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Barley production is severely affected by drought caused by the unpredictable Mediterranean weather patterns, which include uneven rainfall and extreme temperatures. This leads to a decrease in crop yield. However, to tackle this issue, landraces and wild species are crucial sources of variation for stress adaptive traits. By incorporating these traits into improved varieties, we may see an increase in yield and stability under drought conditions. Seventy‐six quantitative traits loci (QTLs) identified traits were mapped using recombinant inbred lines (RIL) population Arta × Harmal‐2//Esp/1808‐4L, evaluated at six dry and semi‐dry areas over 3 years. The study investigated traits such as grain yield, biological yield, harvest index, kernel weight, seed per head, days to heading, kernel filling duration, growth vigour, growth habit, lodging and plant height. Numerous QTLs were discovered that are associated with various phenotypic traits related to grain yield, kernel yield, duration of filling period and days to heading. For areas with less than 250 mm/annum of rainfall, QTLs were identified on chromosome 2H for biological yield, days to heading, and kernel weight, on 1H for harvest index, and on 2H, 4H, and 5H for kernel weight. For semi‐dry areas with rainfall less than 450 mm, QTLs were found on chromosome 6H for grain yield, 2H and 5H for kernel weight, 1H and 6H for seed per head, and 2H for days to heading. Notably, these QTLs significantly explain more than 10% of phenotypic variation. The 2H chromosome was found to have the most important QTL and pleiotropic effect for yield and its components, such as kernel weight, days to heading, and biological yield. The cross Arta/Harmal was adapted, and mechanisms were developed to cope with drought stress, reflected by the significant and positive correlation of biological yield and harvest index with grain yield. Chromosomes 1H, 2H, 4H and 5H harbour more than 60% of mapped QTLs for dry areas. It is worth noting that the QTLs mentioned earlier, along with the kernel weight QTLs (QKW 1.5, QKW2.7b, QKW4.1, QKW6.7, QKW6.9), have consistently exhibited positive effects on crop yield in semi‐dry and dry areas, making them potential candidates for breeding drought‐tolerant crops. Genomic co‐localisation of the QTL for Arta/Harmal population suggested that selection for drought through linked markers can be an option for drought tolerance selection for barley in dry areas. [ABSTRACT FROM AUTHOR]

BACKGROUND: Detection of the inoculum of phytopathogens greatly assists in the management of diseases, but is difficult for pathogens with airborne fungal propagules. Here, we present experiments to determine the abundance and distribution frequencies of the ascospores of Leptosphaeria (Plenodomus) species that were collected on the tapes of volumetric Hirst‐type traps near oilseed rape fields in Poznan, Poland and Harpenden, UK. Fungal detection and species discrimination were achieved using a SYBR‐Green quantitative polymerase chain reaction (qPCR) with two different pairs of primers previously reported to differentiate Leptosphaeria maculans (Plenodomus lingam) or L. biglobosa (P. biglobosus). RESULTS: Detection was successful even at fewer than five spores per m3 of air. The primer pairs differed in the correlation coefficients obtained between DNA yields and the daily abundance of ascospores that were quantified by microscopy on duplicate halves of the spore trap tapes. Important differences in the specificity and sensitivity of the published SYBR‐Green assays were also found, indicating that the Liu primers did not detect L. biglobosa subclade 'canadensis', whereas the Mahuku primers detected L. biglobosa subclade 'canadensis' and also the closely related Plenodomus dezfulensis. CONCLUSIONS: Comparisons confirmed that application of qPCR assays to spore trap samples can be used for the early detection, discrimination and quantification of aerially dispersed L. maculans and L. biglobosa propagules before leaf spot symptoms are visible in winter oilseed rape fields. The specificity of the primers must be taken into consideration because the final result will greatly depend on the local population of the pathogen. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Phoma stem canker is an economically important disease of oilseed rape, caused by two co‐existing fungal pathogen species, Leptosphaeria maculans (Plenodomus lingam) and Leptosphaeria biglobosa (Plenodomus biglobosus). Leptosphaeria maculans produces a phytotoxin called sirodesmin PL. Our previous work showed that L. biglobosa has an antagonistic effect on the production of sirodesmin PL if it is simultaneously co‐inoculated with L. maculans. However, the effects of sequential co‐inoculation on interspecific interactions between the two pathogens are not understood. RESULTS: The interactions between L. maculans and L. biglobosa were investigated in liquid culture by inoculation with L. maculans first, followed by L. biglobosa sequentially at 1, 3, 5 or 7 days later and vice versa; the controls were inoculated with L. maculans only, L. biglobosa only, or L. maculans and L. biglobosa simultaneously. The results showed that L. biglobosa inhibited the growth of L. maculans, the production of both sirodesmin PL and its precursors if L. biglobosa was inoculated before, or simultaneously with, L. maculans. However, the antagonistic effects of L. biglobosa were lost if it was co‐inoculated 5 or 7 days after L. maculans. CONCLUSION: For the first time, the results of this study provided evidence that the timing when L. maculans and L. biglobosa meet significantly influences the outcome of the interspecific competition between them. Leptosphaeria biglobosa can inhibit the production of sirodesmin PL and the growth of L. maculans if it is inoculated before L. maculans or less than 3 days after L. maculans in liquid culture. There is a need to further investigate the timing of co‐inoculation on interactions between L. maculans and L. biglobosa in their host plants for improving the control of phoma stem canker. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Phoma stem canker is caused by two coexisting pathogens, Leptosphaeria maculans and L. biglobosa. They coexist because of their temporal and spatial separations, which are associated with the differences in timing of their ascospore release. L. maculans produces sirodesmin PL, while L. biglobosa does not. However, their interaction/coexistence in terms of secondary metabolite production is not understood. RESULTS: Secondary metabolites were extracted from liquid cultures, L. maculans only (Lm only), L. biglobosa only (Lb only), L. maculans and L. biglobosa simultaneously (Lm&Lb) or sequentially 7 days later (Lm+Lb). Sirodesmin PL or its precursors were identified in extracts from 'Lm only' and 'Lm+Lb', but not from 'Lm&Lb'. Metabolites from 'Lb only', 'Lm&Lb' or 'Lm+Lb' caused significant reductions in L. maculans colony area. However, only the metabolites containing sirodesmin PL caused a significant reduction to L. biglobosa colony area. When oilseed rape cotyledons were inoculated with conidia of 'Lm only', 'Lb only' or 'Lm&Lb', 'Lm only' produced large gray lesions, while 'Lm&Lb' produced small dark lesions similar to lesions caused by 'Lb only'. Sirodesmin PL was found only in the plant extracts from 'Lm only'. These results suggest that L. biglobosa prevents the production of sirodesmin PL and its precursors by L. maculans when they grow simultaneously in vitro or in planta. CONCLUSION: For the first time, L. biglobosa has been shown to inhibit the production of sirodesmin PL by L. maculans when interacting simultaneously with L. maculans either in vitro or in planta. This antagonistic effect of interspecific interaction may affect their coexistence and subsequent disease progression and management. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Light leaf spot, caused by Pyrenopeziza brassicae, is amongst the most damaging diseases of winter oilseed rape (Brassica napus), and currently the sterol 14α‐demethylase (CYP51) inhibitors (azoles) represent the main class of fungicides used to control light leaf spot development. However, a shift in sensitivity to azole fungicides in P. brassicae populations has been observed in different European countries, including Ireland. RESULTS: To assess the sensitivity status of Irish P. brassicae populations to azole fungicides, three collections of P. brassicae from 2018–2020 were tested in vitro against tebuconazole and prothioconazole‐desthio, and the PbCYP51 gene targeted by this class of fungicides was genotyped in different isolates. A change in sensitivity to azole fungicides was observed and differences in sensitivity to tebuconazole between Irish populations were present. There were two substitutions within PbCYP51 (G460S and S508T) and inserts of different sizes in its promoter region. The presence of the G460S/S508T double mutant was reported for the first time, and the diversity in insert size was greater than previously known. Compared to wild type isolates, those carrying G460S or S508T were less sensitive to both fungicides and, where inserts were also identified, they further reduced sensitivity to azole fungicides. CONCLUSIONS: The results of this study suggest that azole fungicides are still very effective in controlling light leaf spot in Ireland. However, using azole fungicides in mixtures of fungicides with different modes of action is recommended. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Crop diseases affect crop yield and quality and cause significant losses of total food production worldwide. With the ever‐increasing world population and decreasing land and water resources, there is a need not only to produce more food but also to reduce agricultural greenhouse gas (GHG) emissions to mitigate climate change and avoid land use change and biodiversity loss. Thus, alternative climate‐smart farming systems need to adapt to produce more food per hectare in a more sustainable way than conventional high‐input farming systems. In addition to breeding new high‐yielding cultivars adapted to future climates, there is a need to deploy Integrated Crop Management (ICM) strategies, relying less on synthetic inputs for fertilization and crop protection and less on fossil fuel‐powered machinery to decrease yield losses due to pest and pathogens and guarantee food security. In this review, we compare some low‐input farming systems to conventional agricultural systems with a focus on ICM solutions being developed to reduce synthetic inputs; these include crop genetic resistance to pathogens, intercropping, canopy architecture manipulation, and crop rotation. These techniques have potential to decrease crop disease frequency and severity by decreasing amounts and dispersal of pathogen inoculum and by producing microclimates that are less favourable for pathogen development, while decreasing GHG emissions and improving environmental sustainability. More research is needed to determine the best deployment of these ICM strategies in various cropping systems to maximize yield, crop protection, and other ecosystem services to address trade‐offs between climate change and food security. [ABSTRACT FROM AUTHOR]

Pyrenopeziza brassicae, cause of light leaf spot (LLS), is an important pathogen of oilseed rape and vegetable brassicas and has a wide geographic distribution. Exploitation of host resistance remains the most sustainable and economically viable solution for disease management. This study evaluated 18 oilseed rape cultivars or breeding lines for host resistance against P. brassicae in glasshouse experiments. Selected cultivars/lines were inoculated with eight single‐spore isolates of the pathogen obtained from three different regions in England. Analysis of P. brassicae infection‐related changes on host plants identified leaf deformation as a characteristic feature associated with P. brassicae infection, this showed poor correlation to LLS severity measured as the amount of pathogen sporulation on infected plants. Resistant host phenotypes were identified by limitation of P. brassicae sporulation, with or without the presence of a necrotic response (black flecking phenotype). Investigation of this pathosystem revealed significant differences between cultivars/lines, between isolates, and significant cultivar/line‐by‐isolate interactions. In total, 37 resistant and 16 moderately resistant interactions were identified from 144 cultivar/line‐by‐isolate interactions using statistical methods. Most of the resistant/moderately resistant interactions identified in this study appeared to be nonspecific towards the isolates tested. Our results suggested the presence of isolate‐specific resistant interactions for some cultivars. Several sources of resistance have been identified that are valuable for oilseed rape breeding programmes. [ABSTRACT FROM AUTHOR]