Ralf T. Voegele

BACKGROUND Pentastiridius leporinus (Hemiptera: Cixiidae) is the most important vector of syndrome ‘basses richesses’ (SBR), a new disease that leads to severe economic losses in sugar beet. In this study, different soil tillage methods (ploughing and cultivator) and crops (winter wheat, spring wheat, maize and bare soil) following SBR‐infested sugar beet were tested as potential management options in field trials. In the laboratory, the survival and development of first and third instar nymphs on wheat and maize was studied to further assess their suitability as host plants. RESULTS In five out of seven field sites, reduced soil tillage had no effect on adult planthopper emergence compared to ploughing. In two sites, reduced tillage resulted in higher emergence rates. In nearly all field sites, up to 98.9% fewer emerging adults were detected in bare soil and maize, when compared to winter wheat. Under laboratory conditions, the lowest survival rate was found in first instar nymphs feeding on maize seedlings (4.2%), while 66.7% survived on wheat, over a period of 300 days. In contrast, 73.3% and 70% of third instar nymphs survived on wheat and maize over a period of 150 days. CONCLUSION Soil tillage had little effect against Pentastiridius leporinus . Maize is a poor host for first instars but a suitable resource for third instar nymphs, the stage which encounters maize under field conditions. Hence, reductions in planthopper emergence in the field were likely caused by starvation due to the long host‐free period between sugar beet harvest and the sowing of maize. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Fusarium spp. are important pathogens on cereals, capable of causing considerable yield losses and significantly reducing the quality of harvested grains due to contamination with mycotoxins. The European Union intends to reduce the use of chemical-synthetic plant protection products (csPPP) by up to 50% by the year 2030. To realize this endeavor without significant economic losses for farmers, it is crucial to have both precise early detection of pathogens and effective alternatives for csPPP. To investigate both the early detection of Fusarium head blight (FHB) and the efficacy of selected biological control agents (BCAs), a pot experiment with spring wheat (cv. ‘Servus’) was conducted under semi-field conditions. Spikes were sprayed with different BCAs prior to inoculation with a mixture of F. graminearum and F. culmorum conidia. While early detection of FHB was investigated by hyperspectral imaging (HSI), the efficiency of the fungal (Trichoderma sp. T10, T. harzianum T16, T. asperellum T23 and Clonostachys rosea CRP1104) and bacterial (Bacillus subtilis HG77 and Pseudomonas fluorescens G308) BCAs was assessed by visual monitoring. Evaluation of the hyperspectral images using linear discriminant analysis (LDA) resulted in a pathogen detection nine days post inoculation (dpi) with the pathogen, and thus four days before the first symptoms could be visually detected. Furthermore, support vector machines (SVM) and a combination of LDA and distance classifier (DC) were also able to detect FHB symptoms earlier than manual rating. Scoring the spikes at 13 and 17 dpi with the pathogen showed no significant differences in the FHB incidence among the treatments. Nevertheless, there is a trend suggesting that all BCAs exhibit a diminishing effect against FHB, with fungal isolates demonstrating greater efficacy compared to bacterial ones.

Uromyces fabae, the causal agent of broad bean rust, is a major cause of yield losses in North and East Africa, China, and Australia. It has also served as an important model species for research on rust fungi. Early EST sequencing in U. fabae showed that viruses might be present in this species; however, no follow-up investigations were conducted. In order to identify these viruses, we performed purification of dsRNA followed by Illumina sequencing. We also used ultracentrifugation followed by negative staining electron microscopy to visualize virus particles. We identified 20 viral sequences, which we termed Ufvss. A phylogenetic analysis was performed that grouped Ufvss into totiviruses, polymycoviruses, and virgaviruse; three sequences could not be included in the phylogeny. We also found isometric particles. Our findings contribute to the knowledge of mycoviral diversity in rust fungi and point to the importance of further investigation of these viruses.