Table of Content

    Brown Rot of Peach: Cause, Symptoms, Prevention, and Control

    For those of us who grow peaches, few things are more heartbreaking than seeing our fruit suddenly rot and mummify on the tree. It's a sad sight that often signals an invasion by one of the most destructive fungal diseases - brown rot.

    Caused by several species of the ascomycete fungus Monilinia, this disease has spread globally to become one of the major threats to peach production worldwide. Originating from native Prunus hosts, Monilinia spp. are now found wherever peaches are cultivated.

    As fellow peach growers, it's important we understand this fungus's tricks and how to fight back. So let's start by learning more about the pathogen behind brown rot.

    What is Brown Rot of Peach? What are the Symptoms?

    Some key facts about Monilinia:
    • M. fructicola and M. laxa are the main species that cause brown rot on peach worldwide.
    • Survive dormantly in mummified fruit, twigs or blossom blight lesions as sclerotia or mycelium.
    • Conidia are wind-dispersed or splash-dispersed to infect flowers/young fruit, which become latent infections.
    • Symptoms develop when fruit is ripening, as fungus switches to a necrotrophic phase inside fruit.
    • Causes blossom blight as well as fruit rot, leading to significant pre- and post-harvest losses.

    So in summary, we're dealing with an opportunistic fungus that infects blossoms and young fruit before symptoms emerge at ripening. Its survival structures allow Monilinia to persist dormantly.

    Spotting the Symptoms of Brown Rot of Peach

    To catch infections early, it's important to regularly inspect trees for these telltale signs:
    • Blossom blight appears as brown, water-soaked lesions on individual flowers or clusters.
    • Young fruit show circular, sunken lesions that enlarge over time, turning fruit entirely brown and mushy.
    • Mummified fruit cling to branches even after harvest, serving as inoculum sources.
    Internal fruit tissue becomes watery and disintegrates, often covered in gray mold.

    Take note - symptoms can vary depending on environmental conditions and cultivar susceptibility. But these classic signs mean trouble's brewing.

    Effective Way to Prevent and Control Brown Rot of Peach

    1. Cultural Tactics for Prevention

    Some cultural practices can help suppress brown rot naturally:
    • Prune trees properly for good air circulation to speed drying of fruit/foliage.
    • Use own-rooted or resistant/tolerant rootstocks whenever grafting is required.
    • Control other tree stresses like nematodes, insects or diseases that weaken tree defense.
    • Sanitation is key - remove and destroy all mummified fruit during dormancy to eliminate inoculum.
    • Consider resistant/tolerant cultivars like 'Contender', 'RichLady' or 'RedTop' when available.

    Combined with other controls, cultural practices are foundational in any brown rot management program.

    2. Fungicide Options When Needed

    For commercial growers, protectant fungicides are an important tool against brown rot:
    • Captan: Low-cost, multi-site contact fungicide used for decades to control blossom blight and fruit rot.
    • Thiophanate-methyl: Systemic fungicide with protectant and curative properties effective against Monilinia.
    • Boscalid: Newer fungicide that disrupts fungal respiration, showing excellent control of brown rot.
    • Fluopyram + trifloxystrobin: Premix combination of a SDHI and strobilurin fungicide for resistance management.

    Always rotate between fungicide classes, mixing products or using premix combinations per label instructions to delay resistance development.

    3. Biological Options to Control

    Some eco-friendly options for organic growers include:
    • Bacillus subtilis: Soil bacterium with antifungal properties that may suppress Monilinia spp.
    • Trichoderma spp.: Free-living fungi antagonistic to soilborne plant pathogens like the brown rot fungus.
    • Plant extracts: Cinnamon, clove or other essential oils show direct fungistatic effects against Monilinia in vitro.

    While still being optimized, biologicals offer a low-risk approach - especially as part of an integrated program. More research is needed.

    4. Integrated Tactics for Sustainable Agriculture

    The most durable brown rot control combines cultural, chemical and biological tactics:
    • Start with own-rooted trees or resistant rootstocks and maintain high hygiene standards.
    • Prune properly and remove/destroy all mummified fruit during dormancy.
    • Monitor for symptoms and apply protectant fungicides preventatively when needed.
    • Explore biological products that induce resistance or compete with the pathogen.
    • Consult experts regularly to adapt your strategies based on changing conditions.

    With diligence, vigilance and a commitment to integrated practices, we can significantly curb this fungus's impact on our peach harvests for years to come. Our livelihoods depend on it.


    Thank you for taking the time to learn more about this destructive disease. Please feel free to reach out if you have any other questions. Also continue networking with other growers - together, with consistent vigilance and adaptation, we can safeguard peaches from brown rot's ever-present threat. Wishing you bountiful harvests for many seasons to come!

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