Leaf curl on Peaches Apricots and Nectarines can be controlled with a few easy steps.
Look around Tasmanian gardens at the moment and you will see the first signs of spring. The buds are swelling and ready to burst. So now is the time to make sure you have everything ready for the rest of the productive seasons.
The cause of leaf curl.
Leaf curl effects a range of trees in Tasmanian home gardens. The majority of the cases we see here are caused by a fungus called Taphrina deformans.
Identification of leaf curl
Usually you will see the deformed young leaves as they emerge. They are twisted and buckled with red blisters. Eventually they host a whitish bloom across the whole leaf. This white color is made of asci that break through the cuticle of the leaf. One ascus consists of eight ascospores that create conidia, which are ejected in early summer and spread by rain and wind.
Transmission of the leaf curl fungus.
Young trees are particularly susceptible to leaf curl but any tree can be effected in a growing season. The fungus over winters on the bark and the buds of an infected tree. When the new leaves break from the buds, spores of the fungus are transmitted onto them. Once the spores have infected the new leaves, there is not much to be done but pluck them off as you see them and dispose of them by burning or putting them in the garbage.
Treatment of leaf curl.
Now is the time to treat leaf curl successfully. Get to the buds before they burst and spread those nasty spores! This means a simple spray with a fungicide. Copper based mixtures such as Bordeaux are one way to go. You can get a ready made concentrate at your nursery or you can follow the Guru Peter Cundall’s recipe below. One application should be fine unless the tree is severely effected or there is a lot of rain post spraying.
You can Peter Cundall’s own recipe for Bordeaux mix is here:
http://www.abc.net.au/gardening/stories/s1631445.htm
Bordeaux Mixture:
1 Dissolve 100 gram of builders’ (hydrated) lime in half a standard (plastic) bucket of water. (About 5 litres). 2 Dissolve 100 grams copper sulphate (available at garden centres) in a separate half bucket of water. 3 Keeping the lime mixture agitated to prevent settling, pour it steadily into the half bucket of dissolved copper sulphate. 4 If necessary add enough extra water to make up a total of 10 litres. This is Bordeaux mixture. It is at its most effective strength when freshly mixed so must be used immediately or within a couple of days. 5 It is sprayed to completely cover the main (bare) branches of peach, nectarine and other stone fruit trees to help control leaf curl and brown rot disease.
Another organic alternative is spraying with a Trichoderma mix, which is a natural organic fungus which feeds on the other fungus. Whereas copper applications often defoliates the tree, Trichoderma will only attack the area where the leaf curl is on the leaf, the remaining section remains intact and continues to grow.
The advantage of the organic method is that it can be applied to leaves as well as buds, where the Bordeaux mix is only for buds and will damage already formed leaves.
Identifying plant pests, diseases and disorders are key elements of our Certificate 2 and 3 in horticulture courses in Tasmania. Have a browse through the course details and see if there is one to suit your needs. If you would like a more tailored approach, contact us at GlobalNet Academy for a chat.
References:
http://en.wikipedia.org/wiki/Leaf_curl
http://www.sardi.sa.gov.au/pestsdiseases/horticulture/horticultural_crops/apricot_pests__and__diseases/leaf_curl
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