Strawberry leaf spot Photo: Chad Behrendt

Leaf spot and leaf scorch are two different diseases causing similar symptoms on strawberry leaves. Both diseases can occur on a plant at the same time. However, leaf spot is caused by the fungus Mycosphaerella fragariae and leaf scorch by the fungus Diplocarpon earlianum.

Spores are produced on plant debris infected the previous year. These spores are wind blown or rain splashed to susceptible tissue during cool, moist weather in the spring. Symptoms of both diseases initially appear as round, purple spots approximately 1/8" to 1/4" in diameter. With strawberry leaf spot, the centers of the spots become white to gray in color as the disease progresses, whereas the spots remain reddish purple when infected with leaf scorch. Spots may eventually coalesce, causing large portions of infected leaves to appear red or purple.

Leaf spot and leaf scorch do not usually cause serious damage to the plants. If infection is severe, both diseases could kill leaves, weaken plants, or reduce fruit production. Control of leaf spot and leaf scorch should include the following cultural practices.

• Use disease resistant varieties when available.
• Choose a proper site with good air circulation and adequate sunlight.
• Keep row widths from 18 to 24 inches and avoid extremely thick plantings. This will allow better air circulation and reduce moisture on plant surfaces.
• Keep the site free from weeds.
• Avoid overhead watering. This will reduce moisture on the leaves and help prevent the spreading of spores to healthy leaves.
• Remove all infected plant material after harvest. This prevents fungal spores from overwintering.
• Perform yearly renovations on the bed.

Fungicides such as Captan or copper may be used if leaf spot and leaf scorch have been a problem in previous years. Read the label carefully and apply only as directed.

Representative trade names may be included along with generic names. This information is supplied with the understanding that no discrimination is intended and no endorsement is implied.

P224S
Revised 12/99
Chad Behrendt, Crystal Floyd