Evaluation of fungicide efficacy against Neofusicoccum species
causing dieback disease of blueberries in New Zealand
K. M. S. Tennakoon
Hayley J. Ridgway
Marlene V. Jaspers
E. Eirian Jones
Received: 13 February 2018 /Accepted: 23 May 2018
Australasian Plant Pathology Society Inc. 2018
Several Botryosphaeriaceae species have been reported to cause stem canker, twig blight and dieback of blueberries, with
different species being reported in different parts of the world. Pruning wounds are regarded as primary infection sites for these
pathogens. This research evaluated in vitro and in vivo efficacy of fungicides against the main Neofusicoccum species associated
with blueberry dieback in New Zealand. In vitro evaluation showed that four out of the nine fungicides tested were effective at
reducing mycelial growth and/or conidial germination and germ tube growth of three pathogenic isolates each of N. australe, N.
luteum, N. parvum and N. ribis. In vivo evaluation carried out with fungicides on wounded and non-wounded plant tissues on
potted and field blueberry plants showed that carbendazim and tebuconazole were the most effective for protecting blueberry
plants from infection by Neofusicoccum species. This research showed the importance of protecting both wounded and non-
wounded tissues, with more than one application of fungicides likely to be required to provide effective control of the disease
under natural inoculum levels.
Natural infection levels
Va cc iniu m a s h ei
Blueberry [Vaccinium corymbosum (highbush) and V. ashei
(rabbiteye)] orchards extend from northern to southern New
Zealand, with currently over 400 ha planted in blueberry.
Among the blueberry diseases reported in New Zealand,
botryosphaeria dieback is an emerging problem. In New
Zealand, recent sampling of blueberry plant material from
both nurseries and fields demonstrated that Neofusicoccum
australe, N. luteum, N. parvum,andN. ribis were the most
prevalent species (Tennakoon et al. 2018a).
Wounds, especially pruning wounds, are regarded as pri-
mary infection sites for Botryosphaeriaceae species which
cause cankers and shoot dieback (Milholland 1995;
Polashock and Kramer 2006). However Tennakoon et al.
(2017, 2018b) reported that although N. luteum and N. ribis
inoculation of non-wounded green blueberry shoots did not
result in the production of visible lesions, both species were
recovered from the underlying wood tissue indicating the po-
tential for infection of non-wounded shoots.
Although fungicide efficacy against Botryosphaeriaceae
species has been studied in other perennial crops, such as
grapevines, there is little information relating to fungicide ef-
ficacy against botryosphaeria dieback in blueberries (Bester et
al. 2007; Amponsah et al. 2012). Although Espinoza et al.
(2009) reported that in in vitro studies isolates of N. parvum
from blueberries were sensitive to fludioxonil and iprodione,
these fungicides were not evaluated under field conditions.
Latorre et al. (2013) studied the effectiveness of pastes
(wound protectants) formulated with 0.1% benomyl, 0.5%
tebuconazole, and 0.06% iprodione, against N. parvum infec-
tion, on the pruned stems of Duke blueberries under field
conditions. Results showed that benomyl, tebuconazole and
iprodione were, in order of efficacy, the most effective fungi-
cide treatments providing significant protection. In New
Zealand, no fungicides have been evaluated against the
Botryosphaeriaceae species which cause infections in
* E. Eirian Jones
Department of Pest-management and Conservation, Faculty of
Agriculture and Life Sciences, Lincoln University, PO Box 85084,
Lincoln, New Zealand
Present address: The New Zealand Institute for Plant & Food
Research Limited, Christchurch, New Zealand
Berryworld Ltd, Tai Tapu, RD2, Christchurch 7672, New Zealand
Australasian Plant Pathology