Peach Tree Diseases: How to Treat Them

Peaches in a peach tree.

There’s nothing like biting into a juicy peach you just picked from a tree in your yard, but sometimes peach trees, like people, get diseases.

Knowing what to look for and how to treat common peach tree diseases will keep your trees producing fruit for years to come.

Here is a look at the most common problems you’ll run into with your peach tree and what to do about them:

1. Bacterial Canker

Bacterial canker is an infection that causes split bark and weeping cankers on the stems, branches, and trunks of affected peach trees. Bacterial canker is a serious condition that can kill your peach tree, especially if lesions appear low on the trunk and cause girdling.

The bacteria destroy or block the phloem, which carries water and nutrients to all parts of your peach tree. The bacteria doesn’t affect the roots of your peach tree.

Symptoms: Long, oozing cankers form around bud bases and on the trunk and limbs of affected peach trees. Dark, recessed areas of dead plant material have long streaks that reach out into healthy tissue. Affected areas may die, including the peach tree itself. Diseased tissue under the bark has a characteristic sour smell. Bacterial canker shows up as small, brown-red dots on fruit and causes deformities and pulp cracking

Treatment: When bacterial canker causes peach tree leaves to drop early, apply high concentration sprays of fungicides that contain copper. Prune back damaged stems and twigs, a few inches behind the canker. For cankers on or near the trunk, get professional help. Avoid spreading the bacteria by only working on dry bark and keeping tools sterilized.

Cause: The bacterium Pseudomonas syringae.

Risk factors: Peach trees planted in deep, sandy soil or areas with nematodes have an increased risk of infection. Extended periods of warm, wet weather also increase susceptibility. Avoid applying high-nitrogen fertilizer from the middle of June through September. Don’t encourage late fall growth. Stressed and young peach trees are particularly vulnerable, especially if they have freeze damage or sunburn.

Season: Spring and summer

Threat level: High; can lead to the death of your peach tree.

2. Bacterial Spot

Bacterial spot damage on peaches
Bacterial spot damage on peaches / Christine Shimek / Flickr / CC BY-ND 2.0

Bacterial spot can be mild or so severe that you lose your entire peach season. This pathogen affects leaves, twigs, and fruit. Severe leaf loss will hurt fruit development and make buds and wood less able to handle winter weather. Your peaches also may become sunburned or crack due to bacterial spot.

Symptoms: Tiny, purple, black, or brown lesions appear on leaf tips and then migrate to the leaves’ center. Affected areas die off and leave holes. Heavily infected leaves turn yellow and fall off your peach tree. In peaches, bacterial spot shows up as small, olive-colored circular spots that become darker and depressed as the bacteria take hold. The spots may develop cracks, leaving your peaches open to rot.

Treatment: Bacterial spot will overwinter in bark cracks, near buds, and in leaf scars. Dormant sprays are essential in the fall to protect the stems of your peach tree. Use a copper-based fungicide on your peach tree’s leaves when they begin to fall.

Cause: The bacterium Xanthomonas arboricola pv. pruni (formerly Xanthomonas campestris pv. pruni)

Risk factors: Peach trees are at higher risk of bacterial spot when they are planted in nutrient-poor or light, sandy soil and areas with nematode infestations. Moist, wet conditions above 65 degrees make it easy for bacteria to infect newly emerging leaves or enter through the bark’s wounds.

Season: Infections occur throughout the growing season, but bacteria begin to spread in late winter.

Threat level: Low to high. Bacterial spot can ruin peach crops and is difficult for home gardeners to manage.

3. Brown Rot

Brown rot peach mummy
Brown rot peach mummy / Scot Nelson / Flickr / CC0 1.0

Brown rot, one of the most common peach tree diseases, is a serious fungal infection, affecting fruit, flowers, and shoots. Contamination spreads fast and must be proactively treated.

Symptoms: Brown rot spores infect peach tree blossoms in the spring, moving into shoots, and fruit. Flowers wilt and wither, gummy cankers form on twigs, and peaches that develop brown spots quickly rot. Affected fruit grows into spore-covered fruit mummies.

Treatment: Remove infected fruit mummies from trees and also any that have fallen to the ground. Prune your peach tree in the winter to remove cankerous areas and ensure proper airflow. Use fungicides with propiconazole or captan (make sure they’re safe for peach trees). Start spraying at full bloom and repeat twice at 10- to 14-day intervals. Once your peaches begin to change color, start spraying every seven days. You also can use Clemson Fruit Bags to prevent infection.

Cause: The fungus Monilinia fructicola.

Risk factors: Moist, wet environment, and overgrown trees. Leftover fruit mummies, dead blossoms, and cankers will reinfect trees throughout the growing season. The pathogen will survive the winter.

Season: Brown rot begins at bloom in the spring and can cause many infections throughout the year.

Threat level: Serious without prompt intervention. Brown rot can ruin your peach crop and be labor-intensive to treat. Diseased fruit, flowers, and shoots are all vectors for reinfection and need to be safely removed.

4. Crown Gall

Crown gall is widespread, affecting many plants, including peach trees. While it probably won’t kill your peach tree, it may cause stunting and problems with fruit production.

Symptoms: Irregularly shaped tumors grow on roots, the crown, and sometimes on the branches, trunks, and stems. Lumps start small and soft, hardening to a woody texture. Peach trees grow slowly and become stunted; leaves may be smaller than expected; and the tree may not bear fruit. Galls can prevent water and nutrients from circulating.

Treatment: Dip peach tree seedlings into an antibacterial wash before planting. Prevention is critical, so avoid injuring trees and practice proper pest control to keep insects that bore at bay.

Causes: The bacterium Agrobacterium tumefaciens.

Risk factors: Moderate; can contribute to overall poor health or death. Makes your peach tree more vulnerable to wind damage and drought stress. It can kill young peach trees if galls are large or numerous. Crown gall likes warm, moist conditions.

Season: Crown gall can infect peach trees at any time.

Threat level: Low

5. Peach Leaf Curl

Peach leaf curl damage
Peach leaf curl damage / Scot Nelson / Flickr / CC0 1.0 

When you see symptoms of peach leaf curl, it’s too late to treat your tree. Like all fungal diseases, peach leaf curl thrives in warm, wet conditions.

Symptoms: Look for thickened leaves that curl and pucker. Peach leaf curl also can infect fruit and shoots. Swellings appear on the upper side of young peach leaves, turning the affected area red. Leaves fade to yellow and fall to the ground. Compromised peaches have small white spots that rot.

Treatment: Prevention is the most important tool you have against peach leaf curl. As soon as temperatures warm to 50 degrees, the fungus begins reproducing and releasing spores. Before this happens, treat your peach trees with a spray containing copper. The best times to spray are in the fall after leaves have dropped and in early spring before buds open.

Cause: The fungus Taphrina deformans.

Risk factors: Warm, wet weather.

Season: Spring

Threat level: Moderate; peach leaf curl stunts growth in affected branches and shoots and makes them more vulnerable to frost. Peach leaf curl damages fruit.

6. Peach Scab

This fungal disease can affect a small number of your peaches or completely destroy your season. Infection occurs in spring, but symptoms don’t show until much later.

Symptoms: Raised spots affect fruit, leaves, and shoots.

Treatment: By the time peach scab spots appear, it’s too late to treat. Proactively spray your peach tree about two weeks after flowers drop. Use a sulfur or captan fungicide. Spray three times, with seven to 10 days between applications.

Cause: The fungus Cladosporium carpophilum.

Risk factors: Your peaches might be smaller than expected and more susceptible to other diseases.

Season: Spring

Threat level: Low to moderate; in severe cases, your peach crop will be lost to secondary infections, cracking, or rot.

7. Powdery Mildew

Powdery mildew generally affects green fruit, but it also can show up on leaves and new shoots. Powdery mildew often is spread to peach trees from rose bushes and apple trees.

Symptoms: Patchy, white circular spots appear on green fruit. Affected areas become brown, leathery, and can crack, leaving your peaches vulnerable to secondary infection and rot. Powdery mildew deforms leaves.

Treatment: Remove diseased plant parts when pruning. When blossoms drop, apply a general fungicide.

Causes: The fungus Sphaerotheca pannosa.

Risk factors: Nearby rose bushes and apple trees are common disease vectors for this fungal infection. Powdery mildew likes warm, wet conditions.

Season: Spring

Threat level: Low; the powdery mildew fungus overwinters on shoots and leaf bud scales, causing new infections in the spring.

8. Rust

Is your peach tree dropping leaves early? If they’re peppered with small, yellow dead spots, you probably have a fungal rust outbreak.

Symptoms: Bright yellow, angular spots on leaves that eventually cause leaves to drop prematurely. Look for rust-colored spore masses. Rust also may affect fruit. Rust produces cankers with powdery rust-brown spores.

Treatment: Apply sulfur-based or sterol-inhibiting fungicides in the spring.

Cause: The fungus Tranzschelia discolor.

Risk factors: Warm, moist weather.

Season: Summer and fall

Threat level: Low; rust may contribute to secondary infections in your peaches.

9. Shot Hole Blight

Shot hole peach tree disease
Shot hole blight infection on peach / William M. Brown Jr., Bugwood.org / CC BY 3.0 US

Shot hole blight disease affects peach trees and other fruit trees. Leaves, twigs and buds develop lesions, with the leaves falling from the tree. Sometimes these unsightly lesions also appear on fruits.

Symptoms: Small, BB-sized spots on leaves start out dark purple, becoming brown in the center and retaining a purple border. Dark swellings in the center of each spot release spores, spreading the infection. In wet weather, your peaches may develop similar spots. The flesh is hard and pithy around affected areas.

Treatment: Preventative fungicide sprays in the fall, right after leaf drop or in the spring, before buds open. Copper and zinc sulfate are effective.

Cause: The fungus Wilsonomyces carpophilus.

Risk factors: Warm, moist conditions; trees that aren’t thinned for proper airflow; irrigation that wets leaves. Can overwinter in old lesions.

Season: Spring

Threat level: Moderate; may destroy the entire season’s fruit harvest.

10. Peach Mosaic

Peach mosaic isn’t endemic but can be very serious. This virus spreads by grafting or when affected mites pass the disease on to your peach tree.

Symptoms: Delayed leaf growth; small, deformed leaves are folded, with a narrow profile, and have a mottled-yellow coloring. Streaking and color blocking occurs in blossoms. Fruit that develops is lumpy, small, and low-yield.

Treatment: There is no treatment for this disease. Trees may survive for a few seasons, but will never bear viable fruit.

Cause: The peach latent mosaic virus.

Risk factors: Spread by the peach bud mite and infected grafts.

Season: Usually happens during grafting or in the spring.

Threat level: High, if mites are not suppressed.

When to Call a Tree Care Expert

Besides giving you fresh fruit to enjoy every year, peach trees boost the value of your property. Make sure you protect them by bringing in certified arborists to check for diseases, problems in the soil, and to treat any tree issues.

LawnStarter puts you in touch with respected arborists and tree care pros in your area. Enter your ZIP code and get a vetted list of tree care companies to keep your peach cobbler source healthy for years to come.

Main Image Credit: Peach tree / Couleur / Pixabay

Tamiko Wilie

Tamiko Wilie

Tamiko Willie is a sailor with a green thumb. She loves finding community-based solutions to problems, kayaking, and devouring her husband’s amazing food.