How To Deal With Beetle Stem Borers?

Figong said:

You won't like my answer.. but it's best you destroy the plants that are swelling irregularly and bursting in spots.. the borer in question has potentially already laid eggs.. so killing the worm will just prolong the inevitable as the eggs will hatch, and they will spread to other plants and quite possibly wipe out your whole crop. As another tip, keep the weeds and grass trimmed for a small section around the plants in question - this will help a bit, but it's still possible this will be recurring.. based on the other types of plants/weeds/foliage in close proximity. If you'd rather not destroy your crops without a fight... operate on the stems -carefully- around any bulges and splits.. -gently- scrape any eggs out you find and destroy them with smashing. Pull out all worms you find and slice them parallel to their body, down the middle, and remove all pieces from the growing area. After you remove any eggs and worms found, get toothpicks and use 2 per stem, one on each side, use tape to patch, then bind the plant - hold on tight to see if it pulls through or ends up dead.

Good luck with thiThey

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markexpress said:

Posted this in Outdoor, no replies. Hopefully you guys can help.

In my area, I have some serious pests that I deal with, the worst one is the beetle borer. See pictures attached. I need some help/advice in dealing with this nemesis.

First of, here a description of the pest and what it does. Starting with second or third week of June, these small worms appear that are looking for a plant host. Once it finds the plant it likes, it will climb the stem - first it will climb all the way up and then back down - to assess the size of the plant and the stem width. If the stem is too small or too hardy it will leave. Otherwise, once the worm determines the height of the plant it will then borrow a hole inside the stem about half-way up, and the worm then proceeds with eating the inside of the stem - ALWAYS going up the plant stem first and then after the stem becomes too thin on the top, it goes down the plant. Once the worm reaches the bottom, it migrates to some part of the stem where it awaits for the plant to grow more and then burrows inside the side branches stems. As a result, the centre of the stem becomes hollow, and some plants can even collapse or die. Typically the worm enters in the middle of the plant. Often more than one worm can enter the same plant during the season. The time frame for the worm's burrowing activity is early-mid June to the end of July. After which time the worm lays eggs inside the stem and transforms first into a fat black grub-like creature, then eventually becoming a small black beetle. Sometime in early August the beetle makes an exit hole and leaves the plant, until the next year. All this information is based from my observations, none of it is made up and nothing is assumed.

So why do these worms/beetles target cannabis plants? Well, I found out why this past summer. Turns out there is a species of native weeds that are endemic to this part of Ontario (don't ask which part), which the beetles typically target. The weed's stem is almost exactly the same, both on appearance and inside. I found the same holes and same results inside. EXCEPT, those weeds are dealing fine with these intruders and the weeds dont collapse or die.

I tried some sprays, powder and pellets to no success against this smart pest. I tried applying stuff to the bottom of the stem, around the stem, and to a certain degree they repel this pest but eventually the beetle worm finds its way up the plant sometimes. On average I end up having 40-60% of my small number of plants infected with this bug. The ONLY thing that had some level of success was using Bonide Annual Tree and Shrub Insect Control (see Amazon link: http://www.amazon.com/Bonide-Annual-Insect-Control-Gallon/dp/B002ITL19A/ ). Its very effective for the roots. At the end of the season I pulled out the plants, and the ones I applied that chemical to had ZERO creatures of any kind in the roots. Just soil. Not even one soil worm. Have not noticed the effect on the smoke (I never smoked a bud in my life, just taking my customer's word for it). The problem is that its a chemical that it taken up by the roots of the plant, and takes at least 1-2 weeks to take effect for the stems and the leaves. Sometimes I noticed the bugs attempted to burrow inside the stem, only to abandon their attempt and leave. Victory. I saw the partial entrance holes, proving that this chemical had some effect. Sometimes the results were not-so-good, and actually did more damage: the worm burrowed its way in, only to die inside the stem a few inches into its climb. The plant's stem then collapses at that point where the bug died - typically half-way or two-thirds of the way up.

So how does this bug affect the plant? Well, munching the centre of the inner stem does not often kill the plant (only about 25% of plants die), but it causes long-term damage. The plants end up being shorter, with smaller buds and take longer time to finish flowering. Last year I had 8 of G13 Pineapple Express plants. Four were infected, two died from half-way up (ended up branching out and getting only half the yield of other plants), while the other two infected plants didn't show signs of problems until in mid September, when I harvested the other plants but these two took an extra two weeks to flower and the buds were a bit smaller - but smoke-wise it was just as good.

Anyways, if anyone can recommend me anything I would really appreciate it. This will be my last year doing a guerilla grow, from which point I will either retire from growing or get a license.

PICTURES of the beetle borer worm I took after dissecting the stem of an infected plant.

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mailman316 said:

Ya I have had the same experience with these damn thing and am also in Ontario. I have tried to research on how to prevent these things but there isn't much info on how to prevent until they have made there way inside the plant. Some old lads I've talked to have said to put ashes around the base of the plant like around the stalk, and I've also heard about wraping tin foil around the stalk at the bottom of your plant but have yet to try it out. But I am willing to give almost anything a shot this year after putting up with these things last grow season. If anyone else has any tips or info on how to prevent these things from even comming close to the plants please post it!!!!! Another idea I was trying to come up with is to make a device that will go around the bottom part of the stalk of the plant and have some kind of sticky substance on it so when they climb the plant they will get stuck to it and DIE!!!! Lol but ya if anyone has any ideas or have heard of anyway to prevent these things please post thanks.

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Burnedman said:

dudes. this year i had a few plants affected with these. 1 particularly bad!
i grew these in my vegetable garden and the worms infested my PPP so bad that there are egg clusters everywhere and i know they got all down into the soil. is this going to be an annual problem?
next year i plan to amend the same soil with a huge amount of diatomaceous earth to shred any hatching larvae.
Any other advice would be helpful.

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Burnedman said:

update: the DE topdress worked like a magic spell. I have had "NO" insect damage of any kind outside this year yet and the same DE topdress application got rid of a plague level gnat fly infestation i had this winter. several hundred flies per yellow trap every few days!!!!! 1 single DE topdress and i havent seen a gnat fly in 4 months and counting.

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smackaplant said:

omg ITS in my plants too ...Ive never seen or had any problems before ...i feel ;like crying i think it was just going in bud . i cut a few and killed the worm in side i cant beleave those are all eggs to get me next year
omg

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