whats wrong with my cactus?

[james2815]

Hey is there anyone who knows what this is on my peniocereus serpentinus and am i able to fix it?
Thanks everyone.

[Steve Johnson]

Hey is there anyone who knows what this is on my peniocereus serpentinus and am i able to fix it?
Thanks everyone.

Ooh, I think it could be scale -- see this.

[james2815]

Thankyou. do u know if a isopropyl alcohol and soap spray mix would help to get rid of it?

[greenknight]

Pretty sure alcohol will kill them.

[Steve Johnson]

Pretty sure alcohol will kill them.

I think alcohol should be sufficient, so perhaps the addition of soap spray may be unnecessary. I haven't had any problems with scale, so I'll leave any further thoughts to people who've dealt with it before. I do use Isopropyl alcohol (IPA) on spider mites and the occasional mealy that pops up here and there. The 70% IPA we get at the store is fine. Mist spray the affected plant(s) thoroughly, although A. keep it(them) away from direct sunlight until dry, and B. continue spraying on a regular basis until you know for sure the infestation has been knocked down. Can't do any more than that until affected plants are in growth and will respond more effectively to an Imidacloprid soil soak. Warm weather in spring is the earliest opportunity for using systemics on mealies and armored scale.

Hope this helps!

[CactusFanDan]

I don't see any bugs. Looks more like mechanical damage or maybe cold damage. Could be some kind of mite though, I guess.

[james2815]

Ye thanks heaps for your reply dont wanna lose my cactus ive now had for 10years. Its Growing atm and has its last flowers coming through is that a good time to spray?

[Steve Johnson]

Ye thanks heaps for your reply dont wanna lose my cactus ive now had for 10years. Its Growing atm and has its last flowers coming through is that a good time to spray?

Actually, it's helpful to know where you live. If you're in the southern hemisphere, that'll be summer for you, and a systemic application would be good now. North of the equator -- use IPA spray until the growing season is well and truly underway. Warmth in winter comes and goes, so IMO you shouldn't rely on consistent growth for a soil soak until then.

[james2815]

I live in queensland, australia so now would be a good time

[Steve Johnson]

I live in queensland, australia so now would be a good time

Okay, then go for it. Soil soaks have a major advantage over sprays because the active ingredient is taken up through the roots and will make the plant's juices toxic to mealies and armored scale. My preferred choice is Bayer Advanced Complete insect killer with 0.72% Imidacloprid. Ratio is 1 tablespoon Bayer Advanced per quart of water thoroughly mixed. Don't know what you can get in Australia, but any of the "cloprids" (for example, Thiacloprid) will do. One application is generally sufficient to knock down infestations for the rest of the growing season. My only caution would be to keep any systemic-laced runoff from getting into your garden soil since neonicotinoids have a negative environmental impact on bees. If that's an issue you'd have to deal with, capture the runoff in an empty jug and dispose of it through a local home hazardous waste center. We have them all over the place in L.A., although once again I don't know if you have easy access to one in your area. I know it seems like kind of a pain, but IMO it beats the heck out of endless spraying.

[james2815]

Thanks again for your reply. Would a general garden store stock that? I think i might go for that idea sounds better than spraying. Is there any down side effects for the cactus?

[Steve Johnson]

Thanks again for your reply. Would a general garden store stock that? I think i might go for that idea sounds better than spraying. Is there any down side effects for the cactus?

The answer to question #1 is yes. Just be sure to look at the product label and verify that it contains a cloprid. My math is lousy when it comes to converting standard (English) to metric, so hopefully you can figure out the proper conversion from my dilution ratio to yours. The answer to question #2 is a qualified no -- potential phototoxic reactions are a problem you'd have only with sprays. If you use a soil soak, the only down side might be with persistent application of a neonicotinoid since it can lead to pest resistance in mealies and armored scale. However, I emphasize the word "might", and I don't honestly know how common pest resistance is in cacti. To be on the safe side regarding that issue, I would avoid using it constantly just as a preventative.

Please let me know if all this works well for you!

[james2815]

Awesome. Will go to my local garden store this saturday ( work till late). Should be able to covert got a conversion app on my phone. Thanks for your help! Will keep ya updated when i give it some:-) just another question will you start to see results within a couple days?

[Tony]

I don't see any bugs either. Did you attempt to remove any of the scars/bugs on the plant? Scars will not come off easily but scale will. Is the damage on the upper most sections of the stems or down low? Could be corking on older stems if it is down low on the plant and or damage caused by the spines when the wind blows the stems into each other.
If you do confirm there are scale insects present, they can be removed really easy with a high pressure nozzle attached to a hose if you don't want to use pesticides.
You just have to be sure to get all of it.