Plant Disease Management Handbook

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Note the red blotches on the leaves and on the unripened fruit.

Photo by Jay W. Pscheidt, 1994.

Cause Botrytis cinerea, a fungus that overwinters as sclerotia or dormant mycelia in old leaves, petioles, and mummified fruit. Plants from nurseries can also be a source of fungi including ones that are resistant to fungicides. Conidia from within the planting are the principal inoculum and are produced readily and for a long time on diseased plant material. Conidia may infect leaves but infections generally remain symptomless until the leaf dies.

Note the gray, fuzzy growth over these berries.

Photo by Jay W. Pscheidt, 1994.

Image related to Strawberry (Fragaria spp.)-Gray Mold (Fruit Rot)

Soft, rotted fruit with a gray mold over the surface.

Dept of Horticulture, OSU

A basket of moldy berries.

Photo by Jay W. Pscheidt, 1997.

Although Botrytis generally occurs on mature fruit it can develop on flowers under ideal conditions.

Jay W. Pscheidt, 2020.

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Strawberry (Fragaria spp.) - Leather Rot

Strawberry (Fragaria spp.) - Red Stele

Image related to Strawberry (Fragaria spp.)-Crown Rot

The entire plant may wilt soon after young leaves become off-colored then collapse and die.

OSU Plant Clinic Image, 2014.

The vascular system of the crown is discolored with dark shades of brown.

OSU Plant Clinic Image, 2014.

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Strawberry Cultivar Susceptibility

Note the small leaf spots with gray centers and purple borders.

OSU Extension Plant Pathology Slide Collection, 1984.

Image related to Strawberry (Fragaria spp.)-Common Leaf Spot

Note that most of the leaf spots on this plant are near the ground and on older leaves.

Jay W. Pscheidt, 1991.

Black seed and necrotic leaf spots.

Photo by Melodie Putnam.

Small gray leaf spots with purple boarders.

Neil Bell, 2017.

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Apple (Malus spp.) - Replant Disease

Strawberry (Fragaria spp.) - Charcoal Rot

Image related to Strawberry (Fragaria spp.)-Black Root Rot Complex

Roots turn necrotic and do not function for water or nutrient uptake.

OSU Extension Plant Pathology Slide Set, 1982.

Note the many necrotic roots on this plant.

OSU Extension Plant Pathology Slide Set.

The roots on the right side are starting to turn necrotic near the crown.

Melodie Putnam, 2007.

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Blackberry (Rubus spp.) - Armillaria Root Rot

Image related to Strawberry (Fragaria spp.)-Armillaria Root Rot

The fungus has attacked the crown of these plants.

OSU Extension Plant Pathology Slide Set, 1964.

The fungus can be seen as white threads near the center of this picture.

OSU Extension Plant Pathology Slide Set.

Cause Several Colletotrichum spp. can cause various anthracnose diseases of strawberry. C. acutatum has been found by the OSU Plant Clinic. This is now considered a species complex where C. nymphaeae predominates on strawberry and C. fioriniae is less frequently found. The diseases of fruit and crown rot were not a problem in the 1900s but were found more often in 2000s.

Image related to Strawberry (Fragaria spp.)-Anthracnose

Crown rot may first be seen as wilting of the entire plant with the youngest leaves appearing to recover but eventually the whole plant dies.

OSU Plant Clinic Image, 2012.

Fruit spots rapidly develop into firm, round lesions that turn dark-brown to black.

Jay W. Pscheidt, 1992.

Cause Alkali yellows is caused by strongly alkaline soil, which can make iron or manganese unavailable to plants. Although soil pH may be the main problem, iron could be lacking in the soil or in a form unavailable to plants. A frequent problem sent into the OSU Plant Clinic from areas east of the Cascade Range.

Image related to Strawberry (Fragaria spp.)-Alkali Yellows

Slide marked iron deficiency.

OSU Extension Plant Pathology Slide Set, circa 1950's.

Symptoms of nutrient deficiency can be seen evenly across the field.

OSU Extension Plant Pathology Slide Set, 1957.

Leaves turn yellow between the veins. The veins remain green.

OSU Extension Plant Pathology Slide Set, 1957.

Cause Xanthomonas campestris pv. incanae, a bacterium that persists in the soil, on or in seed. A vascular disease of the main stem and lateral branches. It often extends into leaf petioles and seed peduncles. Bacteria may be spread rapidly by splash from irrigation water. Cool wet weather favors infection and disease development. Yield losses of up to 90% have been experienced.

Image related to Stock (Matthiola spp.)-Bacterial Blight

Note the stunted plants in the first row.

Photo by Melodie Putnam, 2000.

Stunted plants with deformed leaves.

Photo by Melodie Putnam, 2000.

Cause Turnip mosaic virus has been reported from California for the perennial Limonium perezii. This disease has been sap- and aphid-transmitted to L. sinuatum. The disease spread rapidly, producing irregular patterns in the field. Several other viruses in Europe on the annual L. sinuatum include broad bean wilt virus, cucumber mosaic virus, statice Y virus, tobacco rattle virus, and tomato bushy stunt virus.

Image related to Statice (Limonium spp.)-Viruses

Aster Yellows on Statice.

Melodie Putnam, 2009.