General Conditions: The warm weather continued over the past week, although it cooled down midweek and the forecast is for slightly cooler weather this coming weekend. Hanson received 0.80 inches of rain and needs more. Soils were powdery-dry before the rain. Remind clients to water their plants. A rain gauge is helpful to determine how much rain landscapes may or may not be receiving. The following plants are in full bloom: Sinocalycanthus chinensis, Cladrastis kentukea, Magnolia virginiana, (Sweetbay magnolia), Liriodendron tulipifera (Tuliptree), Rutgers’ Hybrid dogwoods, Cornus kousa, Hydrangea anomala petiolaris, Syringa x prestoniae ‘James Macfarlane’, Syringa ‘Miss Kim’, Wisteria floribunda (Japanese Wisteria), Robinia hispida (bristly locust), Rhododendron sp., Cotinus obovatus, Cotinus coggygria, Calycanthus floridus (Common Sweetshrub), Indigofera sp., Beautybush, Weigela florida, Physocarpus opulifolius (Eastern Ninebark), Lonicera sempervirens, Rosa rugosa, Clematis sp., Azaleas, Viburnum dilatatum (Linden Viburnum), Viburnum dentatum (Arrowwood Viburnum), Stephanandra incisa ‘Crispa’, Clematis, landscape roses like the Knockout roses and Rosa ‘Linda Campbell’, Rosa rugosa, Alchemilla mollis Thalictrum aquilegifolium, Anemone canadensis, Geranium sp., Persicaria bistorta 'Superbum', Persicaria polymorpha, Doronicum, Amsonia sp., Lamium, Siberian Iris, Bearded Iris, Foxgloves, Allium, Nepeta sp., Salvia 'May Night', Baptisia australis and Baptisia hybrids, Dianthus sp., Tradescantia, Lupines, Columbines, Oriental poppies, Corydalis lutea, Arisaema (Jack-in-the-pulpit), Cypripedium sp. (Lady's Slipper) and Valeriana officinalis. Cotinus coggygria (Smokebush) and Cotinus obovatus (American Smoketree) continue in full bloom with their small greenish flowers which will soon produce the "smoke" which will come later. Spiraea sp. and Itea virginica are beginning bloom. Abelia mosanensis, Buglossoides purpurocaerulea and Mazus reptans are ending bloom. Chionanthus virginicus will be ending bloom soon, but this is one plant that comes highly recommended for fabulous fragrance, few pest problems and wonderful yellow fall color. Also, it is a North American native plant. Rhododendron catawbiense (Catawba Rhododendron) look particularly good this year.
Pests/Problems: Winter moth caterpillars are done feeding for the year. Foliage damage by the winter moth caterpillars was not bad this year, compared to previous years. However, trees that were damaged are now starting to put out new foliage and in order to do that, it is important that these trees receive adequate soil moisture. Many people are now commenting about the number of gypsy moth caterpillars they are seeing, primarily on oak. One gardener in Carver sent a video showing his shed and garage covered with caterpillars. (This gardener and a landscaper also reported that they received rashes from gypsy moth caterpillars falling on their neck and arms while doing landscape work.) The caterpillars are feeding most heavily on oak trees, but other plants (willow, roses, etc) are also seeing gypsy moth caterpillar action. There are heavy pockets of gypsy moth caterpillars in various areas of southeastern, MA and based on reports coming in, it appears that where there were heavy infestations last year, those are the areas that are seeing high numbers of gypsy moth caterpillars again this year. Gypsy moth caterpillars are in 3rd and mostly 4th instars and will continue to feed for a few more weeks and can do significant damage in that time; continue to monitor and manage. As of right now, we are not seeing signs of any dead or sickened gypsy moth caterpillars by the caterpillar-killing fungus Entomophaga maimaiga.
A few oak sawfly larvae were observed on oak, but are vastly outnumbered by gypsy moth caterpillars. Dogwood sawfly is now active. Monitor dogwoods and manage if needed.
Andromeda lace bug is active on Japanese andromeda (Pieris japonica).
The native White-spotted pine sawyer is now active. This is one of the many Asian Longhorned Beetle (ALB) look-alikes”. There is a good handout to refer clients to educate them to the ALB imposters: http://massnrc.org/pests/albdocs/ALBLookalikes_Massachusetts.pdf
Ninebark (Physocarpus opulifolius) is a native shrub usually with few insect problems. Today, for the first time, I observed two ninebarks, (Physocarpus opulifolius ‘Diablo’)whose foliage resembled ragged lace, the result of feeding by small, numerous, as yet unidentified, caterpillars. Also, on the plants was a cottony scale similar to Cottony Camellia scale.
Four-lined plant bug nymphs (orange-red with black coloration) are active. The nymphs, as well as the adults, (gold-green, with 4 longitudinal black stripes) feed on the foliage of many perennials. Feeding by their piercing-sucking mouthparts results in numerous, small, round, brown-black spots on the foliage; often mistaken for a disease.
The small white maggot of the Orthacheta Bud Fly (Iris bud fly) remains active. Remove and destroy the newly damaged flowers and stems.
Lily leaf beetle adults and the feces-covered larvae remain active on true lilies. Euonymus caterpillars remain active. Look for branch tips webbed together by the cream-colored larvae with black spots, feeding on the foliage. Manage as needed and remember that Bacillus thuringiensis (Bt) does not work on sawfly larvae.
Cottony camellia scale (also known as Cottony Taxus Scale) remains active on Taxus and Meserve hollies; monitor and manage as needed.
Roseslug sawfly remains active and will skeletonize rose plant foliage if not managed. Azalea sawfly is done feeding for the year.
Biting flies (deer flies and horse flies), azalea whitefly, elongate hemlock scale, hemlock woolly adelgid, spider mites, spittlebugs, aphids, deer tick nymphs, dog ticks, carpenter ants, snails, woolly beech aphid, ants, wasps, hornets, boxelder bugs, carpenter bees, and mosquitoes remain active. Mosquitoes are numerous and aggressive. Encourage clients to empty containers of standing water and to consider using Bti (Bacillus thuringiensis israelensis) in plant saucers, birdbaths, and other water features where mosquitoes breed.
Sod webworm moths are active. At dusk, look for the small tan moths, flying low, and zigzagging over turf, as the females lays eggs, which will hatch into sod webworm caterpillars that feed on turf species. https://ag.umass.edu/fact-sheets/sod-webworms-0
Azalea leaf gall (Exobasidium vaccinii) continues to show up on deciduous azaleas; hand-pick and destroy the galls before they turn white.The foliage of ‘Arnold Promise’ witchhazel continues to be affected by Phyllosticta hamamelidis (Witchhazel blight) turning the foliage brown.
Many people have commented about now noticing white pine decline, as a result of reading Nick Brazee’s White Pine Decline fact sheet in the disease section of the Landscape Message last week.
White pine yellow pollen has been falling constantly and thickly this past week, covering everything in its’ way with yellow “dust”.
Wild turkeys (pecking at plants), chipmunks (chewing and digging up plants) and numerous rabbits (eating lilies, Echinacea, Baptisia, Rudbeckia, etc) are becoming more troublesome and annoying in the landscape.
Multiflora rose, another Massachusetts invasive plant is in full bloom. Clearweed has emerged. Continue to remove weeds and mulch landscapes to manage weeds before they become too large.