Is This Leaf Pattern on Camellia and Gardenia a Disease?

6 years ago

last modified: 6 years ago

I have an in-ground gardenia next to an in-container camellia. The camellia has some minor leaf discoloration appearing, and I want to check if this could be a disease.

The first photo shows two leaves from the camellia. One is developing a brown tone. Eventually, the leaf will be consumed by that brown discoloration. The second leaf from the camellia - in the first photo - shows a white section that is equally white on both sides. It is a very discrete area, almost like a chemical burn. Affected leaves will have two or three white spots like that.

The second photo shows leaves from the gardenia. About 5% of the plant has leaves like that, so it is wider-spread. Maybe whatever the gardenia has was given to the camellia?

Does any of this show a disease, and how do I treat that?

Featured Answer

luis_pr

6 years ago

last modified: 6 years ago

Soil that is alkaline is tolerated by gardenias but only up toa point. When it becomes too alkaline, the leaves turn light green or yellow, except for the leaf veins which remain green. At this point, it is advisable to acidify the soil using some garden sulfur, greensand or iron-chelated liquids (sold in most nurseries). The pics do not show that condition.

As for gardenia leaf yellowing, just about anything makes them yellow out the leaves, especially when they are potted: too much shade, watering too much, temperatures getting too low or dropping from very high to very low, the presence of pests/insects, just before leaf drop, root injury when transplanting, etc. I usually ignore the yellowing (of a few) unless the plant looses a large percentage of leaves to yellowing (10-20% of the whole shrub say?). I always start by checking sun and water issues; then check for pests; then check recent weather changes. Remember that it is summer so you should be watering it more than in Spring.

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Comments (7)

luis_pr
6 years ago
last modified: 6 years ago
These two things do not appear related except time wise.

What information can you supply about the camellia soil? Have you tested it regularly to make sure it is not dry or soggy? You can do this by inserting a finger into the soil to a depth of 4". Then determine if the soil feels dry, moist or soggy/wet. This time of the year, when temps start to exceed 85F, many plants react to heat, low humidity, too little water or too much water.

The white lesions that look like little paint drops, can you look at them with a lens to see if they are fungi? Sometimes one can tell by looking. Watering of the leaves (should not do that) or watering too much can make the environment nice for fungi.

I assume there is nothing going on on the back of those two leaves? Also, where is the pot located? From what hour through what hour does it get direct sun?

Is there any chance that you have fed too much fertilizer to the azalea? Exceeding the amount suggested in the product's label's directions can cause accumulation of salts and salt burn. Then the leaves look like that. Their roots are tiny and fibrous so try not to feed them too much.

Azaleas do not need more than one fertilizer application per year, provided the soil has no issues (like being sandy or mineral deficient, for example). And once established you can quit fertilizing and just let them feed off the decomposing mulch.
westes Zone 9b California SF Bay thanked luis_pr
westes Zone 9b California SF Bay
Original Author
6 years ago
@luis_pr The white spot on the camellia goes straight through the leaf to the back. It is not paint. It is more like a chemical burn.

The camellia is in a temporary container and the soil seems appropriate. I finger-test it to make sure it is not getting soggy.

The azalea was never fertilized so probably that is not the reason for the burn.
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westes Zone 9b California SF Bay
Original Author
6 years ago
I am embarrassed to say that the plant I thought was an azalea was actually a gardenia. Does anyone have an insight into the yellowing leaves I posted of that gardenia? I guess I could suspect the soil is too alkaline? How could I treat that?
Meyermike(Zone 6a Ma.)
6 years ago
What kind of water are you using for that gardenia?

Mike
westes Zone 9b California SF Bay thanked Meyermike(Zone 6a Ma.)
westes Zone 9b California SF Bay
Original Author
6 years ago
@meyermike Our city water tests at a pH of about 6.2. I do not treat it in any way.
Meyermike(Zone 6a Ma.)
6 years ago
last modified: 6 years ago
Yeah, it's not the acidity I would be concerned about but the salts that eventually accumulate in the mix and kill the roots. Gardenia are notorious for needing rain or fresh water untreated, very low in salt content. That is why I use only rain water...I can't grow one using tap, nor most of my tropical s unless the mix is very very porous or with very little peat.
westes Zone 9b California SF Bay thanked Meyermike(Zone 6a Ma.)