Every fall, dig down around the base of the tree and bury moth balls that have pdcb as active ingredient. These are basically all mothballs that do not contain napthalene. These will gas off over winter and kill borers in the soil and bottom few inches. Around the first of May, or now if it hasn’t been done earlier, put one ounce of neonicatinamide insectiside in a gallon or two of water and drench all sides of the trunk, allowing excess to go into ground around the trunk.
This wont undo damage but should prevent any future damage if done yearly. I fear it will also harm your nematodes however.
Read this among other harmful effect of PDCB, I would not put it anywhere where you are producing food crops!
Mothballs in the Garden: Bad Idea
While the fumes from mothballs may keep some animals from munching on your gardenplants, they are not intended for this type of usage. Using them in the garden or anywhere else outdoors is not a good idea, as these products could be harmful to pets, young children or wild animals that find the mothballs.
Both naphthalene and PDB mothballs placed around plants leech chemicals into the soil and potentially the groundwater, as rains wash some of the chemicals into storm sewers, wells and waterways. Plants also absorb these pesticides, so if you are growing a vegetable garden, placing mothballs around your crops means that your produce most likely contains these potentially toxic chemicals. Naphthalene is toxic to some oysters, fish and other aquatic creatures. PDB is also toxic to some aquatic life.
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Greater peach tree borer (at base of trunk just under soil) - pour permethrin mix 18” high coating trunk all around and soaking ground next to it once a month for about 3 months starting in late June or early July based on degree days
Peach twig borer (at new growth and later ripe fruit) - spinosad on canopy according to degree model
The Utah TRAPS phone app has alerts based on degree models by pest for weather stations near you, including outside of Utah, that I find useful.
I was told napthalene is worthless for this purpose. The recommendation for pdcb was given to me directly in response to this question from the Texas Ag Extension fruit and nut specialist, now retired.
If you chose not to use it, he will probably be O.K. with that.
Spinosad you have do 2oz per gallon in a five gallon bucket drench anywhere you think borers are on the trunk and drench the base of each tree. Once peaches are damaged after all this water in this heat those holes will juice a bit until they are healed.
Nematodes should be applied in a sprayer that has never had pesticides in it. You can dust them just harder to spread them evenly that way then you want them watered in well and not exposed to UV. Nematodes are a long term solution and most people don’t use enough. However buying the right kinda a few eventually multiply and help provide natural control to pests in the soil and seem to help increase earthworm and other beneficial insect populations.
I was advised by an uncle, who is nearing 80 and has been growing fruit trees since the 1970’s, to put plenty of wood ash around the base of peach trees. He said he battled borers until an older gentleman told him about this. For the past few decades he says he’s had zero issue with them.
My oldest peach tree is in it’s 4th year and the base is ~3" in diameter. I’ve had about an inch deep and from the base out to about 1’ radius, covered in wood ash the entire time. Have yet to see a borer or have to deal with one. Perhaps I wouldn’t have even without doing this, but wood ash is plentiful for me and I need to dispose of it some way anyhow, so why not. I try to stay somewhat “organic” so these trees get sprayed with a little Neem and sometimes Spinosad if necessary. Nothing like the “paint it on undiluted” strategy I’ve seen mentioned in the past. Maybe that is why I see no borers, or maybe it’s just the trees age?
Just in case it helps I’ve put it around apple and cherry and plum trees too. Again, I’ve got a lot of it, we heat our home with an outdoor wood stove. The soil here is slightly acidic so the alkaline effect of the ash probably doesn’t hurt either.
I did some googling on this and didn’t find anything specifically mentioning peach borers, but there are some scientific studies about it’s effectiveness with various weevils and other pests.
It’s been a few years so I probably need to refresh it around this tree:
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I shouldnt have said “sprinkled” for the nematodes, i soaked them per the instructions and then applied the liquid.
I will not be using mothballs and absolutely never neonicatinamide. Im not about to apply chemicals that are a likely culprit in the demise of bees and would encourage everyone to avoid that chemical group and anything treated with it.
I assume spinosad will kill all insects where applied, no? This isnt ideal, but i dont want to lose these trees forever. How far around the tree should it go (as in radius around the trunk)? Is it safe to use once peaches are on the tree or should it be saved for post harvest application?
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If you want organic treatment, follow @scottfsmith ’s method here
Look under the heading -Peaches, Plums, Apricots, Cherries
Scott described how he does it in details.
When the weather first starts to warm, I dig down with my fingers for slime and I crush the larva to death multiple times till the borer season is over. I have not lost a peach tree yet.
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Cheers buddy!
Spinosad only kills bees sprayed directly or the open flower sprayed directly, because of its smell its assumed bees would likely leave spinosad sprayed flowers alone until it wears off as the smell is the dead bacteria in the product.
It will not be systemic and does not go into the tree like neonectinoids and is only effective where you spray it. When i say douse it into the trunk i mean douse and i try to cover a good 4 x 4 with the drench but apply most of it directly down the roots.
The bacteria also does not reproduce and this is a good thing really but does not give it much lasting power passed a few days. I did paint the trunks of my trees with the 50/50 neem scott reccomended and the only place i seem to get borers is high up in my branches. Usually i just trim those out as im trying to control size anyways.
Its interesting about the wood ashes i wonder if sometimes peoples trees are just deficient in minerals?
Google is your friend.
A new threat to bees? Entomopathogenic nematodes used in biological pest control cause rapid mortality in Bombus terrestris
My recommendation is to not dilute the neem and to paint it on, don’t spray it. Cover the bottom six inches of trunk to the soil and let plenty drip down the tree into the ground. I had a borer nightmare and neem treatments ended it completely. It needs to be done once a year in June or so, that is when the eggs are laid and the worms are vulnerable. I currently use a mix of neem, linseed, and sesame oils so it is a bit cheaper (neem is expensive).
I don’t think spinosad will do anything, it is only active for about a week. The neem will last all summer.
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@RichardRoundTree - Just read your post… I found frass and one borer larvae below soil on one peach tree today. Wasn’t able to find any holes, per se, but one area of bark below soil is missing (shown here).
Do you know if spinosad is effective for larvae that may already be under the bark (I assume they can be). Also, have you had to re-apply? If so, how often? Sounds like in my case I’d just spray the lower 6" of the tree and the area I’ve excavated below ground (a few. inches), then the soil that is around the immediate base of the trunk.
Are you saying you apply to a 4’ by 4’ area? Just making sure I am reading correctly.
As an experiment, I’m trying a borer prevention treatment that completely avoids all chemicals; but I’m not sure that it will work. I only started this last year on a Redhaven peach tree planted in 2021.
I used some old, expired floating row cover material to wrap the bottom of the trunk with multiple layers from the root zone to at least a foot above. The material will stretch enough to last a few years before it needs to be replaced, and it is kept from unravelling by winding a few turns of thin wire around it. I have not seen any problems with this approach yet, but can anyone think of potential difficulties?
Wdingus said it. Put wood ashes around your peach trees. My great grandfather used this as simple borer prevention. All the wrapping, spraying, painting with neem, ad infinitum is not as effective as 5 gallons of gray hardwood ashes. It also supplies boatloads of potassium which peaches need.
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The egg laying is the start, and I believe that is always above ground. You could secure nylon screen around the base of the tree with rubber electrical tape and likely stop that, but a strong dose of properly timed Sevin would also do the trick. Just spraying the base of the trees with it may not be organic, but it certainly isn’t very environmentally disruptive or capable of entering the fruit.
The ashes idea is interesting, but doubtful to me. Old anecdotal solutions that really work don’t tend to stay in the previous century. Where there is ample rain it also would quickly drive up the pH well beyond the pile, I would assume. 5 gallons is quite a bit of ashes.
Just my opinion- maybe they do work. I’d like a member here with a real borer problem to try it and get back to us after a decade- one with at least a dozen peach and nectarine trees.
Wood ashes looks hit or miss. See
for someone that it missed on:
I thought the wood ashes I piled at the base of the peaches was detering them but the larva that enters the tree from the soil moved through that barrier apparently and have practically girdled six to eight inch tree trunks at the base…if they are caught early, (watch for a gell oozing at the base of the tree trunk)…there is some hope of limiting the damage by inserting a flexable wire into the tunnel until you are able to squish the invader.
My oldest peach trees were planted in 2018 so I’ve not had a lot of years worth of observation yet. I have raked away the previous ash layer and applied ~5gal of fresh wood ash per tree every year except for 1. I never got around to it that year (2 years ago I think), leaving the previous year’s ash there for a 2nd year. That fall I noticed frass and dug around and discovered quite the infestation of borers. Got those taken care of and applied fresh ashes and knock on wood, no tell-tales so far.
I was hopeful the alkalinity of the ash wouldn’t be a problem since:
Ashes may or may not help, I make zero claims… I just have an ample supply of it, soil pH seems agreeable, and it was recommended to me by someone who had grown peach trees for longer than I’ve been alive. They said it prevented borers and that seemed to mesh with my desire to prefer “natural” solutions over man-made “chemicals”. Stressing the word prefer in that, if it proves to not be effective I’ll go as nuclear as is necessary.
Worth noting that I spray my trees 5 or more times per growing season and somewhat follow Michael Philips “holistic” program. So Neem is being sprayed directly onto the trunk, but at far less concentration than I’ve seen you describe doing on your trees Scott.
Except for that 1 years lapse, so far so good…
