![]() The rot is soft and light brown in color. The blossom infection can enter a dormant period in the calyx or hull, then become reactivated to cause fruit rot. Infection usually starts in the blossom and may destroy the entire blossom stalk. This disease affects blossoms and blossom stalks of green or ripe fruit. Customers usually complain of off-flavored fruit if berries infected with grey mold are eaten. Grey mold is very common and often causes serious losses in strawberries. Losses vary with time and location, as well as weather conditions from first bloom through harvest. Picking and packing are also more costly when these diseases are present in the field. They are capable of destroying a large percentage of the fruit. Diseases Attacking the Fruitīy far the most important strawberry diseases are the fruit rots caused by several fungi. Timely fungicide sprays are an effective method of control. Symptoms are most noticeable on warm, dry days.ĭense shelterbelt plantings that restrict good air flow will favour the spread of this disease. If a severe outbreak occurs before picking, the crop may be greatly reduced. The spread is gradual and may not be noticed until most plants in the field are infected. Infection begins in the spring soon after plant growth starts. Powdery mildew develops in the spring and fall. A white, powdery fungus growth may be seen on the underside of severely affected leaves. Infected leaves curl upward, become purplish on the underside and, in severe instances, develop badly burned areas at the margin. Leaves, flower calyxes and fruit all support mildew growth. Powdery mildew affects all above ground parts of the strawberry plant. Some cultivars are more susceptible to leaf spotting than others. Spores of the fungus form on the spots and are spread by rain, hands, tools and clothing when plants are wet. The leaf spot fungus may also attack the fruit and cause black seed. Plants and leaves are mostly susceptible early in the growing season and in late summer, especially where growth is very succulent. Leaf petioles or stalks, stolons, runners and, to some extent, calyxes (caps or hulls) may be attacked. The centers become grey or white with reddish to purplish borders. Later these spots enlarge to a diameter of 0.13 to 0.25 in (3 to 6 mm). This disease first appears on leaves as purplish spots that resemble leaf scorch (see color section). Leaf spot (Mycosphaerella fragariae Lindau) Tops are an inoculum source that may reinfect foliage the following year under suitable conditions. Risk of strawberry leaf and fruit diseases is reduced with renovation and removal of tops from the field. After renovation, a healthy foliage canopy must be maintained for fruit bud set and storage of winter food reserves. Prairie strawberry growers do not regard leaf diseases as a serious concern since they do not appear until after picking. Strawberry fruit fungal diseases are usually not a problem during an average dry prairie summer. ![]()
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