| Popis: |
First identified in 1997, Exobasidium leaf and fruit spot has emerged as an important disease of both rabbiteye and highbush blueberry in the southeastern US. Yield losses up to 60% have been recorded on ‘Premier’ rabbiteye blueberry. The pathogen, recently described as Exobasidium maculosum M. T. Brewer, is a species unique to the region. The life cycle of the pathogen is currently not known. Infection of leaves and fruit appear to occur simultaneously or in close sequence in early spring, with leaf symptoms appearing in spring and berry symptoms most obvious when fruit ripens. Berry infections appear as green unripe spots on otherwise ripe, blue fruit. Leaf infection produces round, pale-green spots averaging 7-8 mm in diameter that are white when viewed from below. Symptoms do not occur on later leaves, suggesting a springtime, mono- or oligocyclic disease cycle. Disease intensity appears to be highest in wet fields with dense growth and poor air circulation. Fungicides applied beginning at bud break are effective in reducing disease intensity, but there is evidence of resistance to some fungicides. Single, delayed-dormant applications of lime-sulfur have provided significant control in initial trials in Georgia. |
