Black marks on cactus - Is this scale or something else?

GemcapMarch 25, 2012

I have a couple of cactus which have these black "marks". I first thought they were on account of sun burn - but they have grown / spread a bit in the last couple of months. (Photo attached) I manually prised them out using a toothpick. They come off quite easily though a fleshy impact in the cactus is visible.

They are not flat and appear to have a kind of "hook" into the cactus to feed off it. (Photo attached)

Is this scale or some other pest? Will it jump to other cactus. Other than manual removal, what other remedies would you recommend.

Many thanks for your assistance?

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FerocactusLatispinus(Zone 4/Sunset 43 WI)

I'm pretty sure it's scale. If it's been continuing to spread over the cactus, it is very likely this is a scale infestation. I have a cactus which had scale, and those lesions on the skin of your plant look just like the one I had. Luckily, I only had one scale insect to deal with, but I would definitely use a chemical approach to this problem. Physically removing the scale is a great step, but the adults will quickly produce offsping and you'll have another batch of scale on the way.

I really hope that your plant gets well!
Just keep up the treatments and you'll be fine!!

    Bookmark   April 2, 2012 at 9:23PM
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That is definitely scale.

Scale, like mealybugs, quickly move from plant to plant. Make sure you isolate!

    Bookmark   April 21, 2012 at 8:13PM
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If it's a small amount of scale, take a Q-tip or something small and dip it in rubbing alcohol and dab it on each scale to get them wet. This will kill the scale and them you can gently scrape them off.

    Bookmark   May 25, 2012 at 11:03AM
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