#pathogenicity

This comprehensive study aimed to investigate the causal organisms, disease incidence and pathogenicity of microorganisms affecting gerbera plants in the Dhaka zone of Bangladesh. Nine sites of Agargaon, Savar, Gazipur, and Narayanganj were surveyed to identify the diseases based on symptomological studies. Diseases caused by fungi including cercospora leaf spot (Cercospora sp.), alternaria leaf spot (Alternaria alternata), sclerotinia wilt (Sclerotinia sclerotiorum), anthracnose (Colletotrichum capsici), powdery mildew (Erysiphe sp.), blight (Curvulariageniculata), graymold (Botrytis sp.), stem rot (Fusarium oxysporum), and viral diseases such as leaf curl (Leaf curl virus) and mosaic (Mosaic virus) were identified. Among all the identified diseases, the highest disease incidence (66.67%, Gazipur) was exhibitedby alternaria leaf spot and the lowest disease incidence (5.56%, Narayanganj) was shown by graymold. The rate of reduction of plant height due to cercospora leaf spot, alternaria leaf spot, blight, anthracnose, graymold, sclerotinia wilt, stem rot, powdery mildew, mosaic, and leaf curl diseases was 28.1%, 28.42%, 12.47%, 12.69%, 28.36%, 30.67%, 19.14%, 28.08%, 12.89%, and 22.06%, respectively. The rate of reduction of other plant parts of gerbera was also recorded. To confirm pathogenicity, Curvulariageniculata, and Erysiphe sp. were tested on healthy gerbera plants following Koch’s postulates. The plants exhibited the disease symptoms of Curvulariageniculata and Erysiphe sp. after 9 and 6 days of inoculation, respectively, while the control plants remained symptom-free. Thus, the pathogenicity of Curvulariageniculata and Erysiphe sp. was confirmed.

The current study aimed to identify symbiotic bacteria associated with previously identified native entomopathogenic nematodes from southern Benin and evaluate their biocontrol potential on fifth instar larvae of Spodoptera frugiperda. Colony characteristics, bioluminescence capacity, and a molecular approach using the 16S rRNA gene were used to identify the symbiotic bacteria. Pathogenicity tests against fifth instar larvae of S. frugiperda were also conducted. The results indicated that all the eighteen bacterial isolates isolated from strains of Heterorhabditis sonorensis are identical (99% sequence similarity) to Photorhabdus isolate R-66822 (accession number MF353507). The symbiotic bacteria associated with the single strain of H. indica are identical (98% sequence similarity) to the Photorhabdus bacterial isolate R-52361 (accession number MF353497). With regard to pathogenicity tests, nine bacterial isolates were pathogenic to S. frugiperda larvae at 35°C, with insect mortalities varying between 0.24 and 78.47%. Better yet, seven of them could still kill the insects at an exposure temperature of 40°C, inducing insect mortalities ranging from 4.86 to 63.65%. Moreover, bacterial densities of 0.450 x 106 CFU/mL and 0.483 x 106 CFU/mL were sufficient for the bacterial isolates BSKassehlo and BSZoundomey, respectively, to kill 50% of the fifth instar larvae of S. frugiperda, whereas BSKissamey, BSAzohoue2, and BSZe1 needed 3.173 x 106 CFU/Ml and 2.900 x 106 CFU/mL, respectively. These findings are sufficiently encouraging to initiate further investigations into the potential of these native bacterial isolates for sustainable management strategies against S. frugiperda in agricultural areas.

This comprehensive study aimed to investigate the causal organisms, disease incidence and pathogenicity of microorganisms affecting gerbera plants in the Dhaka zone of Bangladesh. Nine sites of Agargaon, Savar, Gazipur, and Narayanganj were surveyed to identify the diseases based on symptomological studies. Diseases caused by fungi including cercospora leaf spot (Cercospora sp.), alternaria leaf spot (Alternaria alternata), sclerotinia wilt (Sclerotinia sclerotiorum), anthracnose (Colletotrichum capsici), powdery mildew (Erysiphe sp.), blight (Curvulariageniculata), graymold (Botrytis sp.), stem rot (Fusarium oxysporum), and viral diseases such as leaf curl (Leaf curl virus) and mosaic (Mosaic virus) were identified. Among all the identified diseases, the highest disease incidence (66.67%, Gazipur) was exhibitedby alternaria leaf spot and the lowest disease incidence (5.56%, Narayanganj) was shown by graymold. The rate of reduction of plant height due to cercospora leaf spot, alternaria leaf spot, blight, anthracnose, graymold, sclerotinia wilt, stem rot, powdery mildew, mosaic, and leaf curl diseases was 28.1%, 28.42%, 12.47%, 12.69%, 28.36%, 30.67%, 19.14%, 28.08%, 12.89%, and 22.06%, respectively. The rate of reduction of other plant parts of gerbera was also recorded. To confirm pathogenicity, Curvulariageniculata, and Erysiphe sp. were tested on healthy gerbera plants following Koch’s postulates. The plants exhibited the disease symptoms of Curvulariageniculata and Erysiphe sp. after 9 and 6 days of inoculation, respectively, while the control plants remained symptom-free. Thus, the pathogenicity of Curvulariageniculata and Erysiphe sp. was confirmed. )

Fungal diseases are one of major constraints on groundnut production in Burkina Faso. Among these diseases, early leaf spot caused by Cercospora arachidicola (Hori.) is one of the most important economic diseases of groundnut. Aim of contributing to search effective control methods against this disease, we undertook the present study, which consisted in (i) study morphological diversity of different Cercospora arachidicola isolates (ii) study the level of pathogenicity of Cercospora arachidicola strains identified (iii) evaluate the efficacy of some bio-fungicides on the strains identified. The study was carried out in 14 villages in the Hauts Bassins and Boucle du Mouhoun regions of Burkina Faso with regard to prospecting and sample collection, and at the INERA Bobo Dioulasso plant pathology laboratory for isolation, identification, pathogenicity and biofungicide efficacy testing. A total of five strains of Cercospora arachidicola were identified. The pathogenicity test was used to classify the five strains according to their virulence. In decreasing order of virulence, the strains were Fara, Darsa, Logo, Santi and Kod. In vitro evaluation of biofungicide efficacy shows that PLANSAIN biofungicide provides better control of Cercospora arachidicola strains. Trichoderma hazanium, the active ingredient in PLANSAIN, inhibits the radial growth of Cercospora arachidicola strains to a greater extent.