CSIRO PUBLISHING www.publish.csiro.au/journals/app Australasian Plant Pathology, 2005, 34, 369–376 A survey of fungal plant pathogens associated with weed infestations of barberry (Berberis spp.) in New Zealand and their biocontrol potential N. W. Waipara A,B , L. A. Smith A , A. F. Gianotti A , J. P. Wilkie A , C. J. Winks A and E. H. C. McKenzie A A Manaaki Whenua Landcare Research, 231 Morrin Road, Tamaki Campus, University of Auckland, Private Bag 92170, Auckland, New Zealand. B Corresponding author. Email: waiparan@landcareresearch.co.nz Abstract. Since the introduction and subsequent naturalisation of five species of Berberis into New Zealand, two species, B. glaucocarpa and B. darwinii have become aggressive invaders of both agricultural and native ecosystems throughout many regions. Both are now targets for a biological control program. A survey for pathogens to be used as potential classical or inundative biocontrol agents was initiated on weed infestations in New Zealand. Five species of primary plant pathogens were found to be associated with systemic leaf, flower and/or fruit disease symptoms, Colletotrichum gloeosporioides, C. acutatum, Pestalotiopsis sp., Phomopsis sp., and Sclerotinia sclerotiorum. The aecial stage of a barberry rust, Puccinia graminis, was recorded from the flowers of B. glaucocarpa, which is a new host record for New Zealand. Additional keywords: inundative biological control, invasive weed, plant diseases, barberry rust. Introduction Five species of Berberis have naturalised in New Zealand. Berberis darwinii (Darwin’s barberry) and B. glaucocarpa (barberry) have been widely dispersed throughout New Zealand and have become serious environmental weeds. A third barberry species, B. vulgaris (European barberry), although widespread in Canterbury and Otago (Webb et al. 1988) does not yet appear to be as invasive. The remaining two species (B. soulieana and B. wilsoniae) have very limited distributions (Webb et al. 1988). B. darwinii is endemic to Chile and Patagonia (Webb et al. 1988). First introduced into New Zealand in 1946, this species is now widely distributed from the East Cape region southwards, with major stands occurring in Southland and lower North Island. An evergreen shrub growing to ∼4 m tall and found particularly in higher rainfall areas, this species is invasive of native forest or plantation pine (Pinus radiata) stands as well as open hill slopes. Farmers and regional councils view B. darwinii as an expanding threat to pastoral and conservation values and, as a recent immigrant, it will likely continue to move into suitable habitats. Further large infestations are likely to be identified (McGregor 2002). B. glaucocarpa, from the western Himalaya, is common throughout lowland areas of New Zealand (Webb et al. 1988). Extensively used as hedging, this species of barberry, like B. darwinii, is invasive in a wide range of habitats with stands occurring in coastal reserves, grazed dairy pastures and drier sheep grazed slopes from Northland to Southland. First recorded in 1916, it arrived in New Zealand earlier than B. darwinii, and has had longer to naturalise and occupy its potential range. Large stands, as seen with gorse (Ulex europaeus) and broom (Cytisus scoparius), occur but are not yet common. According to a feasibility study (McGregor 2002), both species are serious threats primarily to sparsely vegetated areas of bush and scrub. The invasiveness of these species arises mainly from their production of large quantities of fruits, which are eaten and subsequently dispersed by birds and possums (Allen and Wilson 1992; Williams and Karl 1996). B. vulgaris has a more restricted distribution than either B. darwinii or B. glaucocarpa, being found predominantly in inland areas of Canterbury and Otago. Although first recorded in the wild in New Zealand some 40 years before any other species of barberry, it appears far less invasive than B. darwinii and B. glaucocarpa; its propensity to disperse seems to be more limited (McGregor 2002). This paper presents the results of a survey of fungal pathogens associated with Berberis species and the potential for their use as biocontrol agents of the weed is discussed. Such a survey also represents step 4 in a classical biological control program (Harley and Forno 1992). © Australasian Plant Pathology Society 2005 10.1071/AP05049 0815-3191/05/030369