Wilt and root rot of poinsettia caused by three high-temperature-tolerant Pythium species in ebb-and-flow irrigation systems

Poinsettia plants growing in ebb-and-flow irrigation systems developed wilting and root rot during the summer growing seasons of 2010 in Gifu Prefecture and 2011 in Aichi Prefecture. Pythium species were isolated from roots with rot symptoms. The isolates were identified as P. helicoides and P. myriotylum on the basis of morphological characteristics and sequence homologies in the rDNA internal transcribed spacer regions. In pathogenicity tests, these isolates caused severe wilting and root rot. This is the first report of poinsettia root rot disease caused by P. helicoides and P. myriotylum, although P. aphanidermatum was reported as a pathogen of poinsettia root rot. To better understand these diseases, we performed an epidemiological study of three high-temperature-tolerant Pythium species, P. aphanidermatum, P. helicoides and P. myriotylum. Disease incidence as a percentage of diseased plants was greatest at 35 °C for all three species. Disease severity using the rating scale of root rot was also highest at 35 °C, particularly with high zoospore inoculum densities (100.0 zoospores/mL). Although the disease incidence and severity were reduced at lower temperatures, the three Pythium species were able to cause disease at temperatures as low as 20 °C.     

Efficacy of phosphonate in controlling white powdery rot of fig caused by <Emphasis Type="Italic">Phytophthora palmivora</Emphasis>

Pre- and post-infection activities of phosphonate and fungicides (azoxystrobin, chlorothalonil, cyazofamid, copper hydroxide, and copper sulfate) against white powdery rot on fig leaves caused by Phytophthora palmivora were determined. Phosphonate and fungicides were applied at 3, 7, or 14 days before inoculation and 16, 24, or 40 h after inoculation. Phosphonate and four fungicides (except for chlorothalonil) had protectant activity for up to 14 days before inoculation. Protectant activity between phosphonate and the four fungicides did not differ significantly. These fungicides did not have a curative activity, whereas only phosphonate had a curative activity when applied 16 h after inoculation. The pre-infection activity of phosphonate was determined in fig fields. Phosphonate provided excellent protectant activity, and its activity did not differ significantly from that of the copper fungicides. The activity of phosphonate in the life cycle of P. palmivora was compared with that of the five fungicides. Half-maximal effective concentration of the inhibition of mycelial growth was low for phosphonate, chlorothalonil, and the two copper fungicides. Mycelial growth was least affected by azoxystrobin and cyazofamid, but n-propyl gallate, an alternative oxidase inhibitor, in combination with these fungicides, significantly inhibited mycelial growth. Sporangium formation was sensitive to all compounds. Germination of encysted zoospores was sensitive to azoxystrobin, cyazofamid, and chlorothalonil and least sensitive to phosphonate and the two copper fungicides. The activity of phosphonate on mycelial growth and sporulation of P. palmivora suggests it has potential for controlling the disease.     

A New Race of Spinach Downy Mildew in Japan

A new race of spinach downy mildew caused by Peronospora effusa occurred in Fukui, Japan. The fungus was capable of affecting spinach cultivars resistant to races 1, 2, 3 and 4, but not some other cultivars. Thus, the fungus had different pathogenicity from race 3 and race 4 of the pathogen and was considered to be a new race of spinach downy mildew in Japan. Received 26 April 2001/ Accepted in revised form 17 August 2001     

Mitochondrial DNA variation in the Japanese marten Martes melampus and Japanese sable, Martes zibellina

Genetic relationship among Japanese sables, Martes zibellina and the introduced Japanese martens, Martes melampus in northern Japan was revealed by analyzing a 521-524bp DNA sequence from the cytochrome b (112bp)/transfer RNA-threonine (67bp)/tRNA-proline (65bp) and control region (277-280bp) of the mitochondrial genome. Intraspecific differences in sequences of M. zibellina and M. melampus (3.8-15.0% and 1.9-16.4%, respectively) were similar to interspecific differences between these two species (5.8-16.6%). Comparison of sequence data exhibited five haplotypes of M. melampus and four haplotypes of M. zibellina, which clustered into two groups (clusters-A and-B). Cluster-A included two haplotypes of M. melampus and two haplotypes of M. zibellina, whereas cluster-B included three haplotypes of M. melampus and two haplotypes of M. zibellina. Results of this study lead three possible explanations. Firstly, past hybridization between M. zibellina and M. melampus might have occurred. Secondary, these two species might have similar heteroplasmy of mtDNA. Thirdly, these haplotypes might have come from nuclear genome. Although further intensive studies are needed to make a conclusion, detection of hybridization with the Japanese marten are occurred or not is quite important to conserve the Japanese sable.     

Distribution patterns of settlement-stage juveniles of <Emphasis Type="Italic">Girella punctata</Emphasis> and <Emphasis Type="Italic">Girella leonina</Emphasis> on the rocky coast of the Kanto–Izu region,Japan

The early life history of girellid fishes in Japanese waters is unclear, and little is known about their species-specific reproductive strategies. We examined seasonal changes of distribution patterns for settlement-stage juveniles of Girella punctata and Girella leonina on the rocky shore in the regions of Kanto and Izu, Japan, to infer the influence of the Kuroshio Current on their reproduction. We collected 813 settlement-stage juveniles mainly in Sagami Bay and genetically identified the species. The juveniles of G. punctata were collected on the rocky shore in Sagami Bay during April to August, with the abundant catch in May and June. Thus, we infer that juvenile G. punctata ubiquitously inhabit the rocky shore in the area in spring and summer. By contrast, juveniles of G. leonina were rarely collected in Sagami Bay, with a total catch of only 66. Notably, no juveniles were collected during the wintertime in Sagami Bay, although an abundant catch of G. leonina had been previously reported for Sagami Nada off Sagami Bay during January to March. This clear-cut difference between the areas likely reflects the difference in proximity to the path of the Kuroshio Current. We expect that the Kuroshio Current strongly influences the reproductive success of G. leonina.     

Effects of water temperature on early development of Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>

ABSTRACT:   To determine an optimal temperature range for efficient production of healthy eel larvae Anguilla japonica , the effect of water temperature on hatching, survival, and deformity rates was examined. The early ontogeny of morphological features in this species by incubating eggs at five different temperatures (19, 22, 25, 28 and 31°C) was examined. Hatching occurred at 24, 28, 46 and 58 h after fertilization when incubated at 28, 25, 22 and 19°C, respectively; no eggs hatched at 31°C. The growth rate of prefeeding larvae increased as water temperature was elevated and acquisition of feeding ability was also accelerated at higher temperature. Significantly high hatching rates (76–86%, P  < 0.05) and survival rates (61–86%, P  < 0.05) were observed at relatively high temperatures (22–28°C). The deformities were 'open lower jaw', 'pericardial edema', and 'notochordal bending', in which the mouth was deformed with a downward projecting lower jaw, the pericardial cavity was swollen, and the notochord was bent or twisted to various degrees, respectively. Open lower jaw and pericardial edema were especially predominant at 19°C, with rates of 68 and 92%, respectively, compared with 31 and 10% at 25 and 28°C, respectively. The occurrence of notochordal bending was not affected by temperature. The optimal temperature for incubation and rearing A. japonica eggs and prefeeding larvae is approximately 25–28°C.     

Carbonization of bamboo and consecutive low temperature air activation

Raw moso bamboo (Phyllostachys pubescens) was examined to optimize the carbonization and the consecutive air activation procedure. Influence of sample size, nitrogen flow rate, heating rate and final temperature on the carbon yield and the pore structure was investigated for the raw bamboo. The short length cutting along bamboo trunk and the increase in heating rate to 40°C/min and nitrogen flow rate up to 500 ml/min was found to be advantageous for the carbonization of raw bamboo at 500°C, resulting in a surface area of 230 m²/g with a bamboo char yield of 25% on dry base. In the next step, effects of air treatment temperature, ash content and its composition on the pore development were studied for the prepared bamboo char in comparison with coconut shell char. Additional increase in surface area by 200 m²/g with 97% yield could be achieved conducting the 2-hour air treatment at 280°C for the bamboo char, whereas only a 100 m²/g rise in surface area was attained for the coconut shell char, partly due to the difference in K₂CO₃ content in the char.     

Enzyme-linked immunosorbent assay to detect Lawsonia intracellularis in rabbits with proliferative enteropathy

Lawsonia intracellularis is an obligate intracellular pathogenic bacterium that causes proliferative enteropathy in domestic and experimental animals. Antiserum against synthetic peptides of the Lawsonia surface antigen (LsaA) well recognized L. intracellularis in infected ileum by immunohistochemistry. The synthetic peptides in LsaA showed strong reaction with serum from rabbits infected with L. intracellularis by enzyme-linked immunosorbent assay. These results suggest that ELISA used synthetic peptides in LsaA and anti-LsaA serum might be useful to diagnose for proliferative enteropathy.     

Identification and morphological characteristics of dental neonatal line in sika deer (Cervus nippon)

The dental neonatal line of the sika deer (Cervus nippon) was identified experimentally using chronological labeling methods. In the enamel, prominent dark lines were observed under transmitted light, and the number of increments between the dark line and labeling line was almost consistent with the day-age at the time of labeling injection. Therefore, we identified the dark line as the enamel neonatal line. In the dentin, the bright line was observed under polarized light. Since the bright line corresponded to the enamel neonatal line, we recognized the bright line as the dentin neonatal line. Neonatal lines intersected with the enamel-dentin junction at approximately one-third cervical in the first molar. Using these features, it would make possible to distinguish the neonatal line in wild sika deer.