Comparative Efficacy of Plant Extracts in Managing Whitefly (Bemisia tabaci Gen) and Leaf curl Disease in Okra (Abelmoschus esculentus L)

Abstract Okra leaf curl disease (OLCD) is an important disease responsible for yield losses in okra in all okra growing regions in the world. Effective management of the OLCD is very important in order to improve yield. The study was conducted to evaluate the effectiveness of different botanicals in the management of the OLCD. The treatments applied were 10% (w/v) crude extract each of neem leaf, garlic, mahogany bark, chili pepper fruit, pawpaw dried leaf, bougainvillea leaf and the control (water), in a randomised complete block design with four replications. The plant extracts significantly reduced the population of whitefly vector, as well as the incidences and severities of OLCD infections and increased fruit yield compared to the control (P< 0.05). Neem leaf extract followed by garlic extract significantly (P< 0.05) reduced the populations of whitefly and the incidences and severities of OLCD but significantly increased ((P < 0.05) fruit yield compared to crude extracts of mahogany, bougainvillea, chili pepper, and pawpaw leaves. The population of whitefly was positively correlated with severity of OLCD (r = 0.679; P> 0.05). Fruit yield was also negatively correlated with the severity of OLCD (r = -0.857; P< 0.05) and whitefly population (r = -0.750; P< 0.05). Farmers can manage OLCD in their okra fields by spraying with neem leaf or garlic extracts in order to improve fruit yields

“A reference genome assembly and adaptive trait analysis of Castanea mollissima ‘Vanuxem,’ a source of resistance to chestnut blight in restoration breeding”

Forest tree species are increasingly subject to severe mortalities from exotic pests, pathogens, and invasive organisms, accelerated by climate change. Such forest health issues are threatening multiple species and ecosystem sustainability globally. One of the most extreme examples of forest ecosystem disruption is the extirpation of the American chestnut (Castanea dentata) caused by the introduction of chestnut blight and root rot pathogens from Asia. Asian species of chestnut are being employed as donors of disease resistance genes to restore native chestnut species in North America and Europe. To aid in the restoration of threatened chestnut species, we present the assembly of a reference genome for Chinese chestnut (C. mollissima) "Vanuxem," one of the donors of disease resistance for American chestnut restoration. From the de novo assembly of the complete genome (725.2 Mb in 14,110 contigs), over half of the sequences have been anchored to the 12 genetic linkage groups. The anchoring is validated by genetic maps and in situ hybridization to chromosomes. We demonstrate the value of the genome as a platform for research and species restoration, including signatures of selection differentiating American chestnut from Chinese chestnut to identify important candidate genes for disease resistance, comparisons of genome organization with other woody species, and a genome-wide examination of progress in backcross breeding for blight resistance. This reference assembly should prove of great value in the understanding, improvement, and restoration of chestnut species