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Common Tree Pests, Problems and Solutions in CT

Connecticut has a unique set of tree pests and problems that property owners and managers may run into. These include insects, disease, and environmental conditions.  The list below contains some of the things we run into most often in New Haven and Eastern Fairfield county.


Hemlock Wooly Adelgid

Hemlock Wooly Adelgid in CT
Hemlock Wooly Adelgid

Hemlock Wooly Adelgid is a small nearly microscopic insect that feeds by sucking the nutrients out of a plant, it is a non native invasive insect that only feeds on Hemlock trees and does significant damage to Eastern (Canadian) Hemlock which is an important native forest tree in CT. Despite the onslaught of the invasive Hemlock Wooly Adelgid which has killed up to 80% of wild Eastern Hemlock trees the remaining trees still remain an important asset to our CT forests.  Canadian Hemlock is also a popular ornamental landscape tree.  There are a number of reliable options for treatment including organic and non-organic horticultural oil, as well as systemic insecticides….CLICK HERE for more information on hemlock wooly adelgid…


Emerald Ash Borer

Emerald Ash Borer is a new arrival in the United States. The full scope of it’s damage is yet to be seen.  This beetle’s larval stage bores into Ash trees cutting off the vital flow of nutrients between roots and canopy, quickly killing the trees. Many species of Ash are susceptible, but our CT native ash tree the White Ash is especially susceptible to damage from this invasive insect. The Emerald Ash borer has just entered CT within the last few years and its range is spreading quickly throughout Fairfield and New Haven Counties as well as the rest of the state.  There are a few good treatment options including an inexpensive preventative, but If your an Ash tree is already infested then a high volume trunk injection treatment is your best option…..CLICK HERE for more information on emerald ash borer…


Spider Mite

Spider mites are very small arachnids that suck sap and nutrients from plant foliage such as leaves and needles.  Spider mites are very difficult to see with the naked eye therefore they are often overlooked.  Spider mites cause leaves and needles to become speckled and yellowish leading some people to diagnose the problem as a nutrient deficiency, drought or some other environmental condition. Spider mites can be scouted for by holding a white paper under suspected infested foliage, shake the white paper and search the small debris that falls from the plant with a 10x or 20x magnifying glass.  If mites are seen it does not always mean there is an infestation of sap sucking mites, some mites are beneficial, if you live in New Haven or Eastern Fairfield County contact GreenWorks to assist in identifying mites or diagnosing any other plant health care problem. There are a few reliable treatment options for mites including organic and non-organic horticultural oil spray.


Evergreen Needlecast

The most common type of foliar fungal problems that we see are evergreen needlecasts.  There are a number of different types of evergreen needle casts that affect a range of needled evergreens including Spruce, Pine and Douglas Fir.  These fungi cause specific patterns of needle browning and eventual needle loss. The fungal infections usually start at the bottom of the tree and work up, foliage will look brown and eventually fall off leaving bare branches behind.  The most effective treatment is 2-3 applications of foliar fungicide in the spring.