Gray mold is caused by a fungus (Botrytis cinerea). It is the most damaging rot of strawberries, attacking both flowers and berries, and greatly reduces the amount of edible fruit. The flowers are infected when in bloom and may not produce berries. Berries are attacked at all stages of development. They are infected directly when a healthy berry touches a decaying one, the ground, or a dead leaf. Infected berries are inedible. The fuzzy gray mold on the berries is composed of fungal strands and millions of microscopic spores. The fungus is most active in cool, humid weather and is spread by splashing water, people, or infected fruit. Crowded plantings, rain, and overhead watering enhance its spread.

Several types of weevils attack strawberries. The brown to black, hard-shelled, 1/4-inch-long adult beetles with long snouts feed on the leaves at night. They hide during the day under leaves and clods of soil. Their feeding causes little damage but is a warning sign that their larvae, grubs, may be present. Only one generation occurs per year. The adults are present from spring through summer, laying their eggs in the crowns of plants in early summer. The grubs that hatch burrow into the soil and feed on the roots until late fall, then resume feeding in the spring. Their feeding reduces berry production and sometimes kills the plant. Adult weevils occasionally become a nuisance in the house. As they migrate in search of more food, they enter homes through open doors and windows and cracks in the foundation. Although they may feed on some houseplants, they do not eat food or clothing.

These mites, related to spiders, are major pests of many garden and greenhouse plants. Spider mites are larger than cyclamen mites, which also attack strawberries. Spider mites attack older leaves, while cyclamen mites attack younger leaves. Spider mites cause damage by sucking sap from the undersides of leaves. As a result of their feeding, green leaf pigment disappears, producing the stippled appearance. Spider mite webbing traps cast-off skins and debris, making the plant messy and reducing berry production. Mites are active throughout the growing season but are favored by hot, dry weather (70°F and up). By midsummer, they have built up to tremendous numbers.

Ancylis comptana This moth larva damages plants by feeding from inside the rolled leaves. This feeding weakens the plant, causing leaves to die and fruit to be deformed. Leafrollers hibernate as larvae and pupae in plant debris and folded leaves. In spring, the adult moths, rusty red with brown and white markings, lay their eggs on the undersides of leaves. The larvae that hatch from these eggs roll the leaves and feed inside. After feeding for 4 to 7 weeks, the larvae pupate in the rolled leaves; they emerge as adults to repeat the cycle. Two generations occur per year in northern regions and as many as four in southern regions.

This wilt disease affects many ornamental plants. It is caused by soil-inhabiting fungi (Verticillium dahliae and V. albo-atrum) that persist indefinitely on plant debris or in the soil. The disease is spread by contaminated seeds, plants, soil, and equipment. The fungus enters the plant through the roots and spreads up into the crown and leaves through water-conducting vessels that become discolored and plugged. This plugging cuts off the flow of water and nutrients to the leaves, causing leaf yellowing and wilting. Affected plants may or may not recover and yield fruit the following year. Sometimes the disease appears in mother plants but not in rooted daughter plants.