Organic mulches are a traditional method of groundcover management in temperate commercial orchards, now largely replaced by herbicides and synthetic fertilisers. As a potential contribution to ...improving orchard sustainability, we hypothesised that the addition of organic mulches would: (H1) improve soil fertility and lead to greater tree growth and yields; (H2) support a larger and more biologically active community of soil organisms, assessed as increased soil respiration and greater earthworm numbers and biomass; and (H3) increase leaf litter decomposition and burial, potentially reducing the risk of apple scab disease (Venturia inaequalis). Cuttings from two legume-based cover crop mixtures grown in the alleyway spaces between tree rows and two traditional mulch materials, straw and compost, were trialled alongside a bare soil business-as-usual control for two years, using a randomized complete block design in a conventionally managed commercial ‘Gala’ apple orchard in the UK.
Compared to the control, the compost mulch significantly increased both soil carbon and nitrogen by over 50 %. The straw mulch effectively suppressed weeds by about 90 % and increased soil moisture by about 5 %. Cover crop cuttings increased moisture levels and increased earthworm numbers and mass by 1.7 and 1.8 times greater respectively in the double-rate ‘legume-grass’ cuttings treatment. Increasing the quantity of cover crop cuttings produced more positive effects; the cumulative addition of cuttings can benefit several soil-derived ecosystem services. This study took place in a commercial apple orchard, the findings may therefore be applicable to other orchard and row-grown perennial crops.
•Mulches can improve soil moisture, soil carbon and nitrogen, and weed suppression.•Cuttings from orchard alleyway cover crops can be used as cost-effective mulches.•Cover crop-derived mulches can increase earthworm abundance and mass.•Organic mulches can support greater soil biota and soil biological activity.•Mulches can increase the decomposition of disease-harbouring leaf litter.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Apple scab, compared to other fungal diseases, consistently causes the most significant economic losses for growers. Venturia inaequalis infection not only reduce actual crop quality and quantity. ...Impaired tree vitality due to defoliation and a reduced number of buds in the following season are also the consequences of uncontrolled attack of apple trees by this fungal pathogen. Therefore the control of apple scab using fungicides is an essential part of the orchard life cycle. Knowing the sensitivity of local populations of V. inaequalis to active substances used in fungicidal sprays is a key factor for the sustainable protection of apple plantations against scab. In the years 2020–2022, V. inaequalis populations isolated from experimental and production orchards in the Czech Republic were tested for sensitivity to the active substances cyprodinil and difenoconazole. The assessment was carried out using in vivo tests on seedlings of the cultivar ‘Golden Delicious’. The monitored orchards showed the sensitivity to cyprodinil, where only two populations had reduced sensitivity. The majority of tested populations were also sensitive to difenoconazole. Only one population was found to be resistant to difenoconazole, and two populations were found to have reduced sensitivity to this agent. The results are consistent with similar foreign studies.
•A combination of complementary management strategies is needed to tackle apple scab.•Autopolyploidy in ‘Gala’ and ‘Makali’ reduces severity of apple scab disease.•The effect is attributed to a ...reduced presence of V. inaequalis.•The Rvi6 resistant ‘Makali’ is more susceptible to V. inaequalis race 6 than ‘Gala’.
Apple (Malus × domestica Borkh.) production is significantly affected by apple scab disease caused by the fungus Venturia inaequalis. Currently, management of the disease is largely based on fungicide applications and less on the inherent resistance in apple cultivars carrying resistance (Rvi) genes. Moreover, the durability of both approaches is questionable, since new virulent strains with resistance to fungicides and/or Rvi genes can develop. Hence, a combination of complementary management strategies is needed to tackle apple scab. To broaden the management options, a viable approach might be the breeding for polyploid cultivars and their implementation in commercial orchards. Apple germplasm is substantially characterized by polyploidy, which throughout the evolution of angiosperms often led to improved adaptation to adverse climatic conditions and abiotic stresses. However, the role of polyploidy in conferring resistance to biotic challenges is less clear. Here, we show that autopolyploidy in two apple cultivars, i.e. the susceptible ‘Gala’, and the resistant ‘Makali’ which carries the Rvi6 scab resistance gene, can reduce severity of apple scab symptoms upon inoculation with two different V. inaequalis isolates. Leaves of tetraploid plants show reduced sporulation symptoms in comparison with their diploid counterparts upon infection with both pathogenic strains, attributed to a reduced presence of V. inaequalis. These results suggest that polyploidy enhances resistance of apple cultivars against different V. inaequalis isolates. However, the degree of the enhanced resistance depends on a plant-pathogen-specific interaction. The knowledge provided here offers a relevant framework for improving our understanding of polyploidy-enhanced resistance to biotic stress in plants and may set the stage for implementing polyploidy breeding for further genetic improvement of apple.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Pyribencarb is a fungicide used to control the apple scab disease in Hokkaido. It functions as a quinone outside inhibitor (QoI). QoI-resistant strains of Venturia inaequalis, carrying the G143A ...mutation, have recently been identified in Hokkaido. This mutation affects mitochondrial cytochrome b in V. inaequalis. The sensitivities of the V. inaequalis isolates collected from Hokkaido to pyribencarb and trifloxystrobin were compared. Isolates carrying the G143A mutation exhibited reduced growth on a medium containing pyribencarb than on that containing trifloxystrobin.
Apple scab, caused by Venturia inaequalis, is a major fungal disease worldwide. Cultivation of scab-resistant cultivars would reduce the chemical footprint of apple production. However, new apple ...cultivars carrying durable resistances should be developed to prevent or at least slow the breakdown of resistance against races of V. inaequalis. One way to achieve durable resistance is to pyramid multiple scab resistance genes in a cultivar. The choice of the resistance genes to be combined in the pyramids should take into account the frequency of resistance breakdown and the geographical distribution of apple scab isolates able to cause such breakdowns. In order to acquire this information and to make it available to apple breeders, the VINQUEST project ( www.vinquest.ch ) was initiated in 2009. Ten years after launching this project, 24 partners from 14 countries regularly contribute data. From 2009 to 2018, nearly 9,000 data points have been collected. This information has been used to identify the most promising apple scab resistance genes for developing cultivars with durable resistance, which to date are: Rvi5, Rvi11, Rvi12, Rvi14, and Rvi15. As expected, Rvi1, together with Rvi3 and Rvi8, were often overcome, and have little value for scab resistance breeding. Rvi10 may also belong to this group. On the other hand, Rvi2, Rvi4, Rvi6, Rvi7, Rvi9, and Rvi13 are still useful for breeding, but their use is recommended only in extended pyramids of ≥3 resistance genes.
Apple scab, which is caused by the fungus Venturia inaequalis, is one of the most important diseases of apple trees. It mainly affects leaves, fruits, and sometimes also flowers and shoots. The aim ...of this work was monitoring the resistance of Venturia inaequalis to pyrimethanil and stobilurins fungicides. Part of our work included evaluation of the monitoring and assignment of the population to the relevant category of resistance to the active substances. A total of 46 populations were tested. Our results show that the population of V. inaequalis was generally more sensitive to pyrimethanil while resistant to strobilurins. A large percentage of the populations (76 %) was sensitive to pyrimethanil and just 1 was moderately resistant, only 31 % of the population was sensitive to strobilurins and 62 % were resistant.
In order to understand mechanisms of ontogenic resistance to apple scab, we analyzed various aspects of young and old leaves. We have introduced an apple plants cultivation system where in vitro ...propagated and rooting explants produce a genetically uniform population of apple (Malus domestica cv. Idared) plants. In this work, we demonstrate that apple plants produced in our cultivation system showed susceptibility to Venturia inaequalis, the cause of apple scab disease in young leaves and resistance in old leaves, which is similar to orchard situation. Our analysis shows that the cessation of epidermal cell expansion and shape formation coincided with the onset of ontogenic resistance in older leaves. Formation of specific cuticular lamellar structures did not coincide with ontogenic resistance onset. Further, chemical composition analysis of wax from young susceptible and old resistant leaves did not reveal specific compounds involved in ontogenic resistance. Differences in homogalacturonan content in cell walls in susceptible and resistant cells as well as decreased methylesterification of pectin in resistant leaves suggest that polysaccharide composition of the cell wall may play a role in mycelium growth and nutrition.
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