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Cocoa is a commercially important beverage crop that faces new challenges in the context of climate change, which can alter pest and disease dynamics in cocoa plantations. In the Dakshina Kannada district of Karnataka, India, an abrupt increase in cocoa wilt was observed during the 2017–18 and 2018–19 seasons. Systematic examination of affected trees revealed consistent attacks of Euwallacea perbrevis (Schedl, 1951; Coleoptera: Curculionidae: Scolytinae). In-depth studies of the wilted trees revealed the association of the plant pathogenic fungus Fusarium sp. with Euwallacea perbrevis. The identity of the obtained pure culture from the insect and infected tree was confirmed as Fusarium sp. using amplification of ribosomal DNA, RNA polymerase II largest subunit (RPB1) and translation elongation factor 1 (Tef1) genes. Notably, this study reports a remarkable case of mutualistic association between ambrosia beetles and Fusarium sp., belonging to the Fusarium solani species complex (FSSC), rather than the Ambrosia Fusarium clade (AFC). This finding highlights the intriguing diversity of mutualistic relationships in nature and sheds new light on the complex interactions between organisms. The present study also investigated the impact of rainfall on the colonization and spread of the Euwallacea-Fusarium complex. The findings revealed that rainfall was identified as a predisposing factor for the incidence and spread of attacks. Additionally, the study conducted a comprehensive analysis of the modeling of Euwallacea-Fusarium complex spread over a specific period of time. • An abrupt increase in cocoa wilt was documented in Karnataka, India during the periods 2017–2019. • Investigation unveiled incidence of Euwallacea fornicates , an ambrosia beetle, and Fusarium sp. fungus, belonging to the Fusarium solani species complex. • The study identified rainfall as a predisposing factor for the incidence and spread of Euwallacea - Fusarium complex. • This is the first report of Euwallacea - Fusarium complex causing wilt disease of cocoa in India. [ABSTRACT FROM AUTHOR]

A new sprout decay and seedling stunting disease of unknown aetiology in upland cotton (Gossypium hirsutum L.) affecting nearly 5%–10% of young seedlings was noticed in vertisols of central Vidarbha (Maharashtra state, India) in July of 2017. The bacterium was consistently isolated from diseased seedlings and identified with a polyphasic method of characterization, including morphological, physiological, biochemical and 16S rRNA gene sequence analysis. The bacterium strain CICR‐MGMG1 was isolated from diseased plants identified as Enterobacter sp. Inoculation of healthy cotton seed with an axenic culture of strain CICR‐MGMG1 isolated from diseased young seedling reproduced disease symptoms of yellowing, stunting and deformed growth similar to the symptoms reported from infected field condition. The strain CICR‐MGMG1 was consistently isolated from both diseased seedlings and stunted plants. Thus, the pathogenicity test of Koch's postulates was confirmed with the bacterium Enterobacter sp. strain CICR‐MGMG1 as the causal organism of sprout decay and seedling stunting. To the best of our knowledge, this is the first record of Enterobacter sp. causing sprouts decay and seedling stunting of cotton. [ABSTRACT FROM AUTHOR]