A new antifungal compound, (3S)-4,6-dihydro-8-methoxy-3,5-dimethyl-6-oxo-3H-2-benzopyran (4), was isolated from Penicillium expansum. During the isolation procedure 4 was determined to be unstable and readily reacted with methanol, ethanol, and water, forming three new isochromans, (1S,3S)-6-hydroxy-1,8-dimethoxy-3,5-dimethylisochroman (1), 1-ethoxy-6-hydroxy-8-methoxy-3,5-dimethylisochroman (2), and 1,6-dihydroxy-8-methoxy-3,5-dimethylisochroman (3), respectively. (3S)-6-Hydroxy-8-methoxy-3,5-dimethylisochroman (5) was reisolated from P. expansum. In fungicide disk assays, compounds 1, 2, and 4 inhibited the mycelial growth of Lasiodiplodia theobromae at 100 microg/mL by 76%, 74%, and 69%, respectively.

Scratch method for simple, rapid diagnosis of citrus huanglongbing using iodine to detect high accumulation of starch in the citrus leaves. Jpn. J. Phytopathol. 73: 3-8 We demonstrated a rapid and simple diagnostic method (scratch method) for citrus huanglongbing (HLB) by detecting high accumulation of starch in the citrus leaves with the iodine-starch reaction. The average quantity of starch was 514.2 mg/kg in HLB-infected citrus leaves and 85.6 mg/kg in healthy leaves (Welch's t-test p<0.01), a significant difference in starch levels between diseased and healthy leaves. Based on this result, we devised a scratch method using abrasive paper for HLB diagnosis. Scratch the surface of a citrus leaf at least 20 times with abrasive paper, put the abrasive paper into 1 ml water in a vinyl pack, add to about 25 µl iodine solution 50 mM for dyeing starch. Iodine-reacted solutions show mostly 'dark brown or black' and 'yellow or orange' which are HLBpositive and negative, respectively. The scratch method and PCR assay of field samples showed more than 90% agreement. In addition, the scratch method did not give false HLB-positive reactions for healthy, nutrient-deficient or other disease leaves infected with Citrus tatter leaf virus and Hop stunt viroid. Therefore, the scratch method will be useful for rapid, simple detection of HLB in the field.

We isolated an antimicrobial compound from the aerial tissue of Geranium carolinianum and identified it as ethyl 3, 4, 5-trihydroxy benzoate (ethyl gallate) by 1 H-NMR and 13 C-NMR and gas chromatography-mass spectrometry.The antimicrobial activity of ethyl gallate against three potato pathogens was assayed by the paper disk method. The activity against Ralstonia solanacerum, Streptomyces scabies, and Streptomyces acidiscabies was observed at concentrations >200, >300, and >300 mg disk -1 , respectively. These results suggest that the antimicrobial activity of Geranium carolinianum against soil-borne plant disease pathogens is partly related to ethyl gallate.

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.

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).

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Since 2002, papaya black rot has been spreading over several islands of Okinawa Prefecture, Japan. To devise a prevention strategy for the disease, microbiological research on the pathogen was conducted. Twelve strains were isolated from papaya infected with black rot showing symptoms such as water‐soaked lesions on stems and petioles, black spots on fruits, and rotted leaves turning yellow with necrotic spots. Through Koch's postulates, we confirmed that the isolated strains caused papaya black rot. Bacteriological assays showed that the strains have characteristics different from the type strains of Erwinia mallotivora, E. papayae, and E. psidii. Moreover, 16S rDNA sequence similarity searches showed that the isolated strains had less than 98.6% similarity with type strains. Additionally, phylogenetic analysis of 16S rDNA sequences suggested that the isolated strains were possibly a novel species belonging to the genus Erwinia, as the strains formed an independent cluster and had low sequence similarity with the type strains. Earlier studies indicated that papaya black rot is caused by E. cypripedii. Therefore, we propose to add the Erwinia sp. isolated in this study to the list of papaya black rot pathogens.