Red leaf spot / leaf curl, in River red gum

[Fluorine]

Hi All,

Just seeking some help on a remedy for my dreaded problem. I've recently noticed on my river red gum, that new leaves develop red spots or blotches and start to deform, they tend to survive the ordeal but end up sickly-looking before dying off, just as they are about to harden. I'm not game to apply any fungicide at the moment if it is fungal, only because the temperatures are in excess of 35 degrees at the moment. Is it something I should be concerned about? Any help would be great.

Plant: E. Camaldulensis
Soil: 50% river sand / 50% native mix. Last repotted December 2014, was hoping to not have to repot until next summer.
Feeding rate: ~ 1 in 2 weeks, with a liquid feed and 6 monthly application of slow release fertiliser.
Watering: timer set to 2 times a day in summer, morning and night. I also give it an additional drink if I feel it needs more.


Your help is much appreciated

[KIRKY]

No mention of fungus here is what I found on Diseases and Pests
Due to widespread planting and use, considerable disease and pest information is known about this species. It has low to high susceptibility to insect attack, depending on provenance and individual, but sapwood is susceptible to attack by lyctid borers.
Riverine provenances are damaged by sawfly (Perga spp.), gumleaf skeletoniser (Uraba lugens), Christmas beetle (Anoplagnathus spp.), psyllid/lerp (Cardiaspina spp., Glycaspis spp.), leafblister sawfly (Phylacteophaga froggatti), leaf beetle (Chrysophtharta spp., Paropsis spp.), shothole miner (Perthida sp.) and cup moth (Doratifera spp.).
Inland provenances e.g., ‘Silverton’, ‘Flinders Ranges’ and clones are more resistant to lerp and leafblister sawfly, but susceptible to sawfly, gumtree hopper (Eurymela spp.) and tip-feeding bug (Amorbus spp.).
Disease and pest problems may be reduced by careful selection of provenances and by minimising environmental stresses through watering and adequate nutrient status, with fertiliser used where appropriate.
Perhaps an insecticide spray and put it in the shade for a few days, if you are worried about leaf burn.
Cheers

[shibui]

Camaldulensis usually survives these problems. Mature trees are often regularly defoliated but still regrow.
I think it is probably insect attach, possibly 2 different things. I'd try a systemic insecticide like confidor and see what happens.
Assuming there are other eucs in your area these pests will keep coming in so regular treatment will probably be needed.

[KIRKY]

"systemic insecticide like confidor"
If you don't want to spray confidor does come in tablet form. Pricey though. Not sure how they work, or how long it takes to activate in this form. Perhaps someone here has tried them and can offer some details on them.
Cheers

[bamboos]

Hi Flourine
Looks to me like myrtle rust the only colour I have seen is orange not red but the leaf distortion are the same and the end result is similar. As the disease progresses it turns to orange coloured pustules on the leaves
Confiding tablets are terrific where you need systemic insecticide but I think this is fungal
I have found the only thing that works for me is triforine at recommended dose sprayed weekly until you have control the once a month for the rest of the year ( excluding winter)
Myrtle rust only affects the myrticea family which includes Eucs mels etc and was introduced a few years ago and started ( I think) on the central coast of nsw
It is about the worst disease we have! And will kill the tree in the end
Steve

[Fluorine]

Thanks all and thank you Steve. I fear you may be right. I recently bought an E. Leucoxylon and had it sitting next to my River red, both plants did end up with the same issue. The river red was quite healthy prior to my new purchase. Anyhow, deductive logic tells me I most likely brought the fungus in to my backyard. Lesson learnt, it's off to buy some fungicide. I've cut it back hard now, but will still apply the fungicide and keep you posted.

Cheers, Fluorine.

[bamboos]

Hi Flourine
There is no need to remove infected leaves just spray the trees all over with triforine ( it's used for black spot on roses ) it will get the outbreak under control quickly . Spraying has to be done every week for 2 or 3 weeks then monthly to keep the rust away.
Steve