Plant Health Management for Backyard Strawberry Plantings

Prepared by

Mike Ellis Professor and Extension Specialist and Omer Erincik

Graduate Research Assistant

Department of Plant Pathology The Ohio State University

OARDC/OSUE Wooster, OH, 44691

Common Diseases on Fruit

Gray mold (Botrytis fruit rot) Leather rotPathogen: Botrytis cinerea Pathogen: Phytophthora cactorum

Gray moldSymptoms:

gray, dusty-looking fungal growth on ripening berries

Early (left) and late (right) stages of botrytis fruit rot on strawberry.

Gray mold

Disease Development:Most infections occur during bloom. The fungus can infect petals, flower stalks,

fruit caps, and fruit. The disease is favored by wet conditions,

such as rain, dew, or sprinkler irrigation.The disease is generally most severe

in shaded areas where humidity is higher and air movement is poor

on berries touching the soil

Leather rot

Symptoms:On green fruit, brown, firm spots

develop. The entire berry may be discolored (brown).

On ripe fruit, light to dark purple or brown areas develop. These areas are generally dull in color.

Infected fruit have a distinctive bitter taste and unpleasant odor.

Leather rot

Disease Development:The fungus can infect berries at any stage of

development.Disease can develop very quickly during wet

conditions.a wet period of two hours is sufficient for infection.

Fungus spores are spread by splashing or wind-blown water from rain or overhead irrigation.

the disease is most severein poorly drained areasin places where berries are in contact with the soil

Management of fruit rot diseases

Free water (wet conditions) is required for most fungal pathogens to infect fruit. Any practice that promotes faster drying of fruit and foliage is beneficial for disease control.

Management of fruit rot diseases

Site selectionSelect a site with good air movement and sun

exposure (promote faster drying).Canopy control

Control timing and amount of nitrogen fertilizer to prevent excessive growth.

Control weedsweeds decrease air circulation. controlling weeds promotes faster drying of fruit

and foliage.Mulch

Use a layer of straw mulch to create a barrier between fruit and soil.

Management of fruit rot diseases

IrrigationIrrigate early in the day, so plants dry faster.

HandlingPick fruit carefully, avoid bruisingProcess and or refrigerate fruit immediately after

harvest.Renovation

Remove old leaves and diseased plant parts after harvest.

Common diseases on leaves

Leaf spot Leaf scorch Leaf blight

Symptoms of leaf diseases

Leaf spot Small reddish purple spots develop with tan to

grayish white centers surrounded by a purple margin.

Leaf scorch Round to angular or irregular dark purple

spots or blotches developed. Eventually the entire leaf may turn red.

Leaf blight Spots are initially reddish-purple, Later they develop a darker brown or reddish-

brown center surrounded with a purple border.

Strawberry leaf diseases

Disease Development:Leaf spot

Pathogen: Mycosphaerella fragariaeInfection may occur throughout the growing season.

Leaf scorchPathogen: Diplocarpon earlianaInfection may occur throughout the growing season.

Leaf blightPathogen: Phomopsis obscuransDisease is found most commonly on plants after harvest.

Management of strawberry leaf diseases

Use disease free planting stock Use resistant varietiesProper site selection

Choose a site with good air circulation and sun exposure (promotes faster drying).

Weed controlWeeds decrease air circulation. Controlling weeds reduces drying time of the plants.

Remove old foliage just after harvest (renovation)helps to reduce pathogen populations.

Common Diseases Attacking Roots

Verticillium wilt Red stele Black root rot

Verticillium wilt

Symptoms:Older leaves turn

brown or reddish yellow at the edges, then turn entirely brown and collapse.

Roots have areas of dark brown decay.

Verticillium wilt

Disease Development:

Caused by the soil borne fungus Verticillium albo-atrum

The fungus can be introduced into uninfested soil on seed, tools, garden machinery and roots of transplants.

The fungus can survive in soil for many years.

Favored by cool, overcast weather interspersed with warm days.

Red stele

Symptoms:Many roots may have a

rattail appearance, with few or no lateral roots.

When infected roots are split, the center core (stele) is brownish or red.

diseased healthy

Red stele

Disease development:caused by a soil borne fungus,

Phytophthora fragariaefavored by high soil moisture (saturated soil)

and cool temperature.most destructive in heavy clay soils that are

saturated with water during cool weather.

Black root rot

Symptoms:Plants are stundedRoots show areas of brown to black discoloration.Eventually, all or part of the main root system is black and dead.

Black root rot

Disease Development:The disease has been associated with

several factors, and is not clearly understood.

One or more of the following factors has been associated with the disease:soil fungi, nematodes, winter injury, fertilizer burn,

soil compaction, herbicide damage, drought stress, excessive water, improper soil pH.

Probably not caused by any single factor. Considered to be a “Disease Complex”.

Management of root diseases

Use healthy planting stock Use resistant varieties Proper site selection

Plant in well-drained soilSelect a site that does not have a previous

history of problems with any of the root diseases.

RotationDo not replant strawberries where disease has

been a problem for at least 2 years.Control weeds

Using Fungicides For Strawberry Disease Control

Fungicides can be important in commercial strawberry plantings; however, fungicides are generally not recommended for backyard “strawberry” production.

Effective fungicides registered for use on strawberry are usually very difficult or impossible for backyard growers to obtain.

If not used properly, they are generally not effective.

For backyard growers that do wish to use fungicides in the disease management program, fungicide recommendations are available in Bulletin 780 “Controlling Disease and insects In Home Fruit Planting”.

Emphasis for disease control in backyard strawberry plantings should be placed on:

Use of the various cultural practices for disease control mentioned previously.

Use of disease resistant varieties.

The most effective method for controlling most strawberry diseases is the use of varieties with good disease resistance.

Several strawberry varieties have resistance to many of the common strawberry diseases. The following are some common varieties with multiple disease resistance.

Selected literatures for backyard fruit production and plant health management:

Bulletin 591. “Growing and Using Fruit at Home”

Bulletin 780. “Controlling Diseases and Insects in Home Fruit Planting”

Bulletin 861. “Midwest Small Fruit Pest Management Handbook”.

These can be obtained through your county extension agent or the Extension Publications Office, The Ohio State University, 385 Kottman Hall, 2021 Coffey Road, Columbus, Ohio, 43210-1044

To get more information about plant diseases visit the websites below.

http://www.ag.ohio-

state.edu/~plantdoc/extension.php

http://www.ohioline.ag.ohio-state.edu