Bronze Birch Borer Treatment | Seacoast Tree Care

That ugly critter you see in the photo is what we call a Bronze Birch Borer and they represent a huge issue with regards to the health of Birch trees along the seacoast and greater New England.
What they are, what they do?
Bronze Birch BorerCredit: Dept of Entomology, U of M
 anBirch borers are insects that well… feed on birch trees and can be identified by their bronze/coppery thorax, legs and abdomen. They have a relatively short life span – breeding in the winter, hatching in the warmer summer months and then dying off mostly in the fall. But don’t let that short life span fool you. They can do a lot of damage in a short period of time. 

As soon as they’ve hatched (and even a little before they’ve hatched) – the Bronze Birch Borer is busy wreaking havoc. They start by chewing up the phloem on the inside of a birch’s bark as tiny larva. Then as they mature – they chew deeper and deeper into the tree – eventually reaching the cambium. Once in the cambium, they begin disrupting routine nutrient transport and to the point where it can eventually kill the tree’s root system. With each bore comes a new galley (nest) of eggs and residually over time – the damage becomes more widespread.

From there, the domino effect takes place as the tree can’t provide adequate water supply and dieback begins to occur in the branches and further limits the tree from producing food and nutrients. If not treated – the tree will almost surely die. 

What are the signs of infestation?

The three primary indications that your birch may be infested are:
  1. Yellow Foliage – especially towards the top of the tree.
  2. Gradual or accelerated dieback towards the top of the tree
  3. Bored out, almost D-shaped holes in the trunk of the tree; holes that are usually lined with a rust-colored sap.

If you see one or a couple of these symptoms, your tree SHOULD be able to be saved with treatment. If it’s displaying all of these traits – there is a significant chance you’re too late and the tree will have to be destroyed in order to prevent the Bronze Birch Borer population from expanding into surrounding trees. 

What kinds of treatment options are available?

As with any kind of pest, the best form of treatment is always prevention. That means keeping up on your trees, checking on them annually and doing the necessary things to keep your birch trees happy and healthy. In the particular case of birch trees, that means:

-Watering your birch frequently. Birch trees thrive in water and camp conditions. Especially during dry spells and drought – a slow, deep watering routine every few weeks helps the surrounding soil maintain the kind of moisture levels your birch will need to adequately nurture itself and ward off invasion.

-Mulching is also key. Especially in conditions where a birch is in ‘competition’ with other foliage for water – mulch can help localize moisture and soil temperature. About 3 inches of mulch placed just under the drip line can do the trick. Mulching is also extremely beneficial to the birch’s overall root system.

-Fertilizing can also help, but that is true of any tree. The thing to be aware of with birches however – is keeping an eye on how much nitrogen is in the fertilizer. Too much nitrogen and you can actually increase your tree’s susceptibility to birch borer. 

You second option for treatment is what we call preventative insecticides. If you live in an area that’s consistently compromised by drought and dry conditions, you may want to take the plunge and apply pesticides that prevent Bronze Birch Borers from ever taking hold of your tree. But again – as is the case with any chemical – you really should call a professional arborist. There is a wide range of options to choose from – all with varying degrees of effectiveness on not only the birch itself – but also the area around it. Decisions are mostly made on a case-by-case basis. Obviously the best time to apply these treatments is in the fall. You CAN apply these treatments in the spring and summer – but you won’t get the same results. 

The final form of treatment is called Therapeutic treatment. Therapeutic treatment is usually reserved for trees that are already showing a significant level of infestation.  What kind of pesticide you use is almost directly related to the degree of infestation. For example – you’ll want one or two applications for trees around a ¼ canopy loss. For fast-acting treatments with more advanced stages of infestation, you’ll want a pesticide that can be absorbed into your tree in less than a week. Again – as we mentioned above – this is a job for the pros, so you should call an arborist. 

Before we go, some takeaways

Bronze Birch Borers are a serious infestation and immediate action should be taken. If treatments or pesticides/insecticides are to be used – then it’s time for a pro. Preventative maintenance however – is always best and involves a wide range of simple things that you can do yourself to give your trees the best possible chance to survive. 

It’s worth noting, however – that the average laymen can frequently misdiagnose Bronze Birch Borer. Some of the symptoms can frequently be confused with simple construction damage, aging or basic draught damage. So again – before you go wild budgeting out treatment options – call the local pro up and have them come by to get a definitive diagnosis and pest control in Greenland, NH.

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