How to revive sick trees?

[E-mck01]

Hi, I have two sets of trees in my garden that are currently not doing too well - the first I have identified as a robinia mop-top (I think) and the other I can't figure out myself (they are evergreen trees).
I have noticed on the mop-tops that leaves are going brown but not dry, and that they are just in general looking a bit unhealthy. There are some other symptoms as well, shown in the photos (some of the other leaves are curling at the edges but it has been pretty dry, could this second issue just be a lack of water? as far as I can tell the leaves that are curling aren't the ones that are simply going brown so this it's a separate issue) - see photos 1 - 5
with the other tree, I have noticed a-lot of the inner leaves are getting a brownish coating (I can scratch the brown stuff off with my nail). The outter leaves don't seem to be affected too much but the inner ones are all getting this coating and dropping? See photos 6-10
Can anybody help me with either or both tree problems? could they be a related problem just shown in different ways on the different trees? Am I even able to help them at this point?
Thanks for any info

[MitchellMc]

Welcome to the Bunnings Workshop community @E-mck01. It's fantastic to have you join us, and many thanks for your question about plant care.

It sounds like your mop-top robinias and evergreen trees are experiencing different issues, though there may be some common factors at play. The browning and curling leaves on your robinias could be a sign of water stress, especially if it's been particularly dry or wet. However, if the browning is irregular or patchy, it could also indicate a pest or fungal issue. Overall, the plant looks healthy, and if there are only a few stems that are affected, I would remove them and dispose in hard rubbish. What's your watering regime like and does the soil stay sodden for a few days after watering? If the soil is quite dry and you haven't seen much rain, you might like to water the plant every few days to see how it responds. Ensure you leave enough time in between waterings for the soil to start drying out.

The brown coating on your evergreen tree's inner leaves appears to be rust, and it's likely a fungal infection. Rust fungi thrive in humid conditions and can cause premature leaf drop if left untreated. Removing affected leaves, improving air circulation, and applying a suitable fungicide can help manage the issue. As with the robinia, dispose of the affected leaves in hard rubbish and do not compost.

Let me also tag @mich1972 and @Noelle to see if they have any thoughts.

Please let me know if you have any questions.

Mitchell
 

[E-mck01]

Thanks for the reply! That's all super helpful!

with the robinia - we have been meaning to give them a good prune anyway, is there a limit on how much to prune them? it looks like their previous owners had been chopping off the whole tree head but it's hard to tell and worried that would cause too much stress?

@MitchellMc 

[MitchellMc]

I'd keep it to a slight trim at the movement @E-mck01. Remove the damaged stems and you could also do a light re-shaping, but I wouldn't go removing the top. You can try some Seasol as well to help with health. Once affliction is overcome you can move on to more substantial pruning.

Mitchell