1987年から1996年までの10年間,コムギの連作ほ場においてコムギ眼紋病の発病を調査し,気象要因との関係を検討した.コムギ眼紋病の重症茎は,5月上旬の最低気温と負の関連性,11月上旬の1 mm以上の降水日数と正の関連性が認められた.コムギ眼紋病の発病推移を2ヵ年調査した.初発は10月下旬に認められ,融雪後の4月下旬以降に発病は急増した.11月上旬の降雨は第一次感染に影響し,5月上旬の最低気温は感染期間の長期化に影響しているものと推察された.チオファネートメチル水和剤およびプロクロラズ乳剤を用いて散布時期別の防除効果を3ヵ年検討した.最も効果が高い時期は5月上旬(GS31)で,その前後の4月下旬(GS30)と5月中旬(GS33)の効果も高い傾向にあることが明らかになった.本研究によって,5月上旬までの気象要因から本病の多発を予測し,5月中旬に薬剤散布を行うことによって効率的に防除を行うことができる可能性が示唆された.
In 2016, malformation and spotted wilt of leaves and fruit malformation were observed on cucumber (Cucumis sativus) in Kanagawa Prefecture. RT-PCR to amplify an RNA dependent RNA polymerase gene region of tospovirus and sequencing of the amplified fragment indicated highest identity with watermelon silver mottle orthotospovirus (WSMoV). The virus was isolated through two rounds of single lesion isolation and identified as WSMoV based on the nucleocapsid gene sequence. Cucumber plants inoculated with the isolated virus developed the same symptoms, and only WSMoV was shown to be present in RNA from symptomatic plants; nine other cucumber viruses were absent. This is the first report describing WSMoV symptoms on cucumber.
Aboveground parts of mizuna plants were sprayed with 100 μg/ml L-methionine solution 3 or 10 days before inoculation. These plants were replanted in soil including Fusarium oxysporum f. sp. conglutinans (FOC). Disease severity scored at 14 days post-inoculation (dpi) was lower on L-methionine-treated plants than on untreated plants. No effect of L-methionine on mycelial growth of FOC was visible microscopically. Quantitative RT-PCR analyses of marker genes for plant defense responses (BrPR1, BrBGL2, BrLOX2, BrVSP2) in root tissues at 2 dpi showed that expression of these genes was higher in treated plants than in control plants.
Satsuma dwarf virus (SDV) causes serious damage to citrus production, reducing fruit quality and yield. In this study of the effect of SDV infection on growth of 2-year-old pot-grown trees of Satsuma mandarin (Citrus unshiu) and citrus hybrids ‘Setoka’, ‘Tamami’, and ‘Harumi’, SDV-infected trees of Satsuma mandarin, ‘Tamami’, and ‘Setoka’ had altered leaf shapes, shorter leaves and tree forms than did virus-free trees, but these traits did not differ significantly between SDV-infected and SDV-free trees of ‘Harumi’.