General Conditions: While this August has been a bit cooler than previous Augusts with fewer 90 degree days than in past years, there have been some hot days in the 80’s with high humidity and little rain in many areas of Plymouth County. While many other Massachusetts areas have benefited from rainstorms, Hanson has received only 3.75 inches in the past 8 weeks, and only 0.70 inches of rain the past 4 weeks. Unirrigated soils are dry and some trees are dropping leaves, while other trees and plants (rhododendron, hosta, kousa dogwood, etc. are wilting and showing signs of marginal leaf browning. Many oaks that were defoliated this year and in previous years continue to struggle to re-foliate and their canopies are very thin. Remind clients to water high value plants especially those defoliated by caterpillars.
Albizia julibrissin, roses, Rose-of-Sharon, Campsis radicans, Hydrangea paniculata, Hydrangea macrophylla (mostly lacecaps), Hydrangea quercifolia (Oakleaf Hydrangea), Hydrangea arborescens (Smooth Hydrangea), Rubus odoratus, roses, Phlox paniculata (Garden Phlox), Echinacea sp., perennial Hibiscus likeHibiscus 'Summer Storm’, and Hibiscus ‘Old Yella’,Hosta plantaginea and other late blooming Hosta,Persicaria amplexicaulis ‘Firetail’, Joe-pye-weed,Heliopsis ‘Summer Sun’, Helianthus sp., hollyhocks,Liatris spicata, Perovskia atriplicifolia,Ligularia dentata ‘Desdemona’, Goldenrod, Shasta daisy, Nepeta sp., Rudbeckia triloba, Asclepias tuberosa, Rudbeckia fulgida, Rudbeckia ‘Herbstsonne’, Rudbeckia subtomentosa ‘Henry Eilers’, Coreopsis ‘Harvest Moon’ and Campanula sp. are in full bloom. Many ornamental grasses are beginning to bloom, or, are in full bloom.
Clerodendron trichotomum, Lysimachia clethroides , Clethra alnifolia, Echinops ritro (Globe Thistle), Veronicastrum virginicum, and Monarda didyma (Beebalm) are ending bloom.
Monarch and swallowtail butterflies continue to frequent the gardens. Hanson has 3,097 GDD (Growing Degree Days) base 40.
Pests/Problems: Insect pest activity has slowed down, as it usually does in August, but continue to monitor for the following insects which remain active and manage, if found, and needed: Lacebugs, especially on Rhododendron, Pieris and Azalea; dogwood sawfly larvae; Asiatic garden beetles; redheaded pine sawfly larvae; introduced pine sawfly larvae; hibiscus sawfly larvae; spider mites; elongate hemlock scale; lilyleaf beetle larvae. As in past years, Japanese beetles were fewer in number, with not much perceptible damage. Oriental beetles remain active but appear to be about done for the year.
The following insects and pests also remain active: slugs and snails; boxelder beetles; stinkbugs; leafhoppers; ticks; biting flies; sunflower moth caterpillars.
Continue to monitor susceptible trees like maples, horsechestnut, elm, poplar, willow, etc. for signs of Asian Longhorned Beetle (ALB), as peak emergence is usually in August and this insect attacks healthy trees.
Beneficial insects like ladybugs, hoverflies and ambush bugs also remain active.
Unirrigated lawns in many areas are turning brown and it may be due to lack of soil moisture but also consider monitoring those lawns for chinch bugs, grubs, and sod webworm larvae, whose damage may resemble that of drought stress.
Mosquito populations remain high. Continue to take precautions and use a repellent, like DEET, when working outdoors. http://www.mosquitoresults.com/
Continue to watch for wasp and hornet activity while working outdoors; especially while mowing beneath low-hanging branches or when pruning. The grey paper-like nest of the bald-faced hornet is often shaped like a football or basketball and is often well-hidden, hanging within the branches of trees and shrubs.
Tar spot is showing up on Norway maples and is highly visible at this time.
Powdery mildew is beginning to appear on the usual hosts: lilac, dogwood, Beebalm, garden phlox, etc., but not as heavy in past years. Ragweed is in bloom and distributing its’ pollen to which many people may be allergic. Unfortunately, goldenrod often gets blamed.
Deer continue to browse and chipmunks were observed eating all the foliage and stems on ornamental sweet potato vines.