First Report of Black Branch Dieback of Cashew Caused by Lasiodiplodia theobromae in Brazil

Abstract

Cashew nut (Anacardium occidentale) is one of the most important cash crops of northeastern Brazil. A new disease, named here as black branch dieback, caused by Lasiodiplodia theobromae, was observed causing serious damage on as many as 30% of the trees in some orchards in both coastal and inland semiarid cashew-growing areas of Ceará and Piauí states of Brazil, respectively. The disease symptoms are first observed as darkened, elongated lesions on stems near the branch apexes of herbaceous tissues. Gum exudation is common from lesions, which expand rapidly to affect the entire branch, leading to branch death. Diseased plants were collected, and L. theobromae was consistently isolated from canker tissues. Fresh mycelial disks of the fungus were used for artificial inoculation of healthy plants. Shoots of young cashew plants were inoculated on the apex by inserting a 3-mm plug taken from actively growing colonies on potato dextrose agar into an incision made with a sterile scalpel. Agar plugs with no mycelium were placed into incised plant shoots to serve as controls. Plants were incubated in a greenhouse at 28°C. Symptoms developed within 15 days after inoculation. Artificially inoculated plants showed symptoms similar to those that were naturally infected. L. theobromae was consistently reisolated from inoculated plants. The disease seems to occur throughout the year, but it spreads faster during the rainy season. A contagious disease pattern within the orchard was observed with a decreasing gradient from the orchard perimeter to the interior of the field, suggesting an external source of primary inoculum. All improved dwarf cashew clones were susceptible, but the newly released clone END-189 was the most susceptible. Black branch dieback may reduce tree growth, nut yield, and eventually cause plant death. Plant susceptibility is not related to its age however; only herbaceous tissues are vulnerable to natural infection. A similar disease on floral shoots of cashew caused by L. theobromae was reported by Olunloyo and Esuruoso in Nigeria (1). To our knowledge, this is the first report of L. theobromae causing branch dieback in cashew orchards in Brazil. Reference: (1) O. A. Olunloyo and O. F. Esuruoso. Plant Dis. 59:176, 1975.

Diversity of genusLasiodiplodiaassociated with perennial tropical fruit plants in northeastern Brazil

“…Upon cropping, these plants have been subject to selection, which rendered them more susceptible to diseases and other pests that were previously regarded as having secondary importance in the region (Freire et al ., ). Among these diseases are those caused by the fungus Lasiodiplodia theobromae sensu lato , which was once considered a weak pathogen impacting stressed plants, but became one of the major pathogens affecting the survival and yield of tropical fruit plants in Brazil by causing symptoms such as stem cankers, gummosis, dieback, and postharvest fruit decay (Cardoso et al ., ; Freire et al ., ).…”

“…Lasiodiplodia theobromae has been described as a causal agent of cashew gummosis, which has become the most important disease impacting cashew orchards in the semi‐arid conditions of northeastern Brazil. This disease causes damage of up to 30% stand losses in localized orchards in the states of Ceará and Piauí (Cardoso et al ., ), infecting commercial clones of cashew trees (Moreira et al ., ) and causing nut decay (Freire, ). In Spondias , this fungus has been reported affecting all cultivated species at different levels of disease severity, depending on host susceptibility (Lima et al ., ), and it is a seedborne pathogen of soursop (Cardoso et al ., ).…”

Dieback of Cashew (Anacardium Occidentale) in Cameroon

“…Among these diseases, dieback is a common one in cashew orchads. Dieback is a disease which attacked many plant species in many countries like cocoa trees in Cameroon (Mvondo et al, 2018;Mbenoun et al 2007), mango trees in Burkina Faso, Togo and Pakistan (Dianda et al2018;Tedihou et al, 2017;Kazmi et al, 2005), citrus (Tedihou et al, 2017), cashew in Brasil and Nigeria (Cardoso et al 2002;Hammed and Abedideji, 2008;Cipriano et al 2014), Fortunella margarita (Lour) and Aquilaria sinensis in Taiwan (Ko and Wang 2004;Fan et al, 2013), and Camelia oleifera in China ( Zhu et al, 2014). Lasiodiplodia theobrome is the largest causal agent of this disease.…”

First report of <i>Lasiodiplodia theobromae</i> (Pat.) Griffon & Maubl causing root rot and collar rot disease of <i>Jatropha curcas</i> L. in Benin

“…(Kaushik et al, 2001) and Botryosphaeria dothidea (Mougeot: E.M. Fries) Cesati & De Notaris (Rao et al, 2011). Lasiodiplodia theobromae is a ubiquitous pathogen of tropical woody trees, causing shoot blight and dieback of many plant species (Mohali et al 2005;Latha et al, 2009) including: dieback and gummosis of mango (Khanzada et al, 2004); black branch and dieback disease of cashew in Brazil (Cardoso et al 2002); and collar rot of peanut in Virginia and North Carolina, USA (Phipps & Porter 1998). To our knowledge, this is the first report of Lasiodiplodia theobromae causing disease to Jatropha in Benin.…”