I would be grateful for help in identifying what the problem might be with my Camellia hedge. I believe it may be some kind of fungal problem (see attached pics). I would be grateful for help in identification of the problem so I can eradicate it.
For background: We bought our home with the hedge already in place 4 years ago. I believe the hedge to be approx. 5 years old. Since we have owned it, we have regularly watered (a good soak approx. once per week), fertilised with slow release granules as per the instructions on the product (specific to azaleas and camellias), composted and mulched as the season demands. The hedge surrounds two sides of our garden, one section had much more sun than the other as it backs onto a tin shed. I have lost all of the trees near the shed and at the time I put this down to the area being far too hot for this type of plant - although the same fungal problem was also found on that section of the hedge. The shaded hedge, the only section now left, has done much better in that it has lasted a season longer - but I recently lost two trees from this section as well. The leaves discolour and then the branches die back. In an effort to stop infection spreading, I recently removed all the trees showing this same problem and stripped the soil back and replaced it with new soil and mulch.
My immediate reaction was the same as Paul's...this would be scorching of some sort, either poor watering (too much or not enough) or, more likely from your description of weekly good soaking, which sounds good...a problem with the water you're using. The fact the hedge has declined after many successful years makes me suspicious of salt, minerals or bicarbonate in the water which has gradually degraded the soil. Can anyone test your tap water there, or does your utility have that info, (assuming it's municipal water and not your own well).
Rain water would always be very good for your camellias if there was any way to collect it, say from your gutters.
Paul and growest: Many thanks for your thoughtful replies. You have inspired me to try testing the soil and separately, the water, to see if there are any issues I need to consider. I do have access to tank-water so will start with changing the watering regime on these particular plants. I do have many other camellias in the garden, but none display this same discolouration of the leaves. With reference to my photos, should I be concerned about the black mould type stuff on the underside of the leaves and the grey/white fungal looking stuff on the tree trunk? Or do you think these are secondary reactions to the initial problem? Actually, come to think of it... Could lime be the problem? I used some on the lawn beside this hedge some time ago.
The leaf mold does look secondary, resulting from the death of that tissue which then has no resistance to decay organisms like the mold fungus. I wouldn't focus on that, nor on the trunk, which is normal stuff in our wetter climate here...that also shouldn't hurt the plant at all.
Lime isn't generally recommended around camellias...same as for rhodos and other such woodland type shrubs...tho all plants do need some calcium which the lime contains. A soil test might clear this up quickly...tho getting rid of high pH and excess salt is not as easy as raising pH or adding more salt, smile...!
Definitely use your tank water for starters...it will start to wash out excesses from the soil if you are watering deeply enough to be draining right down past the root zone.
Your mild winter climate might be even better for camellias than mine, but your dry hot summers are a challenge as well, especially with the droughts you folks have been battling for many years now. Tho our summers are very dry generally, we do always have dependably enormous winter "monsoons" that can leach all excesses out of our soils pretty quickly here. You might have to duplicate that leaching a few times a year with collected rain water to keep camellias happy there...otherwise I bet yours look awesome in bloom...without frosts and showers expected like we usually get here, groan...
if you can take the time, wipe off all what you see with cottonwool soaked in Methilated spirit...or buy a bottle and usually a small hand sprayer will fit bottle and spray it all over...stems too, normally start in leaf axils..if you remove too many leaves,it probably won't be able to grow them back this year,but you can ...the most infested ones.. also give it a sachet of Sequestered iron, it's a kind of conditioner and also still feed it ...best is a 10-12-27.