Critical aspects in management of fungal diseases of ornamental plants and directions in research

The production of ornamental plants is a thriving and expanding industry, which is economically important in the United States of America, Canada, South America, Australia, and Europe as well as in many developing countries. During the last few decades significant changes have occurred, with many new crops being introduced, new products such as pot plants replacing cut flowers, and improved techniques for growing, treating and handling plants being introduced. Such changes have had a profound influence on disease development and management. This review focuses on critical aspects of the disease management of ornamental crops, considering the role of breeding strategies, cultural practices, chemical and biological control, natural products, regulatory control and diagnostic tools. Finally, the research needs in this sector are critically analysed

Use of 1-methylcyclopropene for the control of Botrytis cinerea on cut flowers

Cut flowers are marketed for their ornamental characteristics making post-harvest flower life an important determinant of crop value. Botrytis cinerea is one of the most significant post-harvest fungal pathogens causing losses in ornamental plants. Disease caused by this fungus seems to be enhanced by the presence of a ethylene hormone, that both the plant and the fungus are known to synthesize. The aim of the experiment was to determine if 1-methylcyclopropene (1-MCP), an ethylene antagonist, could be used to reduce B. cinerea damage to cut flowers. Six cultivars of four ornamental species: Dianthus caryophyllus ‘Idra di Muraglia’, Rosa × hybrida ‘White Dew’ and ‘Ritz’, Ranunculus asiaticus ‘Saigon’ and ‘Green’, and Cyclamen persicum line ‘Halios Bianco Puro Compatto’ were given three concentrations of 1-MCP (0.38 μl L-1, 1.14 μL L-1, and 3.62 μL L-1) for 24 hours. Subsequently, 10 petals per cultivar were treated with a B. cinerea conidial suspension (5×103 conidia cm-2) and stored in air-tight vases. To evaluate B. cinerea development an arbitrary damage scale (1–7) was used. A high concentration of 1-MCP significantly reduced B. cinerea damage on D. caryophyllus ‘Idra di Muraglia’ and C. persicum ‘Halios White Pure Compact’ petals. In carnation, 1-MCP treatment slowed B. cinerea infection; its threshold level was reached three days after that of the control. In cyclamen, treated petals and control petals remained aesthetically good until day 53 and day 28 respectively. At low concentrations, 1-MCP slowed grey mould on R. × hybrida ‘Ritz’ for up to three days beyond the control. On the two buttercup cultivars ‘Green’ and ‘Saigon’, 1-MCP treatments were not effective. In conclusion, 1-MCP limited pathogen development; its effect depended on the species and the 1-MCP concentration. Further investigations will be performed to improve methods to reduce B. cinerea development on the petals of cut flowers

Evaluation of non-chemical seed treatment methods for the control of Alternaria dauci and A. radicina on carrot seeds

The current study was initiated to evaluate the efficacy of physical methods (hot water, aerated steam, electron treatment) and agents of natural origin (resistance inducers, plant derived products, micro-organisms) as seed treatments of carrots for control of Alternaria dauci and A. radicina. Control of both Alternaria species by seed treatment with the resistance inducers was generally poor. Results were also not satisfactory with most of the formulated commercial micro-organism preparations. Based on the average of five field trials, one of these, BA 2552 (Pseudomonas chlororaphis), provided a low but significant increase in plant stand. Among the experimental micro-organisms, the best results were obtained with Pseudomonas sp. strain MF 416 and Clonostachys rosea strain IK726. A similar level of efficacy was provided by seed treatment with an emulsion (1%) of thyme oil in water. Good and consistent control was generally achieved with the physical methods aerated steam, hot water and electron treatment. Aerated steam treatment was, apart from the thiram-containing chemical standard, the best single treatment, and its performance may at least partially be due to extensive pre-testing, resulting in dosages optimally adapted to the respective seed lot. In some of the experiments the effect of the hot water treatment, which was tested at a fixed, not specifically adapted dosage, was significantly improved when combined with a Pseudomonas sp. MF 416 or C. rosea IK726 treatment. The results are discussed in relation to the outcome of experiments in which the same seed treatment methods and agents were tested in other seed-borne vegetable pathosystems

STOVE: Seed treatments for organic vegetable production

The aim of the EU-financed research project „STOVE“ (Seed Treatments for Organic Vegetable Production) is to evaluate different methods potentially suited for seed treatment of vegetables in organic farming regarding their efficacy, to optimise these methods, and where feasible to combine them with each other. Scientists from seven European research institutions and a producer of organic vegetable seeds carry out the project

Alternatives to Methyl bromide in Strawberry Production in the United States of America and the Mediterranean Region

Methyl bromide (MB) is a broad-spectrum soil fumigant, which has been critical in strawberry production for forty years. Strawberry and other high-value cash crops benefit from pre-plant soil fumigation with MB and chloropicrin (Pic). Mixtures of these two fumigants work synergistically in controlling a wide range of plant pathogens and pests, including fungi, nematodes, insects, mites, rodents, weeds, and some bacteria. Methyl bromide was listed in 1993 by the Parties of the Montreal Protocol as an ozone-depleting compound. According to the Montreal Protocol, the import and manufacture of MB in the United States of America (USA) and other developed countries will be banned by 2005, after stepwise reductions in 1999, 2001, and 2003. Currently, there is no single registered alternative fumigant for all of the MB uses and there is a need for environmentally sound and economically feasible alternatives. The fumigants 1,3-dichloropropene (1,3-D) and Pic in combination with methyl isothiocyanate (MITC) generators have shown to be the most promising alternatives to methyl bromide for strawberry production. Studies with the experimental fumigants methyl iodide and propargyl bromide suggested that these compounds have higher reactivity than MB as stand-alone fumigants. This review evaluates the commercially available and experimental alternatives to MB soil fumigation for strawberry production based on relevant scientific publications, proceedings, and personal communications

Alternatives to Methyl bromide in Strawberry Production in the United States of America and the Mediterranean Region

Methyl bromide (MB) is a broad-spectrum soil fumigant, which has been critical in strawberry production for forty years. Strawberry and other high-value cash crops benefit from pre-plant soil fumigation with MB and chloropicrin (Pic). Mixtures of these two fumigants work synergistically in controlling a wide range of plant pathogens and pests, including fungi, nematodes, insects, mites, rodents, weeds, and some bacteria. Methyl bromide was listed in 1993 by the Parties of the Montreal Protocol as an ozone-depleting compound. According to the Montreal Protocol, the import and manufacture of MB in the United States of America (USA) and other developed countries will be banned by 2005, after stepwise reductions in 1999, 2001, and 2003. Currently, there is no single registered alternative fumigant for all of the MB uses and there is a need for environmentally sound and economically feasible alternatives. The fumigants 1,3-dichloropropene (1,3-D) and Pic in combination with methyl isothiocyanate (MITC) generators have shown to be the most promising alternatives to methyl bromide for strawberry production. Studies with the experimental fumigants methyl iodide and propargyl bromide suggested that these compounds have higher reactivity than MB as stand-alone fumigants. This review evaluates the commercially available and experimental alternatives to MB soil fumigation for strawberry production based on relevant scientific publications, proceedings, and personal communications