Summary Several Fusarium species cause harmful cereal diseases, such as fusarium head blight and crown rot, which, during pathogenesis, may result in significant grain yield and quality losses. Several species of agricultural weed are believed to be alternative and reservoir hosts for Fusarium spp.; however, studies have not comprehensively evaluated those weed species in cropping systems that may harbour these fungi. The objective of this study was to determine weed species in cereal‐based crop rotations that are asymptomatically colonised by Fusarium spp. We sampled all species of weed present in fields that were managed under six different crop sequences in 2015 and 2016. The study yielded 2326 single‐spore isolates of Fusarium spp. derived from various organs of asymptomatic weeds. Isolates were identified morphologically and then confirmed using PCR with species‐specific primers and/or sequencing of tef1α gene fragments. Isolates of nine Fusarium spp. were obtained from 689 of the 744 individuals collected that represented 56 weed species. Each weed species harboured at least one species of Fusarium, and >80% were colonised by 3–9 Fusarium spp. In total, we identified 27 dicotyledonous weed species that were previously undocumented as Fusarium hosts and 251 new weed × Fusarium species combinations were revealed. Consequently, there is a greater risk of negative Fusarium impacts on cereal crops than was previously thought. We suggest effective weed management and inversion soil tillage may help mitigate these impacts.

Fusarium graminearum, the cause of Fusarium head blight (FHB), is an important cereal pathogen. Moreover, some non-graminaceous crops are also known to be susceptible to F. graminearum infection. This study assessed the presence of F. graminearum species complex on non-cereal plants, grown in a cereal crop rotation and evaluated its pathogenicity to non-cereal plants in vitro and to spring wheat under field conditions. The relative density of Fusarium species isolated from oilseed rape, pea, potato and sugar beet plants was assessed in 2015 and 2016. A total of 403 isolates of Fusarium spp. were obtained from non-cereal plants and only 5% of the isolates were identified as F. graminearum. The pathogenicity test revealed that isolates of F. graminearum from spring wheat and non-cereal plants caused discolourations on leaves of faba bean, fodder beet, oilseed rape, pea, potato and sugar beet. The pea was the crop most susceptible to F. graminearum isolated from spring wheat. The pathogenicity of F. graminearum from sugar beet, oilseed rape, pea and potato to the same hosts differed depending on isolate and inoculated plant. Under field conditions, F. graminearum isolates from pea, potato, oilseed rape and wild viola were able to cause typical FHB symptoms in spring wheat. Based on the information generated in this study, we conclude that under congenial conditions, growing faba bean, pea, sugar beet, fodder beet, oilseed rape and potato plants in a cereal crop rotation may serve as alternative or reservoir hosts for F. graminearum pathogens.

Fusarium head blight (FHB) is an important crop disease worldwide and is mainly caused by members of the Fusarium graminearum species complex. F. graminearum sensu stricto is the most common cosmopolitan and predominant FHB causal agent in Europe. Thus far, the majority of studies have focused on the primary hosts (wheat and barley) of this pathogen, while the relationships between other sources of infection remain unclear. We monitored and sampled test fields over the course of 3 years and acquired 804 F. graminearum isolates from different sources: primary hosts and other plant species included in the crop rotations, weeds from the test fields, decaying plant residue, soil samples, and crop seed. Of these isolates, 73.3% had the 15-acetyldeoxynivalenol genotype and 26.7% had the 3-acetyldeoxynivalenol genotype. F. graminearum isolation rates from weeds (>50%) were much higher than from soil (< 10%) or decaying plant matter (4%). Variable number of tandem repeat markers were used for population analysis. Noticeable genetic differentiation was detected between isolates from living plants and soil biome. In contrast, absence of any noticeable division between primary and alternative plant host communities indicates the importance of weeds and other segetal plants for FHB control and prevention.

Healthy seeds are essential for the optimal plant population and yield, but seed-borne pathogens, such as Fusarium spp., may reduce seed germination, quality and cause damping-off of the seedlings. Fusarium graminearum is a dominant pathogen of cereal crops and can cause significant losses of grain yield and quality. It is important to evaluate the role of alternative inoculum source in crop rotation. The aim of this study was to assess the impact of F. graminearum infection on different plant seed germination and seed infestation. The research was conducted at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry, in 2017. Visually healthy seeds of bean (Vicia faba L.), pea (Pisum sativum L.), lupine (Lupinus angustifolius L.), soybean (Glycine max. (L.) Merr.), lucerne (Medicago sativa L.), white (Trifolium repens L.) and red (Trifolium pratense L.) clover were inoculated with 10 mL of F. graminearum suspension, adjusted to 1×10 6 conidia per mL. Seed infection was counted 2 and 6 days after inoculation (DAI), seed germination energy and reduction rate-after 3 DAI and germination index-6 DAI. Results showed that all inoculated seeds were covered with typical to F. graminearum red-purple mycelium. The results of inoculated seeds with F. graminearum showed red-purple mycelium growth on the seeds (infection from 21.25 up to 100%). The results showed that germination energy decreased on pea (2.56%) and lupine (7.79%) seeds. Our results suggest that various plant seeds differently react to F. graminearum infection. The highest infection of F. graminearum was obtained on pea, lupine seeds and the least on red clover.

The last year research shows that pathogenic bacteria Pseudomonas syringae which cause leaf blight and basal glume blotch are spreading in Lithuania. The loss of grain yield because of P. syringae caused diseases might be from 5 to 50%. The decrease of grain yield depends on many factors, including environment conditions (especially temperature and humidity). The aim of the study is to identity how different strains and infection of Pseudomonas syringae influence winter wheat (Triticum aestivum) yield in Lithuania. In vitro five varieties of winter wheat (Dagmar, Janne, Edvins, Skagen and Artist) have been infected by cell suspensions of eight different P. syringae strains (1.0 × 106 KSVml–1) in different growth stages (BBCH 61, BBCH 63-65, BBCH 70- 71 and BBCH 75). The wheat has been sprayed by sterile distilled water in the control variant. Grain weight differences between the investigation variants have been estimated after wheat achieved full maturity (BBCH89). With reference to the analysis data of three statistical factors we can say that the P. syringae infection time did not have a significant influence on the grain weight (P = 0.1970), but the influence of the varieties and P. syringae strains was statistically significant (P = 0.0000). The interaction between different factors such as the infection time and varieties, the infection time and P. syringae strains as well as P. syringae strains has been statistically significant. The referential bacteria P. syringae pv. syringae (strain No. CFBP 4108 Van Hall 1902) and P. syringae pv. Atrofaciens (strain No. CFBP 3587 Mac Culloch 1920) reduced the grain weight mostly (P = 0.0000), respectively, 10.2 and 9.1% compared to the control.