2. Fusarium wilt symptoms
In fields with no or inadequate fumigation, strawberry plants can show initial symptoms of decline as early as 30 days after transplanting; these plants will stop growing and be stunted when compared to healthy plants. However, often the initial symptoms of Fusarium wilt in strawberry occur after the plants are well estab- lished and begin to flower or produce fruit, at which time the older leaves wilt, turn gray green in color, and begin to dry up. As disease progresses, virtually all of the foliage will collapse and dry up with the exception of the central, youngest leaves. Plants can eventually collapse and die. When internal tissues of plant crowns are examined, vascular and cortical tissues are dark brown to orange brown. Internal tissues of the main roots may also be discolored and dark brown in color. Environmental and other stresses can cause the disease to develop more rapidly and severely. Such fac- tors may include the following: weather extremes, particularly high temperatures; water stress from insufficient irrigation or prolonged saturation in the root zone; poor soil conditions; pressure from pests such as mites.