Survey of blueberry farms for Botryosphaeria dieback and crown rot pathogens

Abstract

Dieback and crown rot affect about 18 of blueberry plants in the main New Zealand production areas costing about 500000 annually due to yield losses and replanting costs Samples of symptomatic plants and stems were collected from six blueberry farms in the central North Island to determine which pathogens were responsible From the 70 plants collected numerous isolations from branch bases and tips stem lesions and crowns revealed the apparent presence of Botryosphaeria species in 69 645 543 and 70 of samples respectively These Botryosphaeria spp were also found in a few roots and leaves but not fruit from symptomatic plants nor in healthy asymptomatic stems Morphological examination of conidia from 40 cultures identified B lutea B parva B lutea/australis and B obtusa with one unidentified Botryosphaeria species apparently of the Neofusicoccum type Molecular identification of 14 representative isolates from these 40 confirmed the presence of B lutea B parva and B australis