First report of Fusarium oxysporum f. sp. cubense Tropical Race 4 (VCG 01213/16) associated with cavendish bananas in Laos

The popular Cavendish banana (Musa spp., AAA) constitutes about 45% of all bananas grown worldwide (Lescot, 2015). Mainland China is one of the leading producers of Cavendish bananas, and to satisfy local demand for the fruit, commercial production is expanding into neighbouring countries such as Laos, Myanmar and Vietnam. In Laos, local banana varieties such as "kuay nam" (Silk, AAB), "kuay hom" (local Cavendish, AAA) and "kuay klai" (Horn Plantain, AAB) are preferentially grown for food and income generation. The expansion of Cavendish production from China into Laos, therefore, presents significant risks to these varieties, such as the introduction of Fusarium oxysporum f. sp. cubense tropical race 4 (TR4; VCG 01213/16), a soil-borne fungus that causes severe epidemics and crop losses in Cavendish plantations in southern Chinese provinces. In November 2016, Laos Department of Agriculture staff reported wilting plants from Luang Namtha and Borkeo provinces. In February 2017, yellow leaf symptoms typical..

First report of Sclerotium rolfsii in the Lao PDR

In May 2010 basal stem rot of snake bean (long bean) (Vigna unguiculata subsp. sesquipedalis) caused by Sclerotium rolfsii was discovered in Vientiane Capital, Lao PDR, during an ad hoc disease survey. The disease had resulted in death of some infected plants. The basal stem region had a bleached appearance, a typical symptom of this disease. Abundant small, round, brown sclerotia were present on the stem base, and on the adjacent soil and dead leaf material. The fungus was isolated into pure culture and Koch’s postulates were fulfilled. This is the first report of S. rolfsii in the Lao PDR, and the first report of basal stem rot of snake bean caused by this pathogen in the Lao PDR

Complex multiple introductions drive fall armyworm invasions into Asia and Australia

Abstract The fall armyworm (FAW) Spodoptera frugiperda is thought to have undergone a rapid ‘west-to-east’ spread since 2016 when it was first identified in western Africa. Between 2018 and 2020, it was recorded from South Asia (SA), Southeast Asia (SEA), East Asia (EA), and Pacific/Australia (PA). Population genomic analyses enabled the understanding of pathways, population sources, and gene flow in this notorious agricultural pest species. Using neutral single nucleotide polymorphic (SNP) DNA markers, we detected genome introgression that suggested most populations in this study were overwhelmingly C- and R-strain hybrids (n = 252/262). SNP and mitochondrial DNA markers identified multiple introductions that were most parsimoniously explained by anthropogenic-assisted spread, i.e., associated with international trade of live/fresh plants and plant products, and involved ‘bridgehead populations’ in countries to enable successful pest establishment in neighbouring countries. Distinct population genomic signatures between Myanmar and China do not support the ‘African origin spread’ nor the ‘Myanmar source population to China’ hypotheses. Significant genetic differentiation between populations from different Australian states supported multiple pathways involving distinct SEA populations. Our study identified Asia as a biosecurity hotspot and a FAW genetic melting pot, and demonstrated the use of genome analysis to disentangle preventable human-assisted pest introductions from unpreventable natural pest spread