How I'm winning against root aphids in soil

I had mentioned this briefly on my grow log, but figured I'd throw it out here.

At the hydro store, I had asked the clerk about treatment for root aphids in the soil (and there are winged root aphids, along with fungus gnats). Before the clerk could answer, an excited patron chimed in and recommended, "GoGnats".

All in all, it's cedar oil. For some reason these concentrated oils seem to get a bad wrap for their effectiveness against insects. However, it is a fact that cedar oil kills aphids and larvae on contact. The problem in soil is getting it to them.

The patron advised to used 12ml/gallon (even though the label says 20ml/gallon), and said to do a light soak where water just barely comes out of the bottom of the pots.

I did exactly as he described, and I have to say that the fliers were gone for awhile. Digging around in the soil I saw no movement like before.

Deciding that root aphids are notoriously difficult to eradicate, I took the liberty of applying Bayer Fruit and Veg (imidacloprid). This stuff says to treat no more than once per year, and claims to kill aphids, and prevent them from establishing in unaffected systems.

After a couple of more days, I notice a flier come out of the canopy and into the light. I also look and see a winged root aphid on the leaves of one of the plants. I went to touch the aphid and it tried to fly away and couldn't. It's movement was lethargic and less than deliberate; a big contrast to how these things normally behave. I chalked this up to the imidacloprid working.

For good measure, I reapplied the GoGnats at 20ml/gallon. It has been several days and there are no fliers and no movement in the soil.

I like to take my bulb out after a couple of days and inspect for insects. Usually, I'd have anywhere from 10-20 every few days, dead on the bulb. All winged root aphids.

Since the last administration of GoGnats, the bulb has been clean.

This did not come without casualties. I had an enormous Deathstar and a smaller Acapulco Gold that were too far gone to recover. However, four other plants in soil sitting next to these that did have root aphids have been doing fine and seemed to survive the infestation thus far (knock on wood). As I'm closing in on the first week of flower, I'm keeping a close eye on development, and will apply the GoGnats every other week, or once weekly if there is evidence of bugs.

If I were to ever grow in soil again (moving to drip hydro), I would for good measure apply GoGnats and the imidacloprid. I can say that the plants do not mind either treatment at all. As a matter of fact, they may even like it a bit.

I suppose the effectiveness of this treatment has a lot to do with the particular aphids in question, their numbers, and paths of recontamination. For me however, this combo seemed to do the trick, and the aphids were established enough to take down two adult, healthy plants.

I identified the source as rockwool that had root aphid larvae in it.

root aphids in my mother room was only thing aside from broad mites that has gotten me to the point of using non-organic controls. Tried SNS 203, which smells heavenly, but didn't seem to work. Imidocloprid finally kicked them for me.

Greensome said:

View Image

I identified the source as rockwool that had root aphid larvae in it.

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how'd you figure?
I'd think it'd come in on your soil, or as in my case from cuts I was given.

also, be aware, imidocloprid is systemic, I've heard plants testing positive up to 60 days later. This is why I only have used in on mothers.

Bayer says it gives protection for a year. That tells me something. I don't want to smoke it. Good luck. -granger

Nes said:

how'd you figure?
I'd think it'd come in on your soil, or as in my case from cuts I was given.

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Good question.

I used a fresh bag of coco and had gone through the unused stuff and there were no bugs. Later, I put other plants in FFOF that I got from a store. It was clear of bugs as well.

I was going through and cleaning my stuff and noticed some discoloration on my rockwool. When I opened up a few cubes, there were little black specks that ended up being aphid larvae.

The imidcloprid I wouldn't doubt would be around. However, the threshold for human interactions is 450mg/kg which is more than I used on the entire grow.

I don't like using chemicals like these. However, it was that or lose the plants. There are much harsher options (Mallet and Minx). I know of people that use Mallet and that's the same stuff as the Bayer, but about 80x stronger.

Granger2 said:

Bayer says it gives protection for a year. That tells me something. I don't want to smoke it. Good luck. -granger

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I totally understand your point. But it's that or don't smoke for me

Here, check out Minx. This stuff is used all the time in dispensaries here. I'm sure a good chunk of members here smoke(d) plenty of weed with this stuff in it...

http://www.cdms.net/LDat/mp9KS003.pdf

> Here, check out Minx. This stuff is used all the time in dispensaries here. I'm >sure a good chunk of members here smoke(d) plenty of weed with this stuff in
> it...

That's unfortunate.

> I totally understand your point. But it's that or don't smoke for me

There are other options. Check the Fungus Gnats or Winged Root Aphids thread. Good luck. -granger

This stuff works-

http://www.amazon.com/Valent-Gnatro...e=UTF8&qid=1406243345&sr=8-4&keywords=gnatrol

Soil drench at 1 tbsp/gal once a week for 3 weeks. Worked so well that I now use 1 tsp/gal once a week forever. Whatever they were, the little winged culeros that damaged my last grow are gone or hiding really, really well.

If Gnatrol worked, they must have been Fungus Gnats. Good luck. -granger

Let me clear up some confusion and help explain by why Gnatrol is ineffective on controlling Root Aphids.

The active ingredient in Gnatrol/Mosquito Bits/Mosquito Dunks is bacillus thuringiensis israelensis (BTI) with a Mode of Action of a "mid-gut membrane disruptor" on young larvae. Fungus Gnats go through a larvae stage--but Root Aphids do not--they molt.

First--here is the Fungus Gnat lifecycle...



BTI is most effective against the young first instar larvae, which at the 4 o'clock position in the above pic. The bacteria must be ingested by the larva, after which a toxic protein crystal is released into the insect's gut. Larvae stop feeding and die.

Fungus gnats life cycle is 20-28 days and as you can see, BTI is effective only 2-3 of those days--primary reason why BTI must be applied at the "right time"--or it is a waste of money.

Root Aphids are a completely different breed and have been known to develop a resistance of sorts to many chemical pesticides (hence why some never get rid of them after repeated applications--while others get rid of them after a single application).

Hope this helps!

Granger2 said:

If Gnatrol worked, they must have been Fungus Gnats. Good luck. -granger

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You're probably right. Fungus gnats can apparently be more of a problem than they're made out to be, because my girls were hurting 3-4 weeks into flower & I caught lots of flyers on fly strips.

Poking around, I found this interesting POV-

http://www.thenorthwestleaf.com/pages/articles/post/preventing-grow-pests-like-phylloxera

If they're spread with cuts, as he suggests, then my chances of having them would be very small growing from seed.

Serious tropical fish hobbyists quarantine new acquisitions because the consequences of not doing so can be dire. That has to be a very difficult proposition for growers, I'm sure.

EclipseFour20 said:

Let me clear up some confusion and help explain by why Gnatrol is ineffective on controlling Root Aphids.

The active ingredient in Gnatrol/Mosquito Bits/Mosquito Dunks is bacillus thuringiensis israelensis (BTI) with a Mode of Action of a "mid-gut membrane disruptor" on young larvae. Fungus Gnats go through a larvae stage--but Root Aphids do not--they molt.

First--here is the Fungus Gnat lifecycle...

View Image

BTI is most effective against the young first instar larvae, which at the 4 o'clock position in the above pic. The bacteria must be ingested by the larva, after which a toxic protein crystal is released into the insect's gut. Larvae stop feeding and die.

Fungus gnats life cycle is 20-28 days and as you can see, BTI is effective only 2-3 of those days--primary reason why BTI must be applied at the "right time"--or it is a waste of money.

Root Aphids are a completely different breed and have been known to develop a resistance of sorts to many chemical pesticides (hence why some never get rid of them after repeated applications--while others get rid of them after a single application).

Hope this helps!

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Thanks for that.

I think that a gnat infestation means that there are gnats at all stages of development all the time. They're not like cicadas. So saying that BTI needs to be applied at the right time doesn't seem quite right. It needs to be re-applied periodically to maintain effective concentration in the soil at all times until eradication is achieved.

Jhhnn said:

Serious tropical fish hobbyists quarantine new acquisitions because the consequences of not doing so can be dire. That has to be a very difficult proposition for growers, I'm sure.

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having a small tent for quarentine if great for taking in cuts. I put mine in a little 2x4 tent with a t5 for a few weeks to try and adress any issues that may be coming home with them. Short of that, I've heard of people using dunk buckets with spinosad, abamectin, or imidocloprid. Some dispensaries will have them so you can dunk your cuts, soil and all before you leave. Otherwise, you can keep one near the entry to your house, and dunk them on the way in...
seeds are safer though, if you don't mind the wait, the males, and the crapshoot.

Jhhnn said:

Thanks for that.

I think that a gnat infestation means that there are gnats at all stages of development all the time. They're not like cicadas. So saying that BTI needs to be applied at the right time doesn't seem quite right. It needs to be re-applied periodically to maintain effective concentration in the soil at all times until eradication is achieved.

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Exactly...that is why I prefer Mosquito Bits (not dunks); dunks are compressed donuts made of calcium carbonate and bark...Bits are corn cob bits sprayed with vegetable oil--both contain the exact same amount of BTI (by weight). As the Bits breakdown in the soil BTI is released--think "time release". Whereas Gnatrol and Dunks release their BTI immediately--which is effective for 24 hours or so...48 at the most. At least that is what the people "that wear pocket protectors" at Summit (mfg of Mosquito Bits/Dunks) explained to me.

Hence the reason one must make repeated applications of Gnatrol. With a 30-45x magnifier you can look at the larvae and almost predict what stage the gnats are and then time the Gnatrol application--or something like that.

has anyone tried predatory nematodes?

EclipseFour20 said:

Exactly...that is why I prefer Mosquito Bits (not dunks); dunks are compressed donuts made of calcium carbonate and bark...Bits are corn cob bits sprayed with vegetable oil--both contain the exact same amount of BTI (by weight). As the Bits breakdown in the soil BTI is released--think "time release". Whereas Gnatrol and Dunks release their BTI immediately--which is effective for 24 hours or so...48 at the most. At least that is what the people "that wear pocket protectors" at Summit (mfg of Mosquito Bits/Dunks) explained to me.

Hence the reason one must make repeated applications of Gnatrol. With a 30-45x magnifier you can look at the larvae and almost predict what stage the gnats are and then time the Gnatrol application--or something like that.

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Meh. Gnatrol instructions call for 1-2 tsp/gal once a week for 3 weeks (light infestation) or 4-8tsp/gal once a week for 3 weeks(heavy infestation). I have them in front of me. I split the difference, 3tsp(1tbsp)/gal once a week for 3 weeks. A week after that, I put out a fresh "Victor fly catcher strip". A month later, I captured zero flyers. I now use 1tsp/gal once a week as a preventative measure.

And like I said, if the infestation has been around for awhile, gnats exist at every stage of development due to the variability of the lifecycle at 20-28 days. It can be no other way.

Jhhnn said:

Meh. Gnatrol instructions call for 1-2 tsp/gal once a week for 3 weeks (light infestation) or 4-8tsp/gal once a week for 3 weeks(heavy infestation). I have them in front of me. I split the difference, 3tsp(1tbsp)/gal once a week for 3 weeks. A week after that, I put out a fresh "Victor fly catcher strip". A month later, I captured zero flyers. I now use 1tsp/gal once a week as a preventative measure.

And like I said, if the infestation has been around for awhile, gnats exist at every stage of development due to the variability of the lifecycle at 20-28 days. It can be no other way.

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Let me help you, first these paragraphs should also be in those instructions--

"Apply Gnatrol WDG with adequate water by soil drench
to sufficiently wet the soil surface. Reapply as needed. In
situations where all life forms (eggs, larvae, pupae and
adults) are present, such as with existing infestations,
make (3) weekly applications at the suggested range rate
for heavy infestations. Regular follow-up using suggested
light infestation rates will establish a long termmaintenance
program.
Gnatrol WDG is a larvicide and will not control adult
gnats, therefore, applications must be timed for a stage of
development when larvae are present in the soil."


And the real deal from http://www.oardc.ohio-state.edu/floriculture/images/05-08_Pest_Mngmt.pdf--

"Gnatrol® is an insecticide distributed by Valent USA Corporation, which contains the active ingredient, Bacillus thuringiensis spp. israelensis. Bacillus thuringiensis (Bt) is a naturally occurring soil-bacterium. Different strains work on different classes of insects. The strain, israelensis, is only active on mosquito and black fly larvae, and fungus gnat larvae. Gnatrol® does not control fungus gnat adults as the material only
works on the larvae stage and it is not active on shore fly larvae. Bt has to be consumed in order to be effective; it is not a contact insecticide. Bt produces crystals (endotoxins) when ingested by fungus gnat larvae during feeding. The larvae have an alkaline midgut, which attracts and activates the toxin. The toxin paralyzes the digestive system by rupturing the midgut cell walls, which allows the alkaline contents of the gut to spill into the blood (septicemia). Fungus gnat larvae stop feeding within hours. Death generally occurs in 24 to 48 hours. Gnatrol® is more effective on young (1st instar) fungus gnat larvae than the older (2nd and 3rd instars) larval stages.
Gnatrol® is primarily applied to the growing medium as a drench. However, the material may also be applied by injection into drip or overhead (sprinkler) watering systems. It is important to get uniform distribution throughout the growing medium profile in order to place the material near fungus gnat larvae and maximize effectiveness. Gnatrol® can be applied underneath benches, which is an area where fungus gnats can breed.
Avoid injecting or using Gnatrol® in combination with fertilizers or fungicides containing copper (e.g. Phyton 27®) or chlorine because this may degrade the active ingredient. However, the chlorine levels normally present in potable water sources will not reduce the performance of the material.
Gnatrol® is not effective as a “rescue treatment” when fungus gnat populations are “high.” The material needs to be applied before populations’ build-up and reach levels that require more frequent applications (3 per week), which can increase costs. Gnatrol has short residual activity lasting only several days. In addition, the material may bind to organic matter thus reducing efficacy. Gnatrol® has two use rates: one for “light” infestations (16 to 32 oz/100 gallons) and one for “heavy” infestations (64 to 128 oz/100 gallons). It is one of the few insecticides registered for fungus gnat control on greenhouse-grown vegetables, and is OMRI (Organic Materials Review Institute) approved. It is a good idea to rotate with other insect growth regulators such as Adept® (cannot be used on poinsettia, Reiger begonia, and hibiscus), Citation®, and Distance® in order to avoid the onset of resistance developing."

Sorry, but thems are the facts: BTI is "is more effective on young (1st instar) fungus gnat larvae than the older (2nd and 3rd instars) larval stages" (period). Now you know!

I'm a proffessional root aphid and fungus gnat grower, pretty good at Spider Mites too! LOL

Every time I've found root aphids, it was after noticing I had a LOT of fungus gnats flying around.

The two are always found together in my experience. I think the RA's cause dead roots, and the fungus gnats go crazy because of that.

Root Aphids are near impossible to completely eradicate. It IS however possible to knock them back enough to not affect yields or quality IME.

I tried everything, and the only thing that worked for me was Imidicloprid.
MET 42 worked once or twice but then didn't work. BTI my RA's laughed at it.

Bayer T&S at first (most Imid) but that changed, found "Annual Tree and Shrub" brand that had the same strength Imid as the old Bayer stuff, but Merit 75 is by far the best.

Merit 75 is a powdered form of Imid, much more economical.

In my rooms, after root drenching with Merit 75, I found the fungus gnats also dissipated and went away completely, gradually, over 2 weeks. No RA's, no FG's.

A follow-up of Azamax root drench a week after the Imid seemed to really kick their asses. I've since had great success with just the Merit 75 and no Azamax follow-up.

This has allowed me to finish without ill effects, although at the very very end, I would find a RA flyer here and there, but too late to care about it.

Yes, Nematodes work great. That is, provided they are fresh. I've found that buying them locally is iffy at best. Buglogical says to keep them no longer than 10 days in the frige. Most local suppliers have them in the frige for who knows how long. Best to buy them and have them overnighted this time of year. Spring and fall have them shipped by 2nd day. I usually get an overwhelming number, apply half, wait a week, apply the other half. Good luck. -granger

Agree with Granger, nematodes work....but they got to be fresh; fresher the better.

I too have seen a correlation between Fungus Gnat activity and Root Aphids...it seems the Gnats are little airliners that carry Root Aphids eggs, direct flights from here to everywhere. Guess we can call gnats, "Trans-garden Airways"....lol.

Yep, imidacloprid works--but the half-life is measured in hundreds of days/years. Also cannabis testing labs include imidacloprid in their pesticide tests...which means, heavy dosers/users can/will get caught.

Talking to my fellow "grow/farmer pals", I was told last month that local OC "organic grower" flowers had tested positive for high levels of Imid....ahhh, "oh, what a tangled web we weave: When first we practise to deceive!" Amazing what a $50 test will tell you.