Disease-Causing Agents in Cashew: A Review in a Tropical Cash Crop

Abstract

Due to the high market value of cashew nut, cashew became a significantly important cash crop in many countries. Originating from Brazil, the plant was introduced into Africa, India, and Southeast Asia and is nowadays found across most of the tropical regions. However, the diseases that threaten and compromise crop production have not yet been comprehensively documented. The aim of this study was to examine the published scientific data on cashew diseases, to identify current knowledge gaps, and to present a review of the most important diseases and pathogens affecting cashew productivity. The most described diseases are caused by fungi genera—mainly Colletotrichum, Lasiodiplodia, and Erysiphe (worldwide); Cryptosporiopsis (East Africa); and recently Fusarium in Tanzania. Other fungal genera (e.g., Septoria, Pilgeriella, and Pestalotia) may correspond to emerging local cashew diseases that have not yet expanded to other geographic regions or for which records are lacking. Gummosis (Lasiodiplodia spp.), which is considered the most prevalent and damaging disease of cashew, has a pantropical distribution. There is large discrepancy concerning the causal agents of cashew diseases that might be explained by the lack of proper species identification through morpho-cultural and molecular approaches. This, in turn, can easily lead to misdiagnoses that have serious negative consequences for the implementation of specific control actions. It is important to establish a standardized identification workflow that will allow a reliable identification of the disease-causing agent and to determine the occurrence and/or expansion of a given pathogen across cashew-producing regions.

Preliminary experiments on potential use of blue monochromatic light for identification of cashew diseases

“…Significant discrepancy concerning the causal agents of cashew diseases is common due to lack of proper species identification through morpho-cultural and molecular approaches (Monteiro et al, 2022). In this set of experiments a beam of blue light at 405 nm was successfully used to distinguish some cashew diseases.…”

“…Disease diagnoses requires both host symptoms, pathogens' signs, morpho cultural and more recently molecular studies (Monteiro et al, 2022). This becomes more complicated when, in nature and more frequently, the exhibited cashew symptoms reflect more than a single pathogen infection.…”

Enhancement of Cashew (Anacardium occidentale L.) Seedlings Growth in Semiarid Regions Using a Superabsorbent Hydrogel Composite

“…Beyond Brazil, cashew is extensively cultivated in all tropical areas, notably in India and East Africa . In these countries, the cashew crop represents one of the primary sources of employment and income generation for small farmers, particularly in the semiarid region of Brazil …”

“…2 In these countries, the cashew crop represents one of the primary sources of employment and income generation for small farmers, particularly in the semiarid region of Brazil. 3 In this context, income generation is directly correlated with the productivity of the cashew crop managed by these small farmers. Among the various factors that influence productivity, establishing and maintaining healthy cashew orchards is crucial.…”

The CfAtg5 Regulates the Autophagy and Pathogenicity of Colletotrichum fructicola on Camellia oleifera

“…are the casual agents of anthracnose and cause anthracnose spots and blights on almost every crop, ranking Colletotrichum spp. in the top 10 fungal pathogens in molecular plant pathology [6][7][8][9]. Generally, Colletotrichum spp.…”