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Orange damage on Coryphantha

Posted: Sun Jun 24, 2018 10:05 am
by nikki_cav
Morning all!

Could anyone give me some insight into what might me going on here please.

These marks are fairly new on this plant (this growing season) and are uniformly all over the plant.

It's one of two I have that are like this, both Corys, in a collection of about 2000 mixed cacti, none of the others are affected. The other plant has been like this for about 2 years.

Plants are treated regularly with DE and occasionally with systemic if I've found a problem.

I can't see any mites on the plants and as I said nothing else is affected. I have seedlings in the greenhouse too so would have thought those would have shown damage if it were mites etc.

Any ideas would be gratefully received.

Re: Orange damage on Coryphantha

Posted: Sun Jun 24, 2018 11:06 am
by iann
Certainly looks like mite damage, or perhaps some other pest. Probably not new, just becoming visible now.

Re: Orange damage on Coryphantha

Posted: Sun Jun 24, 2018 11:22 am
by Ali Baba
I would suspect thrips from the damage distribution rather than mites. Thrips often lurk under wool and cause damage which becomes visible as growth ages. I can clearly see thrips damage on the spines in your photo ( pale banding with small black spots). Thrips tend to attack certain plants and leave others alone which goes with your story. They are also quite hard to spot and very few can cause a lot of damage. Unfortunately highly resistant to all chemicals available to the amateur gardener


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Re: Orange damage on Coryphantha

Posted: Sun Jun 24, 2018 3:30 pm
by habanerocat
I have the same thing on my Coryphanthas. I assumed it was RSM.

SB Plant Invigorator seems to be sorting it. New growth is clean. So, so far so good.