In the autumn, we often receive calls from customers asking about their hemlock and other evergreen trees, specifically whether they see any discoloration. It’s likely natural attrition in many situations. Like the maple tree, evergreens naturally shed their inner needles every year. Another thing that could cause needles to turn yellow is insect damage. The hemlock is susceptible to damage from many different types of insects, so our Tri-Cities area ISA-certified arborists at Promier Tree share the details on the blog today about the most common pests that affect hemlocks. That way, you can uncover warning signs and seek treatment before it’s too late.
Common Hemlock Pests
The woolly adelgid and the elongate hemlock scale are invasive exotics that were accidentally brought to New England from Asia but have now become a problem for hemlock trees. The hemlock woolly adelgid is a well-established pest in Massachusetts, where it has been present since 1988. Since its discovery in New York in 1908, the elongate hemlock scale had spread rapidly and become a serious problem in the state of Massachusetts, though nobody is quite sure when it first showed up there. Both species’ females are unable to fly. Thus wind and birds are responsible for transporting them. The hemlock woolly adelgid is recognizable due to the cottony masses it produces at the base of needles, but the elongate scale is much harder to see. The elongate scales on a male are often paler than those on a female and measure only approximately 1/20 of an inch in length.
The two pests are almost interchangeable in terms of the harm they do to hemlocks. Their mouthparts are designed to pierce and drain the sap from trees, progressively killing them over time. Regular treatment is necessary to keep populations of these two pests to a low since they are often found together and may have two generations each year. Our Bristol ISA-certified arborists explain that the invasive pests may be treated with either a topical or a systemic method. After settling on a branch or a needle, the adelgid and the scales will not move. Because of this, horticultural oil, which essentially suffocates the insects where they stand, is often an efficient method of treatment.
Resolving hemlock pest problems
Although horticultural oil may be produced from petroleum, our ISA-certified arborists in Johnson City choose to work with organic mineral oil. A systemic pesticide may be used to treat trees that are infested by these insects in high numbers or in areas where spraying is not an option due to drift problems. The bottom part of the tree trunk is an ideal spot to apply a systemic insecticide, which will be taken up by the tree and dispersed throughout the canopy. Only one application is necessary for the full season. This may be a useful substitute for or addition to a spray program in areas with a high concentration of elongate hemlocks scale. However, when sprayed on the tree’s trunk, bees are protected against the majority of the systemic pesticides in the neonicotinoid family.
Since wind is the primary pollinator of hemlocks, the pesticide presence in pollen wouldn’t harm bees or other pollinators. Elongate hemlock scales and hemlock woolly adelgid adhere themselves to the plant so they don’t break off after treatment, and ancient remains may stay on the tree for years until they naturally fall off. Hemlock woolly adelgid infestations, drought, and other stressors may amplify the severity of long-lasting hemlock scale outbreaks. Thus, keeping trees in good shape will aid in their eventual recovery. Hemlocks’ thin root systems make them particularly vulnerable to dehydration. Therefore ornamental trees should be tended during dry spells.
ISA-certified arborists in Kingsport, Johnson City, and Bristol, Tennessee
There is a good chance that you have one or both pests if you have hemlock trees. You can preserve the hemlocks in your yard if you examine and treat them regularly. If you have any concerns concerning hemlock pests or concerns, please contact our Kingsport ISA-certified arborists at Promier Tree, where you will speak with tree healthcare professionals. Please call us at (423) 765-2626 or contact us online to submit a question or schedule a free consultation today.