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How to Identify and Treat Peach Tree Diseases

Pruning, fertilizing and otherwise tending that peach tree in your backyard certainly pays delicious dividends when the juicy fruit finds its way into pies, ice cream and other treats.

Closeup of peaches on a tree. Knowing about peach tree diseases is an important aspect of growing healthy peaches.

But tending your peach tree also includes a more serious responsibility than routine horticultural care. As part of ensuring your peach tree continues to produce fruit year after year, you need to know something about peach tree diseases, from how to recognize them to how to effectively treat them.

Read on to learn more about peach tree diseases and what you can do to continue enjoying a bounteous harvest.

Bacterial Canker: Deadly Serious in Peach Tree Diseases

Just as you couldn’t survive without water and nutrition, that lack presents a deadly problem for your peach tree. Unfortunately, that’s exactly what can happen when bacterial canker, arguably the most serious of peach tree diseases, gains a foothold.

A peach with lesions on it.

A canker is a slowly spreading area of dead tissue. In peach trees, bacterial canker is caused by the bacterium Xanthomonas arboricola pv. pruni. It attacks the phloem, the vascular system that carries water and nutrients through your peach tree.

Signs of Bacterial Canker

In fruiting season, bacterial canker is revealed as brownish-red dots on developing peaches. It also causes cracking and deformities on your peaches.

Otherwise, bacterial canker, which shows up in spring and summer, can be recognized by a sour smell exuded from under the bark of infected areas. Another sign of bacterial canker is the leaves of peach trees dropping earlier than normal.

Treating Bacterial Canker

If you notice your peach tree dropping it leaves early, and you also see other signs of bacterial canker, the best treatment is highly concentrated spraying of a herbicide containing large amounts of copper.

Otherwise, as with other peach tree diseases, locate the canker sites on your tree, and prune damaged stems and twigs beginning a few inches behind the sites. Be careful to work only on dry areas, away from any weeping. Also keep your tools sterilized with rubbing alcohol, bleach or hand sanitizer to avoid spreading bacteria.

Brown Rot: Common Among Peach Tree Diseases

Brown rot is one of the most common peach tree diseases — and sadly, one of the most damaging, causing the loss of all of the peaches on an infected tree.

Peaches with brown rot spots.

Brown rot is caused by a fungus, Monilinia fructicola. It begins as buds start to bloom into flowers on the tree. Infected flowers will, in turn, affect woody shoots on the tree. Those infections become cankers, which lead to fruit rot as spores from infected flowers and cankers are blown onto growing fruit.

Signs of Brown Rot

On the peaches themselves, fruit rot first appears as a small, round brown spot that eventually withers the entire peach. The fungus can survive the winter on these so-called fruit “mummies.”

This already serious example of peach tree diseases is made worse by the fact that infected fruit can spread spores. And, rather than falling from the tree, the infected fruit remains attached to it for a long time, meaning that spores, and brown rot, become more prevalent.

Treating Brown Rot

The blooming stage of peach development can provide a warning of brown rot potentially settling in on your peach tree.

The use of fungicide sprays on a seven-to-10-day schedule as flowers begin to fall can be helpful in controlling brown rot. And the good news is that only a small number of blooms — less than 1 percent, according to experts — are affected by brown rot.

To treat brown rot in the event that it becomes established in your tree, you’ll need to remove all infected fruit, which means inspecting the tree all the way to the top of its crown to truly ensure its protection against one of the most serious of peach tree diseases.

You’ll also want to remove any fruit that appears to have stunted growth, because those peaches will be particularly susceptible to infection.

Next, cut off any branches exhibiting cankers. Cut them either at the trunk or at the point where the infected branch meets one of the tree’s major branches. Also, take out weak branches in the top of the tree to allow more sunlight into its interior to combat moisture, which helps brown rot thrive.

As a preemptive step against brown rot, applying an all-purpose fungicide before spring blossoms appear can be helpful.

Freckles Aren’t Cute on Peaches: Peach Scab

Dark speckles developing on your peaches aren’t cute at all, instead signaling the presence of peach scab, a very serious development among peach tree diseases, caused by the Cladosporium carpophilum fungus.

Closeup of a peach with small black spots on it.

The fungus is most likely to be seen on peach trees in warm and humid climates. Peach scab can affect the quality of your peaches, including through cracking and premature dropping from the tree.

Peach scab can begin invading a tree in the very earliest stages of fruit development, but symptoms may not be visible for up to 10 weeks after the initial infestation.

Signs of Peach Scab

While it is easily visible on the peaches themselves, peach scab also will infect your peach tree’s twigs and leaves.

On twigs, peach scab shows up as dull reddish spots that eventually develop into lesions. As the infestation progresses, the fungus remains in the lesions and lays the groundwork for a new round of peach scab in the next growing season.

Your peach tree’s leaves will also show signs of peach scab to let you know that you’re dealing with one of the more serious peach tree diseases. The tell-tale yellowing spots can be hard to spot because they develop on the underside of the leaves. But when the yellowing tissue dies, it leaves readily visible holes.

Treating Peach Scab

You can get ahead of peach scab through application of fungicides like captan, chlorothalonil and a class of fungicides known as demethylation inhibitors.

As a precaution against peach scab, apply fungicide when blossom petals begin to fall from the tree, and continue until a few weeks before your peaches mature. A good rule of thumb is to apply the fungicide every two weeks.

Another preventative approach, if you have more than one peach tree, is to be sure to plant them a good distance apart, and to make sure they are planted in a well-drained area.

Curls Aren’t Pretty on Peaches: Peach Leaf Curl Fungus

The fungal infection known as peach leaf curl is similar to peach scab among peach tree diseases, in that the fungus that causes it, Taphrina deformans, establishes itself in the bark and budding areas of peach trees, spending the winter months there.

Closeup of a peach tree branch suffering peach leaf curl diseases.

When spring arrives, and just as buds are emerging, fungal spores infect leaves and shoots. If the infestation is severe enough, the quality and number of peaches on your tree will be reduced, and the tree’s overall health will decline.

Signs of Peach Leaf Curl

Peach leaf curl is easy to spot among peach tree diseases, as it produces puckered and twisted areas on leaves that range in color from yellow to purple. As the fungal infestation progresses, the leaves will turn brown and drop from the tree.

Shoots of your peach tree will show peach leaf curl in the form of small yellowed leaves, or leaves that form in tight bunches. In blooming season, your peach tree’s flowers may not go on to produce fruit. Fruit that does appear will have bumpy skin and will fall from the tree.

Treating Peach Leaf Curl

On its own, peach leaf curl is not enough to kill your peach tree, but it can make the tree more susceptible to stress during drought periods and can also hamper the tree’s ability to withstand the stresses of winter.

Some varieties of peach tree — Frost, Q-1-8 and Redhaven are a few — are resistant to peach leaf curl. But as with other peach tree diseases, proper use of fungicide can keep the disease away from a wide variety of peach trees.

In terms of addressing peach leaf curl, fungicides with active ingredients like chlorothalonil, copper and ferbam can be effective. Make certain, however, that the fungicide you choose to handle peach leaf curl, or any other peach tree diseases, is labeled for use on edible crops.

Short Life: As Bad as it Gets in Peach Tree Diseases

Particularly in the southeastern United States, Peach Tree Short Life (PTSL) — an array of problems that lead to the sudden death of peach trees after three to six years — is a daunting threat.

Closeup of two peaches infected by disease causing lesions.

Among the issues that lead to this most deadly of peach tree diseases are damage caused by cold weather and infection by the Pseudomonas syringae pv. syringae bacterium.

But a number of other things, such as rapidly fluctuating temperatures in late winter and early spring, the timing of pruning the tree’s shoots and branches, and, perhaps most importantly, the ring nematode, are major factors in PTSL.

Nematodes are microscopic worms, many of which are beneficial to the environment, feeding on bacteria and fungi. Some, however, like the ring nematode, feed on plants, damaging roots and impeding the plant’s ability to get water and nutrients.

Signs of Peach Tree Short Life

PTSL is characterized by the sudden wilting of a tree’s leaves, a massive loss of new blossoms, and the quick death of some tree branches. As Peach Tree Short Life runs its course, death of the entire tree comes within weeks of the disease complex’s initial appearance.

Treating Peach Tree Short Life

If you have a peach tree that is affected by PTSL, you won’t be able to save it. There are, however, some things you can do to help ensure that your tree doesn’t become infested with this most serious of peach tree diseases.

First, plant your peach trees in soil that is well-drained, with a pH — a measure of how acidic or basic it is — of about 6.5. There are a number of pH test kits available online or in garden supply stores.

Second, do any pruning of your tree in February or March. It’s advisable to keep your tree at a height where pesticide and fungicide spraying can reach the entire tree.

You can also have your soil tested for nematodes, through either private laboratories or your state’s agricultural extension offices. If necessary, you can spray any problem areas with a nematicide.

General Tips for Preventing Peach Tree Diseases

A first step in preventing peach tree diseases is choosing a variety noted for resistance to disease.

Among the more disease-resistant peach trees are the Clayton, the Champion, the Contender and the Elberta. The Contender has the added advantage of growing well in cold climates, and the Elberta is both disease- and insect-resistant.

Watering also is essential to keeping your tree healthy, but you should recognize that overwatering can lead to any number of peach tree diseases. A good rule of thumb is to water your tree about every two weeks when the weather is warm and dry.

Peach trees should be fertilized during the growing season, with two applications of 12 ounces of nitrogen, once in spring and again in summer, as a guide for younger trees. More established trees should get one pound of nitrogen each year. Don’t fertilize when fruits are growing.

Be in the Know About Peach Tree Diseases!

We hope that this post has educated you, both in how to recognize peach tree diseases, and in what to do if you find signs of peach tree diseases.

Excited for more peach content? Check out my peaches page for growing tips, info guides, recipes, and more!

An unripe peach with spots and weeping, showing signs of disease.