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

Non- chemical methods of seed treatment for control of seed- borne pathogens on vegetables

The aim of EU-project "Seed Treatments for Organic Vegetable Production" (STOVE) was to evaluate non-chemical methods for control of seed-borne pathogens in organic vegetable production. Physical (hot air, hot water and electron) and biologi-cal (microorganisms and different agents of natural origin) methods have been investigated. Trials have been carried out with different patho-systems such as cabbage / Alternaria spp and parsley / Septoria pet-roselini. Good control was generally obtained with the physical methods. In field trials, the yield of parsley naturally infested by S. petroselini was increased by 20 % when the seeds were treated with hot air. In trials performed under controlled conditions, also thyme oil treatment increased the number of germinated seedlings of this crop compared to the untreated control. Treatments with different commercialised microbial preparations reduced incidence of disease caused by Alternaria spp. in cabbage seedlings to a level similar to that achieved after chemical treatment. Many of the non-commercialised microoganisms also reduced disease incidence clearly

Non- chemical methods of seed treatment for control of seed- borne pathogens on vegetables

Abstract – The aim of EU-project "Seed Treatments for Organic Vegetable Production" (STOVE) was to evaluate non-chemical methods for control of seed-borne pathogens in organic vegetable production. Physical (hot air, hot water and electron) and biologi-cal (microorganisms and different agents of natural origin) methods have been investigated. Trials have been carried out with different patho-systems such as cabbage / Alternaria spp and parsley / Septoria pet-roselini. Good control was generally obtained with the physical methods. In field trials, the yield of parsley naturally infested by S. petroselini was increased by 20 % when the seeds were treated with hot air. In trials performed under controlled conditions, also thyme oil treatment increased the number of germinated seedlings of this crop compared to the untreated control. Treatments with different commercialised microbial preparations reduced incidence of disease caused by Alternaria spp. in cabbage seedlings to a level similar to that achieved after chemical treatment. Many of the non-commercialised microoganisms also reduced disease incidence clearly

Control of seed-borne pathogens on legumes by microbial and other alternative seed treatments

Greenhouse trials were carried out in order to test the efficacy of different seed treatments as alternatives to chemicals against Colletotrichum lindemuthianum cause of anthracnose on bean and Ascochyta spp. cause of Ascochyta blights on pea, respectively. Resistance inducers, commercially formulated microorganisms, non-formulated selected strains of different microorganisms (fungi, bacteria and yeasts) and plant extracts were applied as dry or liquid seed treatments on naturally infested seeds. Seedling emergence and disease incidence and/or severity were recorded. Almost all seed treatments turned out to be ineffective in controlling the Ascochyta infections, which is in line with the literature stating that these pathogens are difficult to control. The only alternative treatments that gave some control of Ascochyta spp. were thyme oil and a strain of Clonostachys rosea. The resistance inducers tested successfully controlled infections of bean by C. lindemuthianum. Among the formulated microorganisms, Bacillus subtilis-based formulations provided the best protection from anthracnose. Some strains of Pseudomonas putida, a disease-suppressive, saprophytic strain of Fusarium oxysporum and the mustard powder-based product Tillecur also proved to be effective against bean anthracnose. However, among the resistance inducers as well as among the other groups, certain agents caused a significant reduction of plant emergence. Different alternative seed treatments can therefore be used for the control of C. lindemuthianum on bean, while on pea only thyme oil and a strain of Clonostachys rosea showed some effectiveness against Ascochyta spp

Conversion of the mycotoxin Patulin to the less toxic desoxypatulinic acid by the biocontrol yeast Rhodosporidium Kratochvilovae strain LS11

The infection of stored apples by the fungus Penicillium expansum causes the contamination of fruits and fruit-derived products with the mycotoxin patulin, which is a major issue in food safety. Fungal attack can be prevented by beneficial microorganisms, so-called biocontrol agents. Previous time-course thin layer chromatography analyses showed that the aerobic incubation of patulin with the biocontrol yeast Rhodosporidium kratochvilovae strain LS11 leads to the disappearance of the mycotoxin spot and the parallel emergence of two new spots, one of which disappears over time. In this work, we analyzed the biodegradation of patulin effected by LS11 through HPLC. The more stable of the two compounds was purified and characterized by nuclear magnetic resonance as desoxypatulinic acid, whose formation was also quantitated in patulin degradation experiments. After R. kratochvilovae LS11 had been incubated in the presence of (13)C-labeled patulin, label was traced to desoxypatulinic acid, thus proving that this compound derives from the metabolization of patulin by the yeast. Desoxypatulinic acid was much less toxic than patulin to human lymphocytes and, in contrast to patulin, did not react in vitro with the thiol-bearing tripeptide glutathione. The lower toxicity of desoxypatulinic acid is proposed to be a consequence of the hydrolysis of the lactone ring and the loss of functional groups that react with thiol groups. The formation of desoxypatulinic acid from patulin represents a novel biodegradation pathway that is also a detoxification process

Evaluation of non-chemical seed treatment methods for the control of Phoma valerianellae on lamb`s lettuce seeds

The aim of the present study was to identify seed treatment methods for eradicating Phoma valerianellae from lamb`s lettuce seeds in organic vegetable production. Using seeds naturally infested with the pathogen, the effect of three physical methods (hot water, aerated steam, electron treatment) and different agents of natural origin (micro-organisms, plant derived products, resistance inducers) was tested on moist filter paper, in seed trays under controlled conditions and in the field. In an initial screening, none of the tested putative resistance inducers prevented infection by P. valerianellae , while two out of seven formulated micro-organism preparations and six out of 16 experimental microbial strains were effective. When selected agents and the three physical seed treatment methods were compared in blotter and seed tray tests, the physical methods were generally the most effective treatments, while the micro-organism treatments were clearly less efficacious. However, in field experiments with the same seed lots and the same treatments, a statistically significant increase in plant stand was not obtained with any of the treatments. Combinations of the three physical treatment methods with selected non-chemical agents did not perform better than the physical treatments alone. The most effective alternative seed treatments identified in the present study, aerated steam, hot water, electron treatment and thyme oil (0.1%), can be recommended for eradication of P. valerianellae from lamb`s lettuce seeds in organic farming. Because their efficacy was generally as high as that of the chemical fungicide Aatiram (active ingredient thiram), they are also potentially suited for use in conventional vegetable productio

STOVE: SEED TREATMENTS FOR ORGANIC VEGETABLE PRODUCTION

Abstract – Production of pathogen-free seeds is a major goal in organic farming. In the framework of the EU-funded project “STOVE” (“Seed Treatments for Organic Vegetable Production”) physical and biological methods of seed treatment (alone and in combination) were investigated in different vegetable / pathogen systems. Overall, the physical treatments (hot water, hot air and electron treatment) resulted in a moderate to good control of the respective diseases. Also, from all biological treatment groups (microorganisms, plant extracts and inducers of resistance) candidates with promising control properties could be identified. The influence of the biological methods on emergence was often more prominent under greenhouse than under field conditions. The efficacy of given single and combined treatments depended strongly on the host / pathogen system investigated. Moreover, it turned out that the cultivar and also the seed lot differed to a large extent with respect to their sensitivity, so that selection of treatment parameters need to be considered thoroughly for each vegetable species and seed lo