General Conditions: The weather remained cool and damp for most of the last week. In the Hanson area, temperatures most days were in the 50’s. News reported that this May was the coolest since 2005. Hanson received 1.50 inches of rain and soils are moist. Once again, cool temperatures and sufficient rain have help to extend color in the landscape and the following plants are, or remain in bloom: Styrax obassia, Rutgers hybrid dogwoods (Stellar series), Prunus serotina (black cherry), Aesculus x carnea (Red Horsechestnut), Liriodendron tulipifera (Tuliptree), Cornus kousa, Cornus controversa, Cornus alternifolia, Laburnum watereri (Goldenchain Tree), Weigela florida, Indigofera sp., numerous Rhododendrons, early azaleas,Wisteria floribunda (Japanese Wisteria), Robinia hispida, Calycanthus floridus (Carolina allspice), Kerria, Aristolochia durior (Dutchman's pipe), numerous viburnums (including Viburnum opulus, V. plicatum var. tomentosum (Doublefile viburnum), V. sargentii), Beautybush, Abelia mosanensis, Chionanthus virginicus, Cytisus scoparius (Scotch broom), Rhododendron, late lilacs like Syringa x prestoniae ‘James MacFarlane’ and Syringa ‘Miss Kim’, Clematis, Camassia sp., Allium, Baptisia australis and Baptisia hybrids, Tradescantia , Anemone canadensis, Amsonia sp., Thalictrum aquilegifolium, Geranium sp., Buglossoides purpurocaerulea, Doronicum sp., Tiarella cordifolia (Foam Flower), Lamiastrum galeobdolon, Lamium, Dicentra spectabilis (Bleeding heart), Saruma henryi, Cypripedium sp.(Lady’s Slipper), Polygonum bistorta ‘Superbum’, Corydalis lutea, Siberian Iris, bearded iris, Phlox subulata, Phlox divaricata, Phlox stolonifera, Hyacinthoides hispanica, Trillium sp., Galium odoratum (Sweet Woodruff), Convallaria majalis (Lily-of-the-valley), Myosotis sylvatica, Polygonatum sp. (Solomon's Seal), Stylophorum diphyllum (Wood Poppy), Arisaema dracontium, Arisaema ringens, and other Arisaema sp. (Jack-in-the-pulpit), Ajuga, Bearded Iris, Lunaria annua (honesty or money plant), Mertensia virginica (Virginia bluebells), Aquilegia sp. (Columbine) Myosotis sylvatica (Forget-me-not), Vinca minor and Baptisia. Cotinus obovatus (American Smoketree)and Cotinus coggygria (Smokebush) are also in full bloom, with their small, greenish-yellow flowers; the interesting and colorful “smoke” is produced later, following full bloom. Lawns are green. (Hanson is at 860 GDD, (Growing Degree Days), Base 40)
Pests/Problems: Winter moth caterpillars are in 4th and mostly 5th instar and have started to pupate and should soon be done feeding for the season. Throughout the winter moth season, except on roses, it has been difficult to find many winter moth caterpillars while scouting. The population was very low this year and damage from winter moth caterpillars appears minimal in many areas.
Gypsy moth caterpillars are actively feeding and were observed to be at 2nd, mostly 3rd and some 4th instars. They are feeding on a wide variety of deciduous material, but seem very fond of Fothergilla and Hamamelis, along with oak, crabapple, apple, etc. Gypsy moth caterpillar feeding activity appears scattered. In one area in Hanson, the gypsy moth caterpillars were in high numbers on many oaks. In another area, there were hardly any. There was significant damage high in the canopies of sugar maple and oak in some areas, but it is difficult to determine what is or what was causing it. Gypsy moth caterpillars will continue to feed for the next few weeks, and that is when damage should become evident. Cool, wet weather has been conducive to the formation of the caterpillar-killing fungus, Entomophaga maimaiga, and a few fungus-killed caterpillars were observed. Hopefully, these numbers will increase over the next 2-3 weeks, as the gypsy moth caterpillars continue to feed and grow.
Tiny nymphs ofAndromeda lacebug are actively feeding on the undersides of foliage of Japanese andromeda (Pieris japonica). Monitor or inspect Pieris japonica plants showing damaged foliage from last year. Look for bronzy-yellow stippled foliage on the upper leaf surface and then look beneath for the tiny small lacebugs. https://ag.umass.edu/landscape/fact-sheets/andromeda-lacebug. Rhododendron lacebugs are also active. Inspect rhododendrons showing damaged foliage from last year. Look for bronzy-yellow stippled foliage on the upper leaf surface and then look beneath for the tiny small lacebugs. Cottony camellia scale (also known as Cottony Taxus Scale) is active on Taxus and Meserve hollies. Inspect stems and the undersides of foliage for the white cottony egg masses. In heavy infestations, you may also see black sooty mold and yellowing foliage.
Monitor Siberian iris, Iris pseudacorus and bearded Iris for the small white maggot of the Orthacheta Bud Fly, sometimes referred to as the Iris bud fly. The maggots feed in the developing buds, and the emerging flowers appear tattered. The maggots feed down into the base of the flower then into the stem. Not much can be done to prevent this damage now, but removing and destroying the newly damaged flowers and stems may help to manage it for next year.
Euonymus caterpillar (cream colored with black spots) is active. Look for leaves webbed together near the tips of branches as the caterpillars feed and web the new foliage together. The webs are small now, but will grow in size as the caterpillars feed and develop.
Asiatic garden beetles, have started to emerge. These small copper-colored beetles feed at night on herbaceous and woody plant foliage.
Roseslug sawfly remains active on roses and if left untreated, the sawfly larvae will skeletonize the rose foliage. Bt (Bacillus thuringiensis) is not effective on sawflies. Azalea sawfly remains active on deciduous azaleas like Exbury and Weston hybrid summer flowering azaleas and foliar damage is now apparent.
With all the wet weather, mosquitoes are numerous this year. Remind clients to empty containers of water to help prevent breeding and consider using Bti (Bacillus thuringiensis israelensis) in birdbaths, plant saucers, etc.
The following insects remain active: European pine sawfly, lily leaf beetles, elongate hemlock scale, aphids, hemlock woolly adelgid, spruce spider mites, spittlebugs, deer tick nymphs, dog ticks, biting flies, carpenter ants, azalea whitefly, snails, woolly beech aphid, ants, wasps, hornets, carpenter bees, and bumblebees. Beneficial insects are active and so far, it appears to be a good year for swallowtail butterflies.
Deer tick nymph season is here and there are many ticks out there! This is the stage often thought to be most responsible for transmitting Lyme disease. Take precautions and conduct tick checks frequently.
Again, blame all the wet weather, but foliar diseases are making their appearance: apple scab on apples and crabapples; leafspots on dogwoods; Monilinia (brown rot) on Kwanzan cherry, and anthracnose on sycamore and dogwood.Shiny green galls of the fungal disease, Azalea leaf gall (Exobasidium vaccinii) have started to show up on deciduous azaleas; hand-pick and destroy the galls before they turn white.Phyllosticta hamamelidis (Witchhazel blight), a fungal disease, is showing up on thefoliage of ‘Arnold Promise’ witchhazel. Look for irregular shaped brown splotches. http://extension.illinois.edu/hortanswers/detailproblem.cfm?PathogenID=54
More and more Eastern white pines appear to be turning brown and not doing well. See the White Pine Needle Damage report in the disease section of the May 12, 2017 Landscape Message.
The following weeds are in bloom: ground ivy, oxeye daisy, cinquefoil, narrowleaf plantain, buttercups and veronica.