossoms of winter aconite (Eranthis hyemalis) have faded but those of witchhazels (Hamamelis spp.) and snowdrops (Galanthus spp.) are just starting to wither. Spring flowering bulbs dominate the current blooming landscape. Among these bloomers are Siberian squill (Scilla siberica), striped squill (Puschkinia scilliodes), Narcissus spp., glory of the snow (Chionodoxa luciliae), and Crocus cultivars. Japanese butterbur (Petasites japonicus ) and Hellebores (Helleborus spp.) are in full bloom.
Warmer air and soil temperatures coupled with moist soils have prompted growth in turfgrass. Grass should reach mowing height by this weekend or next week. For most lawn grasses, mowing height should be set at 2 ½ - 3 inches. Lower cutting heights will interfere with spring root development of turfgrasses.
Phomopsis leaf and stem blight on Japanese holly (Ilex crenata 'Soft Touch'). Young plant that was transplanted in spring of 2017. By September of last year, symptoms of transplant shock and dieback (yellowing leaves and branch dieback) appeared. There was a dense mat of fine roots present but the root flare was buried and encircled with roots. The roots appeared relatively healthy and testing for Phytophthora was negative. Phomopsis was abundant on blighted leaves and shoots. Opportunistic cankering and foliar blight pathogens are common on Ilex species suffering from transplant shock and other stresses.
Black canker of weeping willow (Salix babylonica) caused by Colletotrichum. Tree is approximately 50-years-old and resides in a residential setting with half sun. Several years ago the tree suffered from construction-related injury and symptoms of canopy dieback appeared in autumn of last year. Leaves and stems become blackened, wilt and die as a result of infection, leading to progressive canopy dieback once the fungus is established. Soils at the site are described as sandy with good drainage, suggesting that drought conditions in 2015 and 2016 may be a predisposing stress that facilitated disease development.
Leaf and branch dieback of mountain laurel (Kalmia latifolia) caused by Colletotrichum. Submitted leaves exhibited interveinal chlorosis, which can be the result of micronutrient deficiency, such as iron or manganese. Last year’s foliage was stunted with blighted margins. The plant is approximately 15-years-old and resides in a shaded landscape setting with compacted clay-loam soils. Colletotrichum has a very broad host range and was abundant on the blighted tissues after a brief incubation.
New reports from the blueberry grower in Hanson, MA monitoring winter moth egg hatch indicate that on 4/25/2018, of the limited 20 eggs she has available to monitor on a banded tree, 13 of those eggs have turned blue at this time. Reports from a blueberry grower in Franklin, MA mention that on 4/25/2018, 75% of approximately 60 eggs have turned blue on the single tree being monitored. In Barnstable, MA, winter moth caterpillars have already been detected in crabapple buds on 4/23/18. (See Cape Cod Region report above.) Winter moth egg hatch is under way in eastern Massachusetts following the recent warmer temperatures and accumulation of growing degree days. With the warm weather forecasted for next week, insect development, including that of winter moth, should increase dramatically and caterpillars may be found feeding in the foliage of expanding host plant buds. Although it is predicted that winter moth caterpillar populations will be reduced this year, it is recommended that you monitor host plants for the presence of winter moth caterpillars. For region-specific information, see the Scouting Reports above.
In landscape settings in eastern Massachusetts, there may still be small, pocketed areas where ornamental trees and shrubs need protection from winter moth in 2018. For protection in landscapes, it is best to wait until the leaves of susceptible hosts completely unfold and monitor for feeding caterpillars, prior to treatment, especially since populations in Massachusetts are so low this year. For more information about the life cycle and management of winter moth, please visit thisfact sheet: Winter Moth Identification and Management https://ag.umass.edu/landscape/fact-sheets/winter-moth-identification-management .
Winter moth is a non-native insect that was identified in Massachusetts for the first time in 2003 following persistent reports of defoliation in eastern areas of the state such as Cape Anne and on the North Shore near Cohasset, Hingham, and Rockland on the South Shore in the late 1990’s. For more detailed information about the history of this insect pest in North America and Massachusetts, please visit this fact sheet: Winter Moth in Massachusetts: History and Biological Control https://ag.umass.edu/landscape/fact-sheets/winter-moth-in-massachusetts-history-biological-control .
Gypsy Moth:(Lymantria dispar) The outlook for the 2018 season in regard to gypsy moth is significantly better than it would have been if Entomophaga maimaiga didn’t infect the gypsy moth caterpillar population in late June of 2017. At that time, many dead caterpillars were seen hanging from tree trunks and branches, killed by the fungus, which was aided by the wet spring weather earlier in the year. Need a reminder of what that looked like? Go to https://ag.umass.edu/landscape/news/gypsy-moth-caterpillars-dying-across-massachusetts . Unfortunately, prior to the fungal epizootic, gypsy moth caterpillars were able to defoliate over 923,000 acres across Massachusetts in 2017, according to the MA Department of Conservation and Recreation. For a map of where this occurred, visit: https://www.mass.gov/guides/gypsy-moth-in-massachusetts .
Egg hatch for this insect is not yet upon us and occurs after winter moth egg hatch. Gypsy moth egg hatch typically occurs between 90-100 Growing Degree Days, using a base of 50°F and average temperatures. This is usually around the first week in May in Massachusetts, but variations in temperature may lead to early egg hatch in the last week in April. This can also coincide with serviceberry (Amelanchier) bloom. After egg hatch occurs, groups of tiny gypsy moth caterpillars may remain on their egg mass just before crawling to the canopy of their host plant, where they can disperse using a technique known as “ballooning”. Ballooning occurs when very young caterpillars spin a silken thread and catch the wind to blow onto a new host plant once the thread breaks. This method of dispersal can lead to host plants becoming defoliated that previously did not have egg masses directly on them, however egg masses may be present on nearby oaks, for example, and provide a local population of caterpillars.
Balsam Twig Aphid: Mindarus abietinus is active between 30-100 GDD’s, base 50°F. Inspect the needles of Balsam fir, Fraser fir and other true firs for “stem mothers” that will soon be reproducing. Young aphid feeding will lead to distorted foliage. (Needles curl.) Excessive amounts of honeydew are produced and cause needles to stick together. Monitor for the presence of reproducing females and treat with an oil application as weather permits, according to label instructions.
Anyone working in the yard and garden on springtime cleanup should be aware that there is the potential to encounter deer ticks at this time. The deer tick or blacklegged tick can transmit Lyme disease, human babesiosis, human anaplasmosis and other diseases. Preventative activities, such as daily tick checks, wearing appropriate clothing, and permethrin treatments for clothing (according to label instructions) can aid in reducing the risk that a tick will become attached to your body. If a tick cannot attach and feed, it will not transmit disease. For more information about personal protective measures, visit: http://www.tickencounter.org/prevention/protect_yourself .
The UMass Laboratory of Medical Zoology does not give medical advice, nor are the results of their tests diagnostic of human disease. Transmission of a pathogen from the tick to you is dependent upon how long the tick had been feeding and each pathogen has its own transmission time. TickReport is an excellent measure of exposure risk for the tick (or ticks) that you send in to be tested. Feel free to print out and share your TickReport with your healthcare provider.
Elongate Hemlock Scale: Fiorinia externa is found on eastern, Carolina, and Japanese hemlock, as well as yew, spruce and fir. Crawlers will be present this month and throughout the growing season and the overlap of many developmental stages at any given time can be observed. Treatments for the crawler, or mobile, stage of this insect may be made in late May through mid-June, or between 360-700 GDD’s, base 50°F.
Emerald Ash Borer: (Agrilus planipennis, EAB) This wood-boring beetle readily attacks ash (Fraxinus spp.) including white, green, and black ash and has also been found developing in white fringe tree (Chionanthus virginicus) and most recently, has been reported in cultivated olive (Olea europaea). Adult insects of this species will not be present at this time of year. Signs of an EAB infested tree may include (at this time) D-shaped exit holes in the bark (from adult emergence in previous years), “blonding” or lighter coloration of the ash bark from woodpecker feeding (chipping away of the bark as they search for larvae beneath) and serpentine galleries visible through splits in the bark, from larval feeding beneath. Positive identification of an EAB-infested tree may not be possible with these signs individually on their own.
European Pine Sawfly: Neodiprion sertifer caterpillars will be active roughly between 78-220 GDD, base 50°F. The primary host in MA is Mugo pine but it can be found on Scots, red, jack and Japanese red pine It is also found on white, Austrian, ponderosa, shortleaf and pitch pine when near the aforementioned species. This dark colored caterpillar feeds in tight groups and small numbers can be pruned or plucked out of host plants and destroyed. Larger numbers can be treated with an insecticidal soap spray when the caterpillars are still small. Spinosad products can be used whenever the caterpillars are actively feeding, usually by mid-May and when caterpillars are still small. Bacillus thuringiensis Kurstaki is not effective against sawflies.
Lily Leaf Beetle: Lilioceris lilii overwintering adults have been spotted by scouts in central Massachusetts (Worcester County) during recent spring clean-up activities. Adults prefer to over winter in sheltered places, like in soil or plant debris in the garden or in the woods, and not always in close proximity to host plants. As daily temperatures begin to rise and as soon as susceptible hosts such as Lilium spp. (Turk’s cap, tiger, Easter, Asiatic and Oriental lilies) and Fritillaria spp. break through the ground, the adult lily leaf beetles will begin to feed on the new foliage. (Note: daylilies are not hosts.) Typically, mating will occur in May and each female will begin to lay 250-450 eggs in neat rows on the underside of the foliage. If there are only a few plants in the garden, hand picking and destroying overwintering adults can help reduce local garden-level populations at this time.
Snowball Aphid: Neoceruraphis viburnicola becomes active on certain species of viburnum roughly between 148-298 GDD’s or around redbud bloom. This insect is particularly noticeable on V. opulus, V. prunifolium and V. acerifolia. Stem mothers, appearing blueish-white, can be found in curled up and distorted foliage. Damage caused by this insect pest is mostly aesthetic.
The adults and immatures of this species damage host plants by feeding on sap from stems, leaves and the trunks of trees. In the springtime in Pennsylvania (late April - mid-May) nymphs (immatures) are found on smaller plants, vines and the new growth of trees and shrubs. Third and fourth instar nymphs migrate to the tree of heaven and are observed feeding on trunks and branches. Trees may be found with sap weeping from the wounds caused by the insect’s feeding. The sugary secretions (excrement) created by this insect may coat the host plant, later leading to the growth of sooty mold. Insects such as wasps, hornets, bees and ants may also be attracted to the sugary waste created by the lanternflies, or sap weeping from open wounds in the host plant. Host plants have been described as giving off a fermented odor when this insect is present.
Spruce Spider Mite: Oligonychus ununguis is a cool-season mite that becomes active in the spring from tiny eggs that have overwintered on host plants. Hosts include spruce, arborvitae, juniper, hemlock, pine, Douglas-fir and occasionally other conifers. This particular species becomes active in the spring and can feed, develop and reproduce roughly through June. When hot, dry summer conditions begin, this spider mite will enter a summer-time dormant period (aestivation) until cooler temperatures return in the fall. This particular mite may prefer older needles to newer ones for food. When damaging spruce spider mite populations are known from last season, dormant oil applications can be made (when temperatures are appropriate according to label instructions) between 7-121 GDD’s, base 50°F. Magnification is required to view spruce spider mite eggs. Tapping host plant branches over white paper may be a useful tool when scouting for spider mite presence. (View with a hand lens.) Spider mite damage may appear on host plant needles as yellow stippling and occasionally fine silk webbing is visible.
Viburnum Leaf Beetle: Pyrrhalta viburni is a 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 is now overwintering in the twigs of the host plant as eggs, which will hatch soon after bud break. Now is the time to inspect susceptible plants (including but not limited to viburnum such as V. dentatum, V. nudum, V. opulus, V. propinquum and V. rafinesquianum) for over-wintering eggs on stems toward branch tips. Inspect branches for egg laying sites created by female viburnum leaf beetles last season. These will appear as small holes approximately 1 mm. in diameter that have been capped with a lid made of chewed bark and excrement, which may appear raised above the surface of the twig. Removal and destruction of infested stems, if small in number, can help reduce populations of this insect pest. If management this way is not possible, larvae may be treated with a product containing spinosad once they appear soon after bud break. Larvae are typically first present between 80-120 GDD’s, base 50°F, which often coincides with redbud bloom. Some viburnum have been observed to have varying levels of resistance to this insect, including but not limited to V. bodnantense, V. carlesii, V. davidii, V. plicatum, V. rhytidophyllum, V. setigerum and V. sieboldii. More information about viburnum leaf beetle may be found at http://www.hort.cornell.edu/vlb/ .

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