Aphelenchoides besseyiParasitizing Common Bean in Brazil

Abstract

Aphelenchoides besseyi is the causal agent of soybean green stem and foliar retention syndrome known as Soja Louca II. This nematode has recently been reported parasitizing cotton in Brazil. In Costa Rica, it causes the symptoms known as “amachamiento” and false angular spots in common bean (Phaseolus vulgaris). Due to the great importance of beans to Brazilian agriculture, the objective of this research was to study the pathogenicity of A. besseyi in common bean under greenhouse conditions, including its endoparasitic relationships by staining root and shoot system tissues with fuchsin acid. In addition, A. besseyi was collected and quantified from shoot systems 30 days after inoculation by washing the tissue in water and blender centrifugal-flotation. We observed the symptoms of “amachamiento”, leaf and vein deformation in the expanded trifoliate leaves, and also leaves with necrotic, brown to reddish and angular lesions, characteristics from false angular spot, and deformed stems characterized by enlargement of nodes, retortions and necrotic lesions. High numbers of nematodes were found inside common bean plants. This is the first report of the pathogenicity and symptoms caused by A. besseyi in common bean in Brazil. These findings are important for development of management strategies to avoid losses on bean cropped in infested areas.

Angular leaf spot inAcmella oleraceacaused by a foliar nematode

“…In Costa Rica, A. besseyi caused losses from 24 to 70% in common beans crops (Chaves et al 2013). In Brazil, although there are no reports of A. besseyi attacking common beans in commercial areas, most planted cultivars were susceptible to this nematode when inoculated under greenhouse conditions (Favoreto et al 2018; Favoreto et al 2021). In addition, A. besseyi is reported in the Midwest and Northern regions of Brazil, causing significant losses in soybean (Meyer et al 2017) and cotton (Favoreto et al, 2018) crops and more recently, identified as inducing leaf spots on yams ( Dioscorea cayenesis Lam.)…”

An emergent plant‐parasitic nematode in Brazil: Aphelenchoides besseyi. Current status and research perspectives

“…This undoubtedly raised awareness of the nematode, and losses in cotton were published in 2018 . In 2021, the pathogenicity of A. besseyi to common bean was demonstrated (Favoreto et al, 2021).…”

“…Cotton farmers have been testing several tools to manage A. besseyi, including fungus-based nematicides, but without promising results (Machado, 2021). There are nevertheless promising microorganisms that are already used in (and registered to) these crops against other PPNs (e.g., Meloidogyne spp.…”

“…After a meticulous investigation, Meyer, Favoreto, Klepker, et al (2017) reported A. besseyi (Christie, 1942) as the causal agent of the green stem and foliar retention (GSFR) of soybean. In 2018 and 2021, A. besseyi was reported to be infecting aerial parts of cotton and parasitizing common bean (Phaseolus vulgaris) (Favoreto et al, , 2021. In fields, symptomatic plants can be distributed in patches, along the rows or uniformly (Meyer, Favoreto, Klepker, et al, 2017).…”

Aphelenchoides besseyi causing leaf spot on cowpea under field conditions in Brazil

“…In Brazil, A. besseyi has been reported in economically important crops such as rice (Oryza sativa L.), causing white tip disease (Bebendo and Prabhu, 2016); in soybean [Glycine max (L.) Merrill], causing soybean green stem and the foliar retention syndrome (Meyer et al 2017); in cotton (Gossypium hirsutum L.), causing stunting, loss of floral buds, foliage distortion and thickened nodes (Favoreto et al 2018); and in yam (Dioscorea cayenensis), causing leaf spot (Noronha et al 2020) under field conditions. Moreover, common bean (Phaseolus vulgaris L.) and cowpea were experimentally infected with this nematode (Favoreto et al 2021(Favoreto et al , 2022, but to our knowledge this is the first report of A. besseyi parasitizing leaves of cowpea under field conditions in Brazil.…”