Hazelnut weevil (curculio nucum) - any permaculturey solutions?

Hi - my first post, but long-time lurker, etc. etc. Good to know "forums" are still a thing out here and it's not ALL happening on Facebook.

About hazelnut weevils, they are a major problem in my part of the world (southern Europe) - they are the ones that get into the very young fruit and then hatch out when the nut is "ripe" having eaten the contents. It seems to be impossible to grow hazelnuts round here, even though obviously there are native varieties growing in the wild (which I am trying to find decent examples of and transplant but didn't manage to this year). When it comes round to harvest time they are almost all hollow and worthless. I think the squirrels must get a fair few too, but if they were getting many viable nuts I would expect to see them sprouting up everywhere and they don't. The producers only succeed by spraying the crap out of them.

I am looking for a permaculturey way of tackling this pest. I know there are nematodes and things you can use, but I don't have time to be spraying trees on an individual basis, I want to just plant in my food forest and forget. Unfortunately I don't have animals that I can graze around there to try to reduce insect numbers. So am looking for some sort of companion planting approach, I guess - maybe there isn't one and I am overly optimistic, but any ideas?

We have quite a few hazelnut groves here, and organic plantations are on the rise because they can get much higher prices and consumers ask for it.
Under this link you can see a picture of one of the plantations. The text says that they mix several traditional varieties:
https://www.waldis-haselnuss.de/bio-haselnuesse/

I guess there is also one where chickens roam under the trees.

The one next to my village has small cows grazing among the trees (I know, not an option for you, just wanted to mention). I don't know if they are organic.

Regarding organic, there are some permitted sprays in Germany, containing for example paraffin oil and rapeseed oil.
Here is a link to the document (try google translate):
http://www.haselnussanbau-verein.de/mediapool/71/714618/data/Pflanzenschutz_Haselnuss_oekologischer_Anbau_2021.pdf
The one against the hazelnut weevil is apparently a mix of rapeseed and pyrethrine.

I would also encourage lots of wildlife like birds to keep the insects in check.

Many people around here have hazelnut bushes and you might get some hollow ones but always enough to enjoy yourselves (and the people here do not spray the bushes in their gardens).

Thanks for the ideas, so it must be possible... I talked to my local nursery and they said that the hollow nuts could also just be a lack of water (which is a major problem in summer where I am) so that's something to also think about. Just bought another variety of hazelnut - a Ludolph, which is a German variety as it happens, and have planted it on a new swale I made recently, will be interested to see if the improved water supply makes any difference.

I get that there are organic treatments that might work. I have actually had some success against a lot of other bugs using diatomaceous earth, especially stinkbugs which are a real problem right now.

But having to individually spray trees just doesn't seem a sustainable way of growing anything, even if it is organic per se. Still hoping that as I build up more of a permaculture "system" in my orchard/garden some of these problems will be mitigated.

Hmm... Apparently they overwinter in the soil. Maybe controlled burns under the bushes at the right time could help? Provided you can do that safely and without incurring the wrath of legal-type people... Otherwise maybe plant something insect-repellent under the bushes, to hopefully stop them from burrowing right there (and move on to the neighbour...) Wormwood (Artemisia sp.) springs to mind. It has been used to repel moths. No idea if it would work against beetles though.

If you find something that works it would be awesome. We just planted our first hazel bushes this year (our approach is similar to yours, I think - plant and forget) and it would suck to have the weevils take all of the nuts, even before the squirrels have their go. I think (hope) that we're possibly too far north for weevils at the moment, but what with climate change and all it would be good to have a solution ready. Please keep us updated!

Yes, fortunately I can burn whatever I want on my land . That's an idea actually.

Having asked the question about weevils though, I talked to the guy at the nursery who said it might not be weevils, that hollow nuts could also just be a lack of water (not at all unlikely in my part of the world) - I must admit, maybe I assumed it was weevils but can't say for sure the telltale holes are on all the nuts I have seen.

On the other hand, my neighbours VERY well established hazel grove produces nothing, and you'd think it would've found some water by now, must be at least 15 years old.

We'll see if my new tree does anything...

I have two large (40 year old trees) in my front yard. We have the same problem with the weevils. I read that they climb the tree in the spring and lay eggs which the nut forms around. They said that if you can keep them from climbing the tree you protect the crop. If you can do it for 3 years you can break the life cycle and eliminate the problem.

That said, the article said to put paper around the tree trunk 4 feet off the ground and smear this sticky stuff in a wide band around the trunk so when the weevils crawl across it they get stuck, like a sticky trap. I used insulation with the fuzzy part to the tree so they couldn't crawl under the paper. It seems to work

When you grow a biodiversity Food Forest, you balance out any problems. It attracts all the right elements. Learn at www.permaculturedesignschool.org 801 808 4424

First, "know thine enemy", the curculio nucum
https://en.wikipedia.org/wiki/Curculio_nucum
When they are inside the nut, it is a bit late and you can't kill them. As I see it, there are 2 "choke points" in its life:
Early in the spring and late in the fall, they are outside of the nut and susceptible to predators such as chickens/ other bug eaters. They overwinter underground, under the hazelnut bushes and come out when the temperature reaches 20 Celsius/ 60 Fahrenheit. That gives you the time of attack. That is true of bushes [wild American hazelnuts]. Cultivars can grow into trees and it seems that their schedule for flowering is a bit different.
https://www.wcngg.com/2020/02/03/choosing-planting-and-pruning-hazelnut-pollinizers/#:~:text=Hazelnut%20fertilization%20is%20a%20unique,3%2D5%20months%20after%20pollination!
At emergence, they are sluggish and immature & start climbing towards the hazelnut flowers, eating on the leaves along the way, then mate.
Hazelnuts are wind pollinated.  They are monoecious, [male and female flowers on the same bush/ branches], yet they are self incompatible: they need cross pollination.
The catkin [male pollen givers] come out the previous fall but are not ready to release their pollen until they acquire their full length and flexibility and pollen starts shedding in the spring of the following year!
The female flower has a gorgeous fuchsia color but is very small and hard to see. Curculio nucum will not attempt to reach that flower [where the nut will be] until after you see the female fuchsia flower. That gives you several clues that the attack by Curculio Nucum is imminent:
* Temperatures of 60F
* Catkin fully extended and flexible, shedding pollen.
* Female Fuchsia flower visible.
All 3 must be present for Curculio Nucum to start doing its damage. The larvae of the egg deposited in the female flower will eat the nut for about one month, then dig its way out & drop to the ground, leaving a small tell tale 1/16" hole in the empty nut. It will winter 3-5" underground.
How can we take advantage of its life cycle? The actual calendar dates vary with the subspecies of hazelnuts and with your climate, that is why I went in great lengths into the cycle of the hazelnut plant and the cycle of Curculio Nucum.
Counter attack:
1/ As soon as the temperature reaches 60F, send in the chickens scratching around the bushes, they will expose [and eat] a number of these emerging youngsters, before they mate.
2/ let them have their fill until you no longer see the fuchsia color on the bush [at that time, the flower is fertilized, the nut is starting to grow and if a curculio nucum is inside, it is too late: The female flower closes over the nut and is safe from any intervention, chemical or otherwise.
3/ As the nuts are starting to swell a bit, some will fall to the ground: they have been attacked and are infested. Just like you remove fallen apples so their parasites are removed from your orchard, so too should you remove these nuts that "don't make it".
4/ This would be the time to apply organic chemicals directly to the ground if you feel you must. Whether fungus like Beauveria Bassiana or chemicals they are designed to kill arthropods [animals with an exoskeleton] like our honeybees.
5/ as Curculio Nucum falls to the ground and gets ready to bury itself before winter, now is another good time to help your chickens get extra protein by disturbing the soil, close to your bushes. chickens can only claw so deep and may not get all of them.
As the snow falls and the ground freezes  you can rest assured that there will be less of these pests on next year's crop. Now, that leaves squirrels! Here, again, "Know thine enemy".
https://animals.howstuffworks.com/mammals/squirrels-really-organize-nuts.htm

If the problem is the solution, you may have the opportunity to do some lucrative small-scale hazel breeding! Especially if, like you say, you have neighbors and wild plants that are more successful. Perhaps they are resistant to the weevil, or more drought resistant, or generally more vigorous than your varieties. I would be asking around for cuttings or nuts to try propitiation and breeding. Obviously this is a longer-term solution but at least it's hazels and not chestnuts! And if you acquire some good varieties that could be very valuable to others in your area.

Thanks for the additional ideas. I am seeing chickens in my future..!

I would love to have them but unfortunately we don't live on the land in question right now and probably won't anytime soon while our kids are still young, going to school etc.

But I would definitely like to keep them in the future, handy little dinosaurs to have around, by all accounts!

Saralee Couchoud wrote:

That said, the article said to put paper around the tree trunk 4 feet off the ground and smear this sticky stuff in a wide band around the trunk so when the weevils crawl across it they get stuck, like a sticky trap. I used insulation with the fuzzy part to the tree so they couldn't crawl under the paper. It seems to work

Be careful with the sticky stuff, not Permie at all as it endangers not only the weevil but lots of other bugs, birds and small mammals like bats. Usage not recommended!

Anita Martin wrote:
Be careful with the sticky stuff, not Permie at all as it endangers not only the weevil but lots of other bugs, birds and small mammals like bats. Usage not recommended!

Yeah, that's got to be a nope, unfortunately, it's too big a stick to deal with that problem I think. I'd be most concerned about small rodents and squirrels getting stuck...