General Conditions: April began with a cold spell, but warmer weather has finally come in and plant and insect development are progressing. Hanson received 1.45 inches of rain this past week, and soils are moist. Damage from the previous cold freezing weather continues to show up, as plant development continues. In Hanson, flower buds of ‘PJM’ rhododendrons blasted as have the buds of Stachyurus praecox, Corylopsis spicata and many cultivars of Hydrangea macrophylla. Tips of some Japanese maple buds were killed by the cold, as were the developing shoots of Arisaema ringens. Many plants, Magnolia stellata (Star magnolia) and Magnolia ‘Wada’s Memory’, M. x loebneri 'Leonard Messel', Forsythia, Chaenomeles speciosa (Common Floweringquince) and Lonicera fragrantissima (Winter honeysuckle),damaged by the early April freeze, have rebounded and are displaying flowers, maybe not as full as in previous years, but it is something. Some Star magnolias that were in full bloom were hit the hardest, but Star magnolias which had buds yet to open are producing flowers. As mentioned last week, many Forsythia buds were killed in February by the freezing weather. Overall, right now, the spring landscape is not as colorful as it usually is. The following plants are in full bloom: Cercidiphyllum japonicum (Katsuratree), Pieris japonica (Japanese Pieris), Pieris ‘Brouwer’s Beauty’, Pieris floribunda, Lindera benzoin, early heaths and heathers, Salix sp. (pussy willow), red maples, Pachysandra terminalis, Vinca minor, Petasites japonicus, Sanguinaria canadensis (Blood root), Corydalis solida, Dicentra cucullaria (Dutchman’s breeches), Trillium, Helleborus niger, H. foetidus, H. x hybridus (formerly orientalis), Ranunculus ficaria, Anemone blanda, Primrose, early daffodils, early tulips, Hyacinths, Crocus, Scilla siberica and Chionodoxa luciliae. Pulmonaria sp., Violets, Lamium, and Brunnera macrophylla have started bloom. Daphne mezereum (February Daphne) Cornus mas (Corneliancherry Dogwood) and Cornus officinalis are ending bloom. Lawns are green and mowing has begun.
Pests/Problems: With the warmer weather, winter moth caterpillar eggs resumed hatching. As of April 13, approximately 50% of the eggs had hatched on the tree we are monitoring in Hanson, and numerous tiny, 1st instar caterpillars were observed on the tree trunk. 1st instar caterpillars were also found in the expanding buds of: apple, blueberry, European beech, Norway maple and Japanese maple. Please see UMass Entomologist, Tawny Simisky’s report in the Insect Section below, especially if you have clients who are growing blueberries or apples. The cold weather may have killed some of the early hatched winter moth caterpillars, but probably not enough to make a difference. Dr. Elkinton’s lab will provide more information on this as the season progresses. Continue to monitor developing buds for winter moth caterpillars on susceptible plants (oak, birch, maple, blueberry, apple, crabapple, etc) with a history of winter moth damage and manage early to minimize damage. Also continue to monitor hemlocks for the white cottony egg masses of Hemlock Wooly Adelgid (HWA). As mentioned previously, there was high mortality of HWA this past winter, but this is an insect that rebounds, so continued monitoring is necessary. Begin monitoring for red Lily Leaf Beetle which should be making an appearance soon, if not already. Lilies are up and on warm days; look for the bright red beetles. Monitor for eastern tent caterpillar on crabapple, wild cherry, apple, plum, cherry, etc. Deer ticks remain active. Continue to conduct deer tick checks frequently and consider using a repellent. Solitary, honey and bumble bees are active. Overwintering insects like ladybugs and western conifer seedbugs are making appearances indoors, all trying to get outdoors. A brown marmorated stink bug was found indoors in an office in Raynham. This is a newly arrived pest and one that also seeks to overwinter indoors. For more information, go to: https://ag.umass.edu/fact-sheets/brown-marmorated-stink-bug
Wild turkeys have started to roam the landscapes. Rabbits are active and browsing plants like: lilies, hosta, tulips, Epimedium, etc. Dandelions and chickweed have started to bloom, and bittercress continues to bloom and set seed. Spring cleanups continue and hopefully, hazard tree assessment and removal will continue. Now might be a good time to prune and renovate any bud-killed spring flowering plants like Hydrangea macrophylla, Corylopsis, 'PJM' Rhododendron, etc. Usually we recommend waiting until immediately after bloom to prune or renovate spring-flowering trees and shrubs, but if the flower buds were killed by cold, why wait?