Strawberry green petal disease is a minor disease caused by ‘Candidatus Phytoplasma asteris’-related strains. Phytoplasmas are bacteria-like microbes that are transmitted from plant to plant by leafhoppers and grow in the phloem. In strawberries, they may also be introduced through infected tissue culture material or other vegetative propagation systems. In annual production systems, green petal disease is uncommon. The pathogen must be reintroduced each season on infected plants, as spread within the field during the production cycle is not known to occur.

Symptoms
Early symptoms include plant stunting and the development of multiple crowns (Figure SS-1; Figure SS-2). As symptoms develop, strawberry fruit may grow leaves (phyllody; Figure SS-3), which may mimic the symptoms of samage from glyphosate applications (Figure SS-4).

Management

Plants in certification programs should be evaluated to ensure they are free of phytoplasma. A rapid diagnostic test can be conducted by a diagnostic laboratory using Polymerase Chain Reaction (PCR).

Figure SS-1: Plants showing a distinct stunting compared to non-infected plants. These plants have multiple crowns and small leaves.

Frank J. Louws

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Figure SS-1: Plants showing a distinct stunting compared to non-infected plants. These plants have multiple crowns and small leaves.

Frank J. Louws

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Figure SS-2: Plants showing a distinct stunting and compressed growth. These plants were harvested form the field in late winter.

Frank J. Louws

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Figure SS-2: Plants showing a distinct stunting and compressed growth. These plants were harvested form the field in late winter.

Frank J. Louws

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Figure SS-3: Odd growth of leaves from strawberry fruit (phyllody).

Frank J. Louws

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Figure SS-3: Odd growth of leaves from strawberry fruit (phyllody).

Frank J. Louws

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Figure SS-4. Phyllody caused by glyphosate

Natalia Peres, CABI, 2019

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Figure SS-4. Phyllody caused by glyphosate

Natalia Peres, CABI, 2019

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• Strawberry Green Petal Disease: A Diagnostic Guide
• Peres, N.A., Duval, J.R., and Seijo, T.E. 2005. Determination of the cause of phylloid strawberry fruit in annual strawberry production in central Florida. Proceedings of the Florida State Horticultural Society 118:115-118.