How to treat apple trees with brown leaves?

[gonkerball74]

I have been growing sweet tango apple trees since August 2024, which are now approximately 30cm high and are in pots in my greenhouse. They all have a brown leaf issue, and some leaves have fallen off. I am looking for suggestions as to why this might be happening and what the remedy for this might be. 

[EricL]

Hello @gonkerball74 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your sweet tango apple trees.

Your Sweet Tango apple saplings appear to be showing signs of stress likely caused by a mix of nutrient deficiency, inconsistent moisture, and possibly fungal infection, all of which can be exacerbated by the warm, enclosed environment of a greenhouse. The brown leaves and leaf drop suggest that the roots may not be getting the balanced nutrition they need, and that fungal leaf spot could be taking hold in the humid conditions. 

To address this, start by improving the growing medium with Scotts Osmocote 25 L Citrus & Fruit Premium Potting Mix from Bunnings, which contains added iron, magnesium, wetting agents, and slow-release nutrients to keep foliage green and healthy. Follow this with a sustained feed using Richgro Plus 2.5 kg Fruit and Citrus Fertiliser or Scott Osmocote 1 kg Citrus & Fruit Controlled Release Fertiliser, both of which are available at Bunnings and will steadily supply essential nutrients for up to six months. 

During the active growing season, give your plants a quick nutrient boost with PowerFeed 1.2 L Pro Series Fruit & Citrus Concentrate every two to four weeks, and maintain soil health and root strength with monthly applications of Seasol 2.5 kg Plus Nutrients Fruit & Citrus. For fungal control, particularly if leaf spots persist or reappear, apply Yates 200 ml Liquid Copper Fungicide early and repeat every one to two weeks during high-risk periods. 

Alongside this feeding and protection plan, improve airflow inside your greenhouse, avoid letting the soil completely dry out or stay waterlogged, and remove any heavily damaged leaves to limit disease spread. This combination of improved nutrition, moisture management, and targeted fungal prevention will give your potted apple trees the best chance of recovery and healthy growth.

Please remember to wear personal protection such as gloves, goggles and a mask when spraying.

If you need further assistance, please let us know.

Eric

[robchin]

Hi @gonkerball74 

I think @EricL has covered off the main things below but I would add that it is Winter in most parts of Oz and NZ. So the plant may be just struggling because they shouldn't have any leaves left on them at this time of the year. Apples are normally deciduous so you need to take that into consideration. 

The other point I would make is about how you are planning to grow these trees.

I wonder if you have grown these from seed? If so - then you might be in for a bit of pain and disappointment down the track. Apple trees are normally budded onto a proven rootstock which gives them increased vigour and growth as well as some other desirable characteristics. The other thing about growing from seed is that you are not likely to get all of the desirable characteristics of the parent variety due to natural variations in seed set - they don't always carry over. With the SweeTango apple that loud crunch, sweetness and distinctive flavour may not come through. There has been a fair bit of breeding gone into this apple and you are likely not to get all of these benefits the way you have done it. 

On the other hand if you have taken cuttings - again  you may have the same characteristics as the parent apple BUT the plants might not grow as well because they are not budded onto a rootstock with the desirable characteristics - as outlined above. 

The only way to guarantee the desirable apples you want is to but the desirable apple onto a desirable rootstock. 

So good luck with it but just give the above some thought before you invest too much more time and energy into these plants. 

One final note on the SweeTango apple. The apple has some Intellectual Property Associated with it. Likely not an issue for you but it would be against IP rules to commercially benefit from the use of this apple i.e. - you couldn't sell or promote the fruit or sell the plants.