Post Harvest Horn Worm Treatment

[dev96]

Living in central Florida we are a mecca for hawk moths and horn worms. We treat with both systemic and contact spraying during growth which does a good job of keeping them under control. However at the end of harvest we suspend treatment 30+ days out.

The issue becomes by the time were harvesting our leaves are usually egg laden and we're loosing an enormous amounts of leaf post hanging for air cure. This year has just been particularly bad for them.

Having a target crop of 200 plus plants were spending a lot of time picking through leaves daily to pull these horrid creatures. This morning I've kinda gotten fed up with the situation after finding another 10 in under 5 minutes and another 8-10 24+ inch leaves leaves totally gone.

We're done for this seasons harvest but I'm trying to game out our next planting that were seeding this week.

I'm thinking about trying to toss our leaves into a curing chamber for 24 hours at 130F before hanging them up to actually cure. The idea being is these guys don't survive at temperatures over 120F so in theory this would kill off any eggs or larva.

However what I don't know is what this would do to our leaves in flash heating and removal... Any takers on that?

To say it in advance, a curing cabinet large enough to handle our whole harvest wouldn't be in the cards, that's a building!!! We only get away with what we grow because we can air dry and cure in our environment.

 

[deluxestogie]

However what I don't know is what this would do to our leaves in flash heating and removal... Any takers on that?

If you go above 104°F prior to color-curing, you will certainly ruin all your leaf. I would suggest spraying the foliage with BT just prior to harvesting. Hornworm eggs hatch in about 96 hours. Any hatched hornworms during the next few days will die of a tummy ache. Since BT is not a toxin, and will surely be destroyed by subsequent management of the tobacco leaf, I would consider that perfectly safe (compared to eating a cabbage a few days after it was sprayed with BT--which I would consider relatively safe).

Bob

 

[wruk53]

Living in central Florida we are a mecca for hawk moths and horn worms. We treat with both systemic and contact spraying during growth which does a good job of keeping them under control. However at the end of harvest we suspend treatment 30+ days out.

The issue becomes by the time were harvesting our leaves are usually egg laden and we're loosing an enormous amounts of leaf post hanging for air cure. This year has just been particularly bad for them.

Having a target crop of 200 plus plants were spending a lot of time picking through leaves daily to pull these horrid creatures. This morning I've kinda gotten fed up with the situation after finding another 10 in under 5 minutes and another 8-10 24+ inch leaves leaves totally gone.

We're done for this seasons harvest but I'm trying to game out our next planting that were seeding this week.

I'm thinking about trying to toss our leaves into a curing chamber for 24 hours at 130F before hanging them up to actually cure. The idea being is these guys don't survive at temperatures over 120F so in theory this would kill off any eggs or larva.

However what I don't know is what this would do to our leaves in flash heating and removal... Any takers on that?

To say it in advance, a curing cabinet large enough to handle our whole harvest wouldn't be in the cards, that's a building!!! We only get away with what we grow because we can air dry and cure in our environment.

I live in Southwest FL and I recently had an infestation of hornworms and other types of caterpillars. I sprayed them with BT last week and within a few days I was finding dead worms and no new live ones. Commercial farmers have been using BT at least since the 80's down here under the brand name "Dipel". I worked for my dad on the farm for a while and we would routinely add a few pounds of dipel to a 500 gallon spray tank. It is non toxic to humans and can be used all the way up to harvest. You can buy it in concentrate liquid form in garden stores. A pint cost me $13.00. Add 1 tbsp per gallon of water, shake well and apply. This stuff works.

 

[dev96]

D and W,

Thanks for the input, I'll try the BT post harvest off of the plant and see what it buys us under a roofed environment. I've not had much luck with it in the field but I can also probably relate that to rain and application timing. Early summer things start getting frustratingly tricky here and you need stuff that does quick effective hits.

I'm thinking I'd end up applying BT twice, these guys hatch time is 5-9 days.



You can see the 24 hour damage in this picture. These are post harvest trash leaves aka "freebies" we get from late sucker growth. These were both whole leaves yesterday.

I had another thought of overnight freezing vs heating... obviously that damages a leafs cell structure but post harvest I wonder if it would matter to drying and curing after.

KyU has a white paper out on freezing but deals with it from the perspective of pre harvest field frost and recovery vs loss. It mentions post harvest pre cure barn freezing over and over and over but in a circular fashion without conclusion on any actual issue loss... It's like they knew you'd want that answer aaaaaand... nope!!!

I'll probably try it just because I'm stubborn.

We are changing crops this planting because of these worms. We test plotted a 100 Sobolchskii 33 this spring to try out vs our usual Virginia Gold. Unexpected side effect, the worms for whatever reasons don't like the 33 and surprisingly the Sobo preformed equally well in a wet hot weather climate. Our fall planting will be 10:1 Sobo / Virginia in hopes of using the Virginia as bait plants.

We tried tomatoes with this same idea of the tomatoes being bait but the results ended up vice versa and Virgina ended up keeping the tomatoes quite safe.

Cut worms, don't ever put a plant in the ground under 8-12 inches tall. Army worms, don't even think of growing corn here. Horn worms, be prepared to see your best 30+ inch tobacco leaves be shotgunned with holes AFTER leaving the field.

If you were a cigar guy you'd prolly go insane.

 

[deluxestogie]

Freezing green tobacco leaf ruins it.

Bob

 

[deluxestogie]

Virginia Gold is a flue-cure variety, whereas Sobolchskii 33 is a burley.

Bob

 

[GrowleyMonster]

I live in Southwest FL and I recently had an infestation of hornworms and other types of caterpillars. I sprayed them with BT last week and within a few days I was finding dead worms and no new live ones. Commercial farmers have been using BT at least since the 80's down here under the brand name "Dipel". I worked for my dad on the farm for a while and we would routinely add a few pounds of dipel to a 500 gallon spray tank. It is non toxic to humans and can be used all the way up to harvest. You can buy it in concentrate liquid form in garden stores. A pint cost me $13.00. Add 1 tbsp per gallon of water, shake well and apply. This stuff works.

I was just fixing to ask about that! I just lost a bunch of hanging leaf to hornworms. None on the plants in the ground. I lost several plants before I started spraying every 10 days or so with Spinosad or BT, alternating. That ended the bug deprivations. Then I started harvesting and I got some leaf color cured nicely but then I hung some more about a week ago and today I saw that some formerly beautiful big leaves were skeletonized and I found one big hornworm close to three inches long. A grip like iron, at least until I finally got him yanked off the stem he was cleaning up on, and smushed him to a smear of bug guts. My question would have been is it safe to use BT at harvest time or even post harvest. Now I know. Thanks.

 

[deluxestogie]

I keep an eye on the floor of my curing shed for hornworm poop, which means I missed one.

from 2017

Bob

 

[MadFarmer]

I bought a uv flashlight because I couldn't keep the moths from the curing barn (my garage.)

 

[Tuco The Ugly]

Bacillus Thuringiensis
I can think of worse things Ive smoked… Nasties can be observed dropping from plants upon spraying. I too watch for insect frass, the new white weed fabric Im using this year makes it much easier to spot.