Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Learn about evergreen and deciduous trees here
Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » May 30th, 2017, 9:10 pm

I'm planning to spray Bt bacteria (Bonide Thuricide) on a small (~15-foot) tree that's being eaten by gypsy moth caterpillars. It's a type of Hickory, but I'm not sure which type. I have a few questions.

1. The label says nothing about trees in the Hickory family. It mostly mentions food crop plants. Please tell me it's ok to spray the tree. Any possible issues? I don't really have time to test a spot and wait a week...not sure what instar they're in, but getting big...1 inch now for some of them. The sooner I spray, the better.

2. If it rains later that day, does that invalidate the efficacy?

3. The caterpillars are on the underside of the leaves. I'm not sure the best way to spray. I bought a small one-gal sprayer I could use...but it'd be tedious, messy, and difficult to spray the undersides up to 15-foot height. Should I consider a hose-end sprayer instead? I have a backflow device I can use...but I'm kind of shying away form using the hose, due to problems with not only possible water supply contamination, but also due to accuracy and possibility of too much water washing it off.

4. You never add surfactant to living organisms, right?

Thanks.

User avatar
andy10917
Posts: 29739
Joined: February 23rd, 2009, 10:48 pm
Location: NY (Lower Hudson Valley)
Grass Type: Emblem KBG (Front); Blueberry KBG Monostand (Back)
Lawn Size: 1 acre-2 acre
Level: Advanced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by andy10917 » May 30th, 2017, 9:14 pm

I'm planning to spray Bt bacteria (Bonide Thuricide)
Bacillus thuringiensis

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » May 30th, 2017, 9:18 pm

andy10917 wrote:
May 30th, 2017, 9:14 pm
I'm planning to spray Bt bacteria (Bonide Thuricide)
Bacillus thuringiensis
Correct. BT is the trade name, but Bt is the bacterial strain. I should've noted that so as not to confuse people.

Charley
Posts: 567
Joined: September 17th, 2013, 11:13 pm
Location: Kentucky
Grass Type: Tall Fescue
Lawn Size: Not Specified
Level: Not Specified

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Charley » May 31st, 2017, 12:31 am

A little unsulphured molasses will work as a wetting agent.

User avatar
PSU4ME
Posts: 1147
Joined: November 29th, 2016, 9:29 am
Location: Metrowest MA
Grass Type: Front: Bewitched/Midnight/Everglade Back: Midnight/Diva/Everest
Lawn Size: 20000-1 acre
Level: Some Experience

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by PSU4ME » May 31st, 2017, 9:22 am

I don't see any issue using it on Hickory, I've used it on many different things without any issues. on a 15 foot tree it would be messy but since it needs to be ingested you'll need to get everything. just suit/goggle up and plan for an immediate shower. i find that the 1 gallon sprayers work well due to the wide shower spray.

You will need to reapply after rain though and if the cats are getting big its less effective.

Last year they were destroying my evergreens (yes that bad) to the point where i had to break out the Sevin.....brutal


Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » May 31st, 2017, 8:47 pm

Thanks. Maybe I should wear a garbage bag poncho when I do it.

There are a lot of caterpillars on the lawn below the trees, too. I wonder if I should spray the grass, too.

Bonide recommends a range of rates for their product for any given plant.

User avatar
PSU4ME
Posts: 1147
Joined: November 29th, 2016, 9:29 am
Location: Metrowest MA
Grass Type: Front: Bewitched/Midnight/Everglade Back: Midnight/Diva/Everest
Lawn Size: 20000-1 acre
Level: Some Experience

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by PSU4ME » June 1st, 2017, 8:03 am

I applied these to my trees. They work great and once the cats pile up, I have sevin in a squirt bottle that I use to knock them down. Huge difference over last year.

Image

Image

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » June 1st, 2017, 12:53 pm

Last year, I pulled them off and threw them on the ground. Believe it or not, it helped.
But this year, the tree it bigger, and also has more leaves due to more rain this year. Last year was dry. I haven't tried that this year. There's also a bigger tree nearby, and they just keep dropping down.

It's been so hard to find a good day to spray. Impending rain or wind get in the way. In the meantime, the leaves have a bunch of holes.

If the combination of the natural fungus and the Bt don't do enough, I'm going to try to find Bayer Natria Insect, disease, and mite control. But in the meantime, everything's getting chewed up. From the bigger trees, leaf fragments are dropping everywhere.

User avatar
PSU4ME
Posts: 1147
Joined: November 29th, 2016, 9:29 am
Location: Metrowest MA
Grass Type: Front: Bewitched/Midnight/Everglade Back: Midnight/Diva/Everest
Lawn Size: 20000-1 acre
Level: Some Experience

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by PSU4ME » June 1st, 2017, 12:56 pm

if they are falling down, the tree wraps do a great job from preventing them getting back up. And, if you go with the insecticide, that should knock the majority out of the tree. The combo works well together.

The stuff i used was a waterproof cardboard paper, twine and something called tanglefoot i got from amazon.

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » June 1st, 2017, 2:26 pm

Thanks.

There's also a natural fungus in the environment (actually added by people over 80 years ago) that is supposed to activate from repeated rain in May and June...but I think it's a bit late to be effective, since they've already chewed up a lot.

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » June 1st, 2017, 8:33 pm

I did the first spray today. 4 tsp in one gallon of water with a little molasses. I couldn't get the upper branches...I'll need a ladder next time.

User avatar
PSU4ME
Posts: 1147
Joined: November 29th, 2016, 9:29 am
Location: Metrowest MA
Grass Type: Front: Bewitched/Midnight/Everglade Back: Midnight/Diva/Everest
Lawn Size: 20000-1 acre
Level: Some Experience

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by PSU4ME » June 1st, 2017, 9:28 pm

Look tmw to see if it's working, it can take 2-3 days until they die. You're prob close to them being too big for BT but hopefully you got them in time

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » June 1st, 2017, 10:07 pm

Good to know...that was my next question...how long it takes.

Some are over an inch, some are under. They're at different stages I guess.

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » June 2nd, 2017, 8:06 pm

PSU4ME wrote:
June 1st, 2017, 9:28 pm
Look tmw to see if it's working, it can take 2-3 days until they die. You're prob close to them being too big for BT but hopefully you got them in time
I didn't see any hint of them dying today. I noticed they're all different sizes, and have different features, even though I guess they're the same species. Some have more bristles than others, etc. The leaves are really getting chewed up.

User avatar
PSU4ME
Posts: 1147
Joined: November 29th, 2016, 9:29 am
Location: Metrowest MA
Grass Type: Front: Bewitched/Midnight/Everglade Back: Midnight/Diva/Everest
Lawn Size: 20000-1 acre
Level: Some Experience

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by PSU4ME » June 2nd, 2017, 9:42 pm

Well once they ingest the BT they are supposed to stop eating immediately and then due in 3 days. If you think they are still eating then you might need to they about something stronger. Sevin, imo, really kicked their butt.

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » June 6th, 2017, 1:44 am

Are they supposed to drop off the leaves at this point? They're still attached. It's hard to tell how many are still eating.

User avatar
PSU4ME
Posts: 1147
Joined: November 29th, 2016, 9:29 am
Location: Metrowest MA
Grass Type: Front: Bewitched/Midnight/Everglade Back: Midnight/Diva/Everest
Lawn Size: 20000-1 acre
Level: Some Experience

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by PSU4ME » June 6th, 2017, 2:39 pm

I think you would see them "hanging".....basically dead but still attached. If after this time period they are still living, I would safely say its not working.

Sevin works just about immediately

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » June 6th, 2017, 5:00 pm

I guess the test would be touching them with a stick to see if they move.
Some of them seem to have slowed down considerably. I can't really tell if many are still eating, though. I'll check again tomorrow after the rain is over; I last checked yesterday. They were still firmly attached to the undersides of the leaves. Should they be dangling off and eventually fall down? My guess is, they could stay attached pretty well even when they're dead.

My back-up plan was going to be the Bayer Advanced Natria Insect, Disease, and Mite Control, with sulfur and pyrethrin. Note, this is different from the plain Bayer brand product with a similar name (which contains Merit) I will not be using that one. The Natria label specifically mentions caterpillars. I was going to try to avoid Sevin, since it's a harsher chemical.

Is the Bayer Natria product safe for this type of tree? I know some trees are sulfur-sensitive.

Also, I looked, but could not find any mention of the proper dilution for the Natria product. It comes in a hose-end sprayer, but I figured I would tank mix it. I just have no idea what mixing ratios to use.

Green
Posts: 6837
Joined: September 14th, 2012, 10:53 pm
Location: CT (Zone 6B)
Grass Type: KBG, TTTF, TTPR, and FF (various mixtures)
Lawn Size: 10000-20000
Level: Experienced

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by Green » June 7th, 2017, 9:21 pm

I did the second spray tonight. Mosquitoes were terrible. Noticed that some of the caterpillars had left the tree for the night or fallen off...not sure which.

Does Bt infect caterpillars that try to eat the leaves after it has dried (e.g. tomorrow)? Or does the spray have to make contact with the caterpillar in order to kill it?

User avatar
PSU4ME
Posts: 1147
Joined: November 29th, 2016, 9:29 am
Location: Metrowest MA
Grass Type: Front: Bewitched/Midnight/Everglade Back: Midnight/Diva/Everest
Lawn Size: 20000-1 acre
Level: Some Experience

Re: Questions on spraying Bt (on a Hickory tree) for gypsy moth caterpillars

Post by PSU4ME » June 8th, 2017, 1:19 pm

Green wrote:
June 7th, 2017, 9:21 pm
I did the second spray tonight. Mosquitoes were terrible. Noticed that some of the caterpillars had left the tree for the night or fallen off...not sure which.

Does Bt infect caterpillars that try to eat the leaves after it has dried (e.g. tomorrow)? Or does the spray have to make contact with the caterpillar in order to kill it?
The cats tend to come down at night, thats why people use burlap traps to catch them so its possible that happened or you thinned out the herd.

I think the BT is fine dried...its more of the rain washing it off thats the problem which is why you have to reapply it often.

Post Reply

Who is online

Users browsing this forum: No registered users and 6 guests