Thank you. I think it is fine that Gasteria get a few spots. Of my many only a few get a few spots, which they seem to have a natural defense against. If we want to grow Gasteria that is what we have to live with, but this particular one is worse than any of the rest.

The only reason it looks as good as it does, is because of the spraying. If I did not spray, it would be completely covered.

Most of my plants get new soil each year. Maybe back in the same pot, but fresh soil, free of salts.

Sounds like you are in the same boat as me, being in the PNW. I wonder if all the humidity is allowing the black spot to thrive on your bicolor. The are from places with very low humidity.

It was the same during the summer. It's just this one that gets it like this. I only have two other plants that get bs, a Gasteria bicolour (got one spots) and a gasterloe (got some more). But, both of them got a couple spots and cleared up right away. But this one.

I am contemplating taking off the two babies that has no signs of disease. Growing them away from mama to see if they are just as bad. As clones they should be the same, but you never know.

If I were you, and I realize I am not ;-), I would throw that plant out. Why spray all the time for one plant? It is cute, but so are others. My absolutely favourite rose grows fine for many people, but for me it always gets rust. I have tried all natural and cultural methods to keep rust away, I have tried growing new plants of it in a different spot, it goes well for a year or two, and the rust is back. So I “spade pruned” the last one. Sorry ‘Heritage’! I would do the same with that Gasteria.

I would think using organic ways to prevent the disease is the best way forward. People have companion planting to prevent aphids. Also, air circulation, temperature and moisture levels could be tweaked.

Whatever you do, don't give it to a friend. I would look for new ground. Saw an episode on busy lizzy which had been blighted and was totally decimated. They introduced a new cultivar which surpassed the disease-prone one in every aspect. That can be a solution.

If you're aiming for a national collection, you probably have to quarantine that one. It might be a good idea to contact specialist suppliers of the plant and see how they tackle the problems. Most gardeners try to mimic the conditions where the plant originates from.

@MYAL plantLOVER it doesn't matter the conditions of this one plant. It gets great air circulation in every spot i have had it. It is never overwatered. The air is fairly dry. The potting soil is very well drained. It is treated no worse than the other 10 or more Gasteria or xGasteraloe. The only organic options I have not tried is composting it.

Can you explain the following? I don't understand

• 'Saw an episode on busy lizzy which had been blighted and was totally decimated. They introduced a new cultivar which surpassed the disease-prone one in every aspect. That can be a solution.'

How is buying another plant going to help this plant get better? I have other cultivar of Gasteria bicolor. They do not have this same problem.

I wasn't talking about your Gasteria in specifics. What I was saying was that gardeners have increasingly been encouraged to focus their efforts on new improved plants. If you know that a certain cultivar will give you sudden death, you break new ground (I would anyway!) - get an improved version. However, if you want to keep the specific gasteria as it is an heirloom, you can do so.

I would not compost it as the disease could go to the soil. Perhaps, let the binman take it as green waste and they might treat it under high temperature or burn it yourself.

gg,

Those usually happen from cultural conditions, IME - too much water, not enough sun/air circulation and/or soil not porous enough.

A good starting point would be to identify which particular condition this is and then use that key information to read up on what, specifically is supposed to help - it isn't, of course likely to be the same fungus that causes black spot of roses.

@MYAL plantLOVER Thank you. I think you are right effort should be focused on supporting plants with better vigour.

@Embothrium it is the same bs that infects roses, but as you know some roses will get bs under ideal conditions. They just lack the immunity to fight it. I believe this Gasteria is no different.

@cactusmcharris, interior BC Z4/5 It is NEVER over watered. It is never crowded. It always has extra air circulation. I have done lots of research on growing Gasteria and I have have many Gasteria.

Below is the only conditions that can be improved, but even when he was under these ideal conditions he got bs.

The only condition that could possibly be improved, which is hard this time of the year is the lighting. The sun hasn't broken through the clouds in days, but prior to that we have two weeks of sun. He's now in a south-west window. My two better windows have Gasteria I do not want to infect. I would love to try him under my nice new grow lights, but they have too many Gasteria and many Aloe that might get infected.

I wont turf him yet, but he may go outside (out of the rain) year round. Unless we get colder than normal conditions I can protect him outside. I just can not protect him from the humidity. Not outside.

More than likely, I will keep him inside. I will not do the preventative spray, except for maybe Rapsody. Rapsody (Serenade) is a bacillus subtilis bacteria that feeds on fungus and does a good job on roses. But, not the best on treating bs, best when used as a preventative.

it is the same bs that infects roses

You have background information supporting this determination, or you just think the condition looks the same and must therefore involve the same organism?

Hosts

Rose species. Common on hybrid teas, grandifloras, and miniature types.

https://web.extension.illinois.edu/hortanswers/detailproblem.cfm?PathogenID=6