Biology and Infection Mechanisms of Cryptosporiopsis spp Fungus Causing Blight Disease on Cashew (Anacardium Occidentale L.)

Abstract

Efficient isolation, purification and identification techniques of a new pathogenic fungus of cashew were developed.In the study, aspects related to identification, characterization of conidial morphology and infection of the Cryptosporiopsis spp fungus were investigated. Macroscopic observations of symptoms and signs of cashew blight disease as well as isolation, culturing and morphological characterization of its causative agent were carried out. Cryptosporiopsis spp fungus penetration and infection mechanisms on susceptible cashew leaves were studied. Cashew leaves were inoculated with fungal suspensions by pricking with pin, clipping with scissors and painting a fungal suspension onto the leaves with a paintbrush. Pathogenecity assays were performed on cashew leaves, nuts and apples. Irregular spot lesions, with a brown margin, formed on leaves especially on the young leaves. Direct conidial transfer was found to be the efficient method of isolation because it was less prone to contamination. Blight macroconidia are typical of Cryptosporiopsis having ellipsoidal, rounded at the apex, tapering into a scar at the base. Stomatal penetration of Cryptosporiopsis spp was visible through the simple staining technique using lactophenol solution. Penetration was by germinating conidia through a cuticle that caused an infection in leaves. Paint brush method of inoculation was found to be more effective as compared to other two methods based on the lesion size. Leaves inoculated with Cryptosporiopsis spp isolate began curling after 72 h thereafter developed dark, irregularly shaped spots with brown margins. An increased understanding of cashew blight is important for developing strategies for its management.

Diseases and Insect Pests associated with Cashew (Anacardium occidentale L.) Orchards in Ghana

“…In order of importance, cashew powdery mildew caused by Oidium anacardii Noack, has been considered the most serious disease [43], [12], in 2003, followed by second most damaging disease 'cashew leaf and nut blight' established to be caused by Cryptosporiopsis spp. [44], [13], [14], and in 2012, Fusarium oxysporum causing Fusarium wilt disease has been reported as the third deadliest disease of cashew in Tanzania [15]. Yield losses of up to 100% has been proposed if not timely controlled [45].…”

“…Other diseases and pathogens that are known to infect cashew include: powdery mildew (Oidium anacardii) [12], [10], leaf and nut blight' by Cryptosporiopsis spp. [13], [14], Fusarium wilt disease [15], Pestalotia leaf spot caused by Pestalotia spp. [16], [17], red rust algal disease caused by Cephaleuros virescens [18], black mold (Pilgeriella anacardii) [19], [10], Angular leaf spot caused by Septoria anacardii [20], Phyllosticta brasiliensis, Corynespora hansfordii, Phomopsis anacardii, Cladosporium sp., Capnodium sp., Curvularia lunata and Microxyphium sp.…”

Morpho-cultural, molecular characterization and identification of the pathogen of the burning of leaf and cashew fruit

“…Then, the plates with PDA were stored in the refrigerator at 4 o C (Fernandez, 1993). After inoculated they were sealed with parafilm (Figure 1B) and kept on an incubation shelf at a temperature of 25 ± 2 °C (Dominic et al, 2014;Cordeiro et al, 2007).…”

Tracking cashew economically important diseases in the West African region using metagenomics

“…Recently, a new pathogenic fungus ( Cryptosporiopsis spp.) causing cashew blight disease was reported in Tanzania ( Dominic et al, 2014 ). Considering the scarce information on cashew diseases, a broad approach that could accurately identify and analyze mycobiota responsible for such disorders would contribute to design effective control measures.…”