Search Results (3)

Soilborne diseases cause losses of 45–70% in faba bean in Ethiopia. Studies were undertaken to define soilborne pathogens and their complexes in Ethiopia. First, the severity of root rot was assessed in 150 field sites across seven Ethiopian regions. Soil samples were collected, and the DNA of 29 pests and pathogens was quantified using a commercial quantitative PCR (qPCR) soil testing service. There was a very high incidence rate of Macrophomina phaseolina, as well as Pythium clades F and I. The other detected species in order of incidence included Fusarium redolens, Rhizoctonia solani, Aphanomyces euteiches, Phytophthora megasperma, Sclerotinia sclerotiorum and S. minor, and Verticillium dahliae, as well as low levels of Thielaviopsis basicola. Five anastomosis groups (AG) of R. solani, namely AG2.1, AG2.2, AG3, AG4, and AG5, were detected, of which AG2.2 and AG4 were most prevalent. We believe this is the first report of occurrence for Ethiopia of A. euteiches, Ph. megasperma, T. basicola, and the five AGs for R. solani. There were very high incidence rates of the foliar pathogens Botrytis cinerea, B. fabae, Didymella pinodes, and Phoma pinodella and of the nematode Pratylenchus thornei, followed by P. neglectus and P. penetrans. The root rot severity and distribution varied significantly across regions, as well as with soil types, soil pH, and soil drainage. Subsequently, metabarcoding of the soil DNA was undertaken using three primer pairs targeting fungi (ITS2), Fusarium species (TEF1 α), and Oomycetes (ITS1Oo). The ITS2 and TEF1α primers emphasized F. oxysporum as the most abundant soilborne fungal pathogen and highlighted F. ananatum, F. brachygibbosum, F. brevicaudatum, F. clavum, F. flagelliforme, F. keratoplasticum, F. napiforme, F. nelsonii, F. neocosmosporiellum, F. torulosum, and F. vanettenii as first reports of occurrence for Ethiopia. The ITS1Oo primer confirmed Pythium spp. as the most prevalent of all Oomycetes. Full article

Peanut Root Rot (PRR) is a devastating disease that significantly limits peanut production worldwide. Although PRR has been frequently reported in Henan Province of China, the predominant Fusarium species and their sensitivity to different fungicides remain unclear. Between 2021 and 2023, we surveyed 81 peanut fields across 17 cities in Henan Province, China, to assess PRR prevalence and Fusarium species distribution. A total of 1131 Fusarium isolates were identified based on the morphological characters and phylogenetic analyses and classified into 11 recognized Fusarium species: F. solani (56.06%), F. oxysporum (20.87%), F. neocosmosporiellum (13.62%), F. proliferatum (4.69%), F. acuminatum (1.33%), F. commune (1.15%), F. graminearum (1.06%), F. pseudograminearum (0.35%), F. ipomoeae (0.35%), F. lacertarum (0.26%), and F. armeniacum (0.26%). Pathogenicity assessments showed that all 11 Fusarium species were capable of causing PRR, with F. solani exhibiting the highest isolation frequency and widespread distribution in all areas. Furthermore, the four Fusarium species (F. solani, F. oxysporum, F. neocosmosporiellum, and F. proliferatum) were highly sensitive to the six fungicides, including prochloraz (EC₅₀ values of 0.02 ± 0.00~0.06 ± 0.01 mg/L), pydiflumetofen (EC₅₀ values of 0.31 ± 0.07~0.67 ± 0.06 mg/L), tetramycin (EC₅₀ values of 0.11 ± 0.02~0.58 ± 0.08 mg/L), tebuconazole (EC₅₀ values of 0.26 ± 0.07~0.65 ± 0.10 mg/L), prothioconazole (EC₅₀ values of 1.14 ± 0.16~3.15 ± 0.81 mg/L), and difenoconazole (EC₅₀ values of 0.62 ± 0.12~3.58 ± 0.76 mg/L). This comprehensive study is the first systematic documentation on the prevalence, virulence, and fungicide sensitivity of PRR pathogens in Henan Province. The findings of the current study will provide a theoretical basis for the effective management of peanut root rot in Henan, China. Full article

Fusarium neocosmosporiellum is the main pathogen of peanut pod rot in China. To investigate the type of F. neocosmosporiellum toxin and its pathogenic mechanism, a macrolide, brefeldin A, was isolated. The structure of the compound was identified by 1D and 2D nuclear magnetic resonance (NMR) and high-resolution electrospray ionization–mass spectrometry (HR-ESI-MS). At the same time, the content of the compound in healthy and diseased peanut capsules was detected, and its plant toxicity to radish, mung bean, rice, and peanut seed radicle elongation and pathogenicity to peanut pod rot were evaluated. The results showed that brefeldin A at 50 μg/mL could significantly inhibit the radicle elongation of rice seeds. Brefeldin A was detected only in pods with peanut rot. Injecting 2 mg/mL brefeldin A solution into peanut pods caused the severe decay of peanut pods at the R3R4 stage, which is consistent with the symptoms of peanut rot. Full article