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Introduction: The Colorado potato beetle (Leptinotarsa decemlineata) (CPB) is a major threat to potato crops in Europe, Asia, and America. In Europe, it is expected that climate change will cause the species to expand its range northwards and allow for an additional generation per year in regions where it is already established. The effectiveness of insecticides, a common method of control, is decreasing due to the emergence of resistance to several substances. Therefore, research into alternative measures is becoming increasingly necessary. One preventive measure that has already been shown to have great effects in past studies is the use of organic mulch. For organic mulching, conserved or freshly cut plant material is spread on the field usually when the potato emerges. Previous research has mainly used cereal straw for this purpose in plots that are relatively small compared to actual agricultural fields. Materials and methods: To address the lack of large-scale field trials in the literature, a series of on-station and on-farm field trials were conducted in this study. Organic, legume-rich mulches were used primarily, which so far have not been extensively investigated. Over a period of four years and in a total of six field trials, CPB and larval infestations were assessed. Results and discussion: Our results show effects on the initial infestation of young plants by adult CPB and on the emergence time of the first two larval stages. By the time of flowering, when the feeding effect of CPB on yield is known to be greatest, L3 and L4 larvae were reduced by about 30% in the on-station trials and by about 40% in the on-farm trials. In addition, when CPB larval stages were used to calculate a weighted daily leaf consumption per stage, total calculated leaf consumption was on average about 40% lower in the mulch treatments across all sampling dates and all trials. The recorded yields were equal or higher in the mulched treatments. In conclusion, organic mulching can effectively reduce CPB damage even on a large scale and can have a positive impact on yield. Further agronomic benefits of mulching, as well as drawbacks and putative mechanisms of action, are discussed. [ABSTRACT FROM AUTHOR]

The main and most efficient measure to control potato cyst nematode (PCN) is the use of resistant cultivars. German and Dutch National Plant Protection Organizations (NPPOs) recently reported the emergence of Globodera pallida populations virulent on potato cultivars carrying resistance against pathotype 2/3. The development and virulence of the virulent population Oberlangen from Germany in comparison to the reference population G. pallida Pa3 Chavornay were investigated on resistant and susceptible cultivars in glasshouse experiments. Various life history traits associated with change in virulence were also assessed. Hatching of second-stage juveniles (J2s) was similar for both populations but incubation of cysts in potato root diffusate resulted in higher hatching rates compared to 3 mM Zinc Chloride and tap water. Both populations showed high penetration rates in the roots of the resistant and susceptible cultivars. However, only the population Oberlangen was able to complete the life cycle in the roots of the resistant potato cultivar. In ‘Seresta’, the resistance response restricted the formation of females by avirulent individuals in favor of males. Oberlangen was virulent on all cultivars tested. No difference in cyst size, number of eggs per cyst, length of juveniles, and males was found for Oberlangen and Chavornay on the susceptible cv. ‘Desiree’. However, cysts of virulent populations from the same region Oberlangen was obtained from had a significantly larger diameter compared to avirulent populations. The population Oberlangen showed a higher reproduction and fitness than the reference population Chavornay on susceptible cultivars and could serve as a future reference population in testing of new potato cultivars for resistance against this new virulence type in Europe.

Root rot pathogens restrict pea and wheat production globally. In the EU, pea and pea-based cereal mixtures are being promoted; however, root rot pathogen dynamics in such mixtures are poorly understood. Winter pea and wheat were grown either in pure stands or in mixtures in the field in western France, and the severity of root rot in pea, wheat, and their mixtures, as well as the key pathogens associated with these crops, were assessed. Disease severity was moderate in pea and low in wheat, with no effect of sowing pattern. Didymella pinodella, a previously unreported pathogen in the pea–root rot complex in France, emerged as the most dominant pathogen in pea. It also occurred in low frequencies in wheat. Subsequent greenhouse aggressiveness tests showed that ten of the commonly grown pea cultivars in France lack resistance to D. pinodella. Among the Fusarium spp. isolated, F. avenaceum was the most frequent, occurring at similar frequencies in pea and wheat. In conclusion, D. pinodella may be an important pea root rot pathogen in France and there is a lack of resistance in the tested pea cultivars. In addition, F. avenaceum is a shared pathogen of wheat and pea. [ABSTRACT FROM AUTHOR]

A winter wheat composite cross population (CCP), created in the UK in 2001, has been grown in Germany, Hungary, and the UK since 2005 (F5 generation). In 2008/09 (F8), a cycling pattern for the populations was developed between partners to test the effects of rapidly changing environments on agronomic performance and morphological characteristics. One CCP was grown by eight partners for one year and subsequently sent to the next partner, creating "cycling CCPs" with different histories. In 2013, all eight cycling CCPs and the three non-cycling CCPs (from Germany, Hungary, and the UK) were included in a two-year experiment in Germany with three line varieties as references. Differing seed weights of the F13 at sowing affected some agronomic parameters under drought conditions in 2014/15 but not under less stressful conditions in 2013/14. In both experimental years, the CCPs were comparable to the line varieties in terms of agronomic performance, with some CCPs yielding more than the varieties under the drought conditions of 2015. The results highlight the potential of CCPs to compete with line varieties, while the overall similarity of the CCPs based on their origin and cycling history for agronomic traits indicates a high buffering potential under highly variable environmental conditions. [ABSTRACT FROM AUTHOR]

In conservation agriculture, conservation tillage potentially influences the physical, chemical, and biological quality of the soil. Although the effects of conservation agriculture on the soil's physical properties have been studied in conventional management systems, studies on organic farming systems, especially concerning long-term changes, are scarce. This study summarizes the results of physical and mechanical soil parameters obtained over the initial 10 years of different conservation management treatments (plowing versus reduced tillage with and without compost application) in an organic field trial conducted in central Germany. Moreover, as a research objective, the effects of soil conservation measures on soil's physical quality were evaluated. Differences in the soil's physical quality during treatments were mainly detected in the topsoil. At a depth of 0.10–0.24 m, the total porosity and air capacity were lower, and the bulk density was higher in the reduced-tillage systems, compared to those of the plowed treatments. Additionally, the soil's mechanical stability (precompression stress) was higher at a depth of 0.10 m for reduced-tillage systems combined with compost application. In addition, the soil's aggregate stability was enhanced in the reduced-tillage systems (higher mean weight diameter, as determined via wet sieving). Overall, the reduced-tillage treatments did not exceed the critical physical values of the soil, nor affect the functionality of the soil (saturated hydraulic conductivity), thereby demonstrating its feasibility as a sustainable technique for organic farming. Future studies should include measures to ameliorate compaction zones in reduced-tillage treatments, e.g., by applying subsoiling techniques in combination with deep-rooting crops to prevent limited rooting space resulting from the high mechanical impedance, especially under dry soil conditions. [ABSTRACT FROM AUTHOR]

A survey across Germany was undertaken from 2016-2019 to evaluate effects of management system (organic vs conventional), pedo-climatic conditions and crop rotation history on faba bean root health status, diversity of major root rot pathogens and yield. Root rot incidence was generally low and there was no effect of the management system on the spectrum of pathogens isolated. Among the most common fungal species identified, frequencies of Fusarium redolens and Didymella pinodella were significantly higher in roots from organic fields compared with conventional and lower was observed for F. avenaceum, F. tricinctum and F. culmorum. Faba bean roots were colonized at similar rates by F. equiseti and the members of the F. oxysporum (FOSC) and F. solani (FSSC) species complexes in both management systems. Almost no legumes had been grown in the 5-11 years preceding the conventional faba beans surveyed while legumes had almost always been present during this period in the organic fields. This difference in rotational histories between the farming systems led to apparent cropping systems effects on the isolation frequencies of several species. For example, D. pinodella was ubiquitous in organic fields with a high frequency of legumes in the rotations but much rarer and often absent in conventional fields. Pedoclimatic conditions, particularly cool conditions at sowing and plant emergence and/or during the vegetative season favored most of the most prevalent Fusarium species identified in this study. In organic systems, yields correlated negatively with D. pinodella and F. redolens frequencies whereas higher levels of F. tricintum in faba bean roots had a positive correlation with yield. In conventional systems, faba bean yields depended more on the total precipitation before sowing and during the main growing season but were also negatively correlated with the frequencies of FOSC and F. culmorum. Phylogenetic analysis based on the TEF1 alpha locus indicated that the FSSC isolates mainly belonged to the F. pisi lineage. In contrast, the FOSC isolates were placed in 9 different lineages, with a conspicuous dominance of F. libertatis that has until now not been associated with any leguminous host. [ABSTRACT FROM AUTHOR]

The Colorado potato beetle (CPB) is an exceptionally challenging potato pest. Some regenerative farmers have reported that the use of transferred green manure mulch can considerably reduce CBP damage. Previous studies confirm this observation, but mainly with straw mulch, which is rarely used in Central Europe, and not embedded in the new regenerative cropping approach. For this, six trials conducted between 2014 and 2019 were evaluated, comparing CPB infestation in potatoes with and without transferred mulch as well as under a plough as a minimum till regime. In three out of six experiments, compost application was an additional factor. (I) Over all experiments, mulch significantly reduced initial infestation (−24%), egg masses (−27%) and larvae (−75%). Compost and reduced tillage added to these effects; (II) Mulch mainly resulted in delayed CPB infestation; (III) In a particularly warm season, when a second generation of CPB managed to emerge, regulatory effects of the mulch were not sufficient; (IV) Combination of transferred nutrient rich green manure mulch with reduced tillage, compost and other regenerative or agro-ecological techniques is recommended to achieve maximum regulation of CPB. [ABSTRACT FROM AUTHOR]

Many agronomic studies have shown the advantages of species mixtures (SM), but for food grain production, they represent only a small niche. Empirical studies that investigate reasons for SM adoption in food grain production are scarce. Here we present an in-depth study based on qualitative expert interviews with nine farmers. By means of interpretative analysis and reconstruction, socially shared models of SM adoption were built to identify the five main factors for SM adoption: (1) perceived relative mixture performance compared to sole crops, (2) suitability within the farm context (3), challenges and opportunities in mixture management due to increased complexity, (4) knowledge and technology as resources to handle mixture management and (5) quality standards in the food value chain. Relative performance was perceived as higher for SM than for sole crops for crop protection, nutrient efficiency, farm diversification, total yield stability and grain quality. The yield stability of individual crop species in SM was perceived as lower and grain impurities higher, requiring increased separation efforts. The economic potential of SM was perceived as highly variable, depending on crop value and post-harvest efforts to attain food quality. Reconstructing the mixture management process revealed that the interspecific plant interactions and emergent mixture attributes increased the cropping system complexity and affected the entire farming process. Adopting SM required knowledge about species interactions, mixture attributes and equipment settings. Large knowledge gaps for food SM were identified. The complexity of SM also provided opportunities for farmers to design mixtures that allow competition control (alternate rows) or avoid separation (relay mixtures). The main conclusions are: (1) increased complexity is a basic property of SM compared to sole crops, enabling advantages and increasing the option space to develop new sustainable cropping systems, (2) specific knowledge and technology are required for SM and are not accessible for most farmers, requiring new information channels and (3) new food SM should be developed more systematically, taking into account mixture properties and their effects on the farming process, as well as needs from the food value chain. [ABSTRACT FROM AUTHOR]

Cropping system diversification through annual intercropping provides a pathway for agricultural production with reduced inputs of fertilizer and pesticides. While several studies have shown that intercrop performance depends on the genotypes used, the available evidence has not been synthesized in an overarching analysis. Here, we review the effects of genotypes in cereal/legume intercropping systems, showing how genotype choice affects mixture performance. Furthermore, we discuss the mechanisms underlying the interactions between genotype and cropping system (i.e., sole cropping vs. intercropping). Data from 69 articles fulfilling inclusion criteria were analyzed, out of which 35 articles reported land equivalent ratio (LER), yielding 262 LER data points to be extracted. The mean and median LER were 1.26 and 1.24, respectively. The extracted genotype × cropping system interaction effects on yield were reported in 71% out of 69 publications. Out of this, genotype × cropping system interaction effects were significant in 75%, of the studies, whereas 25% reported non-significant interactions. The remaining studies did not report the effects of genotype × cropping system. Phenological and morphological traits, such as differences in days to maturity, plant height, or growth habit, explained variations in the performance of mixtures with different genotypes. However, the relevant genotype traits were not described sufficiently in most of the studies to allow for a detailed analysis. A tendency toward higher intercropping performance with short cereal genotypes was observed. The results show the importance of genotype selection for better in cereal/legume intercropping. This study highlights the hitherto unrevealed aspects of genotype evaluation for intercropping systems that need to be tackled. Future research on genotype effects in intercropping should consider phenology, root growth, and soil nutrient and water acquisition timing, as well as the effects of weeds and diseases, to improve our understanding of how genotype combination and breeding may help to optimize intercropping systems. [ABSTRACT FROM AUTHOR]

Species mixtures and heterogeneous crop populations are two promising approaches for diversified ecological cropping systems with increased resilience and reduced dependency on external inputs. Inter- and intraspecific diversity were evaluated in combination using 15 wheat (Triticum aestivum) entries, including line cultivars and heterogeneous populations (HPs), from central Europe and Hungary and one winter pea cultivar under organic conditions. Monocultures and wheat mixtures were evaluated multi-functionally for yield, quality, land use efficiency, crop protection, and wheat entry traits. Mixtures increased cereal grain quality, weed suppression, resource use efficiency, yield gain, and reduced lodging. Effects were stronger in 2018/19, which were characterized by dry and nutrient-poor conditions than in 2019/20 when nutrient levels were higher. Wheat entries varied considerably in protein content and yield in both mixtures and monocultures. Under higher nutrient availability, entry-based variation was reduced in both systems, and peas were suppressed. Because of low disease pressure, the wheat entries varied little in terms of disease protection services, and mixture effects on the disease were low. The multi-criteria framework identified stability of yield, yield gains, and quality under high environmental variability of mixtures as clear agronomic advantages with HPs being considerably more stable than line cultivars. Some line cultivars outperformed the HPs in either protein content or yield across environments but not both simultaneously. Trait analysis revealed a possible link between harvest index and reduced competition in mixtures, which can increase yield performance in specific line cultivars. System cultivar interactions were generally very low and highly dependent on environmental conditions. We conclude that while cultivar breeding for mixtures can be successful in monocultures, high environmental variation highlights the necessity of evaluating cultivars in mixtures. In addition, use of intraspecific diversity within interspecific mixed cropping systems can be a valuable addition to further improve mixture performance and its stability under increasing environmental stresses due to climate change. [ABSTRACT FROM AUTHOR]

Compared to sole crops, intercropping—especially of legumes and cereals—has great potential to improve crop yield and resource use efficiency, and can provide many other ecosystem services. However, the beneficial effects of intercrops are often greatly dependent on the end use as well as the specific species and genotypes being co-cultivated. In addition, intercropping imposes added complexity at different levels of the supply chain. While the need for developing crop genotypes for intercropping has long been recognized, most cultivars on the market are optimized for sole cropping and may not necessarily perform well in intercrops. This paper aims to place breeding targets for intercrop-adapted genotypes in a supply chain perspective. Three case studies of legumes and cereals intercropped for human consumption are used to identify desirable intercrop traits for actors across the supply chains, many of which are not targeted by traditional breeding for sole crops, including certain seed attributes, and some of which do not fit traditional breeding schemes, such as breeding for synchronized maturity and species synergies. Incorporating these traits into intercrop breeding could significantly reduce complexity along the supply chain. It is concluded that the widespread adoption and integration of intercrops will only be successful through the inclusion and collaboration of all supply chain actors, the application of breeding approaches that take into account the complexity of intercrop supply chains, and the implementation of diversification strategies in every process from field to fork. [ABSTRACT FROM AUTHOR]