The relation between thickness of harvested grain and mycotoxin （deoxynivalenol and nivalenol） concentration in Japanese barley cultivars artificially infected with Fusarium graminearum species complex was investigated. One hull-less six-rowed, two hulled six-rowed, and one hulled two-rowed cultivars were tested. The cultivars were grown in fields with two different artificial inoculation conditions, sprinkler-irrigated and non-irrigated, and harvested in 2008 and 2009. Each harvested grain sample was divided using sieves with different sieve sizes in 0.2 ㎜ interval and the mycotoxin concentration of each fraction was analyzed. As a whole, there was a tendency for mycotoxin concentration levels to be lower in the thicker （larger） grain fractions. However, the tendency was not very sharp for the hulled cultivars, especially for the two-rowed one, compared to the hull-less cultivar. Mycotoxin reduction rate for each well-toxin-contaminated sample when sieved with the sieve size which brought around 80 % of yield rate was calculated as 34% and 50% for the hull-less six-rowed cultivar（ n=2）, 15-35% for the hulled six-rowed cultivars（ n=4）, and 9-24% for the hulled two-rowed cultivar（ n=3）. These results suggest that sieve sorting after harvest would be effective to reduce mycotoxin contamination levels in barley, although the effect might not be large, especially for hulled cultivars.
The relation between thickness of grain and mycotoxin （deoxynivalenol and nivalenol）concentration in Japanese barley naturally contaminated with these toxins was investigated. For this study, the toxin-contaminated barley samples were selected from samples collected by the government from some grain-drying and processing facilities such as country elevators in different areas of Japan for the national grain toxin contamination survey in 2006. The five selected samples included one hull-less six-rowed, two hulled six-rowed, and two hulled tworowed cultivars. Each grain sample was divided using sieves with different sieve sizes in 0.2 ㎜ intervals and the mycotoxin concentration of each fraction was analyzed. As a whole, there was a tendency for mycotoxin concentration levels to be lower in the thicker （larger） grain fractions, except the toxin concentration in the thinnest（ smallest） fractions was not highest in three samples among the five. Mycotoxin reduction rate for each sample sieved with each sieve size was calculated. The results were consistent with our similar study on the barley cultivars artificially infected with Fusarium graminearum species complex, which suggested sieve sorting after harvest would be effective to reduce mycotoxin contamination levels in barley, although the effect might not be large.
We examined the pathogenic differences between Ralstonia solanacearum phylotypes I and IV. R. solanacearum phylotypes I （MAFF327001） and IV （MAFF327032） were inoculated to potato using an in vitro screening assay at 22, 24, 26 and 28℃ incubation temperatures after inoculation. As a result, phylotype IV showed high pathogenicity for potato at a lower temperature than phylotype I. The most suitable temperature for evaluating the degree of resistance in potato cultivars and breeding lines was clearly different between phylotypes Ⅰand Ⅳ, with phylotype Ⅰat 28℃，and phylotype Ⅳ at 26℃. However, the degree of resistance in potato cultivars and breeding lines for both phylotypes had a similar tendency at the most suitable temperature conditions. In conclusion, phylotype IV showed pathogenicity at a lower temperature than phylotype Ⅰ, but the results suggested resistance was shown in the potato cultivars and breeding lines regardless of the phylotype（Ⅰ and Ⅳ）.
We examined inoculation conditions for testing the soil rot disease resistance of sweet potato, with the aim of establishing a test method that uses the lesions in tuberous root tissue sections. In inoculation tests with mycelial agar disk inoculum of the pathogen to two sweet potato cultivars and one breeding line with different levels of resistance（ ‘Kokei No. 14’, ‘Purple sweet lord’, and ‘90IDN-47’）, no significant differences were found in resistance characteristics. However, when the inoculation test was performed on tuberous root tissue sections that had been dipped into mycelial fragment suspensions of different pathogen concentrations and then buried in vermiculite with different moisture contents at 30℃, a significant difference in resistance could be observed at an inoculum suspension dilution of 1,000 times （v/w） fresh mycelial weight （approximately 105 CFU/ml） and a soil moisture content of 187.0% （v/w）. In this inoculation condition, the inoculated sweet potato tuberous root tissue sections started to exhibit lesions 3 days after inoculation, and severities of the disease particularly became more intense from 6 to 7 days after inoculation. As a result, it was possible to clearly distinguish the levels of resistance in these cultivars and breeding line.
Glycine soja Sieb. et Zucc., an ancestral wild species of soybean （G. max （L.） Merr.） has been gathering attention as a genetic resource. In addition, considering the cultivation of genetically modified soybean will be introduced to Japan in the future, crossing species might affect biological diversity. Under such a situation, bacterial diseases of G. soja have not yet been reported so far. Therefore, pathogenic bacteria of G. soja and its characteristics were investigated in this study. Occurrence of bacterial disease of G. soja in various parts of Japan was surveyed and 90 bacterial isolates were isolated from the infected leaves. Based on the tobacco hypersensitive reaction（ HR） or hypersensitive like reaction（ HLR）, 17 and 35 isolates of presumably plant pathogenic bacteria were isolated. By homology analysis based on 16S rDNA sequences, 52 isolates comprising 13 genera such as Xanthomonas spp., Pseudomonas spp., Rhizobium sp. and Pantoea sp were identified. After spray inoculation to G. soja and G. max with those 52 isolates, 13 isolates were pathogenic to both plants and divided into isolates with two colony colors of yellow and white. Three white colony isolates had high homology to P. syringae pv. glycinea, whereas 10 yellow ones formed the same cluster with X. axonopodis pv. glycines.
Stemphylium lycopersici is a common pathogen on vegetable crops causing severe disease in the world. In 2009, a preemergence damping-off caused by S. lycopersici was observed on tobacco seeds （Nicotiana tabacum L.） in Fukuoka, Japan. However, the etiology and mode of infection of this pathogen in tobacco seeds have not been clarified yet. In the present study, a primer pair was designed for direct, rapid and specific detection of S. lycopersici based on the sequences of the internal transcribed spacer regions including the 5.8S rDNA. A PCR product of approximately 449 bp was obtained only when the DNA extracted from pure cultures of S. lycopersici was used. No amplification was observed for other Pleospora/Stemphylium species or other genera of fungi. The PCR amplified as little as 100 fg of genomic DNA of S. lycopersici. Furthermore, S. lycopersici was detected from resultant tobacco seeds after the flowers were inoculated with this pathogen. Therefore, the designed primer pair is useful for the specific detection of S. lycopersici in tobacco seeds.
In 2013, clubroot disease on cabbage and ornamental turnip rape for landscape was observed in Ibusuki City, whereas there had been no report of the disease since 2001 when the first incidence was reported in Kagoshima Prefecture. According to the present survey, instances of the disease were observed in eight districts of Kagoshima and there were many infested fields clustered in Ibusuki City, whereas there were few fields infested in other districts. The severity level of these infested fields was relatively low with a range of resting spore densities from 103 to 104/g soil. Averages of the soil pH in each field ranged from 5.5 to 6.3 hence there were no suppressive field soils this pH values exceeding 7, and in some fields the incidence of clubroot might be promoted by soil with a low phosphate absorption coefficient. The virulence of field isolates of resting spores was relatively weak thus the introduction of CR cultivars seems to be an effective tactic to solve with problem.
The reproductive traits of Pseudonapomyza spicata（Malloch）（Diptera: Agromyzidae）were examined on barley and other crops in the laboratory. The regression equation relating temperature（ X,℃） to development rates（Y,d-1） on barley was Y=0.0037X－0.0406 for the eggpupal stage. The estimated lower threshold temperature was 10.8 ℃ and the total effective temperature was 270 degree-days. The longevity and fecundity of P. spicata females on barley were 27.7 days and 195.7 eggs, respectively. Mean generation time （T）, net reproductive rate （R0）, and intrinsic rate of natural increase per day（r） were 35.2, 97.83, and 0.147, respectively. The number of mines as an index of oviposition preference was examined for 10 host plants by exposing each plant for 24 hours. Mean number of eggs laid was estimated as follows: barley（6.9 eggs）, wheat （9.8 eggs）, sorghum （6.5 eggs）, and triticale （2.3 eggs）. However, female adult flies did not lay eggs on other plants tested such as kidney bean, tomato, cherry tomato, chrysanthemum, pak-choi, and oat. These results strongly suggest that P. spicata is a promising candidate as an alternative host for a banker plant system against Liriomyza leafminers.
Conservation of predator Orius spp. with selective pesticide has shown great promise as an effective Integrated Pest Management （IPM） strategy for managing Thrips palmi and other pests in eggplant fields. Moreover, sorghum barrier crops are promoted as a cultural control for eggplant IPM. To evaluate the potential role of sorghum as a source of natural enemies, we investigated seasonal abundance of aphidophagous predators on sorghum（Sorghum bicolor （L.） Moench）. Significantly more predators were found on ‘Kazetachi’（ late flowering and long culm commercial cultivar） than on other sorghum cultivars, ‘Koutoubun’ （sweet sorghum commercial cultivar） and ‘Akaamakibi’ （sugar rich local variety）. In 2007 the early summer peaks in abundance of syrphid and coccinellid predators commenced on sorghum planted late April and early May only, while late summer peaks in abundance of 4 predator groups were found on sorghum, irrespective of the planting dates. In 2008 a similar peak abundance of predators was found in late July to August. However, predator abundance was extremely low in early summer. In the eggplant field, Aphis gossypii was predominant throughout the growing season, with a minor and major peak in June and July to August, respectively.