Managing Winter Issues in Trees with Tim Kohlhauff – Episode 010

Is winter really the best time to prune fruit trees?  What do I do if my tree is damaged by wind or snow?  Do I need to water in the winter? 

Tim Kohlhauff, certified Arborist and the Urban Horticulture Program Coordinator for Spokane County answers these questions and more on this episode of The Evergreen Thumb.

First up is the December gardening calendar.  Then, Tim Kohlhauff joins me to talk about winter issues in trees and shrubs.   Tim and I discuss:

• The best time to prune trees
• How to prevent and treat winter damage
• Winter pests and diseases in trees
• Winter Watering
• Erosion

• Fact sheet on winter injury to leaves of evergreens:  https://pubs.extension.wsu.edu/environmental-injury-winterburn-of-evergreens
• Cold injury to landscape plants:  https://pubs.extension.wsu.edu/environmental-injury-cold-temperature-injury-of-landscape-woody-ornamentals-home-garden-series
• Sunburn or sunscald damage to trees:  https://pubs.extension.wsu.edu/environmental-injury-sunscald-and-sunburn-on-trees-home-garden-series
• Preventing winter injury to grapes:  https://pubs.extension.wsu.edu/protecting-grapevines-from-winter-injury
• Winter Injury
• Much less common but still occurring in Washington is an injury called frost crack: https://pubs.extension.wsu.edu/environmental-injury-frost-cracks-home-garden-series
• WSU Extension Spokane County Trees and Shrubs page
• WSU Extension Spokane Master Gardener Facebook page

[00:00:00]

Erin Landon: Welcome to episode 10 of the Evergreen Thumb. My guest today is Tim Kohlhauff, but first, we need to go over the December gardening calendar.

Being December, there’s a lot less going on in the garden, of course. So it’s going to be kind of a short list. First up for planning is if you plan to purchase a living Christmas tree, be sure you have enough space to plant it in an appropriate location. It is likely going to be a large tree when it’s mature. Don’t keep living trees inside for more than a week, if possible, as indoor heat and low humidity in the winter are very stressful for conifers, and be sure to plant your tree as soon as you’re able.

Another planning idea is to observe how water moves or doesn’t move, if the case may be, and plan how you’re going to make changes to manage that water flow. Be sure to take lots of pictures so that you’ll remember later what the problem was and how you want to manage it. This is especially a good time to do during heavy rain so that you can see. See where those drainage problems are. Tilling, ditching, and French drains may be short-term solutions, but if you have a serious water condition issue, I recommend considering rain gardens or bioswales as a longer-term solution.

In maintenance, you want to check your stored flower bulbs, vegetables, and fruits for rot or fungus issues and then discard anything that is showing signs of rot. Um, for planting in Western Washington, it’s actually a good time to plant trees and landscape shrubs, um, provided that the ground is not saturated, um, because digging in that uh, wet soil can actually damage the soil structure and make it very compacted, but if the ground, if it’s not freezing, and you have some trees and shrubs that you would like to get into the ground and let them get established before spring, this is a good time to do that.

Uh, check for rodent damage around the base of trees and large shrubs, uh, remove weeds to prevent rodents from using that as hiding places. Uh, rodents may also use mulch around the bases of trees as cover. So avoid mounding mulching materials too high on the tree. Sometimes, these are called mulch volcanoes, and if they are too high, they can also cause the bark to rot and, uh, compromise, uh, the health of the tree.

For house plants and indoor gardening, if you bring home poinsettias for the holidays, be sure to protect them from cold, place them in sunlight, but don’t let the leaves touch the cold windows, and be sure to fertilize them with a regular houseplant fertilizer to help maintain their leaf color. Monitor all of your houseplants for adequate water and fertilizer. These requirements generally are lowered in the winter, so you won’t need to water them as often or as deeply, but they do still require some water. And that pretty much covers it for December. Like I said, it’s a pretty short list.

So. Now we will get into our episode with Tim. Tim is here to talk to us today about trees, managing trees, and other issues during winter. Tim is the Urban Horticulture Program Coordinator for Washington State University Extension’s Spokane County office. He has led the local Master Gardener Volunteer Program since 2012. He’s an adjunct instructor at Spokane Community College, where he has taught arboriculture and plant problem diagnosis classes.

For 10 years, Tim was the arborist at the Kalispell Golf and Country Club. He has been an ISA certified arborist since 2004. Tim, thanks for joining us today. Welcome to the show.

[00:03:39] Tim Kohlhauff: Thanks for having me.

[00:03:42] Erin Landon: All right. So to start off, why don’t you tell us a little bit about yourself and, uh, your connection with the Master Gardener program?

[00:03:47] Tim Kohlhauff: All right. Well, um, I, I feel very lucky cause I get to work with Master Gardeners. I started as a volunteer back in the year 2000, and, uh, when I first was accepted to the program, I made my family call me master for like a week after I got the letter and that was exciting. But, um, then I was really excited to be part of it.

And in 2008, I started working part-time, just a little bit to try and help organize our diagnostic plant clinic. And then in 2012, I got the chance to come to work full-time. So now I’m the urban horticulture coordinator for Spokane County, which means that I work with the Master Gardeners but also do some stuff with commercial horticulture.

[00:04:30] Erin Landon: Okay, great. So to start off, this is kind of a very specific question, but is winter really the best time to prune fruit trees?

[00:04:43] Tim Kohlhauff: Yes, and… I’m, I’m learning to say yes, and, uh, it depends a little bit on, uh, what your objective is for the fruit tree and what kind of pruning you’re doing and also where you are in the state.

So, um, dormant season pruning is really good, uh, so that you get the best regrowth from the trees. If you prune during the dormant season and also most of the pests that could take advantage of the pruning. Um, are dormant during the dormant season, right? Because there’s nothing for them to eat. And so you’re avoiding opening up these wounds at the same time that pests are active, so it’s a good time to do that.

However, if you’re in the really cold winter part, parts of the state, you just have to be a little bit careful that you’re not, you’re not exposing tissue to these subzero temperatures that sometimes cause cracking or they’ll kill the newly exposed tissue that’s supposed to, that’s live, that’s supposed to help stop the wound from, from bleeding or start compartmentalizing the wound.

So, in areas like, I’m going to say the, the, uh, Mountains along the northern edge of the state, a lot of our like zone four, zone five places, sometimes you have to be careful. You don’t want the temperatures to get down into the teens or single digits within a week or so after you’ve pruned to try and prevent that damage.

But otherwise, winter is a good time to, to do pruning. For me, it’s a really good time to, to prune because I can see all the branches, right? The leaves aren’t there blocking the view. So, uh, I really like to, to prune during the winter.

[00:06:32] Erin Landon: Okay. So what about… As far as like dead growth or as a, I mean, obviously, in the winter, you’re not going to be able to tell what’s live or dead without inspecting every branch.

But, um, I know personally, I normally cut that off during the growing season just because I can actually see it. Is that the best?

[00:06:50] Tim Kohlhauff: Yes. So. Yeah, you’re absolutely right. So if you see something dead during the season, there shouldn’t be any harm in taking that off. And in some cases, it’s an advantage. On the east side of the state some fruit trees, especially apples and pears, are prone to a bacterial disease called fire blight. And sometimes getting that out of the tree, pruned and removed from the tree quickly is the name of the game. And so if you’re pruning for disease control or disease management during the season, I mean, you don’t have to wait to the dormant season.

It’s a good time to prune, dormant season is a good time to prune in general, but sometimes you need to prune during the season because there’s a disease or that maybe there’s a, an insect infestation that you could just kind of prune out and get rid of before it spreads. Or if you’re doing really light pruning, or say there was a storm which sometimes happens in the spring and there’s some broken branches, you want to address those and not have to wait for the dormant season.

So, yeah, if you’re doing light pruning, if you’re addressing Disease or damage or, or, uh, insect infestation. You might prune during the regular growing season and it should be just fine. The only problem you might, if you’re doing like really heavy pruning uh, in the middle of the season, sometimes you’re opening up the tree to some of those diseases, those pests that take advantage of those wounds, but usually, um, you’re doing that during the dormant season.

So I know, uh, working with some orchardists, they, uh, they prune a little bit all season long just to kind of manage their trees and make sure nothing is really like a disease isn’t really taking hold and doing serious damage and, and it works really well.

[00:08:45] Erin Landon: And is it true too that, I mean, pruning… Like after bud break is going to affect your, um, production if it’s a fruit tree because you could be potentially pruning off producing buds.

[00:08:58] Tim Kohlhauff: Yes, so the, with most fruit trees, I’m trying to think of any exceptions; so the, the, the standard fruit trees that we grow a lot, apple, pears, cherries, peaches, I’m trying to think of some other ones, but those fruit buds set in the, they, they set on old wood, meaning that, uh, they set the fall before the spring when they bloom and set fruit.

So if you’re pruning off last year’s growth in the early spring or in the, in the late winter/early spring, you might be removing some of the flower buds that are going to turn into fruit. However, uh, usually you’re not removing so many that it. damages your whole crop. You’re removing specifically like the the potential fruit in one part of the tree but what’s left is going to be higher quality fruit because you’re not, you’re making the tree put more resources into fewer fruit instead of spreading it out over a wider.

So you might have a hundred really good apples instead of 200 so-so apples if that makes any sense.

[00:10:11] Erin Landon: That makes great sense. So how do I prevent winter damage to shade trees?

[00:10:19] Tim Kohlhauff: A great way to prevent winter damage to shade trees is just to be taking care of them all during the year. So keeping your shade tree healthy in areas where you have to water, or if you have a species of tree that you have to water regularly, regularly to keep it happy, make sure it’s well watered and do what we call structural pruning.

Early in, in a tree’s life, if you, if you prune it for the first, um, 20 years or so, uh, the research shows that it will be much more resistant to damage for the rest of its life if you get it started growing in the right direction.

So you’re pruning it to have a strong structure and that might mean hiring an arborist to come in and do it, or maybe, especially when the tree is smaller, you a homeowner wants to do it themselves and that can actually absolutely, uh, be done. That’s something that a homeowner can do with a little bit of study. But if you do that way ahead of time, you’re going to prevent most of the, the really catastrophic damage that can occur from winter storms.

That’s not to say that you, you’re ever completely safe because we get 70 or or higher 70 mile an hour or higher winds and you know, there’s no telling what might happen. There’s always that element of risk. But if you’re taking care of your tree a little bit, there’s All the time, then you prevent the really bad issues when, when there’s a big storm.

[00:11:56] Erin Landon: Okay, so kind of a very case-specific and um, that just happened here. Our first frost dropped all the way down to 25 and all of our trees still have, are in full leaf; I know they never completed the abscission, so what are the potential risks to those trees for damage with all the foliage still on them?

[00:12:19] Tim Kohlhauff: So a very similar thing happened where I’m in Spokane County and that happened here last year where we had Beautiful summer and and summer seemed to last all through October.

Then we had about three days of fall and then winter and and the leaves didn’t get a chance to drop from the trees. And so I can say with some experience that, uh, we were much more worried than. We needed to be, I was pretty sure that with all those leaves on the tree, it was going to snow a lot, and then the snow load was going to, uh, really damage our trees.

And we lucked out in that we didn’t have as much snow as we sometimes do. And there wasn’t really the level of damage that, that I was expecting. However, When the leaves are still on the trees and when they don’t fall off, then it does provide more surface area for snow to collect. And so, and when that happens, then there’s a greater chance, you know, more snow collecting, more weight on the branch, and then a greater likelihood of it, of it breaking.

It seemed like where we were lucky, we didn’t have as much snow as we were expecting, and then it was more damaged. Um, it was lighter damage, so it wasn’t whole trees falling apart. It was maybe some a few branches that were that were weighed down and broke off the tree. So I’m hoping the same is the case there, that there just isn’t isn’t the level of damage that it seems like there could be, but there is a risk to it.

One of the things I did, uh, that, that I, I think was helpful. I have a Japanese maple that I just love in my front yard and I went out and I kept kind of shaking it and trying to get the leaves off of it. And over time I got most of the leaves off. I didn’t try to cut all the leaves off because that was impossible.

Uh, it was just too big a job, but, um, I did shake. whatever leaves I could off of it. And then whenever it did snow, I went out and if I was able to, uh, I’d go out and shake the snow off so that, uh, when I saw branches starting to bend down, then I could shake the snow off and, and so there wouldn’t be that long term weight pulling on the tree.

One thing that, uh, that we did find here that was a little surprising with that sudden cold snap, some of the plants in our gardens, especially the broadleaf evergreens were just not quite ready for that cold and so in the spring, we saw a lot of damage to rhododendrons and, uh, boxwoods and cherry laurel, which actually wasn’t too bad if that cherry laurel can be a little invasive, so if it was damaged it usually popped right back, but we had damage that seemed to come from that cold, that sudden just, it was lows in the 40s and then it was lows in the 20s and that seemed to catch some of the plants off guard, so there might be more leaves turning brown during the winter than we’re used to.

[00:15:35] Erin Landon: I have an evergreen magnolia that we just planted. So now you have me a little bit worried.

[00:15:41] Tim Kohlhauff: Okay. Well, I’m sorry. I hopefully everything will be okay. But, um, uh, mulch around the roots to hopefully keep those well insulated.

And then, um, and. I guess one thing I should, I should follow up with, or end with is that, uh, don’t panic. Some of the, some of the evergreens that we had over here looked just horrible at the end of winter and people were really, okay, well, I guess I better dig it up, but wait, because a lot of them. put out new leaves and, and they might not look their best for a year or two, but, but they survived even when it looked like, wow, there’s nothing left alive there.

But, but be patient and, and in the spring and let them try to leaf out before making any big decisions.

[00:16:29] Erin Landon: Okay, great. So, uh, if we do have winter damage to trees and shrubs, when is the best time to fix it?

[00:16:37] Tim Kohlhauff: So it, the first thing, the first priority, I guess, would be safety. So if for some reason there’s a branch hanging up in a tree that is over your sidewalk, then getting that dealt with right away is important, or as soon as you can, that’s important.

If it’s something that’s just, uh… A broken branch. The branch fell all the way, so it’s clear it’s not going to fall on anybody, but there’s a kind of an ugly break left in the tree. What I’d recommend is waiting until the worst of winter is over and then addressing it then. So when it’s Clearly warming up on it could be any time from, you know, middle of February all the way in some parts of Washington.

It might be the end of March or mid-April when it’s when we know that winter temperatures are going away. Then that’s the time to make those those clean cuts where we’re getting rid of the jagged broken cuts that that might have been left. If something is, um One of the examples that just jumped into my mind is, uh, so somebody planted a shrub in the fall, and with the wind or with snow load, it fell over and its roots were exposed.

So the best time to address that is right away. Get the roots back in the ground and cover them up. And if you have to even, you know, maybe even stake down, stake the plant so it doesn’t tip over again because the roots are exposed to the cold into the air and they’ll dry out and freeze. But if it’s lighter damage that, uh, isn’t, isn’t presenting really a hazard or an inconvenience for anyone, then you can You can wait until the spring and then do, uh, I’m sorry.

I said spring, but I meant late winter, uh, when it’s warming up and then kind of do your cleanup right then. So it’s before bud break in the spring, but after the worst of the, the cold winter temperatures are, are finished.

[00:18:42] Erin Landon: So how can we protect trees and shrubs from warm spells you get in the late winter that um, you know, they’ll maybe start to bud out or leaf out if you have a nice unseasonably warm week or something, and then it goes, temperatures drop again. Is there? Anything we can do to make sure that they do actually bloom or produce fruit?

[00:19:05] Tim Kohlhauff: So there isn’t a lot that we can do. We can, we can, I tend to, to be a little bit of a worrier and I’ll see, say the magnolia buds start to, to look bigger or, um, or I guess, uh, fruit trees, especially you’ll start to see the buds.

Well, and you think, Oh, no, it’s too soon. Go back. And they don’t ever listen to me like they should, uh, cause I just want the best for them, but it’s really hard to, we can’t really, uh, do anything to stop that usually. The plants are, um, I don’t want to anthropomorphize them too much and say that they know what they’re doing.

Usually, they will start to, to move forward, and then if the temperatures get cold again, they’ll kind of stop in place. Uh, and hopefully, it won’t, there won’t be too much damage. In the orchard areas of this state or the fruit growing areas of the state where there are a lot of orchards, they do have some, some things that they try to do.

So they, for one, they site the orchards where there isn’t a lot of cold temperatures, but then in some places, they do things like they have big fans that look like airplane, airplane propellers that. Push the air through the site. Not really practical for a homeowner. Um, I don’t I don’t have access to a giant fan.

Sometimes what people have done, even , even folks in in orchards. If it’s really if the weather predicts a really low temperature that might wipe out that fruit crop, um, they’ll actually spray water on the buds and hope that ice. forms around the buds and ice will protect the fruit buds from potentially even lower temperatures.

It’s kind of a, um, There can be some damage to the fruit buds or to the flower buds from the ice itself, and so it’s not something you want. It’s not your first like, oh, it’s going to get a little cold. I’m going to go do this. It’s oh my gosh, you know, I see that these buds have started to to swell.

They’re open and, and maybe opening up, I’m going to try this as sort of a last-ditch, you know, I’m going to, I’m going to try and protect him because I don’t want to lose everything for the tree this year, and I’m afraid if I don’t do this, that, you know, the crop will be lost.

[00:21:30] Erin Landon: Yeah, actually, that’s interesting you mentioned that because it occurs to me, we have a, a Weyerhaeuser nursery not far from us, and they actually do that with their seedlings um, to protect their seedlings from the low temperatures.

[00:21:43] Tim Kohlhauff: I could, yes, I can see. And it’s so counterintuitive, right? I mean, you wouldn’t think, well, I’m trying to protect it from cold. Why would I try and make ice on these buds? Ice is cold, but, but, uh, ice gets to a certain temperature, and then it, it protects from even lower temperatures. And, and so it really does work to do that, even though gosh, you know, I just wouldn’t think that putting freezing water on something is going to protect it from freezing.

[00:22:15] Erin Landon: So, what about like with sun scald? Similar scenario, you know, where it warms up, and then the sap starts moving and you get little, I guess little blisters or fissures in the, in the bark of the tree. Um, I know some people like to paint the south side of the trunks. Is there, are there other things that you can do to protect trees from sunscald?

[00:22:37] Tim Kohlhauff: Yeah, I think, I think, and I, um, I know that, so a lot of folks do like to paint the south side of the tree. I’m, uh, and if you, if you dilute the paint, sometimes that works, but I guess one of the things that might work better is, um, making sure that when your tree goes into, into the dormant season. So at the end of end of summer, end of fall probably is a better time.

Make sure that it has a lot of water in it because the more hydrated the plant is, the more resistant it is to that. Now, in some places, um, that a plant can have lots of water in a tree or a shrub can be really well hydrated and that can still happen. And, um, one of the things that you can a, You can do to try and protect trees from that.

Uh, if you’re pruning a tree and you’re doing a lot of pruning work, that’s going to expose the trunk of the tree to the sun and, and, and to the cold in a way that it hasn’t been before. So say I’m, I’m taking some of the lowest limbs off of my, my tree or lowest branches, I might wait until. Later late in the winter, or even the early spring to do that pruning so that it’s still protected during the worst part of the winter.

And then in the spring, when it’s not going to get quite so cold, I’ll I’ll make that cut or those cuts and then it’s okay. Then we can. Uh, then the temperatures aren’t going to vary quite as wildly. It can still happen, but it’s less likely to. And especially if I’m doing both of those, if I’m making sure the tree has lots of water and at the end of the season, and then I’m holding off on that pruning until later, then hopefully I’m giving it its best chance.

And then one last thing that I’ve seen some research on, but I’m not sure that it’s, it’s, uh. It’s not a settled question, but there appears to be a link between planting trees and shrubs too low in the soil, especially trees too low in the soil. In other words, burying that that root flare at the base of the tree and type of sun scald on the trunk, so planting the tree correctly is a way that you can reduce the risk of that, I think, again, it’s not settled science, but we think that there’s a connection there. And so planting it at the right height and then hydration and, and, uh, if you’re removing any of the branches that shade the trunk or protect the trunk, wait until later in the season to do that.

And hopefully, those three things can, can kind of reduce the risk, uh, to the point that it’s not an issue.

[00:25:25] Erin Landon: Winter watering. Do trees or shrubs really need to be watered in the winter? I mean, I know they tend to use a little less water, um, in the winter, but what’s, is there a rule of thumb?

[00:25:38] Tim Kohlhauff: So on the, uh, in the cold winter areas, so I’ll start with where, with what I know, um, at a certain point our soil usually freezes solid and so we could water if we wanted to, but The, the roots can absorb the frozen water in the soil.

So if you’re in an area where the soil really freezes, the best you can do is water as long as you can in the fall and hope the plants take it up and then they should be good to go. Plants do lose water during the winter, especially evergreens because they’ve, they’ve got those leaves that are still prone to losing water, even when it’s really cold out.

And so, um, in areas like where I live, it’s more about getting water in the ground early and then hoping that they’re well hydrated and they’re not going to run out of water during the winter season. Usually, we don’t have to water during the winter. I want to say usually because there are just so many different types of weather than, than have, than we’ve experienced before.

And I know sometimes we get a, a pineapple express in February and all of a sudden it’s really warm and, uh, or, We get lots of wind, which tends to pull moisture out of plants, and so it’s possible that watering during the winter season could be an advantage, could help the plant, but in general they shouldn’t need it, and whatever’s in the ground, especially in those areas of the state where maybe the soil doesn’t freeze solid, whatever’s in the ground that’s still accessible to them should be able to replace the amount of water that they’re losing.

So hopefully we don’t need to do supplemental watering. Now, I’m saying that, and I’m already picturing a whole bunch of people typing in comments saying, well, I, somebody told me I needed to water my whatever it was during the winter, and if somebody specifically said that, if you’ve had an experience where watering was really important to your plant, that might supersede my, my general rules.

I don’t use, I don’t tell people to water in the winter unless, for some, there’s some unusual circumstance that’s, that says, Hey, this, uh, the soil is not frozen. So the water could actually get to the roots of the plant and we’re having some unusual weather pattern, or it’s a new plant I just installed last fall.

I’m worried about it getting enough water to live through the, its first season. But in general, um, I, I try as much as I can to just let nature be nature.

[00:28:17] Erin Landon: So what kind of pests or diseases are a concern in the winter?

[00:28:24] Tim Kohlhauff: One of the, the, um, more common pests that we’ve seen in our plant clinic, the last few winters, uh, there’s something called giant conifer aphid, and they can be active when it’s really cold outside and, and also, um, they tend to be found on, like the name suggests, on conifers. And what conifer do some of us bring inside during the winter and, and decorate in a nice warm area? Um, Christmas trees we have, uh, for those folks who have, uh, fresh cut Christmas trees, sometimes they’ll bring the tree in, they’ll have it decorated… It’s just wonderful, and all of a sudden, it’s crawling with, with aphids, and the Christmas packages under the tree are getting honeydew dripped on them, and it’s just a terrible mess. And just in the last few years, we seem to have had more people asking us about those in our plant clinic in December, and so even though the tree itself, right, it’s it’s dead, it’s going to be discarded. And, um, the, the insects themselves are more of a problem for us because nobody really needs, um, yeah, uh, six-legged Santa’s elves, right? They’re, they’re not bringing presents. They’re not doing us any good. So this, there is a, this insect, giant conifer aphid, that’s particularly one that’s, um, that’s a problem.

There are a few diseases out there that sometimes do well where it’s kind of borderline freezing. And so we’ll see, um, Pseudomonas twig blight will sometimes take advantage of cold temperatures and it will, uh, maybe infect a plant that’s been wounded by cold damage, but we won’t see it until the plant starts to grow in the spring.

And so there isn’t really a way to. To know that it’s happening, but we sometimes, um, where we see this a lot on is on Japanese maples where sometimes, uh, it’s just as simple as, uh, a twig or a little branch gets broken, uh, in a storm or. The weight of snow is on it. And so there’s an opening actually because it’s bacteria.

It doesn’t even need a wound. It could probably get in through the little pores in the bark. And then once it’s in there, um, if it successfully infects the plant, then it can start growing. At, I guess we’d call it the bookend season where it’s, it’s really starting to warm up, but it’s still cool and that’s where that bacteria seem to do really well and seems to, it will kill a lot of the ends of, of branches and sometimes spread to the, to the slightly larger, like the three or four-year-old branches.

And so you sometimes get this dieback that looks for all the world, like winter damage, but it’s actually this bacterial disease, and you only see that if you have a microscope or if you happen to see the particular signs of, of that, there are a few pests out there that take advantage of the, the cool weather.

Thankfully, most of them are a little more like us. And when it’s cold, we, we tend to hibernate and they tend to hibernate and fingers crossed, there isn’t some new pest or disease that I’m, that I’m totally missing.

[00:31:45] Erin Landon: Okay, so with the conifer aphids, are those endemic to this area, or is it something that’s brought in on imported trees?

[00:31:54] Tim Kohlhauff: So I think they are. Um, we find them here. They can be out in the, out in the woods. They can be on our ornamental trees. Uh, we have some, some subalpine fir trees outside of our office here in Spokane. And one year I saw them appear on those trees. I don’t know if they, Showed up because of the samples that people were bringing into us, but we also see them out in the woods, and we see them in Christmas tree plantations a lot and so a lot of them because we prune Christmas trees for really dense foliage, then that’s that’s ideal for those insects.

And so it may be more of an issue in those in those areas where they’re highly cultivated trees. And in the woods, giant conifer aphid probably wouldn’t do too. Much damage, the tree might not even notice that they’re there and they might even attract some beneficial insects that stick around to eat other insects, but it’s the denser foliage and then the.

Sudden warmth of coming into the house that suddenly the aphids are, wow, it’s spring already. I, I set my alarm clock for March and it’s only December, but they, uh, get right into action because there’s apparently there’s good eating on those, on those Christmas trees.

[00:33:10] Erin Landon: Well, that’s why I ask. I live in an area where there’s a lot of, of Christmas tree farms; and so, like I said, they, you know, the Weyerhaeuser seedling farm, I mean, that’s what they sell are the fir trees for Christmas tree farms and stuff.

[00:33:22] Tim Kohlhauff: The good news is that they’re not, like, in the field, they wouldn’t be that hard to treat and it might not even, I mean, it wouldn’t necessarily need a really, what we think of as a harsh chemical or conventional pesticide.

There are some products that could be used that that wouldn’t have any residual or wouldn’t be an issue for us bringing the tree into the house. It’s, uh, it’s just a matter of knowing, Oh, I need to do this. You know, we, as a nursery owner, I might not see that they’re in there because gosh, how many times do I go digging through the branches of my Christmas tree all the way to the trunk where they might be hiding?

So, uh, it might be more a question of just not knowing that they’re there. And then, like I said, I think there are products out there. I know there’s some products out there that are are not that harmful, so they wouldn’t be of a concern.

[00:34:16] Erin Landon: Now I have a couple of questions about erosion and what the, especially like on our side of the mountains, um, we get real heavy fall rains. And, um, so what are some short-term solutions for erosion? Um, since it’s not really a good time to plant.

[00:34:35] Tim Kohlhauff: Right. Well, and it, yeah, so it, it depends a lot on how much time you have and the, how severe the issue might be. Uh, so it can be as simple as, so some people who are thinking way ahead, um, if the, if the environment is right, one of the things that, that people will do for some, some quick erosion control is planting native grass seed if they can, and that’s not an answer for everything because a lot of places there’s too much shade for grass seed to really take hold and to, to root in the way that is really going to provide us maximum erosion control.

But that’s one thing that that people can do. And I always look for native grasses, um, and because there are. Grass is, uh, native to different parts of Washington, and there are some that are also marketed for their, their root system because they provide more erosion control. So just, just be careful when you’re purchase, if you are purchasing grass seed, look for something that’s either native or is, is not going to be invasive and you’re not causing a bigger problem down the road.

So that’s kind of short term, and then over time you might vary the kind of roots, root systems that are in this area, and so you might plant, in addition to grasses, there might be some shrubs, there might be trees, so you’re getting different levels of roots. You’re getting some that are a little bit deeper, some that are fairly surface root, and it’s all combining to hold the soil in place.

Sometimes we don’t have time to wait for all of that. And so there are some, some other ways of trying to prevent erosion that, um, that are quicker, but maybe take more money and I, I hesitate to mention anything too expensive because nobody has any extra money just sitting around that, you know, like, Oh, what am I going to do with all these, this stack of hundred dollar bills?

Um, nobody has that, but there are, um, Things that you can do, like, uh, there’s, there’s a type of, they call them erosion blankets that’s made out of, uh, kind of like burlap or different kinds of organic matter that you can install in an area that, um, if done correctly, it’s going to limit how much of the soil will erode.

Now, before I get too far into this, I should also say usually where there’s erosion, there might be wetlands at the bottom of the slope, and it’s really important, uh, to work or to be aware of the regulations about, um, working around wetlands and allowable sedimentation or allowable erosion rates. And so, um, consult with the Department of Ecology if you have an area that you’re really concerned about.

That said, um, there are some things that homeowners can do, like the planting of seeds and some, some kind of basic, um, trying to reduce erosion by placing different kinds of like landscape rock. For those who have a really serious problem, it might be a question of hiring someone to come in and do the work.

And then there’s a, there’s a process that they might put in an erosion blanket and then under that some kind of looks like gravel. And then what we call riprap, which is loose rock and all of that kind of weights down the soil and holds it in place. So that’s a much more involved and highly engineered solution, and whenever I say the term highly engineered, I hear the cash register dinging in the background because I’m old enough to remember what they used to sound like.

But, uh, there are some, like I said, some things that a homeowner can do that hopefully will limit. How much erosion might happen and at least reduce it enough or by enough time that if it’s a really serious problem, then they can consult with someone else, consult with a professional and have them come in because erosion is, uh, it’s a really serious issue for anybody potentially who, who lives on or near a slope.

And so you want to, as much as possible, do the work ahead of time and not be trying to clean up after. an event, if possible. So if that’s, if you’re thinking to yourself, hmm, that slope, you know, down to the creek, I wonder if I should do something. You don’t have to wonder. You should start thinking or planning for it now because it’s a lot better when you work ahead of time than when you’re trying to catch up.

[00:39:13] Erin Landon: So if you’re adding trees and shrubs to a slope for erosion control for long term, are there particular species or, or families that are better, you know, that have a denser root system or, you know, are best for erosion?

[00:39:28] Tim Kohlhauff: So there are, uh, and there’s a, um, there are some lists out there online and it kind of, it depends a little bit on where you are. So what kind of trees, shrubs, grasses, or perennials do well in your area? Cause obviously you want something that’s going to live and thrive in your particular area and under the conditions that, that already exists. So is it, is it really sandy soil, then something that tolerates sandy soil, or is it, is it highly organic soil?

So something that that is, uh, that thrives there. Um, so there are different, there are lots of different plants out there. One of the things that I learned when I was researching this a while ago was that rather than, than recommending, uh, certain species, it’s more important to have a mix of rooting depths.

And so those grasses for close to the surface and those trees that are a little bit and a mix of species is better than thinking, well, um, There was an old, uh, not research-based idea in eastern Washington that what I want to do is to stabilize my slope is put junipers on it, and it turns out juniper could be one part of erosion control, but just a whole slope of junipers, there isn’t anything about that species that really, that really protects.

In fact, when I was doing some research, I even saw this kind of it. No one was hurt, but there was a kind of horrifying video from Japan where they had planted a lot of cryptomeria, which is a beautiful conifer and native. They had planted cryptomaria on this slope above a roadway. And over time, the cryptomeria had really grown together and it worked really well until a severe storm.

And then there’s this video of watching this whole hillside slide down the mountain because the cryptomeria were all kind of of the same rooting depth and so everything slid together and it was, uh, even though I was watching on a video screen, I got a little bit dizzy watching this hillside move together because it was just, like I said, a little bit horrifying, but the lesson from that was don’t do monoculture, try and plant a variety of things if there’s any way you can do, if you can, mix a variety of natives that are already growing in the area, that’s, that’s going to work better than say, trying to pick out five or six or, or one or two species and, and over-relying on that.

[00:42:09] Erin Landon: That makes a lot of sense. Well, that’s about all the questions I have. Is there anything else you’d like to add about trees or shrubs in winter?

[00:42:18] Tim Kohlhauff: Uh, I wish that, well, I was going to say, go trees, go shrubs. Eh, winter, you know, meh. I guess on that, but, uh, no, I, I think, um, for people who do a lot of ornamental gardening, don’t forget the winter landscape. There’s a lot of beauty out there. And even though I may not, uh, be totally taking my own advice, get out there in the winter and enjoy nature because there’s a lot to see out there and there’s a lot to enjoy.

And, um, yes, it might be a little that’s bit more subtle beauty, but, uh, but think about winter when you’re, you’re planning your garden or your landscape and, and plant lots of trees and shrubs because, uh, they give a lot of benefit to the garden and to the landscape.

[00:43:05] Erin Landon: All right, well, thanks so much for joining us today.

[00:43:07] Tim Kohlhauff: You bet. It was my pleasure.