Nothing peachy about this problem

Leaf curl distorts foliage, but usually doesn't infect the fruit. (Photos: Debbie Arrington)

Sacramento spring created ideal conditions for leaf curl

By Debbie Arrington

“What’s wrong with my peach tree?”

Right now that question is as rampant as its cause: Leaf curl.

This fungal disease is twisting peach and nectarine leaves into knots. Red splotches appear among the crinkles. Eventually, the foliage develops a pale fuzzy coating, then falls off the tree.

What can you do about it? Right now, not much. The time to tackle leaf curl is long before it appears.

Those red splotches are a telltale sign of leaf curl.

Peach leaf curl happens almost every spring, but some years are worse than others. Our March and April rain coupled with relatively cool spring weather helped bring on this outbreak.

According to the UC Cooperative Extension master gardeners and University of California research, leaf curl appears about two weeks after leaves emerge from buds. If the conditions are rainy during that period, look out. Two consecutive days or more of wet weather can bring on a maximum infection.

In addition, this fungal disease loves temperatures in the 60s. Although a tree may be infected, symptoms won’t appear if temperatures remain above 69 degrees and weather stays dry.

And this fungus is everywhere in Sacramento. Taphrina deformans overwinters on the tree or on fallen leaves. It’s also capable of withstanding intense summer heat.

Copper spray, applied in November or December, can cut down on its impact. For particularly bad infections, a second application in late January may be necessary.

Very bad infections can cut down on fruit production, weaken limbs and shorten the life of the tree. The fungus can infect young twigs and shoots, causing them to die back.

But right now, the leaves will just keep curling until they fall. Then, new leaves will appear. Due to heat and dry weather, that second round of foliage is usually healthy and uninfected.

Leaf curl rarely infects the fruit itself. Peaches and nectarines will still develop, although they may be small. More likely, they will show some sunburn or other blemishes, due to lack of protection from leaves. Those problems are cosmetic; the fruit will still be edible.

When planting a new peach tree, look for leaf curl-resistant varieties.

If you have leaf curl this spring, make a note on your calendar to apply copper spray in November. You’ll thank yourself next spring.

For more information on peach leaf curl: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7426.html

Infected leaves will eventually fall off. In warm and dry weather,
healthy leaves will replace the damaged foliage.
deformed foliage