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.

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A collection of 48 isolates selected from various anastomosis groups of Rhizoctonia solani showed at least nine distinct zymograms.Isolates from rice (sasakii type), or its relatives showed zymogram Zym-1.However, other isolates in the same anastomosis group (AG-1), from other host plants (web-blight type) showed several other different zymograms.Isolates from mat rush (Igusa), rice (quasi-sheath blight) and sugar beet in AG-2-2 gave Zym-2-2A which resembled Zym-1.Other members of AG-2-2 from sugar beet gave a different zymogram Zym-2-2B.Isolates of AG-2-1 gave the pattern Zym-2-1 which was quite different from all others.Isolates from potato (AG-3), showed a characteristic zymogram Zym-3. Similar zymograms were given by some isolates of anastomosis group AG-5 which also came from potato.The zymograms roughly agreed with anastomosis groups, but sometimes were more closely correlated with ecological types. The significance of these results and their usefulness are discussed.

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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.Keywords Pitaya Á Fruit rot Á Bipolaris cactivora Á Water-soaked lesions Á Black powdery spot Strawberry pear [pitahaya, pitaya; Hylocereus undatus (Haw.) Britt. and Rose] is a perennial succulent plant in the family Cactaceae. In Okinawa Prefecture, strawberry pear has emerged in recent years as a cash crop with high commercial value. A fungal disease clearly different from anthracnose (Taba et al. 2006) was observed on strawberry pear fruits at an agricultural products store in Itoman city in November 2005. The purpose of this study was to identify the fungus causing this disease and to confirm its pathogenicity. SymptomsBrown spots were initially observed on fruit (Fig. 1a). Water-soaked to depressed water-soaked developed lesions. Olive to black powdery spots then formed in the center of expanding, coalescing lesions (Fig. 1b), ultimately resulting in a soft rot of the fruit. Isolation and identification of the pathogenLesions were cut into ca. 5 mm 3 pieces, immersed in 70% ethanol for 30 s and in 2% hypochlorous acid solution for 1.5 min., washed with sterile distilled water, and air-dried on a clean bench. Surface-sterilized lesion tissues were then placed on PDA (potato dextrose agar) plates and incubated at 25°C. Hyphal tips were aseptically transferred to fresh PDA. Five monoconidial isolates (PBW-1, PBW-2, PBW-3, PBR-1 and PBR-2) were obtained from the PDA cultures. Colonies on PDA consisted of a pale-olive to black aerial mycelium (Fig. 1c). Conidiophores were pale to light brown, caespitose, straight or flexuous, and often swollen at the apex and at the base (Fig. 1d), and were 72.6-238.4 · 4.1-9.7 [length (L) · width (W), average 181.9 · 7.8] lm. Cespitose conidiophores were also present on the diseased fruit (Fig. 1e). Conidia (porospores) with a basal hilum were straight, ellipsoidal, fusiform or obclavate, 2-4 septa, pale light brown to brown (Fig. 1f), and were 35.3-45.5 · 8.5-10.9 (ave. 42.8 · 9.7) lm. The mycelium was often narrow and sclerotized (Fig. 1d).