Cactus and Succulents forum: leaf miner or disease

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Name: Sherry Austin
Santa Cruz, CA (Zone 9a)
Region: California Irises Keeper of Poultry Roses Dragonflies Birds
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Henhouse
May 24, 2018 8:54 PM CST
My daughter has this weird brown "etching" on her Crassula multicava. Both tops and bottoms of the leaves. It's also starting on her Aeonium. This is in Capitola, CA. I've never had this problem.. It looks like something is eating/scraping the outer layer.. Any ideas?

Thumb of 2018-05-25/Henhouse/42f799 Thumb of 2018-05-25/Henhouse/1ed01d
Thumb of 2018-05-25/Henhouse/a65155

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Name: Baja
Baja California (Zone 11b)
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Baja_Costero
May 24, 2018 9:18 PM CST

Moderator

Can't speak for the first plant but the second one looks like straight up sunburn. Is it getting a lot of direct overhead sun right now?

Name: Sherry Austin
Santa Cruz, CA (Zone 9a)
Region: California Irises Keeper of Poultry Roses Dragonflies Birds
Bulbs Foliage Fan Photo Contest Winner: 2015
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Henhouse
May 24, 2018 10:36 PM CST
I'd be surprised if it's sunburn on the Aeonium, but the pictures look very similar. I"m wondering if she got water on them and the sun magnified it. These are in two narrow beds going up to their front door. The Aeonium gets morning sun until about 12-1 this time of year.. and they get a lot of fog where they live. The other side w/ the Crassula gets less sun. They've both been there for a few years w/out showing anything like this.
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Georgia (Zone 8a)
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Hamwild
May 25, 2018 3:46 AM CST
Henhouse said:I'd be surprised if it's sunburn on the Aeonium, but the pictures look very similar. I"m wondering if she got water on them and the sun magnified it. These are in two narrow beds going up to their front door. The Aeonium gets morning sun until about 12-1 this time of year.. and they get a lot of fog where they live. The other side w/ the Crassula gets less sun. They've both been there for a few years w/out showing anything like this.


I read recently that the whole water/magnifying/sunburn effect is a garden myth. Smiling
Name: Stefan
SE europe(balkans) (Zone 6b)
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skopjecollection
May 25, 2018 3:52 AM CST
The magnifying lens part is a myth. Water causes sunburn because of pores on the surface -pores which open mostly at night, or when wet. Or damaging the glauscent bits.
[Last edited by skopjecollection - May 25, 2018 3:52 AM (+)]
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Name: Baja
Baja California (Zone 11b)
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Baja_Costero
May 25, 2018 11:41 AM CST

Moderator

Sherry, morning sun and lots of fog would not typically sunburn that Aeonium. We are coastal here and there's a whole lot of fog, especially morning fog. That fog is a great buffer against sunburn. The plant in my picture only burns at the end of the summer (the photo dates from late August) because that's when we tend to have the least fog, actually. In any case the sunburn will fade over time as the affected leaves are replaced by normal new ones, so I would view it as an indicator but not an actual problem.

I would not know what the dark spots would be otherwise. My instinct going just based on appearance is that it's sun, and not a big concern. The idea of water drops magnifying light is interesting but I don't see it as a real possibility given the water would not stick around on those leaves long enough to have that kind of effect. If those leaves are still wet over that big an area after watering, they are not getting nearly enough light or air flow, or something very strange is going on.
Name: Sherry Austin
Santa Cruz, CA (Zone 9a)
Region: California Irises Keeper of Poultry Roses Dragonflies Birds
Bulbs Foliage Fan Photo Contest Winner: 2015
Image
Henhouse
May 25, 2018 8:03 PM CST
Thank-you all..
I took the picture of the Aeonium yesterday, so it just feels early in the year for sunburn.. I'm not discounting it completely, but a little skeptical given the weather so far this Spring..
Interesting to hear the debunking of water magnifying the sun and burning.. I probably learned that 45 years ago..

I'm more concerned about the Crassula.. It takes up most of those beds by her front door. I would think that slugs & snails would be taking chunks out of the leaves, so I've ruled them out. My gut instinct is to tell her to cut the plants back, spray with insecticidal soap, and put out an all purpose insect bait. ..Or cut back and treat with a systemic.. which if it's spider mites, would probably be more effective. I didn't find any insects or mites when I looked, BTW..


The surest sign that intelligent life exists elsewhere in the universe is that it has never tried to contact us.
Name: Baja
Baja California (Zone 11b)
Cactus and Succulents Seed Starter Foliage Fan Xeriscape Container Gardener Hummingbirder
Native Plants and Wildflowers Garden Photography Region: Mexico Plant Identifier Forum moderator Plant Database Moderator
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Baja_Costero
May 25, 2018 9:07 PM CST

Moderator

It's not spider mites. They hate the humidity. I have never seen a spider mite here and our humidity averages 70-80%.

I would be more concerned about the jade. No ideas really other than it's not a good match for the insect damage that I've seen... insects tend to leave tracks or trails or bite marks or some kind of clue like that, and I'm not seeing it. They also tend to prefer the soft tender new parts and the stem at the base of the leaves.

Definitely consider this an opportunity to prune. Even more so when a particularly brown part can be surgically removed, or you want to shape the plant in a particular way. If you use the systemic be sure to water it in well, maybe in a few passes, so it gets to the roots most effectively. It will probably not cure the currently affected leaves, but it should make a difference with the new ones, if this is an insect thing.

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