First Report of Multiple Species of the Botryosphaeriaceae Causing Bot Canker Disease of Indian Laurel-Leaf Fig in California

Abstract

Indian laurel-leaf fig (Ficus microcarpa L.) is a commonly used indoor and outdoor ornamental tree. F. microcarpa is most frequently encountered as lining city streets, especially in warmer southern California climates. A disease known as ‘Sooty Canker,' caused by the fungus Nattrassia mangiferae (Syd. & P. Syd) B. Sutton & Dyko, is particularly devastating on F. microcarpa. Disease symptoms are characterized by branch dieback, crown thinning, and if the disease progresses to the trunk, eventual tree death (2). Recent taxonomic revisions have renamed Nattrassia mangiferae as Neofusicoccum mangiferae (Syd. & P. Syd.) Crous, Slippers & A. J. L. Phillips (1). An initial survey conducted during the spring of 2011 across four cities in Los Angeles County included, Culver City, Lakewood, Santa Monica, and Whittier. Five symptomatic branches per city were collected from trees showing branch cankers and dieback. Pieces of symptomatic tissue (2 mm2) were plated onto one-half-strength potato dextrose agar. Most isolates initially identified by morphological characteristics, such as growth pattern, speed of growth, and colony color, resembled those in the Botryosphaeriaceae (4). Two representative isolates from each site location were sequenced. Sequences obtained from amplification of the internal transcribed spacer region (ITS1-5.8rDNA-ITS2) and the β-tubulin gene were compared in a BLAST search in GenBank. Results identified isolates as Botryosphaeria dothidea (identity of 99% to EF638767 and 100% to JN183856.1 for ITS and β-tubulin, respectively); Neofusicoccum luteum (100% to EU650669 and 100% to HQ392752); N. mediterraneum (100% to HM443605 and 99% to GU251836); and N. parvum (100% to GU188010 and 100% to HQ392766) and have been deposited in GenBank with the following accession numbers: JN543668 to JN543671 (ITS) and JQ080549 to JQ080552 (β-tubulin). Pathogenicity tests were conducted in the greenhouse on 6-month-old F. microcarpa with one isolate from each previously listed fungal species. Five plants per isolate were stem-wound inoculated with mycelial plugs and wrapped with Parafilm. Uncolonized agar plugs were used as a control. Inoculations were later repeated a second time in the same manner for a total of 10 plants per isolate. Plants were observed for 6 weeks and destructively sampled to measure vascular lesion lengths. Mean vascular lesion lengths were 26, 22, 54, and 46 mm for B. dothidea, N. luteum, N. mediterraneum, and N. parvum, respectively. The mean lesion lengths for all isolates were significantly different (P = 0.05) from the control. Each species was consistently recovered from inoculated plants, except the control, thus fulfilling Koch's postulates. To our knowledge, this is the first report on the pathogenicity of multiple Botryosphaeriaceae species causing branch canker and dieback on F. microcarpa in California. These results are significant since trees along sidewalks in southern California are often crowded and undergo extensive root and branch pruning and some Botryosphaeriaceae spp. are known to enter its host through wounds caused by pruning or mechanical injury (2,3). Further sampling is imperative to better assess the distribution of these canker-causing fungal pathogens on F. microcarpa. References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) D. R. Hodel et al. West. Arborist 35:28, 2009. (3) V. McDonald et al. Plant Dis. 93:967, 2009. (4) B. Slippers et al. Fungal Biol. Rev. 21:90, 2007.

The Botryosphaeriaceae: genera and species known from culture

“…( Denman et al 2003 ), Chamaecyparis lawsoniana, Cupressus sempervirens, C. lusitanica, Juniperus communis, Pinus pinea, Sequoia sempervirens, Thujopsis dolabrata, Thuja plicata ( Alves et al 2013 ), Chrysanthemoides monilifera ( Cunnington et al 2007 ), Crataegus mexicana ( Adesmoye et al 2013 ), Diospyros kaki ( Gadgil et al 2005 ), Eucalyptus sp. ( Denman et al 2003 ), Ficus microcarpa ( Mayorquin et al . 2012 ), Fraxinus angustifolia ( Phillips et al 2002 ), Malus domestica ( Gadgil et al 2005 ), Olea europaea ( Sergeeva et al 2009 ), Persea americana ( McDonald & Eskalen 2011 ), Protea cynaroides ( Denman et al 2003 ), Pyrus communis ( Gadgil et al 2005 ), Pyrus pyrifolia ( Gadgil et al 2005 ), Quercus robur ( Barradas et al .…”

“…Known distribution : eastern Australia ( Denman et al 2003 , Cunnington et al 2007 , Sergeeva et al 2009 ), USA (California) ( Úrbez-Torres et al 2006b , McDonald & Eskelen 2011 , Mayorquin et al . 2012 ), Italy ( Lazzizera et al 2008 ), New Zealand ( Gadgil et al 2005 , Pennycook & Samuels 1985 ), Portugal ( Phillips et al 2002 , Alves et al 2013 , Barradas et al .…”

“…( Inderbitzin et al 2010 , Abdollahzadeh et al . 2013 ), Ficus microcarpa ( Mayorquin et al . 2012 ), Fortunella sp., Fraxinus sp., Juniperus sp., Persea americana, Pistacia vera, Prunus dulcis, Rubus sp., Sequoiadendron giganteum ( Inderbitzin et al 2010 ), Eucalyptus ( Crous et al 2007 , Inderbitzin et al 2010 ), Juglans regia ( Inderbitzin et al 2010 , Trouillas et al .…”

“…Known distribution : USA (California) ( Úrbez-Torres et al 2010 , Trouillas et al . 2010 , Inderbitzin et al 2010 , Mayorquin et al . 2012 ), Greece ( Crous et al 2007 ), Iran ( Abdollahzadeh et al .…”

Botryosphaeriaceae associated with the die-back of ornamental trees in the Western Balkans

“…Several species of the Botryosphaeriaceae, including Botryosphaeria dothidea, Neofusicoccum parvum, Neofusicoccum luteum, Neofusicoccum batangarum, Neofusicoccum magniferae, Neofusicoccum mediterraneum, Neodeightonia palmicola, Lasiodiplodia theobromae, Lasiodiplodia pseudotheobromae, Lasiodiplodia mahajangana and Diplodia cupressi have been found causing disease on ornamental trees worldwide (e.g., Begoude et al 2010;Heath et al 2011;Varela et al 2011;Mayorquin et al 2012;Ligoxigakis et al 2013;Deng et al 2015;Stanosz et al 2015). With the exception of Greece, not much is known regarding species of the Botryosphaeriaceae that occur in the Balkans.…”