swales and voles, protecting trees from voles

Hello Permies !

This new thread is kind of a continuation of an earlier one I started back in August about planting on swale berms and issues around the maintenance of swales https://permies.com/t/38956/permaculture/swale-headaches

I was saying then, among other things, that maintaining my swales - and keeping alive the trees planted on the berms - was a bit of a challenge because of vole activity.

Since then, this activity has intensified - there are vole tunnels wherever the soil is a bit softer or has been mulched (such as around the planted trees), and the swale berms (especially the north-facing side) are riddled with holes. I have noticed two types of vole attacks on trees / shrubs: (a) the voles dig tunnels around the contour of the planting hole, and start gnawing the fibrous roots at the margins, moving progressively towards the central root; (b) they dig down right near the trunk and attack the taproot. (A third type of attack is possible - girdling the base of the trunk - but I prevented this by the use of tree guards on single-stemmed trees).

A couple of interesting points that I noticed regarding trees planted on swale berms, versus those planted elsewhere (on flat ground, e.g., the hedge):

When we planted the swale berms, initially we were in two minds about where to dig the planting hole - should we plant the tree into the top of the berm, or at the base? By choosing the former, we would have ensured good drainage in a very heavy clay soil. By choosing the latter - which we eventually did - we would reduce the risk of trees drying out in prolonged dry weather.

In hindsight, ours turned out to be the right decision. Trees planted at the base of the berm did extremely well and suffered no or minimal vole damage due to being less accessible (despite the swale berm being vole condominium !!!). A few plants (lavender, sage and similar herbs) planted this spring on top of the berm were killed within weeks of planting (the voles went straight for the roots). Trees planted on flat ground - such as those in the hedge - had very modest growth (despite receiving equal treatment in terms of mulch, added organic matter, etc.), and I lost a couple dozen of them to the voles.

To prevent further vole damage, we've tried one more thing - yesterday we mulched our plants - well, most of the 400 or so of them - with gravel. This will hopefully deter the creatures from digging near the tree; in addition, gravel will act as a mulch, with better moisture-retaining properties than the spent mushroom compost we have been using so far). I've inserted some photos for illustration. I hope to be back in spring with news on how the method has worked. Meanwhile, I'd appreciate comments, especially if you have experience with this method.

Levente

I have experienced vole woes. I've planted my fruit trees in the top of the berm. I've lost many a tree to voles on my flat ground. I also use gravel mulch in many places.

So with all of that I haven't lost any trees in the berm yet. I have seen vole holes but so far so good. The gravel doesn't seem to have a huge impact as I see tunnels quite clearly even with the gravel.

What has made a huge difference to us is the moving in of a bunch of cats. A house near us was demolished and it had been a sanctuary for cats. Now they are all moving about. We've had a few move in and have started receiving "presents" at our door.

So I think you should get cats.

Danielle Venegas wrote:I have experienced vole woes. I've planted my fruit trees in the top of the berm. I've lost many a tree to voles on my flat ground. I also use gravel mulch in many places.

So with all of that I haven't lost any trees in the berm yet. I have seen vole holes but so far so good. The gravel doesn't seem to have a huge impact as I see tunnels quite clearly even with the gravel.

What has made a huge difference to us is the moving in of a bunch of cats. A house near us was demolished and it had been a sanctuary for cats. Now they are all moving about. We've had a few move in and have started receiving "presents" at our door.

So I think you should get cats.

Hello Danielle,

A few questions: How thick was your gravel mulch? (I piled mine about 5 cm / 2 in thick). Did the voles start their tunnels within the gravel-mulched area around the tree? Or did the tunnelling start outside the gravel and continue under the gravel?

We are planning to get cats, the only impediment so far has been that we don't live on the property permanently yet. We hear of many farmers around us whose cats give birth and the farmer has to kill the little ones 'cause they're too many - we could salvage a few of those.

Thanks for the reply !
Levente

Levente Andras wrote:

Danielle Venegas wrote:I have experienced vole woes. I've planted my fruit trees in the top of the berm. I've lost many a tree to voles on my flat ground. I also use gravel mulch in many places.

So with all of that I haven't lost any trees in the berm yet. I have seen vole holes but so far so good. The gravel doesn't seem to have a huge impact as I see tunnels quite clearly even with the gravel.

What has made a huge difference to us is the moving in of a bunch of cats. A house near us was demolished and it had been a sanctuary for cats. Now they are all moving about. We've had a few move in and have started receiving "presents" at our door.

So I think you should get cats.

Hello Danielle,

A few questions: How thick was your gravel mulch? (I piled mine about 5 cm / 2 in thick). Did the voles start their tunnels within the gravel-mulched area around the tree? Or did the tunnelling start outside the gravel and continue under the gravel?

We are planning to get cats, the only impediment so far has been that we don't live on the property permanently yet. We hear of many farmers around us whose cats give birth and the farmer has to kill the little ones 'cause they're too many - we could salvage a few of those.

Thanks for the reply !
Levente

It starts outside of the gravel and then tunnels in. I tried to maintain 2 in mulch but it may not be as thick in some places where I started running out of gravel.

We are saving our cats too. Just provide a dog house, food and water and they should be ok.

Hello permies !

It's been a while, so I thought I could post a quick update on this topic, as there have been some new developments.

We adopted two dogs about a year ago. As a result, the neighbour's cats (there were about 5 or 6 of them) which used to patrol our plot and catch voles, were no longer able to perform this useful service. In addition, the presence of the dogs, with their propensity to sniff and dig, meant that we had to quickly abandon the vole fighting method that we had been using up to that point - which consisted in treating suspicious vole tunnels with a rodenticide bait... The dogs were attracted by the baits and kept trying to dig them up & eat them...

So we stopped using the rodenticide, and looked for other solutions.  That's how we discovered the SuperCat vole trap.  

https://www.google.com/search?q=supercat+vole+trap&client=safari&source=lnms&tbm=isch&sa=X&ved=2ahUKEwj0hfeF4f3mAhWk5KYKHU3VC_kQ_AUoAXoECAsQAw&biw=599&bih=418

Initially I was sceptical, but we gave it a try.  The trap turned out to be very effective - there were days when we caught up to half a dozen voles. We ended up buying about 20 traps, so that we could deal with vole tunnels in several spots simultaneously.

And as a bonus, one of our dogs has learned to spot, sniff out, and catch voles.  As a minimum, she seeks out the new vole tunnels - when we see her circling a new spot, it's a sign we need to check for vole tunnels in that spot...

Levente, maybe voles are different in different places, but mine do come up under the gravel, and so do the gophers.  The gravel does work well, though.  I've been using 1 1/2"/3.8 cm crushed rock, not smooth rocks.  It eventually fills in around the roots and seems to stop them.  I have to keep adding gravel as it drops down into the tunnels/holes that show up.   I get a pickup truckload of gravel every spring and have it handy to fill in.  They will figure out a way around the gravel before too long, I suspect.

The other successful things I've planted are daffodil bulbs all around the tree at about 2 hands distance from the tree trunk, down a minimum of 6"-8"/11cm deep.  Also day lillies are very drought resistant and tough.  Garlic does well as a barrier and multiplies nicely.

If you can find a local weed that the voles/gophers avoid that doesn't compete with the tree, that works, too.  I've planted dock around my trees, help it volunteer when it shows up.