Peach leaf curl
From Allotments4All
- Disease type: Fungus
- Order: Taphrinales
- Scientific name: Taphrina deformans
- English name: Peach leaf curl
Biology, reproduction and spread, and the relationship of its spread to its biology: This is an obligate parasitic fungus, which over-winters in cracks in the bark on peach, Prunus persica and almond, Prunus dulcis. As temperatures rise in spring, and the leaf buds start to open, rain washes the fungus spores onto the leaves. When temperatures are in the range 50-70oC the fungus enters the leaf by means of extending root-like structures called haustoria, and feeds on nutrients within the leaf. It is thought that the fungus promotes auxin-like and cytokinin-like compounds, or the leaf produces abnormal combinations of auxins and cytokinins, causing malformed development of the leaf in the form of warping and reddish blisters. A white spore bloom is produced in summer, and the spores are distributed in the wind, so at this point the fungus can freely travel to other trees in the vicinity. Prevention and control treatments and methods. Physical and cultural: Place a cover over the top of the tree during winter and spring to keep the branches dry. Check plants regularly for signs and symptoms of infestation. Pick off any distorted leaves and dispose of them before the white bloom appears. Apply organic matter as a mulch, water and fertilise to keep the tree healthy. Select cultivars with some resistance, for example Prunus persica ‘Redhaven’. Biological – together with benefits and limitations: None Chemical: Apply as a spray over the entire tree, a fungicide containing copper, such as Bordeaux mixture or containing mancozeb, such as Dithane 945. These must be applied before the leaves emerge and according to the recommended timing instructions provided by the manufacturer. They are not effective once the fungus has attacked the leaves. Legislative: None How the disease affects the health and vitality of the host plant: Leaves are damaged and unsightly, and will fall in severe infestations. Even though a fresh crop of leaves may appear, the tree will suffer stress and growth may be stunted. Heavy infestations will affect the peach fruit crop rendering it unfit for sale.
