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Beit Jann, Israel

Zahavi T.,Extension Service | Reuveni M.,Haifa University
European Journal of Plant Pathology

The effect of two training systems on the development of powdery mildew caused by Erysiphe necator in berries of Chardonnay and Cabernet Sauvignon grapevines was examined. Disease development was monitored on berries from vines trained to either vertical shoot positioning or as free-positioned, topped vines with no foliage support wires. No fungicides were applied and powdery mildew development was recorded following artificial inoculation of young berries. Disease incidence was higher in berries collected from the vertical shoot system than in berries from the free-canopy vines. Incubating the berries under the reciprocal training system had a slight effect on PM development with the more susceptible berries of the VSP system but not on berries from the free canopy. The data suggest that the training system decreases disease development mainly through an effect on the susceptibility of the berries. The latter were less vulnerable to artificial inoculation performed in the laboratory after prior exposure to higher radiance intensity. The free-position system may therefore be useful in reducing the use of fungicides. © 2012 KNPV. Source

Sacks M.,Extension Service | Bernstein N.,Institute of Soil, Water and Environmental Sciences
Israel Journal of Plant Sciences

Shortage of water in arid and semiarid areas throughout the world makes utilization of marginal water for agricultural irrigation a necessity. The marginal water most used for irrigation in Israel is secondary-treated urban effluents. In spite of the water treatment process, these waters often contain higher levels of bacterial human pathogens than the potable water from which they were derived. Utilization of the treated effluents for irrigation in Israel is strictly regulated according to the water quality and the irrigated crop. Due to health concerns, and a lack of experimental data, the treated effluents are not yet used for irrigation of vegetables. In the present study we have evaluated safety and agronomic issues involved in irrigation of summer melon with secondary-treated urban effluents, administered to the production field by surface and sub-surface drip irrigation according to the national regulations. Two water qualities were compared, secondary-treated wastewater and potable water. The effluents contained higher levels of EC, pH, Na and Cl, N, P, K, microelements, and heavy metals than the potable water. Potable water was applied by surface drip irrigation, and three irrigation regimes were compared for the treated effluents. These included surface irrigation, and subsurface irrigation at 20 or 40 cm below the soil surface. No differences in yield quantity and quality were found between treatments. Na concentrations and SAR levels of the soil were higher under irrigation with the effluent. Contamination by E. coli, fecal coliforms, and total coliform bacteria were found on the melon peel of all treatments, and the quantity and quality of the contamination did not vary significantly between treatments. E. coli and fecal coliforms were found in the surface 0-2 cm soil samples of treatments irrigated with both water qualities by surface drippers, but no contamination was found in the treatments irrigated by subsurface irrigation. The fact that the microbial contamination of the fruit was not prevented by subsurface drip irrigation or by irrigation with fresh water suggests that environmental factors, rather than an irrigation treatment affect, were the cause for the microbial spread. Further analysis is required concerning effects of environmental factors, such as the interaction between weather conditions and distance from the effluent oxidation ponds on temporal geospatial distribution of the bacterial human pathogens and the potential for subsequent contamination of fresh produce in the field. © 2011 Science From Israel / LPPltd. Source

Hou C.,Institute of Plant Protection | Rivkin H.,Institute of Plant Protection | Slabezki Y.,Extension Service | Chejanovsky N.,Institute of Plant Protection

The determinants of Colony Collapse Disorder (CCD), a particular case of collapse of honey bee colonies, are still unresolved. Viruses including the Israeli acute paralysis virus (IAPV) were associated with CCD. We found an apiary with colonies showing typical CCD characteristics that bore high loads of IAPV, recovered some colonies from collapse and tested the hypothesis if IAPV was actively replicating in them and infectious to healthy bees. We found that IAPV was the dominant pathogen and it replicated actively in the colonies: viral titers decreased from April to September and increased from September to December. IAPV extracted from infected bees was highly infectious to healthy pupae: they showed several-fold amplification of the viral genome and synthesis of the virion protein VP3. The health of recovered colonies was seriously compromised. Interestingly, a rise of IAPV genomic copies in two colonies coincided with their subsequent collapse. Our results do not imply IAPV as the cause of CCD but indicate that once acquired and induced to replication it acts as an infectious factor that affects the health of the colonies and may determine their survival. This is the first follow up outside the US of CCD-colonies bearing IAPV under natural conditions. © 2014 by the authors; licensee MDPI, Basel, Switzerland. Source

Shoshani E.,Extension Service | Hetzroni A.,Israel Agricultural Research Organization

Meticulous planning is required to minimize heat-stress conditions in barns. The objective of this study was to determine optimum barn characteristics for high-yielding dairy cows under Israeli (Mediterranean) summer ambient conditions, by using a new stress model that takes ambient temperature, relative humidity and wind velocity into account. During the summers of 2004 and 2005, three meteorological stations were alternately installed in 39 barns: two stations inside the barn at the prevailing downwind direction, and a third station outside the upwind end of the barn. Ambient temperature, relative humidity, wind speed and direction were measured and recorded every 10 min for 3 to 5 consecutive days at each barn in turn. The data were collected at different geographical and climatic conditions. Therefore, the data collected by an outside station were used as covariates. A heat-stress model was used to determine the threshold temperature (THRT) at which a cow begins to increase its respiratory rate; THRT was the response variable in the statistical model. The THRT model takes in account assumed values of a cow's physiological characteristics: daily milk yield of 45 kg, containing 3.5% fat, and 3 mm fur depth. The independent variables were: orientation, barn type, roof slope, roof ridge, marginal height, roof type (fixed or sliding) and barn width. Results showed that the optimal barn for high-yielding cows is the loose-housing type, oriented with its long axis perpendicular to the prevailing wind direction. Advantageous to the design would be an open ridge or pagoda with marginal height of over 4.7 m for north-south orientation and over 5 m for east-west orientation, roof slope over 11%, and barn width between 43 and 51 m for north-south orientation but lower than 42 m for east-west orientation. A sliding roof was also found to be an excellent solution when outside yards are banned by environmental regulations. Copyright © 2012 The Animal Consortium. Source

Korolev N.,Israel Agricultural Research Organization | Mamiev M.,Israel Agricultural Research Organization | Zahavi T.,Extension Service | Elad Y.,Israel Agricultural Research Organization
European Journal of Plant Pathology

Plots in two vineyards in the Golan Heights, Israel were treated with six botryticides during three growing seasons with 3 applications per season. Applications of fenhexamid, pyrimethanil and cyprodinil + fludioxonil were effective, resulting in 52-65% and 53-63% mean reduction in grey mould incidence and severity, respectively. Carbendazim, fluazinam and iprodione were ineffective or slightly effective. Five hundred and sixteen B. cinerea isolates were collected from infected berries or trapped from the air in the vineyards, and profiles of sensitivity to benomyl, fenhexamid, fluazinam, fludioxonil, iprodione and pyrimethanil were established for each of the isolates based on a mycelial growth test. Seventy-four percent of the isolates were sensitive to the six tested fungicides, and the other 26% of the isolates were classified into 10 phenotypes characterized by resistance to one or more fungicides. Resistant isolates showed fitness parameters similar or reduced in comparison to sensitive isolates. Resistance to benzimidazoles and to dicarboximides was the most frequent (up to 25%) and apparently pre-existed in the populations tested. Increased frequency of benzimidazole resistance, but not dicarboximide resistance, was observed following the 3 years of applications of the fungicides. High level resistance to pyrimethanil was present at a frequency of about 2% in both vineyards in the first 2 years of the sampling survey and reached 10% in the third year at Site 2. A few isolates were resistant to fenhexamid or fludioxonil (0.8 or 0.2%, respectively). No strong resistance to fluazinam was detected, although numerous, less sensitive isolates, presumably possessing multi-drug resistance traits, were recovered at higher frequency from the plots treated with fluazinam than from the untreated plots. © 2010 KNPV. Source

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