They look like the natural aging of blossoms to me. Unless this is how your brand new blooms appear, this looks normal.

I have a nature instinct. If I can not tell what is, I will do a simple study to find it out. The petal rim area is not right. Try:
You might try to select a long branch with a nice size flower bud, showing no petal.
2. Spray it with household sanitizer (not chlorine nor acid base) and later rise it with a fresh bottle water.
3. Then use a large ziplock bag loosely to enclose the flower.Then shade the bag with layers of brown bag.
4. secure the set up with a few cloth pins.

Eventually the flower will be open in the bag, You may even see the flower without openning. I do not want guess the result. You may find that it is possble.better or the same. Then you may draw some conclusion.

Looks to me that it's normal aging of the flower.

To determine if so, answer these questions:
- how long has the flower been open?
- was the damage present when the flower first opened?
- are other flowers on the bush normal?
- or all the flowers affected the same way, and at all stages of growth?

Hello,
Thank you so much for your suggestions and opinions. I am still puzzled. The flowers do not appear to be normal to me. The buds are already touched by whatever it is. They start yellowing almost stright away. And when they are fully opened - well they look just like on my photos. Some buds have no chance to open.They simply drop dead.
I do not get rain- not enought of it, anyway. I tend to water it once a week or so. It is well mulched and was fed few weeks/months ago.

Last year it looked OK.
Am I panicking for no reason?

Regards
Teska

I dond't know your conditions -- weather or soil -- so I don't know if watering once a week is enough or not.

If it's in a pot, very unlikely.

If in a ground, check the condition of the soil one hour after you water. Is it moist, dry, or wet? And how deep?

take a look at the link below and see if your plant's symptoms match these. camellia petal blight is a problem in my area because of high humidity and wet springs.
how's the weather in new south wales?

Here is a link that might be useful: camellia petal blight

Jeff,
thank you very much for this link. I think you may be right about my camellia being under attack of petal blight. I will change mulch. I am a bit reluctant to use chemicals.My garden is an organic garden and I try to keep it free from strong chemicals.
But if it is the ONLY way to save my sick camellia- then be it.
You asked about the weather in NSW. We do not get a lot of rain. It is true that it rained few weeks ago for about few days but frankly, it was not enought to cause a damage to any of my plants. The soil is very dry.
Humidity? No, I am afraid I am not exposed to it. We are in the middle of Australian winter. Hence few frosts but not very significant.
I wonder- could the same problem be caused by insufficient amount of water in the ground? With current water restrictions in NSW I can water it only twice a week. Is this enough?
My other beautiful camellias are doing great and drink only a teaspoon of water (compering to the sick one). They are very healthy and happy.
I invite you to have a look at thumbnail photos- to enlarge them just click on them.

Thanks for helping !
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Very good shot of pictures. I take a close look at the flower and it does not appear to have petal blight idendity. Then it could be the other factor. "May be" the soil down below is very dry. Please use a small shovel to dig about 5 inches. If the soil is getting drier, Then you know. Purely guessing!

Your blossoms don't have camellia flower blight. With that disease, the browning begins in the center of the petals. In your flowers, the browning is at the tip of the petals.

Beyond that, even if your plants did have camellia flower blight, the treatment does little to affect/limit the problem.

I still think your plant is dry for whatever reason, be that dry soil, a root problem, excessively low humidity, wind, or whatever.

compare a damaged bloom to the one in the linked photo.
look for the grey/white ring of mycelium around the base of the calyx.
i really don't know that this is your problem but it sure looks suspicious to me.

Here is a link that might be useful: link

I'm pretty sure we don't get flower blight in Australia as I've only ever read about it the American literature.
I have blooms with this problem too. I've always put it down to dew affecting the blooms prior to opening. I suspect that as the plants get bigger they'd be naturally more protected by the greater foliage area.
Some blooms "ball" and drop before they open.

Also, some varieties (of Japonica in particular) are naturally more affected by these kinds of problems.

Cheers,
Max

Does this bush get morning sun? Could it be frost damage?