N I C O L E W A R D G A U T H I E R , U K P L A N T PAT H O L O G Y

UNDERSTANDING AND MANAGING

BROWN ROT OF PEACH

WHAT IS BROWN ROT?

• Monilinia fructicola

• Fungus

• Moderate temperatures, high humidity or rain

• One of the most common diseases

• One of the most destructive diseases

• Overwinters on mummified fruit and cankers

• Overwinters on ornamentals and wild plum

• Manageable

LIFE CYCLE

• Early spring

• Fungal spores develop on mummified fruit and cankers

• Early spring just as buds break

• Germination 55˚ to 77˚F optimal (32˚to 86˚F possible)

• 3 hours wetness

• More wetness = more spores

LIFE CYCLE

• Infection of flower buds

• Rapid death of blossoms, blighting and browning

• Gummosis, affixed to twig

• Spores produced on blossoms

• Infect late-blooming cultivars

• Keep sporulating (optimal conditions)

This is the first step in

eliminating inoculum

LIFE CYCLE

• Fungal infection progresses down twigs and shoots

• Cankers form

• girdle twig, twigs often die

• blighted leaves remain attached

• Spores produced throughout season (optimal conditions)

• Long-term survival of pathogen

LIFE CYCLE

• Sporulation from infected blossoms and cankers

• Throughout the season

• 55˚ to 77˚F and humidity/wetness

• More rain = more spores

• Disseminated by rain, wind, insects

• Late infections form cankers and fruit rots

LIFE CYCLE

• Fruit infection

• Fruit susceptible beginning at color development

• Damaged fruit more susceptible (hail, birds, insects, wind)

• Symptom development

• Within 48 hours of infection

• Soft, dry rot

• Spread as fruit ripens

• Shrivel and mummify

Critical period for

fungicide applications

LIFE CYCLE

• Overwintering

• Mummies on tree or ground

• Cankers

• Other sources of inoculum

• Ornamental quince or plum

• Wild plum

• Early spring, spores infect

blossoms

• Cycle continues

SCOUTING

• Dormant season, before pink stage

• Prune cankers

• Scout for mummies

• Sample wettest areas of orchard

• Partially buried or weedy areas & in trees

If mummies found = you are at risk for blossom infection

If several trees have mummies = high risk

SCOUTING

• Dormant season, before pink stage

• Scout for apothecia

• Sample wettest areas of orchard

• Partially buried or weedy areas

If apothecia are found = high risk for

blossom infection

SCOUTING

• Shuck fall

• Scout for infected blossoms

• Sample several shoots per tree

If shoots contain infected blossoms = your orchard is at risk

for fruit infection.

If several shoots have infected

blossoms = high risk of fruit infection.

SCOUTING

• Fruit coloring stage

• Scout for infected fruit

• Examine several fruit per tree

• Every 3 to 5 days

When fruit become infected =

high risk of brown rot outbreak

CULTURAL CONTROL

• Sanitation – remove source of inoculum• Remove mummies at the end of the season or

during dormant season

• Prune cankers 6 to 12” below diseased wood

• Thin fruit early before infection thinned fruit more easily decomposes

• Prune trees for air circulation to reduce humidity

• Scout – know your risk• Dormant season

• Bloom

• Shuck fall

• Fruit coloration – 2x/week

CHEMICAL CONTROL

• Pink stage

• Full bloom

• Petal fall

• Shuck split

• First cover – 7 to 10 days after shuck split

• Second cover – 10 days after 1st cover

• Additional covers – 10 to 14 day intervals

• Pre-harvest – beginning 3 weeks before harvest

~10 fungicide applications!

Brown rot

Scab

Powd. mildew

Brown

rot on

fruit

Brown rot

infecting

blossoms

FUNGICIDE ROTATIONS

• Sterol-inhibitors, DMI, class/FRAC 3• Rally, Indar, Elite, Orbit

• High risk of resistance

• Rotate with another fungicide to minimize risk of resistance

• Maximum 5 applications per season

• Iprodione, class/FRAC 2• Rovral, Iprodione

• Maximum 2 applications per season

• May not be used after petal fall

See handout

SYSTEMIC VS. PROTECTANT

• Systemic (locally) fungicides in spring, rainfast

• Iprodione class/FRAC 2 (Rovral, Iprodione)

• Triazoles (SI) class/FRAC 3 (Elite, Indar, Orbit, Procure, Quash)

• Fenhexamid class/FRAC 17 (Elevate)

• Protectant fungicides during dry weather

• Class/FRAC M

• Cheaper

• Not rainfast

• No systemic properties, remain on leaf surface

• Sulfur

• Captan, Captec

• Ziram

FUNGICIDE CONSIDERATIONS

• What is your Risk? • Scout – Is the fungus sporulating?

• Weather – Are conditions optimal?

• Handout – quick reference fungicide guide• Efficacy rating – use fungicides with the highest efficacy when risk

is high

• Systemic fungicide when it’s rainy

• Fungicide rotations, maximum applications per season

• Other considerations• Rate – depends on risk and severity (if there is a range on label)

• Interval – rainy conditions dictate shorter intervals

SPRAY GUIDE

• Peach spray schedule pg 33

• Pre-harvest intervals pg 44

• Efficacy rating pg 45

• Summarized in handout

2012 spray guide

SUMMARY

• Cultural practices – Sanitation

• Risk assessment – Scout

• Consider type of fungicide, interval, rate

= $$$

• Fungicide timing is critical –stay on schedule

• Managing early infections reduce secondary

infections

• Rotate fungicides to reduce risk of resistance,

reduce risk of crop loss

• 2012 Midwest Tree Fruit Spray Guide

Nicole Ward Gauthier

Extension Specialist

Department of Plant Pathologywww.ca.uky.edu/agcollege/plantpathology/people/ward.htm

nicole.ward@uky.edu

Facebook: www.KYPlantDisease.com

UK - Diseases of Fruit Crops, Ornamentals, & Forest Trees

Twitter:@Nicole_WardUK

Blogger:nicolewarduk.blogspot.com

Survey:www.MidwestFruitSurvey.com