Zymoseptoria tritici causes the disease known as septoria leaf blotch in winter wheat and is a major factor in yield loss worldwide. Farmers are inclined to use fungicides to protect their crops; however, the efficacy of these measures is rapidly decreasing due to the natural mechanisms of mutation emergence in pathogen populations. Increasing fungicide resistance is being recorded worldwide, therefore, screening of the current situation in Lithuania is essential to determine the subsequent steps of crop protection strategies. In this study, in vitro fungicide sensitivity tests, mutation detection, and field experiments were carried out. The mean EC50 values for prothioconazole-desthio and mefentrifluconazole were 0.14 and 0.28 mg/l, respectively. Increased frequency of the mutation S524T, linked to DMIs resistance, was observed. Results revealed that the dominant point mutation in the gene CYP51 was I381V, and the most frequent CYP51 haplotype was D13 (V136C, I381V, Y461H, S524T). The mutation G143A, linked to QoI resistance, was detected in ¾ of the population. Mutations conferring resistance to SDHIs were not detected in single pycnidium isolates. Two-year field experiments likewise showed no decline in field efficacy of SDHI fungicide in Lithuania. Moreover, the baseline sensitivity of the Lithuanian Z. tritici population to QiI fungicide fenpicoxamid was established. The findings of this study provide an update on the current status of fungicide resistance in the Lithuanian Z. tritici population.

Validation of models for plant disease management is a crucial part in the development of decision support systems in plant protection. Bespoke field trials are usually conducted to determine the performance of a model under practical conditions. However, field trials are very resource-demanding, and the use of already existing field trial data could significantly reduce costs for model validation. In this study, we took this novel approach to verify the performance of models for determining the need of fungicide applications against leaf blotch diseases in wheat by utilising historical weather data and yield data available from fungicide efficacy field trials. Two models based on humidity factors were used in the study. To estimate how specific humidity settings in the two models affect the number of recommended fungicide treatments per season, historical weather data from a 5-year period from weather stations in Denmark, Sweden, Norway, Finland, and Lithuania was used. The model output shows major differences between seasons and regions, typically recommending between one and three treatments per season. To determine the prediction potential of the models, data on yield gains from either one or two fungicide applications in fungicide efficacy trials conducted in wheat over a 5-year period in the five countries was utilised. The yield responses from fungicide treatments in the efficacy trials varied considerably between years and countries, as did the proportion of predictions of profitable treatments. In general, there was a tendency for the models to overestimate the need to apply fungicides (low specificity), but they rarely failed to recommend an application that was needed (high sensitivity). Despite the importance of having specific trials across regions in order to adjust models to local cropping and weather conditions, our study shows that historical weather data and existing field trial data have the potential to be used in model validation.

Zymoseptoria tritici is the causal agent of Septoria tritici blotch (STB) in wheat, and its spread is reported to depend on environmental conditions. Since the spread of disease is usually controlled by using fungicides, selecting timings of their application is crucial. The aim of the present study was to estimate the effect of two fungicide application programmes for STB control in winter wheat and to evaluate the relationship between the severity of disease and quantified DNA of Z. tritici in leaves. Two field experiments (in monoculture field and in the field after non-host crops) with winter wheat were designed, and six fungicide application treatments were chosen. For the disease control, fungicide Adexar (a.i. fluxapyroxad 62.5 g l-1 + epoxiconazole 62.5 g l-1) in dosages 1.0 and 2.0 l ha-1 was used. In 2019, due to unfavourable meteorological conditions, plant infestation with the pathogen was low. Nevertheless, comparing the experiments from both crop rotations, there were marked trends of higher severity of STB in winter wheat monoculture. Meanwhile, in 2020 and 2021, the values of the area under the disease progress curve (AUDPC) were higher in winter wheat grown after non-host crops. Differences between tested application programmes were more precise at higher disease pressure in 2020 and 2021. According to the results of a three-year field experiment, higher effectiveness of controlling STB showed fungicide application programmes based on weather conditions and two applications per season. A more important influence of fungicide application programmes on grain yield increase was found in winter wheat monoculture. Application of fungicides had a higher impact in the 2020 cropping season, when a higher level (AUDPC 358.6) of STB disease infection was observed. In both crop rotations, the highest grain yield increase was obtained by applying fungicide twice: 8???10 days after rain and two weeks after the first application. In both crop rotations, Pearson???s correlation test showed a strong relationship between visual assessments of disease severity and DNA quantity of Z. tritici in leaves of winter wheat.

The disease pressure from Pyrenophora teres, Rhynchosporium graminicola, and Ramularia collo-cygni varies widely between years and locations, which highlights the need for using risk models to avoid unnecessary use of fungicides. Three disease risk models were tested in thirty-three ?eld trials during two seasons in ?ve countries in order to validate and identify situations favourable for barley leaf blotch diseases in the Nordic-Baltic region. The tested models were: The Crop Protection Online (CPO), which uses number of days with precipitation (>1 mm), cultivar resistance and disease data as basis for risk assessments; the humidity model (HM) which signals a risk warning after 20 continuous hours with high humidity, and the Finnish net blotch model (WisuEnnuste), which calculates a risk based on previous crop, tillage method, cultivar resistance and weather parameters. The risk models mostly gave acceptable control of diseases and yield responses compared with untreated and reference treatments. In the dry season of 2018, the models recommended 88-96% fewer applications than the reference treatments, while in 2019, the number of applications was reduced by 0-76% compared to reference treatments. Based on yield increases, the recommendations were correct in 50-69% of the trials compared to one-treatment references and 69-80% of the trials when references used mainly two treatments.

Risk models for decisions on fungicide use based on weather data, disease monitoring, and control thresholds are used as important elements in a sustainable cropping system. The need for control of leaf blotch diseases in wheat (caused by Zymoseptoria tritici, Parastagonospora nodorum and Pyrenophora tritici-repentis) vary significantly across years and locations. Disease development is mainly driven by humidity events during stem elongation and heading. Two risk models were tested in field trials in order to identify situations favourable for the development of leaf blotch diseases in Lithuania, Norway, Sweden, Finland and Denmark. The Crop Protection Online (CPO) model uses days with precipitation (>1 mm), while the humidity model (HM) uses 20 continuous hours with relative humidity (RH) ≥ 85% as criteria for the need of a fungicide application. Forty-seven field trials were carried out during two seasons to validate these two risk-models against reference fungicide treatments. The season 2018 was dry and 2019 had an average precipitation profile. The two risk models with few exceptions provided acceptable disease control. In 2018, very few treatments were recommended by the models, saving 85–98% of treatments compared to the reference treatments, while in the wetter season 2019, 31% fewer applications were recommended. Based on specific criteria including fungicide input and net yield responses the models gave correct recommendations in 95% of the trials in 2018 and in 54–58% of the trials in 2019 compared with reference treatments dominated by 2–3 sprays. In comparison with single spray references, the models gave correct recommendations in 54–69% of the situations.

Fungal plant diseases driven by weather factors are common in European wheat and barley crops. Among these, septoria tritici blotch ( Zymoseptoria tritici), tan spot ( Pyrenophora tritici-repentis ), and stagonospora nodorum blotch ( Parastagonospora nodorum) are common in the Nordic-Baltic region at variable incidence and severity both in spring and winter wheat fields. In spring barley, net blotch ( Pyrenophora teres ), scald ( Rhynchosporium graminicola, syn. Rhynchosporium commune) and ramularia leaf spot (Ramularia collo-cygni) are common yield limiting foliar diseases. We analysed data from 449 field trials from 2007 to 2017 in wheat and barley crops in the Nordic-Baltic region and explored the differences in severity of leaf blotch diseases between countries and years, and the impact of the diseases on yield. In the experiments, septoria tritici blotch dominated in winter wheat in Denmark and southern Sweden; while in Lithuania, both septoria tritici blotch and tan spot were common. In spring wheat, stagonospora nodorum blotch dominated in Norway and tan spot in Finland. Net blotch and ramularia leaf blotch were the most severe barley diseases over large areas, while scald occurred more locally and had less yield impact in all countries. Leaf blotch diseases, with severity >50% at DC 73–77, caused an average yield loss of 1072 kg/ha in winter wheat and 1114 kg/ha in spring barley across all countries over 5 years. These data verify a large regional and yearly variation in disease severity, distribution and impact on yield, emphasizing the need to adapt fungicide applications to the actual need based on locally adapted risk assessment systems.

Potato crop losses can be substantial when conditions for late blight (Phytophthora infestans) development and spread are favourable. In this study, drivers of differences between the P. infestans population structures in Latvia and Lithuania, two neighbouring countries with similar potato‐growing traditions, were investigated. Genotypes of P. infestans and population genetic diversity were analysed using a 12‐plex simple sequence repeat (SSR) marker assay. High genetic diversity was demonstrated in both populations, with population diversity being higher in Latvia. It would appear that local populations established from soilborne oospores early in the season are well adapted to the conditions in the region. However, somewhat greater spread and survival of local clones was detected in Lithuania, suggesting that potato cropping there is more vulnerable to clonal invasion than in Latvia. For effective disease management, current strategies should be adjusted according to the specific pathogen populations in the region, considering the reproduction and survival of the pathogen. Potato growers should implement late blight preventive measures such as longer field rotation to prevent oospore infections, especially in Latvia, and should use more disease resistant cultivars and high‐quality seed potatoes.

Agricultural production is increasingly based on monoculture farming in Lithuania, which inevitably exacerbates the problems caused by a rising incidence of soil borne diseases. Take-all (Gaeumannomyces graminis), formerly a minor disease, has become common causing substantial damage to winter wheat and winter barley. The aim of the present study was to analyze the influence of different rotation sequences on take-all occurrence and to investigate disease control options with seed treatment fungicides fluquinconazole and silthiofam during the 2014–2015 growing seasons. The total amount of Gaeumannomyces graminis var. tritici (Ggt) and G. graminis var. avenae (Gga) DNA in the roots of winter wheat seedlings grown in the soil collected from different rotations was measured. Significantly higher DNA concentrations of Ggt/Gga were detected in the roots of seedlings grown in the soil of winter barley monoculture, compared to the winter wheat monoculture. Comparable amount of Ggt/Gga DNA in winter wheat seedlings was determined in the soil of winter wheat monoculture and winter wheat after oil seed rape (OSR) in both seasons, while in the second winter wheat it was considerably lower. Higher take-all incidence and disease index were established in winter barley than in winter wheat monoculture. Nevertheless in the rotation with one-year OSR, take-all incidence and disease index were significantly reduced compared to the monoculture and second winter wheat. The highest grain yield of winter wheat in both years was achieved in the rotation with OSR. The tested seed treatment fungicides fluquinconazole and silthiofam resulted in a significant reduction in take-all occurrence and a slight increase in grain yield. The findings of this study demonstrate that the OSR was the most valuable tool for management of take-all in wheat.

The Baltic Sea is one of the largest brackish water bodies in the world. Eutrophication is a major concern in the Baltic Sea due to the leakage of nutrients to the sea with agriculture being the primary source. Wheat (Triticum aestivum L.) is the most widely grown crop in the countries surrounding the Baltic Sea and thus promoting sustainable agriculture practices for wheat cultivation will have a major impact on reducing pollution in the Baltic Sea. This approach requires identifying and addressing key challenges for sustainable wheat production in the region. Implementing new technologies for climate-friendly breeding and digital farming across all surrounding countries should promote sustainable intensification of agriculture in the region. In this review, we highlight major challenges for wheat cultivation in the Baltic Sea region and discuss various solutions integrating transnational collaboration for pre-breeding and technology sharing to accelerate development of low input wheat cultivars with improved host plant resistance to pathogen and enhanced adaptability to the changing climate.

The VNIIFBlight decision support system is intended to identify weather conditions favourable or unfavourable for the late blight outbreaks on potato. To provide an improved choice of fungicide treatment dates, we investigated the use of a standard five-day weather forecast based disease management decision support system VNIIFBlight as well as the use of information about the late blight resistance level of the cultivars used. The efficiency of this decision support system was compared with a seven-day routine program of fungicide treatments in the course of four-year field trials in Moscow region and six-year "virtual" trials in four regions of Russia, three regions of Lithuania, and single regions of Canada, Ukraine, Poland, and the Netherlands.According to the results of field experiments, in the case of a high infection pressure (2004 and 2008), yield losses caused by late blight in the untreated control made up 62% and 39%, respectively, whereas the losses for both compared schemes of protection did not exceed 8.2% for both years. In the case of weak disease development (2005 and 2007), for all studied treatments, including the untreated control, yield losses did not exceed 3%. In all years, the use of the VNIIFBlight decision support system significantly reduced the number of fungicidal treatments as compared to the routine scheme of protection; this reduction in 2004, 2005, 2007 and 2008 made up 62, 50, 50 and 17 %, respectively.According to the results of "virtual" trials, the use of the VNIIFBlight decision support system reduced the number of fungicide treatments of susceptible and resistant potato cultivars by 50% and 60% on average, respectively, as compared with the routine program.

This is the first characterisation of Lithuanian populations of Phytophthora infestans with mating type and virulence on a differential set of 11 R genes of Solanum demissum . The sensitivity to metalaxyl was also determined. In 2010–2012, 93 Phytophthora infestans isolates, collected from all over Lithuania, showed quite high and stable frequency of A2 mating type. On 45% of all studied potato fields, both mating types were recorded, suggesting sexual reproduction of P. infestans and possible oospore production in Lithuanian potato fields. Fourteen metalaxyl-resistant isolates were found among 71 isolates in the current study period, and sensitive isolates prevailed in all three years. Amongst the studied 70 isolates, 38 avirulence pathotypes were found. The Lithuanian race structure was highly diverse and complex (the average number of missing avirulence factors per isolate was 7.2). Most pathotypes were unique, appearing only once, and the four most common pathotypes comprised only 34% of the population.

JENS GRONBECH HANSEN (Denmark)1, BJORN ANDERSSON, LINA SJOHOLM, ERLING LILJEROTH & EVA EDIN (Sweden), RUAIRIDH BAIN & ALISON LEES (Scotland), FAYE RITCHIE (England & Wales), STEVEN KILDEA (Ireland), LOUISE COOKE & GILLIAN YOUNG (Northern Ireland), ALEXEY FILIPPOV (Russia), ASKO HANNUKKALA (Finland), HANS HAUSLADEN (Germany), ERVIN HAUSVATER (Czech Republic), ARNE HERMANSEN & RAGNHILD NAERSTAD (Norway), JOZEFA KAPSA (Poland), EVE RUNNO-PAURSON & MATI KOPPEL (Estonia), TOMKE MUSA (Switzerland), GUNTIS GULBIS (Latvia), ANTANAS RONIS (Lithuania), KEES VOGELAAR, JAN SPOELDER & BERT EVENHUIS (The Netherlands), PIETER VANHAVERBEKE (Belgium), CATHERINE CHATOT (France)

Mycosphaerella graminicola (Fuckel) J. Schrot. (anamorph Zymoseptoria tritici (Desm.) Quaedvlieg & Crous) causes Septoria leaf blotch disease of wheat. The disease can be responsible for yield losses of 30-50% and, when severe, requires management with a fungicide. Single picnidia isolates collected from different locations of Lithuania were tested in vitro for sensitivity to demethylation-inhibiting (DMI) fungicides epoxiconazole, cyproconazole and prothioconazole. Fungicide concentrations were chosen from the proposed Fungicide Resistance Action Committee (FRAC) methods. Microtitre plates with 96-wells were inoculated with suspensions of pycnidiospores taken from single pycnidia of leaves. In total, 196 isolates from 34 locations were tested over the three experimental years (2009-2011). The results showed reduced sensitivity of M. graminicola isolates to epoxiconazole and cyproconazole. The average EC50 values over three experimental years for epoxiconazole varied between 1.02 and 3.15 mg l(-1), for cyproconazole - 1.51 and 10.66 mg l(-1) The sensitivity to prothioconazole of 64 isolates from 13 locations (2011) ranged from 0.43 to 32.28 mg l(-1). Results of field experiments (2007-2011) showed that fungicides epoxiconazole and prothioconazole significantly reduced the area under the disease progress curve (AUDPC) values of Septoria leaf blotch compared with untreated plots in winter wheat. In most cases, a single fungicide application significantly increased grain yield and a thousand grain weight weight.

Eyespot of rye. caused by two fungal pathogens Oculimacula yallundae and O. acuformis, is widespread throughout many cool and wet cereal growing regions. The study was aimed to estimate eyespot incidence in winter rye crops in three agro-ecological zones of Lithuania, and to quantify eyespot disease causal agents O. yallundae and O. acuformis in the population using the real-time polymerase chain reaction (RT PCR) method. During the 2008-2012 periods, 69 winter rye fields were surveyed and eyespot-affected stems were identified in 92.7% of the crops surveyed. The incidence of eyespot in winter rye crops varied from 8.0% to 82.7% depending on the year and location. The average disease incidence in the reviewed crops was 26.0%. The highest incidence of eyespot averaging 34.0% was identified in the winter rye crops of the Middle Lowland zone. Both eyespot causal agents O. yallundae and O. acuformis were often found to co-exist on the winter rye stems. In the majority of the winter rye crops tested, O. acuformis was predominant in the Oculimacula spp. population. In most cases, O. yallundae was identified only at trace-level concentrations.

Residue-borne pathogens that cause leaf spotting diseases of wheat have become increasingly important in Lithuania because more growers are adopting reduced tillage, which leaves crop residue on the soil surface compared with conventional tillage. The objective of this study was to investigate differences in susceptibility to leaf infection by Drechslera tritici-repentis and septoria leaf spot complex (Septoria tritici and Stagonospora nodorum) among some of the currently registered winter wheat cultivars. We also examined the influence of primary field infection on the development of leaf spotting diseases during the whole growing season. The experiments were conducted during the two growing seasons (2002-2003 and 2003-2004) at the Lithuanian Institute of Agriculture in Dotnuva, Kedainiai district. Three winter wheat cultivars Aron, Hereward and Tauras were sown. The field trials were made on two backgrounds: soil surface was covered with naturally infected straw in autumn and natural field infection without straw. Observations of disease severity were made approximately every 7-10 days on each plot starting at the beginning of stem elongation and continuing through the late milk stage. Results showed that the most common disease in winter wheat during the growing seasons 2002-2003 and 20032004 in our experiment was tan spot. Septoria leaf spot complex was less prevalent. At the beginning of stem elongation in inoculated with straw and in naturally infected plots the severity of tan spot was similar for all cultivars. Until winter wheat flowering stage, no significant differences between the severity of tan spot in inoculated and naturally infested wheat were found in both years. At late growth stages straw on soil surface had a significant effect on tan spot severity increase. The reaction of test cultivars to leaf spotting disease was different and depended on growing conditions (with or without straw) and growing season.