Fusarium avenaceum - Fuß- und Wurzelkrankheitserreger der Erbse

Root and foot rot is economically important disease of peas and is caused by complex of more than 20 different species of soil-borne pathogens. In recent years in Germany, Fusarium avenaceum is emerging as important and devastating pathogen and it is together with several other species, including F. solani, F. oxysporum, F. redolens and Phoma medicaginis among the casual agents of the disease that is commonly referred to as pea root rot complex. In 2012, after severe black frost in February that caused failure of the pea crop, F. avenaceum was isolated in high percentage, 42% of assessed roots. All of tested F. avenaceum isolates caused moderate to severe disease symptoms on pea variety Santana. All of composts as well as endophytic F. equisety isolates were able to suppress the root rot disease caused by the F. avenaceum. The suppressive effect of composts was lost after -irradiation

Screening verschiedener Leguminosenakzessionen auf ihre Anfälligkeit gegen wichtige Wurzelpathogene

Leguminous species could provide multiple beneficial services to agroecosystems when grown as cover crops (CC) and/or living mulch species (LM) in rotations with cereals. However, these benefits can only become effective if the pathological risks are thoroughly assessed and solutions for potential problems identified. In order to assess suitability for inclusion of novel leguminous LM and CC species into the rotations, a total of 62 accessions were screened under controlled conditions for their susceptibility/resistance to major legume root infecting pathogens. Majority of tested plant accessions were highly susceptible to Fusarium avenaceum, and low to moderately susceptible to F. oxysporum and F. solani. Peyronelaea pinodella and Didymella pinodes most severely affected Lathyrus accessions, otherwise infections were low

Aggressivität von Fusarium avenaceum, Fusarium solani f. sp pisi und Mycosphaerella pinodes auf Wintererbsen (Pisum sativum L.) unter kontrollierten Bedingungen

Climate change scenarios exhibit a definite warming trend (Schröter et al. 2005), and it will have an impact on crop management strategies. Increase in winter precipitation and higher temperatures favour soil borne pathogens and can lead to an increase in survival rate and to more rapid population buildup (Chakraborty et al. 2000). In recent years, one of the main reasons for declining production of summer pea in organic farming in Germany are foot and root rot pathogens (Pflughöft 2008). On the other hand, predicted increase in winter temperatures is expected to favour winter pea over summer pea varieties. The hope is also, that winter peas are less susceptible to root rot as summer peas. However, few data are available. The present study was carried out to evaluate the susceptibility of winter pea variety EFB 33 against different isolates of Fusarium avenaceum, Fusarium solani f. sp pisi and Mycosphaerella pinodes under controlled conditions in sterile sand. Three weeks after sowing and inoculation, disease symptoms were assessed and plant growth parameters measured. All of the tested pathogens caused root discoloration and development of disease symptoms on pea seedlings. F. avenaceum was the most aggressive pathogen causing severe wilting symptoms and highest reduction in fresh weight of pea. No significant differenceses in aggressivness between F. solani and M. pinodes were observed

Anfälligkeit einer Sommererbse gegenüber Isolaten von Pathogenarten, die von symptomfreien Kleearten und Wicken isoliert wurden

Integration of additional leguminous living mulch and cover crop species holds a great potential for reducing external inputs and improving agricultural sustainability. However, changes towards legume rich crop rotations raises concerns as many of the species of interest share important soil-borne pathogens with some important main crops such as peas, beans and cereals. The pathogenicity towards the spring pea variety Santana was determined for 67 isolates of Fusarium oxysporum, F. solani, F. avenaceum, Didymella spp., Phoma medicaginis and Phoma spp. obtained from seemingly healhty roots of Trifolium subterraneum, T. repens, Vicia villosa and V. sativa. Only one isolate of F. solani and two isolates of Phoma spp. were nonpathogenic. F. avenaceum isolates were the most virulent with disease index up to 100 and reduction of fresh weights up to 98% compared with control plants

Auswirkungen von Fusarium solani f. sp pisi, Fusarium avenaceum und Mycosphaerella pinodes auf Sommererbsen im Topfversuch

Foot rot is an important limiting factor in pea production in Germany (Pflughöft, 2008). The disease is caused by a pathogen complex consisting of Ascochyta complex pathogens (Mycospharella pinodes, Phoma medicaginis and Ascochyta pisi) and Fusarium spp. However, little is known about the specificity of single pathogens of the complex and their impact on plant performance. In order to address this problem pot experiments with five isolates each of Fusarium solani f.sp pisi, Fusarium avenaceum and Mycosphaerella pinodes were carried out in controlled conditions. Three weeks after sowing and inoculation disease symptoms were assessed and plant growth parameters measured. All pathogens caused root discoloration and development of disease symptoms on pea seedlings. However, there were significant differences in symptom severity and effects on plant performance. Fusarium avenaceum was the most aggressive pathogen causing severe wilting symptoms and high reduction in fresh weight of pea. Fusarium solani f.sp pisi was the second most aggressive pathogen, but did not significantly affected plant weight. On the other hand, symptoms due to inoculation with M. pinodes appeared less severe. Nevertheless, plant fresh weights were greatly reduced as a result of infection

Suppression of pathogens causing foot rot of pea by application of yard waste compost

Legume foot and root diseases are mostly caused by broad host-range pathogens. These cannot be managed by rotations alone as often cover crops also are susceptible. Organic amendments such as high quality composts are key management tools for dealing with pathogen pressure. A pot experiment under controlled conditions was carried out to evaluate the suppressive potential of Yard Waste Compost (YWC) against foot rot disease of pea caused by Mycosphaerella pinodes, Phoma medicaginis, Fusarium solani f. sp pisi and F. avenaceum. The spring pea Santana and winter pea EFB33 were grown in sterile sand or sand amended with 3.5 % or 20 % (v/v) YWC as a substrate for three weeks. They were either inoculated at sowing with spore suspensions or left uninoculated. Regardless of variety and pathogen, all application rates of compost significantly reduced the severity of foot rot

Pathogene an Wurzeln von Erbse und Ackerbohne im Demonstrationsnetzwerk Erbse / Bohne

Auf Betrieben des Demonetzwerks Erbse/Bohne wurden in den Jahren 2016 und 2017 von 53 ökologisch und 69 konventionell bewirtschafteten Feldern, die mit Sommer- oder Winterformen von Erbsen oder Ackerbohnen bebaut waren, an je zwei Messpunkten jeweils 10 Wurzelproben entnommen und an der Universität Kassel auf wurzelbürtige Pathogene untersucht. Insgesamt wurden aus mehr als 3000 Pilzisolaten morphologisch 17 Pilzarten identifiziert, die von Didymella pinodes und sieben Fusarium Arten: Fusarium oxysporum, F. solani, F. avenaceum, F. tricinctum, F. equiseti, F. culmorum, F. redolens dominiert werden. Alle Pathogene wurden in konventionellen und ökologischen Feldern gefunden. Ein wichtiges Ergebnis der Untersuchungen ist die Erkenntnis, dass Winterformen der Erbse deutlich häufiger mit D. pinodella befallen sind als Sommerformen. Dies ist das erste Mal, dass Pathogene spezifisch gehäufter auf Wintererbsen gefunden wurden. Die Vielfalt der wurzelbürtigen Pilze auf Körnerleguminosen in Deutschland ist sehr hoch. Die Pathogenität der gefundenen Pilze gegenüber den in Deutschland wichtigen Körnerleguminosen sollte überprüft werden

Organic potatoes, reduced tillage and mulch in temperate climates

The experiments with mulching were done in a systems approach comparing potatoes as they are typically produced in Germany with ploughing to a system of non-inversion tillage combined with mulch. As the plots are integrated in two long-term experiments comparing ploughed versus minimum tillage it was not possible to integrate a mulched ploughed treatment or a non-mulched non-inversion tillage due to restrictions in plot size. We tested the effects of mulching in a ploughed system in 2015. There was no late blight but good erosion control (Pict.5) and yields were increased through mulching. Compost effects on the system were so far not clearly visible. It will most likely take several more years of regular applications to start seeing changes in system performance. Overall, mulching will change the potato system and it will depend very much on the local soil and climatic conditions if and when mulching will be positive (Table 1). On the one hand, mulching is labor intensive and requires the availability of materials to use. Besides freshly cut materials silage is an alternative option some farmers are using in vegetables in Germany. This reduces the dependence on the growing conditions for the mulch early in the season and likely also increases the fertilization effect. Farms that have no animals often mulch grass-clover. This will suppress N-fixation by the clover due to the nutrients in the mulch and thus reduce the usefulness of the grass-clover for nutrient accumulation. In addition it may result in leaching and thus loss of nutrients and even potentially harm the environment. Using the first and most rich harvest as mulch in the potatoes or alternatively making silage for later use is easier than composting such materials. Once the mulch is applied, no more mechanical weed control is done saving labor and energy. More importantly, it will also reduce the mechanical damage done to the potato foliage that makes them more susceptible to infections and it allows for profuse growth of fine roots into the applied mulch materials. Mulching also reduced Colorado potato beetles in both years to some extent but these data need confirmation. Also, the residual effects on the subsequent crop after the potatoes due to the increased input of organic amendments still need to be studied. Ecologically speaking mulching has many advantages. These advantages are especially important in water restricted areas. If and how mulching is feasible and economical depends on the specific conditions and organization of a farm, however

Shifts in the composition of plant parasitic nematodes under different tillage sytems, living mulch, and compost application

Plant parasitic nematodes may cause massive yield reductions in organic farming. Long rotations, often high amounts of weeds and a high frequency of legumes favour parasitic nematodes with a broad host range such as Meloidogyne spp. und Pratylenchus spp. The EU- Projekt OSCAR (Optimizing Subsidiary Crop Applications in Rotations) aims at improving soil conservation through minimum tillage combined with living mulches, cover crops and the use of suppressive composts. An experiment was set up with a rotation of 2-year grass-clover mix followed by wheat and then potatoes. Experimental factors were tillage, cover crops, and compost application. Until now Nematodes were sampled before and after wheat and before potatoes. Population dynamics over time were more affected by the time of the year than by the treatments applied. Sampling will continue will be presented Pratylenchus, Meloidogyne und Helicotylechus/Rotylenchus increased in the first year in all treatments. In the first half of the second year it appears that Meloidogyne has increased with no obvious effect of the treatments so far

Kontrolle bodenbürtiger Krankheiten des Fußkrankheits-komplexes an Erbsen mit Komposten

Soil borne diseases are highly important in organic grain legumes. Suppressive composts are an important measure to control soil borne pathogens in different crops. So far, reports on the foot rot causing pathogens in peas such as Fusarium spp., Phoma medicaginis, Mycospherella pinodes are rare. In our study Phoma medicaginis, Pythium ultimum and Fusarium avenaceum were significantly controlled with yard waste composts demonstrating the principal potential of composts to suppress these diseases. However, the main challenge for organic farmers are to transfer these results to the practise in organic farms. In a field trial with peas 5 and 18 t/ha of compost were applied as broadcast or as strip application while sowing peas with a new developed sowing machine with special tools for strip application of composts. It was shown that the strip application supplying high amounts of composts suppressed the foot rot complex of peas significantly in comparison to the broadcast or the un-amended control plots. Strip application of composts were superior over the broadcast application throughout the season