Sick Echinopsis pasacana
Sick Echinopsis pasacana
Hello! Can anyone identify what’s wrong with my Echinopsis atacamensis/pasacana? It looks to me like fungus, but I’ve never seen something exactly like this before on any of my cacti. I live in the Midwest USA, and it is awfully hot and humid here during our summers, but this condition developed relatively recently, when the humidity and heat have decreased drastically. This cactus is currently in my basement under pretty strong grow lights, almost no water since early October, roughly 65 degrees F, and good circulation. Thanks for your help!
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Re: Sick Echinopsis pasacana
Hello MeloMet,
there is a good reason for you not having received any response to your digital images. I am not sure myself about what could have caused those distinct circular lesions. At first glance I thought, that those off-white spots were the armored scale insect Diaspis echinocacti. However, they looked larger than this scale insect, unless your cactus is quite small. Could you measure the largest spot and tell me the diameter either in millimeters or fraction of an inch? If they are more than 2-3 mm, this is not an insect. You could also use a probe (needle) and gently try to lift one of these lesions off the cactus. If it is a scale insect, it will easily be removed that way.
Are the lesions evenly spread around the cactus or present only on one side?I do see what seems to be a slightly discolored and raised boundary around some of these spots. That would be an edema and might indicate a pathogen or some other kind of irritant. The lesions seem to be too small for a fungus at this stage of development. If you are dealing with a pathogen, the lesions should enlarge and also spread all over your plant. Has anything changed since you took the images?
When you do examine one of these lesions closely, is there a hole in the center? It seems like all do have a darker center. This could indicate, that something did pierce the epidermis of your plant. It could have been a feeding insect with a sucking mouth part or perhaps mechanical damage.
There are a lot of reasons why a plant does not appear to be doing well. Judging correctly what caused the malaise is oftentimes not possible using a digital image. Even some of the highly magnified images I send to our National Mycologists are inconclusive. The grower does have to play detective a bit and take into consideration anything that she/he has done before these symptoms appeared. Plants do respond to a number of things and unless these are known (told) to a plant pathogen diagnostician, it is sometimes highly unlikely to arrive at a valid diagnosis.
Harald
there is a good reason for you not having received any response to your digital images. I am not sure myself about what could have caused those distinct circular lesions. At first glance I thought, that those off-white spots were the armored scale insect Diaspis echinocacti. However, they looked larger than this scale insect, unless your cactus is quite small. Could you measure the largest spot and tell me the diameter either in millimeters or fraction of an inch? If they are more than 2-3 mm, this is not an insect. You could also use a probe (needle) and gently try to lift one of these lesions off the cactus. If it is a scale insect, it will easily be removed that way.
Are the lesions evenly spread around the cactus or present only on one side?I do see what seems to be a slightly discolored and raised boundary around some of these spots. That would be an edema and might indicate a pathogen or some other kind of irritant. The lesions seem to be too small for a fungus at this stage of development. If you are dealing with a pathogen, the lesions should enlarge and also spread all over your plant. Has anything changed since you took the images?
When you do examine one of these lesions closely, is there a hole in the center? It seems like all do have a darker center. This could indicate, that something did pierce the epidermis of your plant. It could have been a feeding insect with a sucking mouth part or perhaps mechanical damage.
There are a lot of reasons why a plant does not appear to be doing well. Judging correctly what caused the malaise is oftentimes not possible using a digital image. Even some of the highly magnified images I send to our National Mycologists are inconclusive. The grower does have to play detective a bit and take into consideration anything that she/he has done before these symptoms appeared. Plants do respond to a number of things and unless these are known (told) to a plant pathogen diagnostician, it is sometimes highly unlikely to arrive at a valid diagnosis.
Harald