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Oyamada K.,Tochigi Prefectural Agricultural Experiment Station | Oyamada K.,Tochigi Prefectural Sustainable Agriculture Extension Center
Japanese Journal of Applied Entomology and Zoology | Year: 2013

Two spotted spider mites, Tetranychus urticae Koch the most important pests of strawberry, have developed resistance to chemical pesticides. We investigated the effects of high carbon dioxide atmospheres on two-spotted spider mites and strawberry plants just before transplanting. Percent mortality of adult female mites, young eggs(24 h after laying), and old eggs(48-72h) exposed to 60% CO2 at different temperatures(25,30, and 35oC) was evaluated over time. Mortality of all spider mite stages increased with exposure duration at each temperature, and the time required to achieve 100% mortality decreased as temperature increased. Exposure to 60% CO2 at 30oC for 16 h was 100% lethal to every developmental stage tested. Furthermore, 24 h of 60% CO2 treatment did not induce external damage or adversely affect flowering of the primary flower clusters on strawberry plants. In a large-scale test of elevated-CO2 atmospheres, the two spotted spider mite population was greatly suppressed relative to untreated fields, and strawberry plants remained healthy. Thus, our findings suggested that CO2 treatment could be used to propagate spider-mite-free plants in strawberry nurseries and enhance strawberry integrated pest management systems. Source

Himi E.,Okayama University | Yamashita Y.,Okayama University | Haruyama N.,Tochigi Prefectural Agricultural Experiment Station | Haruyama N.,Tochigi Prefectural Sustainable Agriculture Extension Center | And 3 more authors.
Euphytica | Year: 2012

A number of anthocyanin- and proanthocyanidin-free mutants (ant mutants) in barley were induced and selected because of breeding interest to reduce proanthocyanidins, which could cause haze and degrade the quality of beer. Ant loci, known as anthocyanin or proanthocyanidin synthesis genes, are classified into Ant1 to Ant30 through allelism tests. However, only the Ant18 gene has been molecularly shown to encode dihydroflavonol 4-reductase (DFR), which is involved in both anthocyanin and proanthocyanidin synthesis. In this study, an R2R3 MYB gene of barley was isolated by PCR and named Hvmyb10 due to its similarity to Tamyb10 of wheat, which is a candidate for the R-1 gene grain color regulator. The predicted amino acid sequences of Hvmyb10 showed high similarity not only to Tamyb10 but also to TT2, the proanthocyanidin regulator of Arabidopsis. Non-synonymous nucleotide substitutions in the Hvmyb10 gene were found in all six ant28 mutants tested. Mapping showed that a polymorphism in Hvmyb10 perfectly cosegregated with the ant 28 phenotype on the distal region of the long arm of chromosome 3H. These results demonstrate that ant28 encodes Hvmyb10, the R2R3 MYB domain protein that regulates proanthocyanidin accumulation in developing grains. The reduced grain dormancy of ant28 mutants compared with those of the respective wild types indicates that Hvmyb10 is a key factor in grain dormancy in barley. © 2011 Springer Science+Business Media B.V. Source

Katoh H.,Utsunomiya University | Fukuda T.,Tochigi Prefectural Agricultural Experiment Station | Nishigawa H.,Utsunomiya University | Natsuaki T.,Utsunomiya University
Journal of General Plant Pathology | Year: 2016

We developed a loop-mediated isothermal amplification (LAMP) assay for detecting Colletotrichum gloeosporioides, which causes anthracnose, in strawberry plants. Primer sets targeted the region from the gene encoding 5.8S ribosomal RNA to internal transcribed spacer 2, which is highly conserved in 25 Colletotrichum species in GenBank. Our results indicated that the LAMP assay, which uses template DNA prepared using microwave irradiation, is a simple and sensitive tool for detecting C. gloeosporioides in infected strawberry plants. Further, our results showed that the LAMP assay could differentiate Colletotrichum species such as C. acutatum, C. aenigma, and C. siamense. © 2016, The Phytopathological Society of Japan and Springer Japan. Source

Kato N.,Japan National Agriculture and Food Research Organization | Kihou N.,Japan National Institute for Agro - Environmental Sciences | Fujimura S.,Fukushima Agricultural Technology Center | Ikeba M.,Agricultural Research Institute | And 4 more authors.
Soil Science and Plant Nutrition | Year: 2015

Huge amounts of radionuclides, particularly radiocesium, were discharged from the Fukushima Daiichi Nuclear Power Plant (FDNPP), and widespread of contamination of the land, including paddy fields, was observed. Because rice is a staple food in Japan, contamination of paddy fields is a serious problem, and practical countermeasures to reduce radiocesium contamination of rice are urgently required. Potassium (K) fertilization was previously shown to be an effective countermeasure in fields contaminated by the Chernobyl accident, but researchers did not study the effects on rice (Oryza sativa L.). In the present study, we performed urgent field experiments to test the use of K fertilization, as well as other soil amendments, to reduce radiocesium contamination of rice. We found that K fertilization was an effective and practical countermeasure to reduce radiocesium uptake by rice from several soil types in Japanese paddy rice culture. Other treatments, including the application of expanded vermiculite or manure, were effective, and the effect appears to be explained by their K content. Based on these results, the recommended level of exchangeable soil potassium to lower the radiocesium content of rice to acceptable levels is about 200 mg K kg–1 soil before the usual fertilization. This K fertilizer application criterion was applied in a wide, low-contaminated area from the 2012 cropping season, and satisfactory results have been obtained generally. © 2014 Japanese Society of Soil Science and Plant Nutrition Source

Suga H.,Gifu University | Hirayama Y.,Nara Prefectural Experiment Station | Morishima M.,Tochigi Prefectural Agricultural Experiment Station | Suzuki T.,Chiba Prefectural Agriculture and Forestry Research Center | And 2 more authors.
Plant Disease | Year: 2013

Fusarium oxysporum f. sp. fragariae is a fungal pathogen causing Fusarium wilt on strawberry. Polymerase chain reaction (PCR) primers that can discriminate F. oxysporum f. sp. fragariae from nonpathogenic F. oxysporum would greatly assist pathogen identification. In order to develop a molecular diagnostic tool for this pathogen, transposable elements in the pathogen were characterized and used for designing a specific set of PCR primers. Portions of the transposable elements Fot3, Han, Hop, Hornet1, and Skippy were detected in all 33 strains of F. oxysporum f. sp. fragariae tested by PCR, whereas Foxy was detected in 32 strains and Impala sequences were detected in 30 strains. Two types of sequences were detected for Hop, two types for Impala, and three types for Skippy. The genomic region between Han and Skippy was amplified by an inter-retrotransposon amplified polymorphism technique, and PCR primers (FofraF and FofraR) to specifically identify F. oxysporum f. sp. fragariae were designed from this region. The developed PCR primers discriminated F. oxysporum f. sp. fragariae strains from nonpathogenic F. oxysporum strains and five other formae speciales. Conidia of F. oxysporum f. sp. fragariae could be detected in brown lowland-type soil by PCR using the primers. After preculturing the soil sample on FoG2 medium, 1 × 102 conidia/g of soil could be detected; without preculturing, 1 × 103 conidia/g of soil were detected. © 2013 The American Phytopathological Society. Source

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