Isolation and Identification of Eutypa lata from Pistacia vera in Greece

The fungus Eutypa lata (syn. E. armeniacae), known as the causal agent of the death of many different woody plants, was found on dead branches of pistachio (Pistacia vera L.) in Greece. Isolations from diseased branches yielded consistently typical colonies of the asexual stage of the fungus (Libertella blepharis, syn. Cytosporina sp.), which proved to be undistinguishable from other cultures of the pathogen obtained from 15 different hosts. Furthermore, all isolates from pistachio tested for pathogenicity on apricot were pathogenic and yielded characteristic cankers.     

Effect of Plant Species on Persistence of Paecilomyces lilacinus Strain 251 in Soil and on Root Colonization by the Fungus

The effect of 12 plant species on the persistence of Paecilomyces lilacinus strain 251 in soil was investigated. After incorporating formulated conidia into non-sterile soil followed by transplanting different test plants, the population dynamic of the fungus was determined over 100 days. At termination of the experiment, the fungal population in the planted soil was compared to the density of P. lilacinus in the rhizosphere and the percent increase or decrease was calculated for each crop. In addition, the potential of P. lilacinus strain 251 to colonize roots endophytically was investigated. Comparison of the slopes describing the population dynamics of the fungus showed no significant differences between soil without plants and soil from the root zone of the majority of the test plants. Bean was the only plant species consistently exerting a negative effect on the persistence of P. lilacinus strain 251 in the soil. For the first time, P. lilacinus strain 251 was isolated in significant numbers from healthy root tissue of barley plants.     

Interactions of Paecilomyces lilacinus strain 251 with the mycorrhizal fungus Glomus intraradices: Implications for Meloidogyne incognita control on tomato

The interactions of Paecilomyces lilacinus strain 251 with the arbuscular mycorrhizal fungus Glomus intraradices and their significance for the control of Meloidogyne incognita on tomato were investigated in greenhouse experiments. Application of P. lilacinus had no effect on the frequency and intensity of tomato root colonization by G. intraradices. Likewise, the decline of the nematophagous fungus densities after single application in soil was not affected by the presence of the mycorrhizal fungus. Single application of P. lilacinus, as pre-planting soil treatment, resulted in significant reduction of nematode damage. In contrast, mycorrhizal inoculation did not provide sufficient biocontrol. Combined application of the two agents did not enhance root protection compared to single treatments. Double treatment of mycorrhized seedlings with P. lilacinus, as seedling drench and pre-planting soil treatment, 4 and 1 week before transplanting, respectively, resulted in the highest reduction of the nematode damage. These results indicate the potential of the commercial P. lilacinus strain 251 and mycorrhiza for integration in nematode control strategies.     

Insecticidal effect of the combined application of spinosad,Beauveria bassiana and diatomaceous earth for the control of Tribolium confusum

Laboratory bioassays were carried out to evaluate the insecticidal effect of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) germinated conidia, a commercial formulation of diatomaceous earth and a liquid formulation of spinosad, applied alone or in all possible combinations on wheat, against adults of the confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae). Diatomaceous earth was applied at one (200 ppm), the fungus at two (100 and 300 ppm) and spinosad at three (0.01, 0.1 and 0.5 ppm) dose rates, whereas all combinations of two or three of the insecticide concentrations were also tested. Insect mortality was determined after 2, 7 and 14 d of exposure. The simultaneous use of B. bassiana germinated conidia with diatomaceous earth notably increased mortality of T. confusum adults by sixfold 7 d after exposure, as compared with either B. bassiana or diatomaceous earth alone. When diatomaceous earth and spinosad were combined, diatomaceous earth did not increase the efficacy of spinosad. In general, the combination of all three agents did not differ from either the application of the agents tested alone, or their binary combinations, in most treatments examined.     

Phialophora parasitica, Causal Agent of Cherry Dieback

Structure-activity relationships of the phytotoxins stemphyloxin I and II from Stemphylium botryosum f. sp. lycopersici were investigated by quantitative comparison of their biological activity with chemically related phytotoxins from Phoma betae, betaenones A, B and C. Phytotoxicity was estimated by inhibition of incorporation of¹⁴C-leucine into proteins of exponentially growing tomato cells. The values of 50 % inhibition for stemphyloxin I and II and for betaenones A, B and C were 0.075, 16, 55, 350 and 1 μM respectively. The β-ketoaldehyde moiety appeared to be essential in, conferring biological activity and its toxicity was influenced by its spatial orientation. The presence of an hydroxyl group in stemphyloxin I and II enhanced activity in comparison with the respective compounds betaenones C and A which lack this group.     

Isolation of Eutypa lata from Juglans regia, and Pathogenicity Studies on Different Wood Plants

The fungus Eutypa lata was isolated from diseased walnut trees (Juglans regia) exhibiting small cankers. The morphological characteristics of the culture and the pathogenicity were compared with those of known isolates of the fungus from other hosts. Inoculation tests with walnut isolates on grape, walnut, almond and apricot yielded characteristic cankers. Furthermore, pathogenicity tests on walnut with isolates from other different hosts resulted in differences in virulence. Similar differences in virulence were observed between 13 single ascospore isolates of the fungus ex apricot inoculated on walnut.     

(Co)variance components, genetic parameters and annual trends for calf weights in a Brahman herd kept on floodable savanna

(Co)variance components and genetic parameters were estimated for body weights of an elite Brahman herd under a designed, supervised management and genetic program, including strategic artificial insemination (AI). Restricted maximum likelihood methods were used with a univariate animal model for birth weight (BW) and a bivariate model for weaning weight (205-day weight, 205W) and 18-month weight (548-day weight, 548W). Models included random animal direct and maternal genetic effects, maternal permanent environmental effect (c2), and sex-year-month of birth-age of dam and genetic group (identified and unidentified paternity), as fixed effects. Analysis A1 included all calves and analysis A2 included only those with identified sires. Of the 8,066 calves born, 36% were progeny of AI, 11% from single sire and 53% from multi-sire herds. They were born from 1985 to 1998, from 2559 dams and 146 sires (78 identified). Estimates of direct, maternal and total heritabilities from A1 for BW, 205W and 548W were: 0.23, 0.07 and 0.30; 0.08, 0.14 and 0.16; 0.16, 0.04 and 0.28, respectively. Corresponding estimates of direct maternal genetic correlations were 0.22, 0.07 and 0.86, and c2 estimates were 0.04, 0.14 and 0.04, respectively. Estimates of direct and maternal genetic, and permanent environmental correlations between 205W and 548W were: 0.66, 0.70 and 1.00. Variances and genetic parameters from A1 and A2 were, in general, very similar. Estimates of phenotypic, and direct and maternal genetic trends per year from A1 were: 0.393, 0.004 and 0.003 kg (BW), 3.367, 0.142 and 0.115 kg (205W), 1.813, 0.263 and 0.095 kg (548W). Estimates of direct and maternal genetic trends from A2 were: 0.033 and -0.002 kg (BW); 0.186 and 0.276 kg (205W); 0.471 and 0.136 kg (548W). The modern selection methods that have been used recently should be continued, with emphasis on the improvement of cow efficiency for sustainable beef production on floodable savanna combined with improved pasture.     

Roditis Leaf Discoloration - A New Virus Disease of Grapevine: Symptomatology and Transmission to Indicator Plants

The symptoms and some characteristics of an unreported disease of grapevine, which was observed during the last years on the cv. ‘Roditis’ in central Greece, are described. The disease is transmissible to V. vinifera‘Mission’ and to some herbaceous test plants. The constant association of a virus to naturally infected plants cv. ‘Roditis’ and chip-budding infected indicator plants cv. ‘Mission’ supports the evidence that the disease is caused by a virus.     

Persistence of the nematophagous fungus Paecilomyces lilacinus strain 251 in soil under controlled conditions

The persistence of the nematophagous fungus Paecilomyces lilacinus Samson strain 251 (PL251) and the effect of application rate, substrate type, as well as the presence of the nematode host on its dynamics after application to the soil were investigated under controlled conditions. In all experiments, increase of P. lilacinus colony forming units after application was not found. In contrast, a gradual decline in fungal densities over time was observed. Application rate had no significant effect on the dynamics of the fungal population. Likewise, P. lilacinus density decline in soil was not significantly affected by the presence of the nematode host. Substrate type had a significant effect on P. lilacinus persistence in soil. The fungal agent persisted longer in silty loam and clay soil, with reduced persistence when sand was added to field soil. Conversely, when organic substrate was added to pure sand, persistence was significantly increased. Although persistence of fungal biocontrol agents in soil depends on various biotic and abiotic conditions, baseline data on persistence such as those reported in this study are helpful for biocontrol and environmental risk assessment and merit further study.     

Epirus Cherry Virus, an Unusual Virus Isolated from Cherry with Rasp-Leaf Symptoms in Greece

Severe rasp-leaf symptoms were observed on a cherry tree in an orchard in northwestern Greece. A virus, given the proposed name Epirus Cherry Virus (EpCV), was mechanícally isolated, which on the basis of biological, morphological and serological properties, appeared different from all known viruses associated with or causing rasp-leaf symptoms on cherry. The virus has at least three types of particles sedimenting as three components in a sucrose density gradient. No serological relations were found with other similar viruses.