Mycobiota of the weed Conyza canadensis (Asteraceae) in Brazil

Abstract

Conyza canadensis is a noxious and notably problematic weed in Brazil whose control is greatly challenging due to the appearance, in the last years, of herbicide resistant populations. An investigation regarding the associated pathogenic fungi of this plant was conducted in Brazil aimed at starting a biological control program to help mitigate its economic impact. Ten fungal species were yielded and described: two ascomycetes (Leptosphaerulina conyzicola sp. nov. and Wentiomyces melioloides), five hyphomycete asexual morphs (Alternaria tenuissima, Cercospora conyzicola sp. nov., Cercosporella virgaureae, and Fusarium fujikuroi), two coelomycete asexual morphs (Phoma conyzaphthora sp. nov., Septoria erigerontis), one rust fungus (Aecidium conyzicola sp. nov.), and one oomycete (Basidiophora entospora). Four among the fungi that were collected represent new taxa, and the others represented either new host-records of known fungal species or new geographic records or both, except for C. virgaureae that had already been recorded on C. canadensis in Brazil. None of the discovered species have any potential to be used as a mycoherbicide or to be introduced somewhere else, nevertheless, the knowledge about this mycobiota will help guide the selection of potential biocontrol agents to be introduced in Brazil.

Assessment of Fungal Pathogens Affecting the Weed Conyza bonariensis in Argentina

“…Previous studies demonstrated saprophytic associations between Alternaria and Conyza species (Caretta et al, 1999;Roy et al, 1994) or related the fungal presence to lesion on leaves (Duarte et al, 2016). In this study, 2 out 10 Alternaria isolates were able to develop symptoms in C. bonariensis and were subsequently isolated from all lesions.…”

“…In this case, all isolates recovered from symptomatic leaves reproduced the disease in pathogenicity tests showing similar aggressiveness. Previous works worldwide have detected diseases in Conyza related to the presence of Septoria species (Duarte et al, 2016;Erper et al, 2010;Priest, 2006;Fatehi et al, 1993). On the other hand, several investigations have reported the use of different Septoria species as biocontrol agents such as S. cirsii in Cirsium arvense, a weed of Asteraceas's family (Leth, 1985), S. polygonorum proposed against species of Polygonum (Mitchell, 2003) and S. urticae proposed against Urtica urens L. (Bello, Perelló, & Monaco, 1993).…”

“…On the other hand, phytopathogenic fungi can be used as producers of bioactive molecules with herbicidal activity (Castro de Souza et al, 2017). Many steps are involved in the implementation of a biological control program but it always includes surveys aimed at identifying the natural enemies associated with the plant in its centre of origin and often also comprises surveys in the region where introductions will be made (Duarte, Santos, & Barreto, 2016). However, no systematic surveys have been carried out on C. bonariensis for suitable agents as it was suggested by Scott et al (2016).…”

Conyza bonariensis as an alternative host for Colletotrichum species in Argentina

“…1994) and Brazil (Duarte et al . 2016) have shown associations between Colletotrichum sp. and Conyza sp.…”

Erzurum ilinde patates tarlalarında Fusarium türlerinin alternatif yabancı ot konukçuları

“…Ayrıca, yabancı otlar üzerinden farklı cinslere ait fungus türlerinin izole edilmesi bu bitkilerin alternatif konukçu olma potansiyellerini göstermektedir. Nitekim yabancı otların alternatif konukçu olduğuna dair çok sayıda çalışma mevcuttur (Demirci ve Zengin 1995, Demirci and Genc 2009, Duarte et al 2016, Hennessy et al 2005, Kazemi and Shimi 2005, Linde et al 2016, Mourelos et al 2014, Yıldız et al 2009. Erzurum ilinde patates tarlalarında ve nadasa bırakılan tarlalarda bulunan 18 yabancı ot türünden 39 Rhizoctonia spp.…”