History repeats itself
In 2016 we had one of the worst extreme droughts in recent recorded history . We also had months of moderate drought in both 2015 and 2017 . Most people know and can recognize the short term effects of drought such as wilted and dry leaves or dying twigs and branches , but there are many long-term implications that may take several years to surface .
When water is in short supply or not available at all , trees and shrubs will try to conserve energy and cut their losses . Leaves will start to curl to conserve moisture by attaining a smaller surface area . Plants will also shed leaves that they no longer can support . There is usually a direct correlation to the loss of small capillary roots that do most of the water and nutrient absorption for the plants . As the small roots die the plant is less able to absorb as much water , consequentially a corresponding amount of leaves and twigs wilt and eventually die .
This weakening and decline can sometimes be temporary and overcome if other necessary conditions are met by the plant . More often it ’ s the start of a downward spiral which is hard to stop . If no relief or intervention is provided for the tree the decline may continue . As the tree weakens it is pre-disposed to other pathogen attacks such as insect borers and parasitic fungi . Once these attacks are underway there is often little chance to help stop the downward spiral . Nature will take it ’ s course and the tree will be severely compromised or even eventually die . In the early 1980s when Scott McPhee was a student at UMass studying with Dr . Francis Holmes , the Director of Shade Tree Laboratories , Dr . Holmes wrote the article , “ Drought After -Effects,” December 5 , 1986 , from which we have included a few excerpts .
“ Analysis of the punch-card records that were kept by the Shade Tree Laboratories ( in the period 1954-70 ) for all its diagnoses of tree pests , injuries and diseases revealed to us that the second year after each drought , a surge of troubles was ascribed to mild pathogens and insects of a “ secondary ” etiology ”.
“ Trees that have been weakened by one or another agency INCLUDING DROUGHT then become liable to attacks made by a whole range of pathogens that seldom harm vigorous , healthy trees ”.
“ In addition to the predisposing certain formerly healthy trees to attacks by secondary pathogens , drought act also in the opposite role . During a drought , the trees that are actually killed outright by drought are usually those that had been subject to earlier stresses from their injuries or diseases ”.
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What can be done to help ? Consistent deep watering will help . The addition of wetting agents , bio stimulants and other stress reducing amendments will also help the tree in this fragile and vulnerable state . If the condition of the tree has progressed to the point where it is vulnerable or attacked by secondary pathogens such as insects and disease , topical or systemic treatments can be applied but are sometimes limited in their effectiveness . As with any illness or infection , early intervention or preventative treatments will be most effective !
WINTER
TO DO LIST
• Review and renew your recommended 2018 Plant Health Care program .
• Inspect trees for safety ; plan pruning with our arborists .
• Plan for new landscape designs for 2018
Gypsy moth outlook for 2018
For those of you who were in the heart of Gypsy Moth Caterpillar country in 2017 , there may be some relief for 2018 .
There was wide-spread , complete defoliation in some areas before Mother Nature stepped in to help . As caterpillars reached full size we had abundant rainfall that helped to activate a fungus in the environment that causes death in Gypsy Moth caterpillars . U-Mass entomologists report that there was up to 95 % caterpillar mortality - good news for sure , as the caterpillars didn ’ t finish their metamorphosis and were unable to reach adulthood to reproduce .
While we can be confident that 2018 will see signs of improvement , egg masses are still prolific on many trees and Gypsy Moth caterpillars WILL be present in certain areas . Treatment is recommended for the areas hardest hit in 2017 . It is important to note that multiple years of defoliation , combined with a few seasons of prolonged drought could mean sure death for mature trees . Extra watering and carefully prescribed soil amendments will improve chances of survival .
Above : Egg laying gypsy moths . Left : Caterpillar killed by fungus
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