Twizeyimana M.,University of California at Riverside |
Mcdonald V.,University of California at Riverside |
Mayorquin J.S.,University of California at Riverside |
Wang D.H.,University of California at Riverside |
And 3 more authors.
Plant Disease | Year: 2013
Members of the Botryosphaeriaceae family have been associated with branch cankers of avocado trees (Persea americana) in California. Canker infections are initiated by spores entering the host plant through fresh wounds such as pruning wounds. With high-density planting becoming more common in the California avocado industry, more intensive pruning may increase the occurrence of branch canker. The objective of this study was to evaluate the preventive ability of some commercial fungicides belonging to different chemical families against fungal pathogens associated with avocado branch canker. Initially, 12 fungicides were tested in vitro for their effect on the inhibition of mycelial growth of three isolates of Dothiorella iberica and isolates (five per species) of Neofusicoccum australe, N. luteum, N. parvum, and Phomopsis sp. Subsequently, azoxystrobin, fludioxonil, metconazole, and pyraclostrobin, selected because of their low effective concentrations that reduce 50% of mycelial growth (EC50 values), and myclobutanil, selected for its high EC50 value, were tested in two field experiments. Azoxystrobin and fludioxonil were used in a premix with propiconazole and cyprodinil, respectively, in field trials. Significant differences (P < 0.05) were observed among fungicides in field trials. Azoxystrobin + propiconazole had the highest percent inhibition at 52 and 62% (internal lesion length) in trial 1 and trial 2, respectively, although this level of inhibition was not significantly different from that of metconazole. A significant correlation (r = 0.51, P < 0.05) was observed between internal lesion length data in the field experiment and EC50 data from in vitro fungicide screening. Application of azoxystrobin + propiconazole and metconazole can play a key role in protecting Californian avocado against fungi causing avocado branch canker. © 2013 The American Phytopathological Society.
Coskun Z.,Viticulture Research Station |
Konukcu F.,Namik Kemal University
Acta Horticulturae | Year: 2014
About 75% of accessible fresh water resources is used for irrigation with about 40% water use efficiency. It is possible to save considerable amounts of water by an efficient irrigation scheduling. Otherwise, excess water use may lead to environmental and economical problems. Therefore, a more accurate, sensitive, simple (farmerfriendly) and automatable method for monitoring of crops' water stress and irrigation time is vital. Methods based on monitoring plant water status are preferred to those measuring soil water status or climatic conditions. Because of the limitations in monitoring plant water status (particularly in orchard trees) in roots and leaves, stem water content measurement (θs) is suggested. The objective of this research was to detect water stress and irrigation time in vines from stem water content (θs) and electrical conductivity measurements (ECs) using TDR (Time-Domain Reflectometer) method. With this aim, four vines were selected and planted in the research area. A 70 mm long probe made from three rods of 1.7-mm diameter stainless steel at 50-mm spacing was installed in each stem. Probes were connected to a multiplexer by 8.0 m coaxial cables and to TDR by 1.0 m coaxial cables. ECs, θs and tree stem temperatures were measured every 30 minutes parallel to soil water content and climatic parameters. Irrigation was performed when 70 % of the available water was consumed within 0-90 cm soil profile by replenishing to the field capacity. The relationship between soil water content and ECs and θs were monitored between April-2011 and September-2011. Stem water content of vines increased significantly in early spring. Later, it fluctuated as a function of plant water stress or soil water status. While the soil water content varied between 18 and 28% between two irrigations, stem water contents changed between 14 and 18%. It gradually decreased towards the end of growing season and eventually gave a minimal response to soil water content variations. ECs and θs produced the same trend. A statistically significant positive linear relationship was found between soil water content and ECs. This implies that ECs can be replaced with the stem as well as soil water content in detecting water stress and irrigation time.
Ates F.,Viticulture Research Station |
Unal A.,Viticulture Research Station |
Cakir E.,Ege University |
Yagci A.,Gaziosman Pasa University
Acta Horticulturae | Year: 2016
Turkey is the major producer and exporter of seedless raisins in the world. The largest area under organic raisin is located in Manisa (2655 ha) then İzmir (580 ha) in the Aegean Region and almost all the grapes are dried and exported to European countries in particular. Organic raisin production constitutes 1.35% of the total raisin production of Turkey. The research was carried out in Alaşehir-Yeşilyurt Enterprise of Viticulture Research Station from 2006 to 2007. The research was established in a 15 year-old 'Sultani Çekirdeksiz' vineyard under irrigable soil conditions in organic parcel. Three different tillage methods: conventional tillage, mulch tillage, and reduced tillage were applied on the trial parcels. The research was carried out as randomized block design trials with three replicates consisting of 12 vines per parcel. Mineral substance analyses of the raisins obtained from the applications were performed using the ICP-AES technique. It was found that there was highest average potassium (K), calcium (Ca), iron (Fe) and copper (Cu) contents of the raisin in mulch tillage; highest average magnesium (Mg), phosphorus (P) and sodium (Na) contents of the raisin in conventional tillage; highest average manganese (Mn) and zinc (Zn) contents of the raisin in reduced tillage at 5% significant level.
Okur N.,Ege University |
Kayikcioglu H.H.,Ege University |
Ates F.,Viticulture Research Station |
Yagmur B.,Ege University
Biological Agriculture and Horticulture | Year: 2015
Soil chemical and microbial parameters are commonly used as soil quality indicators to evaluate sustainable land management in agroecosystems. The objective of this research was to evaluate the impact of organic and conventional management strategies on biological, chemical and yield parameters in vineyards (Vitis vinifera cv. Sultani seedless). Organic plots received a mixture of barley, vetch and broad bean (25+35+75 kg seed ha− 1) as green manure, and farmyard manure (15 t ha− 1) every year. Inorganic fertilizers (NPK) and pesticides were used in the conventional managed vineyards. Conventional and mulch tillage methods were used in conventional and organic plots, respectively. Microbiological and chemical soil properties were determined in the soil samples which were taken four times in 2004, 2005, 2006 and 2007. In addition, the yield and some quality parameters of vineyards were also determined. Soil microbial biomass, and dehydrogenase, β-glucosidase and alkaline phosphatase activity were significantly higher in organic management than in conventional management. Higher Cmic/Corg and lower qCO2 values were found with the organic management. The response of the chemical indicators (Corg, Nt and available nutrient content) of the soils to different management systems appeared after a longer time than with the biological indicators. In the transition zone between continental and Mediterranean climates of West Turkey, soil quality of organically managed vineyards improved after 2 years of the transition period prescribed for organic certification. However, soil quality improvements in organic plots did not result in higher yield. © 2015 Taylor & Francis