Spongy Moth Issues in Christmas Tree Production: What You Need to Know to Sell Your Trees

Spongy moth infestations in Christmas trees aren’t just a minor inconvenience; they can make your trees unsaleable, leading to lost revenue and damaged reputation. While these insects are typically more of an issue during the summer months, they also appear during Christmas tree harvesting season, because they don’t care about when it’s time to harvest or not, they just want to eat! If you sell Christmas trees, here’s what you need to know about spongy moth issues in Christmas tree production.

The outlook for spongy moth on Christmas trees
The spongy moth (BMF) is a pest that has ravaged millions of dollars worth of Fraser fir, Noble fir and Douglas fir trees across many regions of North America. This tiny brown insect has been a big problem for Christmas tree growers since its discovery over 20 years ago, but it’s only recently becoming apparent how significant an issue it could be. That’s because climate change is making conditions more favorable for spongy moth populations to spread. As you plan your Christmas tree production operations, you need to know what steps you can take now to protect your business from BMF moving forward. Here are some things you should know about BMF and how climate change will affect your business…
About Spongy Moth​ What is Spongy Moth? Spongy moth (Ostryodes rileyi), previously known as Ornamented Bunch-moth or Bunch-mottled Spanworm, was discovered in 1996 near Port Hardy on Vancouver Island. Since then, it has shown up throughout large parts of British Columbia – including Kamloops – where there have also been major incursions into Washington State and Oregon.

Symptoms of spongy moth attack
Symptoms vary by individual tree and by tree species. In general, trees become visibly infested with spongy moth when they are 2–3 years old and still growing rapidly. Infected trees initially grow normally, but over time they develop elongated cankers (openings) that expose underlying bark and vascular tissues. One or several cankers often develop on a single tree. Cankers may be seen as soon as late summer of year 1 after infection, although some infected trees do not show symptoms until year 3 or later. As trees age and growth slows, cankers may heal completely and no longer be visible. The most common symptom is dieback of branches starting at twig tips; however, some infected trees have more severe symptoms such as branch death throughout most of their crowns. Other possible symptoms include abnormal needle coloration, premature needle drop, thinning foliage and reduced vigor. Some trees never show any symptoms.

Options for controlling spongy moth damage
For home growers, one of your best options for controlling spongy moth damage is by applying beneficial nematodes. Nematodes prey on many types of insect larvae and can reduce spongy moth populations with regular applications. Growers should apply nematodes when temperatures are between 55-90 degrees Fahrenheit; a five-gallon bucket will cover an area of 30,000 square feet. It’s important to note that while nematodes are effective at reducing spongy moth populations, they won’t kill all of them. To ensure that you don’t have any living larvae left behind after treatment, it’s recommended that you spray trees with neem oil before planting them or put tree guards around them until they’re planted. A second option for control is by using pheromone traps. These traps attract male moths and trap them inside, where they die without reproducing. Pheromone traps can be hung from trees as soon as new growth appears in spring (and then again every four weeks) until harvest time.

How to sell your trees despite spongy moth infestation
The spongy moth infestation has already killed millions of trees in some areas, but there are things you can do if you have a tree with infested needles. Here are five tips for selling spongy moth-infested trees. 1. Always disclose what’s going on with your spruce trees if you plan on selling them… 2. …but don’t just tell people that they’re dead. People don’t want dead trees; they want live ones. 3. If you think your spruce is dead, ask yourself why it looks that way—is it because it was stressed by drought or pests? 4. Make sure you know how to identify an infested tree before you buy one. 5. Make sure customers know how to identify an infested tree before they buy one. In other words, make sure you both know exactly what to look for and how to deal with it.

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