Document Type : Original Article
Authors
1
Plant Pathology Research Institute, ARC, Giza, Egypt
2
Plant Pathology Dept., Fac. of Agric., Ain Shams Univ., P.O. Box 68, Hadayek Shobra 11241, Cairo, Egypt
Abstract
Brown rot disease of Canino apricots and FlordaPrince peaches is a major serious decay disease during cold storage in Egypt and worldwide, Infection of stone fruits may occur during blooming until harvest harvest which cause decay during cold storage. The effect of fungicide safe alternatives, (Chemical salts and Inducing resistance). The effect of fungicide safe alternatives, i.e. sodium bicarbonate, calcium chloride, potassium sorbate, potassium silicate,boric acid and salicylic acid, on growth of Monilinia laxa M. fructigena and Monilinia sp. as major pathogens on apricots and peaches ,was investigated at different concentrations ranged from 1000 ppm to 5000 ppm amended in PDA in vitro. Sodium bicarbonate at 1000 ppm completely suppressed the growth of the three isolates of Monilinia spp., Calcium chloride at 1000 ppm to 5000 ppm, did not show any suppression of M. laxa or Monilinia sp., while it suppressed M. fructigena when used at ≥4000 ppm. Potassium silicate did not show considerable effectiveness against different tested isolates of Monilinia spp. IC50 values (chemical concentration that reduce fungal growth to 50%) of sodium bicarbonate, potassium sorbate and salicylic acid on M. fructigena were less than 1000 ppm. On M. laxa, only sodium bicarbonate showed IC50 less than 1000 ppm, while the IC50 values of potassium sorbate and boric acid were less than 2000 ppm. Regarding Monilinia sp. sodium bicarbonate and potassium sorbate IC50 values were less than 1000 ppm. Generally, sodium bicarbonate, potassium sorbate and salicylic acid showed IC50 values less than 1000 ppm, 2000 ppm, and 3000 ppm, respectively.
These salts and inducers at 3000 ppm, were used as three preharvest sprays starting at growth stage no. 64 and then repeated twice at 10 days intervals in orchard located at Qualyubia and Ismailia, during seasons 2015 and 2016. These salts and acids were also adopted at 3000 ppm on naturally infected or artificially inoculated fruits after harvest at growth stage no. 81 during season 2016. Sodium bicarbonate, calcium chloride, potassium sorbate and boric acid were the most effective treatments to control brown rot disease on apricots and peaches during cold storage at 0oC and 90% RH for 15 days and 30 days, either these chemicals were sprayed preharvest or adopted after harvest. These treatments maintained fruit quality regarding firmness and acidity.
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