International Institute of Tropical Agriculture (IITA-Tanzania), Dar es Salaam P.O. BOX 34441, Tanzania.
Kenya Agricultural Livestock Research Organization (KALRO), Kakamega P.O. Box 57811, Kenya.
Viruses. 2024 Sep 15;16(9):1469. doi: 10.3390/v16091469.
Cassava is an important food crop in western Kenya, yet its production is challenged by pests and diseases that require routine monitoring to guide development and deployment of control strategies. Field surveys were conducted in 2022 and 2023 to determine the prevalence, incidence and severity of cassava mosaic disease (CMD) and cassava brown streak disease (CBSD), whitefly numbers and incidence of cassava green mite (CGM) in six counties of western Kenya. Details of the encountered cassava varieties were carefully recorded to determine the adoption of improved varieties. A total of 29 varieties were recorded, out of which 13 were improved, although the improved varieties were predominant in 60% of fields and the most widely grown variety was MM96/4271. The CMD incidence was higher in 2022 (26.4%) compared to 2023 (10.1%), although the proportion of CMD attributable to whitefly infection was greater (50.6%) in 2023 than in 2022 (18.0%). The CBSD incidence in 2022 was 6.4%, while in 2023 it was 4.1%. The CMD incidence was significantly lower (5.9%) for the improved varieties than it was for the local varieties (35.9%), although the CBSD incidence did not differ significantly between the improved (2.3%) and local varieties (9.7%). Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) were both detected. Most infections were single CBSV infections (82.9%), followed by single UCBSV (34.3%) and coinfection with both viruses (16.7%). Whiteflies were more abundant in 2023, in which 28% of the fields had super-abundant populations of >100/plant, compared to 5% in 2022. KASP SNP genotyping designated 92.8% of the specimens as SSA-ECA for 2022, while it was 94.4% for 2023. The cassava green mite incidence was 65.4% in 2022 compared to 79.9% in 2023. This study demonstrates that cassava viruses, whiteflies and cassava green mites continue to be important constraints to cassava production in western Kenya, although the widespread cultivation of improved varieties is reducing the impact of cassava viruses. The more widespread application of high-quality seed delivery mechanisms could further enhance the management of these pests/diseases, coupled with wider application of IPM measures for whiteflies and mites.
木薯是肯尼亚西部的一种重要粮食作物，但它的生产受到病虫害的挑战，需要进行常规监测，以指导控制策略的制定和部署。2022 年和 2023 年在肯尼亚西部的六个县进行了田间调查，以确定木薯花叶病（CMD）和木薯褐条病（CBSD）、粉虱数量和木薯叶螨（CGM）的流行率、发病率和严重程度。详细记录了遇到的木薯品种，以确定改良品种的采用情况。共记录了 29 个品种，其中 13 个是改良品种，尽管改良品种在 60%的田地中占主导地位，种植最广泛的品种是 MM96/4271。2022 年 CMD 的发病率（26.4%）高于 2023 年（10.1%），尽管 2023 年由粉虱感染引起的 CMD 比例（50.6%）大于 2022 年（18.0%）。2022 年 CBSD 的发病率为 6.4%，而 2023 年为 4.1%。改良品种的 CMD 发病率（5.9%）明显低于当地品种（35.9%），尽管 CBSD 发病率在改良品种（2.3%）和当地品种（9.7%）之间没有显著差异。检测到木薯条纹病毒（CBSV）和乌干达木薯褐条病毒（UCBSV）。大多数感染是单一 CBSV 感染（82.9%），其次是单一 UCBSV（34.3%）和两种病毒的混合感染（16.7%）。2023 年粉虱数量更多，其中 28%的田地的种群数量超过 100/株，而 2022 年为 5%。KASP SNP 基因分型将 2022 年的 92.8%标本指定为 SSA-ECA，而 2023 年为 94.4%。2022 年木薯绿螨的发病率为 65.4%，而 2023 年为 79.9%。本研究表明，木薯病毒、粉虱和木薯绿螨仍然是肯尼亚西部木薯生产的重要制约因素，尽管改良品种的广泛种植正在降低木薯病毒的影响。更广泛地应用高质量的种子传递机制可以进一步加强对这些病虫害的管理，同时更广泛地应用粉虱和螨虫的综合虫害管理措施。
