Leaf Curl

photo: aggie-horticulture

Latest update 22nd August 2016.

Leaf Curl.

• Binomial Name:                           Taphrina Deformans.
• Family:                                       Taphrinaceae.

Notes.

• I have a peach tree and a nectarine tree in my garden, and they are both vulnerable to leaf curl.
• I kept it under control in previous years by spraying with lime-sulphur solution while they were dormant and again just before bud burst.
• Although it is an approved organic pesticide, I have been unhappy about its use because of the collateral damage to biology in and around my trees.  So last year, I didn't use it.
• These days I spray everything in the garden with aerated compost tea every month.  I do this because there is always some new vegetative growth going on in my garden even in winter, and I want it to be protected.
• As extra protection for my fruiting trees I spray their new fruit when still quite young.
• Last year I used aerated compost tea instead of lime-sulphur on my peach and nectarine trees.  They were still affected, but nowhere near as badly as neighbouring trees in my suburb.
• I removed affected leaves every 2 days for about 2 weeks after they first appeared, and the new replacement growth was unaffected.  Both trees went on to produce excellent yields of fruit.

Why Leaf Curl is a Pest.

• Leaf curl is a fungal disease which invades stone fruit trees in spring.  Once it becomes established it is hard to remove and reduces the tree's vigour by attacking the leaves.  
• If left unattended over a number of years leaf curl will stop the tree bearing fruit and eventually kill the tree.

Pest Control.

• The fungal spores which cause leaf curl, are mostly active in wet weather.  They can spread from your neighbour's infected trees through the air and will establish themselves best in moist conditions.
• If your own trees were infected last year, the fallen leaves will harbour spores through winter.
• Once all the leaves have fallen in autumn, a thorough clean up of the ground is an important step, but take care how you dispose of the waste since the spores can stay around for some time and must be destroyed.
• A genuine hot compost will kill the spores, but if you are not confident you are reaching 65 deg C in the heap, dispose of the waste by burning it or burying it 500mm deep in soil well away from the tree.
• Fungal spores are dormant in winter and they will occupy bark fissures on your peaches and nectarine trees.  Spray the whole of each tree with aerated compost tea every month and when fruit forms spray again.
• This process is still experimental in my garden, but last year, the leaf curl infestation was extremely light compared to my neighbour's trees.  They were still affected but, by removing affected leaves and disposing of them in sealed garbage bags, I was able to eradicate it in a couple of weeks.
• I don't like using lime sulphur or copper based sprays because of the collateral damage to the biology on and around my trees, but if you are not able to use aerated compost tea for any reason, apply an organically approved spray as directed.  Just make sure you spray it on a still day and protect understory and soil with tarpaulins or old sheets.