I recently noticed noticed that the leaves on trees have some sort of disease on them. It maybe more than one disease. These seems to be all over the trees. Could you please recommend pesticides and fungicides that i can use to resolve the issue ? I bought Yates 150g Mancozeb Plus Garden Fungicide And Miticide. Will this help?
Hello @HarithK92
I'm sorry to hear that you have a bit of an infestation in your trees. From the photos, I suspect you are dealing mainly with an insect problem rather than a fungal disease, although there may be some secondary leaf spotting. The very distinctive raised, blister-like bumps and distorted young leaves are strongly consistent with psyllid damage, particularly Lilly Pilly psyllid if these are Lilly Pillies. Psyllids feed on tender new growth, causing the characteristic pimples, pits and curled or distorted leaves you're seeing.
There is also some chewing around the edges of the leaves, which suggests another insect may be feeding on the plants. The bronze, reddish or purplish colouring isn't necessarily a separate disease, as Lilly Pillies can naturally develop these colours, particularly on new growth or when the plant is under some stress.
The Yates 150g Mancozeb Plus Garden Fungicide and Miticide you've purchased is a useful product, but I wouldn't use it as the main treatment for this particular problem. Mancozeb Plus is primarily intended for fungal diseases such as powdery mildew, rust, black spot and various leaf spots, while the sulphur component also controls certain mites. It doesn't control psyllids, so it won't address the main cause of those blistered leaves.
I suggest starting by pruning away the worst affected growth, particularly the badly blistered and distorted tips. Dispose of the clippings in your bin rather than leaving them underneath the trees. Don't be too concerned if the plants look a little bare afterwards, as established Lilly Pillies generally respond well to pruning and should produce another flush of foliage.
For the psyllids, I recommend using an insecticide specifically labelled for Lilly Pilly psyllid. Yates currently recommends Yates 1L Ready-To-Use Advanced Garden Insect Killer. Make sure you thoroughly cover the foliage, including the undersides of the leaves, and always follow the product label regarding application and repeat treatments. I wouldn't start combining Mancozeb and insecticides unless there is a confirmed need to treat both pests and fungal disease.
The timing is quite good because we're now in mid-September and heading into spring, when Lilly Pillies start producing plenty of tender new growth. The damaged leaves won't return to normal, so your aim is to control the psyllids and protect the next flush of leaves. Keep an eye on that fresh growth because it will be your best indication of whether the treatment is working.
Keep the Mancozeb Plus on hand in case you identify a fungal problem later. If you do use it, Yates advises against spraying when rain is expected within 24 hours, when temperatures are above 27°C, or when plants are moisture-stressed.
Overall, I wouldn't be overly worried about the trees. There is still plenty of healthy foliage visible. Prune the worst damage, treat the psyllids and watch the new spring growth. With a little attention now, they should have a good opportunity to put on much healthier foliage over spring.
I also recommend having a look at these discussions:
I also suggest having a look at this guide - How to diagnose and revive a sick lilly pilly by @Noelle
Please remember to wear personal protection such as gloves, goggles and a mask when using the chemical spray.
If you need further assistance, please let us know.
Eric
Excellent advice from Eric, @HarithK92 ! Certainly looks like some caterpillar activity too by the chewed leaf margins. The Yates product should look after them as well as the psyllids.
