Zenichi Moromizato

Nematicidal activity of Okinawa Island plants on the root-knot nematode Meloidogyne incognita (Kofoid and White) Chitwood

In order to develop biological control methods that are effective against the root-knot nematode Meloidogyne incognita (Kofoid and White) chitwood, the activity of ethanolic and aqueous extracts of wild plant species distributed on Okinawa Island on the viability and mobility of second stage M. incognita juveniles (J2s) was evaluated. Eleven of the 29 extracts immobilized at least half of the J2 stage nematodes in an in vitro assay. Aqueous extracts of Bidens pilosa L. var. radiata Scherff, Hydrocotyle dichondroides Makino, Oxalis corymbosa DC., Oxalis corniculata L., and Stenactis annus (L.) Cass gave 90% or better immobilization activity. Among these, B. pilosa var. radiata had the highest activity. Significant immobilization, lethality, repellence and egg hatching inhibition were observed with extracts from each B. pilosa plant part, but especially from leaves. The effects of plant extracts on the mobility of M. incognita were higher than on the free-living nematode Panagrolaimus sp., suggesting that M. incognita could be suppressed using B. pilosa extracts without significantly affecting beneficial nematodes.

Alternaria leaf spot of basil caused by Alternaria alternata in Japan

An outbreak of black mottle and dieback on basil (Ocimum basilicum L.; Lamiaceae) was recorded in a greenhouse in Okinawa Prefecture, Japan during 2004. The causal agent was identified as Alternaria alternata (Fr.) Keissler based on morphological characters and growth temperature. This report is the first of Alternaria leaf spot of basil caused by A. alternata.

Fruit rot of Strawberry pear (pitaya) caused by Bipolaris cactivora

Strawberry pear (pitahaya, pitaya) [Hylocereus undatus (Haw.) Britt. and Rose] postharvest fruit rot was found at an agricultural products store in Itoman city, Okinawa Prefecture in 2006. The symptoms included depressed, water-soaked lesions with olive to black powdery spots coalescing into a soft rot. The causal fungus was identified as Bipolaris cactivora (Petrak) Alcorn. This is the first report of strawberry pear fruit rot caused by B. cactivora.