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What Is It?
Leaf curl is a plant disease which occurs in both peach and nectarine trees. The fungus taphrina deformans is responsible for this plant disease which in severe cases may cause leaves on fruit trees to shrivel and drop. Taphrina deformans fungal infections can also cause peach and nectarine trees to produce stone fruits which are wrinkled, or have raised, irregular lesions on them which make them unappealing in appearance. However, this fungal damage to the stone fruit of peach and nectarine trees does not make the fruit inedible, only unsightly.
What Does It Look Like?
Damage from leaf curl in peach and nectarine trees is first visible in the peach or nectarine leaves. The leaves will appear to be thick, puckered and curled and will first manifest this way in the spring. The leaves on the infected peach and nectarine trees will continue to suffer this damage until they finally curl to the point that they dry and drop off the fruit tree entirely. In the spring, new shoots and growth which emerges may appear swollen or it may be severely stunted compared to normal peach and nectarine shoot growth. The foliage and infected shoots begin as green, but quickly progress to a red or orange color. As the fungal infection of taphrina deformans spreads, the foliage will turn back to a pale green or yellowish color. Material that is a grayish white may develop on the fruit tree leaves, and leaf curl is known to cause the leaves to drop off the tree shortly after the appearance of this powdery substance. When fruit develops, its growth may be stunted or the crop may be poor overall. In addition,
How Does It Manifest?
Taphrina deformans leaf curl occurs in peach trees when rain splashed the fungal spores from the bark onto the buds. This then allows the fungus to spread into the leaves. As the season progresses, the infected leaves begin to develop a grayish white covering. On peach and nectarine trees, this grayish white material is made up of fungal taphrina deformans spores. The spores are blown by wind onto other regions of the peach and nectarine trees or are splashed by rain or watering. Such conditions can quickly infect and entire peach or nectarine tree in no time. Infected peach and nectarine trees become increasingly weakened and will often suffer defoliation in early to late summer. However, the worst time for leaf curl is during cool, wet spring weather.
What Can I Do About It?
When you notice that your peach and nectarines have infected leaves, it is unfortunately too late to cure the infection. Defoliation will result, and your best bet is to prevent recurrence of the taphrina deformans infection by spraying the peach and nectarine trees in the fall as soon as the leaves have completely dropped off. A lime-sulfur spray or one containing chlorothalonil will be effective against fungal leaf curl. You can also effective spray using preventive measures in the spring if you do so before the buts open. However, you need to make sure that the peach and nectarine buds have begun to swell or the treatment of insecticide will be ineffective. If you have had repeated trouble with taphrina deformans, you may need to spray in both spring and fall.
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