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Apple Borer Again

Posted by Joanne Corkum 
Apple Borer Again
May 05, 2022 01:33PM
Good day

Here we go again looking for some information to curtail the borer activity in our orchard.

We have 450 cider apple trees on B118. We have grafted and planted out most of these ourselves so over the past 6 years there have been many young trees for the cursed borer to feast on.

For some reason we have a most unusual amount of borer pressure..... at least 25% of our trees have been infested. We have tried to deter them by painting the trunks in early June with white paint,surround, trunk sprays throughout the season of neem (1-2%) , physically removing the larvae ( I have a high kill rate smiling smiley, and hopefully we deter a few with spinosad when we use it.


We are thinking of using screens this year to protect the trunks as well - have read conflicting reports on effectiveness of this.

As Michael told us - you have to have trees to have apples - so we are open to using a bigger "hammer". He suggested Lorsban at one point but then said he thought it not a good idea. I see it has been removed from the market as well.

Does anyone have any suggestions for chemical eradication of this damaging pest? We have adhered to the holistic method since we started this orchard but increasingly we see the need for a drastic measure.


Thanks in advance

Joanne

G2V Farm
Zone 5B/6
Gaspereau Valley, Nova Scotia
Canada
Re: Apple Borer Again
May 16, 2022 11:49PM
In the two other threads about RHAB on the forum Michael Phillips indicated his most recent solution which seems very effective. Painting pure neem oil on the trunks.

You could also call Cummins Nursery and say you have a horticultural question, they'll likely forward you to Steve Cummins or another staff member who you can ask what they do. They've been helpful the couple times I've called in the past.

Vineyard Hills Community Orchard
Grow Ohio Valley
Zone 6a in Wheeling, WV
Re: Apple Borer Again
May 17, 2022 12:37AM
Michael did indeed swear by the neem paste approach so you might try it. There have been reports of problems with some rootstocks and such a thick application, so I would test it on the 118s. I go through our young nursery stock constantly- at least once a month and police for that first entry point which can be remedied easily with a scratch and removal. The trees in the orchard switching to a "serious" screen guard from my usual hardware cloth (for voles). This is a 3 foot long by at least 2 foot high. The 3 foot (or longer for older trees) is to allow for continual wrapping. This allows the screen to "puff out" a distance from the trunk- too far for her to oviposit. Yes, a borer will try to go below or above, but burying the screen will help with the former, and above means it is easy to see and dispatch. We are experimenting with neem as an additional remedy. And lorsban...just kidding.

Walden Heights Nursery & Orchard
Zone 3 in Vermont
Re: Apple Borer Again
May 17, 2022 12:36PM
Thanks for the reply Todd.

We are going to try the 100% neem on the trunks this year. I read somewhere (maybe here) that it had been tried on the B118 with no ill effects. Will proceed cautiously...

As to the screening - could you describe more specifically how to affix the screen? We plan on securing the bottom with pea gravel but havent decided on the top portion...what sort of screen are you using?


Past years I have also used a slurry of kaolin and white paint on the trunks - will forgo that on the trees we use the neem on..

And so it continues. Just starting the second round of borer survey for this year before the creature makes another appearance.

Joanne

G2V Farm
Zone 5B/6
Gaspereau Valley, Nova Scotia
Canada
Re: Apple Borer Again
May 17, 2022 02:10PM
I've had this cursed conversation with a number of growers I consult with. Based on years experience (and constant vigilance) I feel i have struck on the right combination of approaches.

- know when the adults are flying and mating - so understand there life cycle and biology. This goes for dogwood borer as well. with DWB there are pheromone traps to capture adults when they fly. This is also when they are mating.
- DWB you can use mating disruption IF you have a large of acreage and relatively contiguous block of trees.
- paint the trunk with a combo of white latex paint (mixed 1/3 with water) plus sand and spinosad. Do this regardless of anything else. It is not a silver bullet but will deter and reduce mating (not proven scientifically, but observed).
- keep the weedy plant growth down from around the trees. This reduces the places they can hide from predators and sprays.
- those spiral wrap trees guards can protect from rabbits and voles, but are a haven for borers. As well the trunks remain wet and inaccessible for scouting. If you are going to use tree guards, use either the flexible plastic mesh cylinders or my preferred 1/2" hardware cloth. You get the protection from voles and rabbits, but do not create a safe haven for borers. Plus they give you access for weeding and sprays.
- scout, scout, scout - you won't know what you have unless you look.
- sprays - yes, Lorsban works but is also nasty neurotoxin that is no longer legal to use. There are other insecticides that can work, but they are all synthetic. the use of a spinosad plus other insecticides aimed at lepidopteran insects will provide some modicum of protection. But because they are not systemic (like Lorsban), they only work when the insects are on the surface of the plants - so timing is critical. What timing? When the eggs hatch and the larva are still active.
- plant trees deep enough to reduce the potential for burr knots on the rootstocks. Borers love burr knots.
- as trees get bigger, consider 'bark scraping' to remove any loose bark that the moths loves to lay eggs under and the hatching larva love to find as entry points. Also, as trees get older they are less susceptible to any damage that may occur (its a volume thing). In fact, in almost any older tree you can find larva without seeing the damage you might expect - or at least not the effects of the damage.
- lastly if you do get damage, clean the wound (kill the suckers!) back to green tissue. Just a green edge of cambium, not more. remove any frass, rough edges, rotten or decaying wood, etc. THEN apply the pure neem and wrap lightly with a medical gauze (not tape) to seal but also allow it to heal. It will get darkers, this is just the neem oxidizing. Not to worry.
- well, so maybe that wasn't my last thought. if you feel like there are larva in the tree that you can't get to, consider creating a mud poultice of parasitic nematodes. Apply a clay slurry of nematodes to the affected area. Then DO wrap this tightly with a material that won't allow this to dry out - the nematodes can't dry out. Theoretically, the nematodes should move towards the living critter and assist it out of this world. I haven't actually tried this, but I did read about it in The American Fruit Grower for use on Peach Tree Borer.
- Ok, so this is the last one - ashing/peppering - a biodynamic technique for reducing the reproductive capacity of the adults. I'll create a separate thread for this since it is not something that someone can run down to the hardwar store and buy. It is strictly DIY and yet very intriguing way for shifting the energetic balance of the orchard in your favor.

Forgive any typos, errors or omissions. and if anything is unclear, please ask.

Mike Biltonen, Know Your Roots
Zone 5b in New York
Re: Apple Borer Again
May 18, 2022 08:21PM
Thanks Mike!

Lots to think about..

The RHAB starts flying here around the second week of June and egg laying would begin shortly thereafter I would think. I have the feeling that they are active until well into August and maybe even early September sad smiley(

We use plastic spiral guards. Put them on in November and remove them and do the first borer survey in April/May.

Other years I have painted the trunks with white paint and kaolin clay.....the idea of adding spinosad seems like a good idea. How much would you use? How long do you think it would be effective? Would we have to repeat through the season? Would you think that the spinosad mixture would be preferable to the 100% neem?

We keep a clean area around each tree and use peastone in the inner circle.

Nematodes....have considered this before. What specific ones would you use?

Interested to read more about ashing/peppering.

Thanks again for the information - we soldier on.

Joanne

G2V Farm
Zone 5B/6
Gaspereau Valley, Nova Scotia
Canada
Re: Apple Borer Again
May 19, 2022 02:03PM
This is the moment where discussions can become of more usefulness to the membership. Try the neem alone. Try Michael's spinosad spread. Try the screening method. Try a mixture of any of the above. Try a regular spray regime of neem/spinosad or pyganic, etc. (non-paste just traditional periodic spraying). Then compare the results...on your land, in your conditions, under your rhab pressure. Then share your findings. Now everyone else do the same. In a season we will all know what to do. And then we will have to revisit because you can bet there will be a build up of resistance to chemical interventions. Then we will test again.

I will also add that things like borers are a reminder of scale issues. When we keep the vegetation away from that trunk (observe that 1 foot no man's land), and perhaps paint the trunk (watch what you use you certified organic folks) we can see clearly when there is an intrusion. When I have dropped the ball here, it was from simple neglect, generally from numbers. If you have thousands of anything it means you have to use a product to do the work for you, and that product had damn better do the job because at that point we stop monitoring, out of trust. This can be risky. So, the first course of action is to get your rear ends out there and observe.
Re: Apple Borer Again
May 19, 2022 02:57PM
Hi Joanne,
To answer a few of your questions:

1. How much spinosad? Not much. The "normal" rate/acre is 8 oz and so if you calculate and spread that out over an acre's worth of trees you'll be about right.
2. How long will it last? Not very, certainly not an entire season. But if you time it to when the first larvae are hatching you should be able to catch that wave. As much as I'd like to say, don't waste your money with a second application, if you do have a serious problem then I would consider a 2nd app. The issue lies in the fact that the paint seals in the spinosad and so a 2nd app wouldn't necessarily penetrate to where the larva are. You might consider an initial application of kaolin+spinosad+very dilute latex paint (milk paint which can be flaky), followed by a 2nd app of less dilute paint+spinosad+sand. I like the sand approach as it is very abrasive and will also deter rabbits and voles.
3. Neem and spinosad have two different modes in my book. The first (neem) blocks entry, interrupts life cycles through its IGR properties and then heals any damage. The second (spinosad) kills larvae and that's all. They servce different purposes and shoudl be used differently.
4. nematodes - Steinenerma feltiae, S. riobrava, and S. carpocapsae are the there most commonly used. The S. riobrava doesn't survive in cold temps but seems to be the most effective. While S c is less mobile and S f is more mobile. So (if my memory serves) S c needs to be on or very close to the actual larva, while the other two are more mobile and theoretically can move into tunnels and short distances to where their prey is (though I am not sure if that theory has been tested).

Mike Biltonen, Know Your Roots
Zone 5b in New York
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