ISHS Acta Horticulturae 785: International Symposium on Grape Production and Processing
USE OF POTASSIUM BI-CARBONATES FOR THE CONTROL OF POWDERY MILDEW IN TABLE GRAPES |
| Authors: | S.D. Sawant, I.S. Sawant |
| Keywords: | powdery mildew, grapes, potassium bicarbonate, fungicides, surfactant, hexaconazole |
| Abstract:
The results of in vitro and three-year field trials (2002, 2003 and 2004) with sodium, ammonium and potassium bi-carbonates indicated that all the three bi-carbonates namely sodium, ammonium and potassium were equally effective in planta. Since excess sodium and nitrogen can be problematic in grapes, potassium bi-carbonate was selected for further studies as it was found safe for use. In in vitro studies potassium bicarbonate reduced conidial germination gradually at concentrations above 100 ppm. Potassium bicarbonate alone was effective at 10 g/L when given as preventive sprays at 10 days interval starting from 40 days after pruning. The efficacy was on par with sprays of wettable sulfur at 2.0 g/L. When sprayed on infected leaves potassium bicarbonate at 10 g/L reduced sporulation of the pathogen up to 80 percent. Use of a non-ionic surfactant improved the efficacy of potassium bicarbonate to control powder mildew on bunches, probably because of better coverage. Half dose of potassium bicarbonate (5 g/L) in combination with hexaconazole (0.5 ml/L) showed better control of the disease than when these chemicals were used alone. Potassium bicarbonate was also found compatible with Myclobutanil, Flusilozole and Pencnazole and hence can be used in combination with these fungicides also. | |
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