It must be petal blight problem. Fungus infected petals would show the brown color. The diseased petal would grow into mature fungi on the ground to produce millions of spores next year. There is no effective way to eliminate problem. Picking up old flowers, keeping ground clean and timely spraying the environment including the plant might help some.

Thanks for the reply. Would a fungus issue be specific only to white camellias? Most of the whites I've observed in my neighborhood are growing alongside various shades of pink and red camellias that don't exhibit any signs of disease. When they're not in bloom, the whites appear to be no less healthy than their pink/red neighbors. It's curious . . .

Whites show cold or frost damage more readily.

Dear windeaux,
Sterling Macoboy's _The Illustrated Encyclopedia of Camellias_ should help you to identify many white _Camellia japonica_ cultivars, both new and old. _Camellia Nomenclature_, though unillustrated, would also be worth taking a look at.

We have several older white camellia cultivars that perform pretty well in an average Zone 7b winter. 'White Empress,' 'Coronation,' 'Leucantha,' 'Victory White,' 'Imura,' 'Finlandia,' and 'Shiro Chan,' ('Snow Chan') do very well for us. 'Yuki Botan' ('Pride of Descanso') is also a stunning white camellia with huge white semi-double blooms with petaloids. 'Alba Superba' is another truly fine older camellia. These varieties have been around for decades but are still available in the camellia trade. 'Leucantha' is a white sport of 'Tricolor Sieboldii' (sp.?); therefore, its blooms have the heavy, waxy substance of the parent plant. 'Shiro Chan' ('Snow Chan') is the white sport of that famous historic cultivar 'Elegans Chandlerí,' or Chandler's Elegans. 'Coronation,' named in the year of Elizabeth II's coronation, also has large blossoms with a heavy texture. These cultivars are not new but are worth considering for outdoor cultivation.

The flowers of Camellias with white petals, are very sensitive to the atmospheric changes. With the Sun and the cold winds, the petals put of brown colour.

To the flowers with other colours, it does not affect them so much. Also, the petals of flowers with dark colours, it is more difficult than estimate the effect of the Sun and the wind.

I believe that the Sun is the principal problem of the white flowers. Longriver writes on a very bad disease. The disease, " Ciborinia camelliae ", is very bad for the camellias. With the wind, the spores of the mushroom, it spreads to many distance.

I put a few photos of an example of the effect of the Sun in white Camellias.
Regards.
Daniel D.F. oKintos

Camellia japonica ÂMathotiana Alba Group (4)
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Camellia japonica ÂMathotiana Alba Group (2)
Camellias in the shade.
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Camellia japonica ÂMathotiana alba Group (2)
Camellias in the Sun
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Camellia japonica Cv. ÂMathotiana AlbaÂ
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Here is a link that might be useful: Salceda de Caselas Camellias Show

I have had the same problem with my white camellias. Daniel oKintos has stated what a camellia grower has told me. Many of the camellias have very delicate petals, and show sunburn very easily. They can also be damaged by dramatic temperature changes. A cold snap follwed by direct sun on the flower can cause the browning you describe. I love white camellias, and in any future plantings of them, I'll have to be more careful of the planting site.

Sandy

This one group of camellias in the sun. His flowers, sometimes they meet affected by late frosts. They form a hedge of camellias. It is a place of zone 8.
Regards.
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Camellia japonica 'Paolina Maggi' (White)
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Here is a link that might be useful: 2009 International Camellia Show