Weak Branch Unions: A Very Visible Hazard

Weak branch unions are easy to spot before they become a problem…

Weak branch unions are one of the most common hazards we see on clients’ properties. This hazard is easily identifiable and, thus, easily avoided. But what are the signs that tell us a weak branch union likely exists?

The most frequent weak branch union we see is called a co-dominant stem. This is where two stems of roughly the same size arise from the same point on the tree. (This is also known as a “schoolmarm” in forestry circles…but it’s up to you to learn the backstory on that.) The junctions between co-dominant stems are often considered the weakest portion of a healthy tree. They are widespread in forested areas; you’ll often see them on area trees, especially ponderosas. It will look like the tree has two or more tops. This creates a weak branch union because the two stems, or leaders, are growing so closely together that the bark on each leader interferes with the formation of a proper, strong union. This is called included bark, and it doesn’t have the structural strength of a normal branch crotch. Furthermore, included bark can act as a wedge, forcing the weak branch union to split apart.

weak branch unions
Removal of a ponderosa with co-dominant stems earlier this spring. Weak branch unions are especially troubling near structures.

During the windstorms of recent years, we’ve seen countless trees lose one of their co-dominant stems. Wind will point out any weak branch unions you have, if you’d rather not pay a professional to investigate. The problem doesn’t stop with the toppling top of the tree—and subsequent property damage—though. Once one of the co-dominant leaders is gone, a wound remains and leaves the tree structurally weaker and vulnerable to infection. The best approach is to be proactive about trees with co-dominant leaders. Either remove one of the leaders in a controlled environment, or cable the two stems together so they support one another and don’t sway past the trigger point in the wind. We are well versed in both approaches and can talk you through options.

Another example of a weak branch union is when epicormic branches (also known as watersprouts or suckers) are allowed to grow into sizable limbs. Epicormic branches grow quickly—often in response to poor pruning practices, injury or some kind of environmental stress—and they always display weak branch unions. It’s best to tend to suckers when they are newly formed, before they pose any real hazard to structures and people.

Finally, any branch that comes off the trunk at a very acute angle or doesn’t display a ridge of raised bark at the crotch is of potential concern. If you have trees on your property that exhibit any of the signs of a weak branch union, call us for a free consultation and estimate. Considering the widespread impacts of recent windstorms—and the fact that weak branch unions are especially susceptible to failure in wind—a call to us will at least provide peace of mind.

COVID-19 and Tree Work

The COVID-19 pandemic has not yet affected our ability to serve you

Storm damage on Bottle Bay Road

Things felt downright apocalyptic in Sandpoint a couple weeks ago. Just as the COVID-19 pandemic began to feel very real and frightening for all of us, a windstorm of epic proportions hit. Neighborhoods from Baldy Mountain Road to south Sandpoint and across to Sagle were devastated. Falling trees crushed houses and cars. People lost power as the temperature plummeted into the single digits. And we all began looking at our trees a little differently. What we once appreciated for shade or beauty now looks like a threat.

Add to that the threat of COVID-19, and for some of us, it feels like the world is falling apart. Governor Brad Little recently issued a stay-at-home order for Idahoans to mitigate the spread of the virus, but for those whose homes or sense of safety were compromised by the windstorm, there is no feeling of sanctuary.

Thankfully, arborist businesses like Sand Creek Tree Service are considered essential during this time of self-isolation. We can continue responding to your tree needs. Do you have a storm-compromised tree or one that could potentially pose problems in the future? We are happy to help with these needs and more.

Our focus now is not only on your safety as it pertains to trees but also relating to potential transmission of COVID-19. We are taking personal precautions, including: limiting our social contact to just our workforce, shopping only once a week, regularly washing hands and using hand sanitizer, and keeping our distance from clients. If you feel the need, we are happy to discuss your trees over the phone to maintain distance. You can also mail us a check or pay via Venmo or credit card (for a small fee) to limit interactions.

We are taking this thing seriously. And we are grateful to continue working in the midst of it. Thanks for supporting us during this difficult time. We hope to do what we can to help you—and our community—too.

For updates on Sandpoint’s COVID-19 situation, click here.

Winter Tree Care Checklist

You know how to handle the cold season, but is winter tree care on your radar?

By this point in the winter season, many of us feel like we’ve got it all figured out. We’ve worked out the snow removal kinks, have all our firewood in, and know how to keep our family and animals cozy and safe. But what about winter tree care? Has that crossed your mind?

winter tree care

If you’re like most people, unless you’re dealing with broken limbs, probably not.

So, what does winter tree care involve? Thankfully, there’s not much to it, but these few key points are important.

Root protection
The first consideration for roots is insulation. In the Sandpoint area, this is usually not a problem. We get enough snow to insulate roots from cold temperatures. However, it’s still not a bad idea to mulch around the base of your trees for added protection. After the snow melts, get ready for next winter by spreading a two-to-four-inch layer of mulch around the base of your tree, under the canopy. Just be sure to keep mulch away from the trunk.

The other consideration for roots that is an issue in Sandpoint is the use of road salt. This can cause discoloration of foliage in evergreens and bark dieback in all trees. In the long term, it can lead to systemic issues caused by the preponderance of salt in the soil. Several options exist to remediate this issue:

  • Use calcium chloride instead of sodium chloride. It’s more expensive but less harmful to plants. And when you consider the cost of a hazard tree removal, it may be more cost effective in the end.
  • Furthermore, you can mix your road salt with sand for added traction and to lessen the amount of salt used.
  • Extra watering of roadside trees can dilute the amount of salt present on the trees and in the soil.
  • Finally, apply gypsum in late fall, before snow comes, to protect roots.

Trunk protection
Especially on young trees, thin bark is a vulnerability. Deer can do damage by rubbing their antlers on the trunk. Rodents can tunnel through the snow and chew the bark. And even temperature swings can do damage, warming the trunk on a sunny day, only to freeze hard at night, damaging a vascular system that got excited about spring. An easy winter tree care solution to these problems is to wrap the trunks—from the base to the lowest branches—with plastic tree guard. This is especially important for young maple, ash, linden, locust, dogwood, cherry, birch, and crabapple trees.

Branch protection
The best protection for branches is maintenance pruning. This ensures that broken and diseased branches are removed before the snow does it for you. At this point in the season, though, proactive care can include gently removing snow from drooping branches to prevent them from breaking. Do this with a broom rather than by shaking the limb so as not to harm the branch. Also, try to keep from piling snow against your tree, trapping low branches in the process. And finally, if you notice ice covering your tree, leave it. Let it melt and then inspect for damage. Trying to remove ice yourself will likely cause more harm.

With these few tips in mind, your tree should easily weather the winter. Come spring, if you notice any damage from the cold season, call us. We’re happy to assess your tree’s health and suggest any corrective action it might require.

February Was Cold, But Was It Enough to Cause Bark Beetle Die-off?

Just how cold does it have to get to kill those pests?

Many of us like to look for silver linings, and the shining hope of a frigid winter is that overwintering insects suffered more than we did. If there are fewer harmful creepy-crawlers this summer, then maybe that chilly February was worth it.

I can’t speak to how the yellow jackets fared (hopefully poorly), but I do know that our problematic bark beetles—specifically the fir engraver and Douglas fir engraver—took it all in stride. February was hardly a blip on the radar for their sleeping larval selves. It was not cold enough to cause beetle die-off. Thus, expect more browning firs in the months and years to come.

When it comes to winter, beetle larvae are way tougher than we are. They use snow around the base of a tree and the tree’s bark as insulation. The larvae excrete all their stomach contents so the liquid won’t freeze up. Then they fold over on themselves and generate a kind of internal antifreeze. Finally, they wait, able to withstand temperatures of up to -40 degrees.

February’s chill didn’t even come close to that.

This is the characteristic “mining” pattern the Douglas-fir engraver beetle larvae makes when eating the tree’s inner bark. Each beetle has a pattern all its own. Image courtesy of Wayne Brewer, Auburn University, Bugwood.org.

The best hope for temperature-related beetle die-off is to have a hard freeze—below zero—very early or very late in the season. Like in October or now, in March or April. If the freeze comes early, the beetles won’t have yet generated enough antifreeze in their systems to survive; and if the freeze comes late, the larvae will have already woken up with the warmer weather and shed their defenses. However, even in these scenarios, beetles can always fly in from areas that didn’t get as cold.

Thus, it seems, the beetles—and their detrimental effects—are with us for at least another year.

So, in the absence of such beetle die-off, what is a landowner to do? First, keep an eye on the health of your trees. Beetles are opportunists. They’ll go for stressed trees whose defenses are down, and then they’ll spread from there. Cull the diseased trees from your forest to limit infestation opportunities. And while you’re at it, just thin your forest in general. Trees living in competition with one another for light and nutrients don’t have the necessary resources to fend off beetle attacks. Give your trees the room they need to thrive. Finally, if you do have beetle-kill on your property, remove it.

To learn more about beetles, check out these Forest Service documents on the fir engraver and the Douglas-fir engraver beetles. Also, our last post was about bark beetles in North Idaho. Finally, don’t hesitate to give us a call if you have any questions about the health of your trees.

Dieback in North Idaho’s Fir Trees Explained

Rampant dieback is evident in area trees, but why?

This year, many of us noticed conifer dieback —especially affecting fir trees—on our properties and in our surrounding forests. The flaring out (or reddening) of so many trees is alarming to those of us familiar with bark beetle infestations elsewhere, including those decimating entire hillsides in Montana and Colorado. Are our tree stands doomed, too?

The thing is, bark beetles aren’t to blame for what we’re experiencing here; they’re just finishing off a job begun by other factors. The fir dieback we are now seeing actually has its roots in a century’s worth of logging, fire suppression, and the introduction of pathogens like white pine blister rust. This all contributes to more grand fir, Douglas fir, and subalpine fir than North Idaho has traditionally supported.

Next, the hotter, drier summers of recent years have stressed out our trees, leaving them more susceptible to diseases and pests. Thus, pathogens that healthy trees can easily fend off are now flourishing amidst weakened “immune systems.”

One such problem is the myriad native fungi that lead to root rot. Doug fir, grand fir, and subalpine fir are the species most susceptible to root diseases, and these diseases alone—even without the beetles—are leading to massive dieback.

Since the fungi responsible for root rot live in the soil and remain onsite through generations of trees, this problem isn’t going away anytime soon. However, even in the face of drought, there are things a landowner can do to diminish the threat of dieback. The first step is to thin the forest so trees aren’t competing for water and nutrients. Twelve to fifteen feet between saplings (more for larger trees) is a good rule of thumb. The second step is to ensure forest diversity, including a majority of trees tolerant of root diseases. These include (in descending order): ponderosa, Western larch, Western red cedar, lodgepole pine, Western white pine, Western hemlock, and Engelmann spruce.

Fir trees sometimes struggle and survive at the brink of dieback brought on by drought and root diseases, but opportunistic beetles exist to finish off the job. In North Idaho, we have over 100 species of bark beetle, each specializing in different conifers and sometimes even different parts of specific conifers. These beetles are a natural part of our forest, but they are flourishing right now due to the aforementioned factors of drought, overcrowding, fir population imbalances, and root rot.

If you notice fir dieback (or other struggling trees) on your property, give us a call. We can provide an assessment of your trees and forest and how best to tackle the domino effect that runs from drought to dying trees.

For more information on area tree diseases, check out “A Field Guide to Diseases & Insect Pests of Northern & Central Rocky Mountain Conifers.” To learn more about root diseases in particular, visit “Root Diseases in Coniferous Forests of the Inland West.”

 

Mistletoe: There’s Nothing Romantic About It

Mistletoe may be good for those desiring a kiss but not so much for your trees…

We see a lot of mistletoe around here. Unfortunately, that doesn’t mean that love and lingering holiday cheer are in the air, but rather, that the seeds propagating the parasite are soon to be airborne. (And watch out: Mistletoe seeds are ejected from the plant at speeds of up to 60 mph!) It’s something to be aware of as mistletoe is detrimental to the health of your trees.

mistletoe

Note the abnormal branch growth of the witches broom on this fir. Photo by Cephas via Wikimedia Commons

North Idaho is home to a handful of dwarf mistletoes that are specific to our native trees. Larch, Douglas fir, ponderosa and lodgepole pines are all primary host species. In our work, we have seen it most often in larch and Douglas fir.

What does mistletoe look like? It’s most easily spotted when the infection is full-blown and affected limbs have witch-broomed in response. A witches broom is a mass of chaotic branch growth that appears as a dense clump in your otherwise well-formed conifer. The witches broom is a response to the mistletoe but not the mistletoe itself.

mistletoe

Larch dwarf mistletoe shoots begin to sprout in the spring eventually forming clusters of shoots as seen in this plant. Photo courtesy of the USDA Forest Service Archive

Mistletoe is hard to detect early on. For several years, no outward symptoms may be apparent. This is known as a latent infection. After several years, though, scaly shoots emerge. However, since they are only two inches tall and are likely hidden in the canopy of the tree, most property owners don’t notice the early stages of mistletoe infection. Thus, we are often called in to treat more heavily infected trees that have had many years to spread the parasite to surrounding trees. This makes mistletoe eradication difficult.

Mistletoe harms trees in numerous ways. For one, as a parasite, it takes water and nutrients from the tree for its own growth, leaving the tree weaker and more susceptible to other insect and fungal invaders. Infected trees grow slowly, and heavy witch-broomed limbs are prone to breakage due to their weight. Mistletoe often leads to tree death. It also creates a fire hazard. All of this means that a mistletoe infested tree is a hazardous tree.

Our approach to mistletoe treatment is to first assess the tree to determine if the tree is a candidate for pruning or removal. If the infection isn’t too severe, pruning of witches brooms and less affected limbs will be undertaken. Healthy looking limbs adjacent to infected ones may also be removed in case infection is latent. Pruning in subsequent years may be necessary to catch future outbreaks. And pruning is best undertaken in the early spring or late fall when pollen and seeds are not being released from the mistletoe. We don’t want to inadvertently spread more infection.

One last thing to consider is that mistletoe does have its uses. Various birds and forest animals use witch-broomed limbs for cover and as nesting sites. We once found ourselves in a tree, dodging a group of flying squirrels leaping to safety. There is something to be said for leaving an infected tree alone if it is not a direct hazard to you and the health of your forest.

If you have concerns about mistletoe, give us a call for an assessment. And for more information, there are several helpful publications online: