Effects of growth conditions on postharvest Botrytis infection in Gerbera - a nursery comparison

Botrytis cinerea is one of the main postharvest problems in gerbera cut flowers. There are clear differences among growers in the percentage of flowers showing symptoms of Botrytis infection after harvest. Because the factors causing these differences are uncertain, cultivation parameters of twelve different growers were followed and a nursery comparison was carried out. Gerbera flowers ‘Dino’ were sampled twelve times; six times in autumn 2006 and six times in spring of 2007. At the nurseries climate (air temperature, relative humidity, light intensity and CO2 concentration) was logged, and plant density, plant age and other characteristics were monitored. Before each harvest Botrytis spores were trapped in the greenhouses and counted. After sampling, flowers were treated according to a standard transport simulation. Thereafter Botrytis infection was monitored, and statistical analyses were performed on the effect of the pre-harvest conditions on Botrytis infection in the postharvest stage. Clear influence of the spore level in the greenhouse was observed. When a sufficient number of spores were present in the greenhouse environment, the humidity level and the intensity and duration of irradiation had the strongest influence on infection. In general, factors those lead to a dry microclimate such as the use of ventilators, the use of supplemental lighting and a low plant density were related with a lower number of lesions on gerbera petals in the postharvest phase

Trends in rooting media in Dutch horticulture during the period 2001-2005: The new growing media project

An overview of the developments in the area and volume of substrates used for horticultural rooting media in Holland in the period 2001 to 2005 is given. The overview is followed by a discussion of some trends in society and technology including the interest of public and society in a possible substitution of peat, an increase in the use of locally produced renewable carbon based substrates and an increase in nutrient recirculation for soil grown crops. In reaction to growing public concern about peat harvesting for horticultural purposes in parts of Europe, Dutch growers, researchers, potting soil producers, an auction and traders initiated in 2003 a research program named the New Growing Media Project. The aim was: To assess the technical and economical potential of peat alternatives. Develop experience and knowledge of growing on alternative mixtures. During 2004 and 2005, fifteen growers cultivated green and flowering container plants on alternative mixes. The 2004 season was used to test larger numbers of potting soils with relatively small numbers of plants. The 2005 season was used to test the most promising potting soils with larger numbers of plants. The results showed that for Hedera and Schefflera, the ultimate alternative mix was superior to the commercial standard used. For five species, Anthurium, Chrysanthemum, Gerbera, Spathiphyllum and Castanospermum, the alternative mix proved equal to the commercial standard. For eight species, Azalea, Guzmania, Poinsettia, Rosa, Saintpaulia, Adiantum, Crassula and Ficus, results were poorer than on the standard medium. The growers however, felt confident the alternative mixes could do better if the growing system, often the irrigation frequency, could be adapted to the experimental growing medium. Begonia gave poorer results with the new mix. The percentage peat used in the mixes was reduced from 77% on average in the commercial standard mixes to 30% on average in the new mixes. The most popular alternatives were coir products which increased from 17 to 40%. Other alternatives used were various barks, rice hulls, perlite, wood fiber, composts, and rockwool granulate. Those alternatives were used in mixtures from 5 to 30%. General conclusions include a growing interest in locally produced composts, granulates and fibers and for materials with properties such as a high initial air content combined with an improved rewetting rate

Fungicidal management of Alternaria alternata (Fr.) Keissler causing blight of gerbera (Gerbera jamesonii H. Bolus ex J.D. Hook)

Alternaria, the fungal pathogen has wide host range generally attacks the aerial parts of plants causing leaf spots and blights. Gerbera is a genus of ornamental flower plants. Gerbera plants are infected by many diseases. Different disease management practices are adopted in gerbera cultivation. The fungicidal management of Alternaria blight is one of the important strategies for the disease management in gerbera in polyhouse condition. In this study, preventive and curative fungicidal sprays were adopted for the management of blight disease in polyhouse. This study revealed that preventive fungicidal sprays were significant over curative fungicidal sprays for the management of Alternaria alternata blight of gerbera (Gerbera jamesonii H. Bolus ex J.D. Hook) in polyhouse. The preventive sprays made of Bordeaux mixture (0.6 %), tricyclazole (0.1%) and iprodione + carbendazim (0.1%) fungicides were found effective with 95.85 %, 96.59 % and 95.88 % disease control respectively, under polyhouse condition

DEVELOPMENT OF A STOCHASTIC MODEL TO EVALUATE PLANT GROWERS' ENTERPRISE BUDGETS

Increased domestic concentration and international competition in the floricultural industry are forcing growers to improve resource management efficiency. Cost management and cost accounting methods are becoming key tools as growers attempt to reduce costs. These tools allow growers to allocate costs for each crop, increasing their greenhouse planning abilities. Growers have a relative high degree of risk due to potential crop and market failure. Individual growers have different tolerance for risk and risk bearing capacity. Growers need a cost accounting system that incorporates production and market risk, a system that allows them to make informed business decisions. The research reported in this paper developed a greenhouse budgeting model that incorporated risk to allow growers to compare production costs for flowers with different genetics and production technologies. This enables greenhouse growers to make production management decisions that incorporate production and market risk. The model gives growers the option of imputing their own production data to evaluate how various yield and price assumptions influence income and expense projections, and ultimately, profit. The model allows growers to compare total production cost and revenue varying grower type, production time, geographical location, operation size, and cost structure. The model evaluates budgets for growers who market to mass-market retail operations or wholesale intermediaries who sell to merchandisers or flower shops distribution channels. The model was demonstrated with sample data to illustrate how incorporating risk analysis into a grower's greenhouse budget model effects resource allocation and production decisions as compare to a budget model that does not incorporate risk. Deterministic and stochastic models were used to demonstrate differences in production decisions under various assumptions. The stochastic model introduced prices and flowering characteristics variability. The @Risk software was used to generate the random number simulation of the stochastic model, and stochastic dominance analysis was used to rank the alternatives. The result for both the deterministic and stochastic models identified the same cultivar as most profitable. However, there were differences in crop profits levels and rankings for subsequent cultivars that could influence growers' production choice decisions. The grower's risk aversion level influenced his/her choice of the most profitable cultivars in the stochastic model. The model summarizes the sources of variability that affect cost and revenue. The model enables the grower to measure effects that change in productivity might have on profit. Growers can identify items in their budget that have a greater effect on profitability, and make adjustments. The model can be used to allocate cost across activities, so the grower would be able to measure the economic impact of an item on the budget.Crop Production/Industries,

Seasonal Abundance; Damage; and Comparison of Different Heights, Orientations, and Directions of Yellow Sticky Traps for Sampling of \u3ci\u3eLiriomyza Trifolii\u3c/i\u3e (Diptera: Agromyzidae) in Cotton

This study was done to determine the optimum height, orientation, and direction of yellow sticky traps for sampling of Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) in cotton fields. Leaf infestation rates for the whole plants, as well as for each of three plant regions, and number of mines per infested leaf were also determined. Traps were placed at 25 cm above the plant canopy and 30 cm above the ground at two orientations (horizontal and vertical) and two directions (east-to-west and north-to-south) for each height and orientation in Aydin province, Turkey. Horizontally oriented traps captured more flies than vertically oriented traps. More flies were captured 25 cm above the plant canopy than 30 cm above the ground. The upper sides of horizontally oriented traps had the highest capture rates. Direction of traps did not significantly affect capture rate. The infestation rate of leaves was highest (14.1%) the first week of August and generally higher lower on the plant (79.4-100%). No mines were found in the upper region (top third) of the plants. No adults emerged from reared mines. These results are useful in development of sampling protocols to aid growers in making decisions and could be used as an additional component in Integrated Pest Management against L. trifolii in cotton fields

A universal primer for isolation of fragments of a gene encoding phytoene desaturase for use in virus-induced gene silencing (VIGS) studies

We have been using Virus-Induced Gene Silencing (VIGS) to test the function of genes that are candidates for involvement in floral senescence. Although VIGS is a powerful tool for assaying the effects of gene silencing in plants, relatively few taxa have been studied using this approach, and most that have are in the Solanaceae. We typically use silencing of phytoene desaturase (PDS) in preliminary tests of the feasibility of using VIGS. Silencing this gene, whose product is involved in carotene biosynthesis, results in a characteristic photobleaching phenotype in the leaves. We have found that efficient silencing requires the use of fragments that are more than 90% homologous to the target gene. To simplify testing the effectiveness of VIGS in a range of species, we designed a set of universal primers to a region of the PDS gene that is highly conserved among species, and that therefore allows an investigator to isolate a fragment of the homologous PDS gene from the species of interest. We report the sequences of these primers and the results of VIGS experiments in horticultural species from the Asteraceae, Leguminosae, Balsaminaceae and Solanaceae

Effects of different nutrient solutions on growth and flower quality of gerbera (Gerbera jamesonii) grown in hydroponic close system

The nutrient solution is the decisive factor for the growth and development of hydroponic plants. This study was conducted to determine the effect of five nutrient solutions, namely, Hoagland, Knop, Hydro Umat F, BKFAST, and Bio-Life, on the growth and development of gerbera (Gerbera jamesonii) in the hydroponic system. The results show that Hydro Umat F is the most suitable solution for planting gerbera in terms of plant height, number of leaves, leaf size, and root volume. In addition, the flower yield of the gerbera plants nourished on Hydro Umat F is also the highest, with 8.7 flowers per plant after five months in the hydroponic system. The flowers have a diameter of 9.8 cm and natural durability of 19.67 days. Meanwhile, gerbera plants stop growing after 15 days in the Bio-Life solution and 30 days in the Knop solution

Cultura em substratos orgânicos de Gerberas

O cultivo sem solo de Gerbera (Gerbera jamesonii) tem-se revelado uma técnica adequada, permitindo ultrapassar alguns dos problemas surgidos na cultura tradicional, em solo. No âmbito do Projecto Agro no197 “Cultura sem solo com reutilização do efluente, em estufa com controle ambiental melhorado”, desenvolvido pela Direcçao Regional de Agricultura do Algarve, pelo Cento de Hidroponia e Utilidades Hortofrutícolas e pela Universidade do Algarve testou-se o cultivo de gerbera em substratos alternativos, no Centro de Experimentação Hortofrutícola do Patacão. Cultivaram-se quatro cultivares de gerbera: Monika, Junkfrau, Venice e Lady, em substratos preparados à base de resíduos orgânicos: casca de pinho e bagaço de uva, durante dois anos consecutivos. Os resultados obtidos sugerem que os substratos testados apresentam características adequadas à cultura da gerbera, tendo-se obtido as produções mais elevadas com o bagaço de uva compostado e a casca de pinho não compostada. Das cv. em estudo, no 1o ano a Venice apresentou o maior número de flores comercializáveis, seguida da Lady com mais flores na classe Extra. No 2o ano, a produção foi mais equilibrada entre as cultivares, sendo de registar o aumento da produção em duas cv., Junkfrau e Monica