Superior performance of kresoxim-methyl (Stroby) and trifloxystrobin (Flint) against Botrytis blight (Botrytis gladiolorum) of gladiolus (Gladiolus x hortulanus Bailey)

Efficacy of strobilurin fungicides, viz. kresoxim-methyl, (Stroby 50 WG, 0.1%), trifloxystrobin (Flint 50 WG, 0.1%) and azoxystrobin (Amistar 250g/L, 0.1%) and two systemic acquired resistance (SAR) compounds, viz., benzothiadiazole, (BTH, as Bion 50 WG, 0.01%), and salicylic acid (SA, 0.005%) was tested against Botrytis blight of gladiolus. None of the compounds reduced floral infection in a significant manner over the control. However, the efficacy of strobilurins against foliage infection was remarkable. Two strobilurins, viz. Stroby and Flint reduced foliar infection in a highly significant manner over the control. These fungicides registered a disease rating of 1.67 and 2.00 compared to 3.67 in the control plots, on a rating scale of 0–4 on cv. “Sancerre”. The yield increases in terms of corm and cormel weight were also highly substantial (Stroby: corms - approx. 2X, cormels -approx. 9X; Flint: corms - approx. 1.5X, cormels - approx. 6X). Furthermore, the plants treated with these two compounds remained green for two additional weeks as compared to those in the control plots. The third strobilurin, i.e. Amistar, neither reduced disease severity nor improved yield in a significant manner. Stroby was found to be the best of the three. The SAR compounds tested, viz., BTH and SA, neither reduced the disease nor improved yield in an appreciable manner over the control.