Sick trident maple advice

[Shills]

Hi,

My trident maple's leaves have slowly being turning dull, dry, dusty and spotty . I was hoping someone here might have a suggestion for what is going wrong. Please see the photos included and I have supplied some other info below:

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In the photos you can see that there is usually a tuft of healthy growth at the end of the whips but the leaves along the stem have gotten sick. The leaders still seem to have healthy growth too.

-This tree is at the end of the grow pot stage and I was starting to do trunk chops and think about form. I trunk chopped early November 18 without any problem.
-I then foolishly left the tree in the bathroom for 2 weeks with a slow dripping tap to water it while I was overseas. The soil was very moist when I returned and most leaves had died. However I reported it, removed some of the roots I thought might be at risk of rot (it looked okay with no smell) and the plant sprouted new growth fine enough.
-The month of December and January have been pretty hot (Rhodes, Sydney) and very different from the conditions the tree had for most of its life (in Randwick eastern suburbs). I think a potential large problem is the fact that the tree only get direct afternoon sun from about 2:30pm and that sun, plus the heat we have been having is pretty severe, so I have just started using a shade-cloth (50%).
-I water with about 5L everyday if hot, and the soil is supposed to be quick draining (and does run out the bottom).
-have been using Thrive fertiliser weekly.

Any help is much appreciated!
Thanks so much.

[Beano]

Very good description of how the tree is kept. Direct sun from late in the afternoon and Sydney being humid occasionally along with the mottled leaf and your description of fuzz make me think it has powdery mildew. Extra damp conditions, poor sun and poor air circulation promote its growth. Also it’s self defoliation from being kept inside for 2 weeks, then repotted, might have stressed it a bit, increasing its susceptibility.

[shibui]

My thoughts exactly Beano.
A bit more sun if possible and more air movement would be good.
I've heard spray with milk can deter mildew but a fungicide from the nursery would probably be a better bet.

[Shills]

Thanks for your tips Beano and Shibui. I will start using some fungicide and see how that goes.

Also, even though lack of sun could be an issue, would you suggest limiting sun (even more so than my 50% shade cloth) because often sick tress need to be shaded?

Cheers for that!

[shibui]

That doesn't make much sense. We suggest that lack of sun may be causing the problem and you propose limiting sun even further

The current leaves are already damaged. They probably won't recover but any new ones that grow need to be healthy. Give them the sun they need to be healthy. Sun is good for trees, even sick ones. Just make sure you manage the water accordingly. Water well but only when the soil starts to get a bit dry. With the damaged leaves it may not be using a lot of water now but as new leaves grow it may begin to need more so check every day. If you have not been feeding this tree I think it could also do with some fertiliser to help kickstart recovery.

[Shills]

Thanks, yes that makes sense Shibui. I asked because I have read that some times a break from sun is good for sick plants, but in this case lack of all day sun is one of the likely culprits so taking the tree out of sun doesn't make sense.

Will use fungicide and fertilizer and see how it goes!

[KIRKY]

If it was the beginning of the season you could defoliate all the leaves and liquid feed and place in full sun. However as Autumn is around the corner it will soon lose all its leaves anyway. Suggest you treat it with a sulpha spray in winter make sure you also spray the top of the soil this will help kill the spores. I do this with my English Oak that are prone to mildew too.
Cheers
Kirky

[Beano]

Not only that, but it hasn’t had sun for all that time you were away as well. More sun better for both reasons. But I know what you mean, some books etc say don’t put a stressed plant in full sun. Yes it is stressed and yes, putting it in full sun now might actually cause the leaves to get sunburnt but sunburnt leaf edges can still photosynthesise. They just look ugly. But then the tree will respond with new leaves because it has been able to photosynthesise and produce itself some energy.

Most tridents can look a bit shabby in summer from sunburnt leaf edges anyway. So I’d say put it in the most full sun you can get at your house and ditch the shade cloth. You will need to pay attention to the soil dryness as per shibui’s suggestion.

[Shills]

Thanks for ideas guys. Fingers crossed the tree gets better quickly.

[Shills]

Hi,

I just wanted to give an update on the results of my treatment of the sick tree--so we can all learn what appears to work in these situations.

So I did what some of you said and gave it as much sun as possible and withheld water a bit. In hindsight, I was watering too much given the conditions.

I sprayed about 6 times over about 40 days with liquid copper and anti-rot (both from Yates) and I feel that the anti rot worked the best (I stopped using liquid copper after 3 goes). Maybe it is the 'systematic' aspect if the anti-rot that is the key. I really drenched every leaf top and bottom with the ani-rot and than any left over I tipped in the soil.

I gave it good feeds. Slow release and liquid. As the new buds came out I defoliated the ugly infected leaves.

Now the tree looks pretty good with nice healthy leaves.

So I think the key points were giving the tree good sun and less water. The shade and water may have been what lead to the infection. I think the anti-rot did a good job on the mould and so far it looks close to 100% gone, so I'm happy with that.

Cheers for your help guys!

[shibui]

Thanks for the update.
Hard to attribute the changes to any one of the treatments or any combination. Tridents are normally really resilient and may have recovered even without the fungicide but it is great to hear the tree has returned to health.

Biggest lesson I think is try to give trees the best conditions to prevent problems in the first place.