This study was conducted to identify a cheap and suitable culture medium for the mycelial growth and sporulation of Stemphylium vesicarium and to determine the cultural and morphological variability of this pathogen. A total of 24 isolates of S. vesicarium collected from eight different onion growing areas were characterized in terms of cultural and morphological aspects. Front colony colors were greenish brown to dirty white, deep grey to whitish, light grey to whitish, deep greenish white, light grey and dirty white to greenish. Reverse colony colors were brown, deep brown and light brown. Colony shapes were circular and irregular with umbonate, raised and flat type colony elevation. Colony textures were cottony, fluffy and velvety with entire, undulate and filiform type colony margin. Among the culture media, V-7 juice agar found to be the most suitable culture media for mycelial growth of S. vesicarium. The sporulation of the fungus was remarkably influenced by V-7 juice mixed with potato dextrose agar (PDA) media, this media exhibited the highest sporulation (87.76-169.0/mm 2 ) of S. vesicariumin comparison with other media. The minimum days (28 d to 31 d) for conidial production were observed on V-7 juice agar medium. The length of conidia varied from 14.6 µm to 30.6 µm. The maximum mean length of conidia was 29.97 µm found in isolate DSSA, while the minimum mean length 17.36 µm was found in isolate MSMM 02. The breadth of conidia ranged from 4.7 µm to 15.7 µm. The maximum mean breadth of conidia was 12.55 µm found in the isolate DSSA, while the minimum mean breadth 9.760 µm was found in the isolate CCKH 02. The horizontal septation varied from 1 to 3 and the longitudinal septation varied from 0 to 4.

Planting material BARI mungbean-5 and two phytochemicals viz. Imitaf, active ingredient imidacloprid and ACmix, active ingredient chloropyriphos (50%) + Cypermethrin (5%) were used in this experiment. In case of Imitaf, the lowest percent disease incidence (10.12% per plant and 3.51% per plot) and severity (7.21%) were recorded in four times spray (T 4 ) at 70 DAS. The highest percent disease incidence (36.50% per plant and 11.37% per plot) and severity (23.33%) were recorded in no spray (T 0 ) at 70 DAS. In case of ACmix, the lowest percent disease incidence (12.21% per plant and 4.21% per plot) and severity (7.53%) were recorded in four times spray (T 4 ) at 70 DAS. The highest percent disease incidence (36.49% per plant and 11.37% per plot) and severity (36.67%) was recorded in T 0 at 70 DAS. The highest number of flower, no of pod and yield was found in four times spray (T 4 ) that was higher in Imitaf than ACmix. The highest chlorophyll content was recorded in four times spray (T 4 ) for Imitaf (49.62 µmol•m −2 •s −1 ) and ACmix (56.80 µmol•m −2 •s −1 ), and the lowest chlorophyll content was recorded in T 0 for Imitaf (42.01 µmol•m −2 •s −1 ) and ACmix (48.34 µmol•m −2 •s −1 ). However from the results of this experiment it was revealed that Imitaf gave the better performance to control the insect vector (Whitefly) of MYMV with four times spray.

The experiments were conducted with a view to establish a protocol for virus free mini-tubers production, in vitro, using potato meristem as explant, collected from potato sprouts of three popular potato varieties Diamant, Cardinal, Granola. In the present study four levels of GA3 (100, 200, 300 and 400 ppm) were used to assess the influence on sprouting abilities in three selected potato verities. The maximum sprouting efficiency was observed in 400ppm GA3 treatment within short period of time in Granola variety. The effect of different combination and concentration of IBA, 2, 4-D and BAP was used along with fresh MS media to inoculate meristems of potato sprouts. IBA concentration were 0.25mg/L, 1.5mg/L; 2, 4-D concentration were 0.125mg/L, 0.25mg/L, 0.37mg/L, 0.50mg/L, 1.0mg/L 2.0mg/L and BAP concentration were 0.5 mg/L, 1.0 mg/L, 1.5 mg/L and 2mg/L. The effect of combined hormones was also studied. The Diamant  variety showed the maximum callus size (0.74cm) within a very short period of time (2 days) while treated at the concentration of 0.25 mg/L IBA, 0.25 mg/L 2, 4-D and 1.00 mg/L BAP. Granola meristem inoculated in hormonal treatment showed the best results regarding minimum days required to shoot initiation (5.34 days) followed by Diamant (6.68) days and Cardinal (7.64 days). The highest number of shoots/plantlet (4.33 shoots/plantlet) and the longest plantlet (9.32 cm) was found in Granola variety followed by Diamond (3.67 shoots/plantlet; 7.53cm) and Cardinal (4.0 shoots/plantlet; 7.62 cm). Maximum numbers of leaves were also found in Granola variety (15 leaves) in the treatment combination of 0.25 mg/L IBA, 0.125 mg/L 2,4-D and 0.5 mg/L BAP. Granola gave maximum performance in respect of maximum length of root (6.55 cm roots/plantlets) within a short time of root initiation (20 days), followed by Diamant (4 cm roots/plantlets) of root initiation (4.47 days) and Cardinal (4.53 cm roots/plantlets) of root initiation (26.39 days). Rooted plantlets were gradually acclimatized and successfully established in the field. However, in overall observation in this study, Granola showed better performance from meristem tissue culture and all plants were found normal and free from potato viruses that were tested through ELISA test.