Saturday, December 5, 2015

@%$& mealybugs on barrel cactus

I’m fond of this barrel cactus. I brought it home from Mariscal Cactus & Succulents in Desert Hot Springs on our February 2011 trip to the Southern California desert. The guy at the nursery said it was a “fishhook cactus,” which I took to mean Ferocactus wislizeni. However, when Greg Starr was here in the spring, he thought it was Ferocactus herrareae, which some taxonomists consider a subspecies of Ferocactus wislizeni. Whatever it may be, exactly, I’m emotionally attached to it, nasty spines and all.

Take a look at the photo below. From a distance it looks good, doesn’t it?

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Now look closer.

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Yes, that weird noise in your ears was me screaming through cyberspace.

The fluffy white stuff isn’t an awkward attempt at flocking this poor cactus for the holidays. No, it’s from the scourge of my gardening life: mealybugs. You’d think the epidermis of a cactus is too thick for mealybugs to penetrate but apparently they’re getting something otherwise they wouldn’t be here. They were having the time of their lives this summer, no doubt because of the heat and drought.

I chose to attack the problem with the most low-tech solution possible: water. I hauled the pot out to the front law and tipped it over so it rested on a piece of wood. This would allow me to use a hard, directed spray from the bottom of the cactus to the top.

While I was setting everything up, it started to rain. I decided to wait so the rain could soften up the mealybug gunk. When it stopped a few hours later I blasted everything off with a hard spray.

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Remarkable how effective this was! My cactus is nice and clean now. Of course I have no idea what’s in the soil. I suspect that’s where the mealybugs are hiding. The first order of business next spring will be to administer a good dose of system insecticide. Maybe that’ll keep them in check.

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All in all, the mealybugs did relatively little damage to the cactus. It’s epidermis is thicker, after all, than that of a sempervivum or echeveria—favorite mealybug snacks.

21 comments:

  1. You got rain??? You lucky person.

    Instead of using a systemic, could you take it out of the pot and gently wash or soak all the old soil away from the roots and little hidey-holes at the base of the plant? That way even if the mealybugs or eggs were resistant, they would be gone.

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    1. I may actually plant this cactus in the new succulent area that will replace the front lawn. In that case, I'll have the opportunity to wash the roots. I have quite a few potted barrel cacti which, although still small, would love to be in the ground. Maybe the new area will be primarily a cactus garden. That would be cool, actually.

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    2. That would be wonderful, Gerhard. Can't wait to see it!
      Unfortunately, my barrel cacti will have to remain forever potted in Portland. :(

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  2. spraying with a horticultural oil usually takes care of this for me....

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    1. Great tip! Thank you! I have a bottle of horticultural oil in the shed. Will give it a try next year.

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  3. After your last report of mealybugs, I decided I should take another look at the agave I treated in late summer. They were making another go at taking over (aided by their protectors, the ants) so I treated them as you did, with a blast from the hose. Just today, when I removed a pup from an Agave 'Blue flame', I noticed evidence of them there too. It's a never-ending battle.

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    1. Oh no! At least on this cactus there weren't any nooks and crannies for them to hide. Agave rosettes are another matter. It would be much harder to remove them with a blast of water, especially if it's a clump with multiple pups.

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    2. I have the best luck dabbing in the rosettes with 70% rubbing alcohol. Doesn't seem to hurt the agaves and the mealys die immediately. I had an Arizona webberi Arizona Star pup I just found yesterday that was being attacked and I attacked back. I fear they may be in the soil too though.

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  4. And even though I won last winter's battle with mealys on my 'Joe H' I see they've come back to attack a couple of other "basement" Agaves...they're evil. They will not win.

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    1. Vigilance is key. And I must admit I'm not always vigilant enough.

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  5. Always a sign of a plant under environmental stress, and for those of us living in Argentine Ant country, impossible to eliminate permanently without giving the affected plant better suited growing conditions to better resist. Thankfully not a major problem for me here in Berkeley, but I've given up growing species I can't keep pest free due to lack of sufficient heat or sun. Keeping dead foliage removed on mass planted Aeoniums and Echeverias is important to control mealybug, but seldom reaches crisis proportions. I'd recommend a soil drench, and I find Orange Oil is quite effective at keeping ants away.

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    1. David, this cactus doesn't get enough sun. As you said, that's most likely a reason why it was so susceptible. I'll plant it out next spring so it'll get full sun from late morning on.

      What soil drench would you recommend?

      Thanks also for suggesting orange oil. I've never seen as many ants in the garden as I have this year.

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  6. It's those blankety-blank ants, as David said. I just saw them on one of my precious 'Snow Glow'. Time to go spray them off.

    Watch the plant, as the pests may have left eggs that will hatch and re-infect. And you got actual rain? Oooooh!!!!

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    1. 'Snow Glow'? I'd go ballistic. That's my favorite agave at the moment and almost impossible to replace.

      We had a few hours of rain. I doubt it was than a 1/10th of an inch.

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  7. I'm loving on the cactus garden idea these days :~)

    I don't see a lot of mealies here, but that could be because of my old eyes. When I do spot them, I spray them with straight rubbing alcohol (in late afternoon, when plants will be in shade until the next day). Seems to work, but as always, YMMV. Water seems kinder.

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    1. LOL, my eyes are pretty bad, too. Who knows what kinds of things I miss. Often it's better not to see or know too much.

      Rubbing alcohol plus a few drops of Dr Bronner's castile soap is my remedy of choice but this infestation was so bad and so hideous to look at, it needed to be sprayed off anyway.

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  8. Glad it was "easy" to take care of -- for now. Love the spines on that cactus -- nasty! :)

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    1. Not only are the spines ferocious to look at, they're actually remarkably sturdy. I bet you could lift the whole cactus by holding on to a few of the dominant spines.

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  9. yes, the mealies, the ants -- it's gotten so buggy with this drought. Agaves and aloes used to be trouble-free, bullet-proof plants. I assumed cacti would be too...better go check mine.

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    1. Ants were everywhere this summer. I fully expected them to migrate into the house with the cold weather but no trace of them yet. Knock on wood!

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    2. In my addition, the ants seem to only be interested in plants with aphids growing on them. When I get rid of the aphids, I think the ants lose their source of nectar. Or whatever they are after. Am I crazy or what?

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