What is peach leaf curl disease?
Did your peach, nectarine, apricot or almond look odd with reddened, screwed up, puckered leaves?. Or did it have no crop, or very little? That’s most likely the result of the fungal disease “peach leaf curl”. Peach leaf curl disease is caused by a fungus, Taphrina deformans. It will attack the tree species of peach, nectarine, apricot and almond. The symptoms are the development of large reddish blisters on the leaves. The tree is weakened as photosynthesis by the leaves is seriously affected. Eventually the tree is starved to death as it is no longer able to make the carbohydrates it needs through photosynthesis. Leaves tend to fall prematurely and growth comes to a complete standstill.
The fungus attacks the tree from late January until the middle of May. After May the fungus is no longer producing spores and therefore cannot cause new infections.
How to deal with peach leaf curl disease
There are various options for controlling peach leaf curl. Some varieties are more resistant than others. However this is no help if you already have to cope with this problem.
Peach leaf curl and orchard hygiene
When you prune your peach, leaves affected by peach leaf curl should be removed completely. Pruning should be performed in mid May or late August, never later. The basic concept is to remove old wood to make room for new shoots to form. This is essential as the fruits of peach and nectarine are formed on one year wood only. Seal the pruning cuts with “Prune and Seal”, a compound available from your garden centre. The foliage of a well pruned tree dries up quickly, with less chance of new infections.
When the leaves fall from the tree in late October/early November, make sure the leaves are all collected up, infected or not, put in a plastic bag and then put in the non-recycling bin. The fungal spores survive over winter on the fallen leaves!
Once the soil underneath those trees is clear of all litter, cover the soil with a 4 cm-deep layer of straw-based farm yard manure. Leave no gaps uncovered. The entire area below the tree canopy should be covered with mulch. Ensure that the mulch is not in contact with the trunk, to prevent damage by mice.
Make sure the tree is well watered and does not stand in a carpet of weeds and grass. Apply a full watering can of water twice a week, particularly during the summer months.
Preventing peach leaf curl by protecting the tree from moisture
Peach leaf curl can be avoided by covering your peach tree (or your apricot, nectarine or almond) to stop the new young foliage becoming wet, from late January until the middle of May, every year. Make a framework, and cover the tree with plastic or garden fleece. The framework is needed to stop the plastic or garden fleece cover touching the limbs, branches or twigs of the tree. By keeping the young newly-emerging foliage dry, the spores of the fungus are unable to germinate on the leaves and blossom.
Don’t forget that these trees flower very early in the season. The cover will also protect the blossom from damaging spring frosts. And finally when the fruits are nearly ready, the wooden frame is also very useful to fasten on some netting, to stop the birds eating your peaches or apricots. Make sure the wind cannot affect the fleece or lift it off. Keep your eye on the tree and if a tear develops in the fleece after particularly bad weather, repair the damage properly. This fleece needs to stay in position until the second week of May. After that time, carefully remove the fleece.
Preventing peach leaf curl by growing in containers
Peach leaf curl disease is spread by rain droplets. The fungus over-winters and is hidden in crevices of the bark and between the bud scales. Therefore consider planting a peach, apricot, nectarine or almond tree in a 15 to 18 inch diameter pot. By the end of January, wheel the potted tree into a cold shed or a cold green house or a cold poly tunnel. In that way no fleece is needed as the tree is sheltered from the winter rains. By the middle of May it is safe to take the pot outdoors again. Then position the tree in a warm sunny place and water it weekly or twice a week when very warm weather is occurring. Never let the tree go short of water as it will surely die. Feed the tree monthly with a suitable foliar feed, obtainable from garden centres.