Efficacy of Natamycin for Control of Mucor Rot in Pear Fruit
Author: Dr. Rachel Leisso
Published: 2025
Summary: Mucor rot is caused by the pathogen Mucor piriformis, which can be responsible for severe post-harvest decay in pears. For this study, the efficacy of BioSpectra 100SC (active ingredient natamycin) was tested in a laboratory setting. Testing was conducted at harvest and at five-months post-harvest. The most effective treatment was found to be the highest label rate of BioSpectra 100SC (1000 ppm natamycin) applied at harvest which reduced Mucor rot infection by 73%. Applying BioSpectra 100SC as soon as possible after harvest was more effective than applying later in the storage season. The 1000 ppm natamycin treatments resulted in lower numerical disease incidence and smaller average lesion diameters when compared to the lowest label rate of BioSpectra 100SC (500 ppm natamycin) when the at harvest and at five-month postharvest trials were combined and averaged. Additional laboratory trials were also conducted to determine the amount of disease incidence incurred in ‘d’Anjou’ pears when BioSpectra 100SC and Mucor piriformis inoculum are combined in an experimental dump tank. On average, the dump tanks with 500ppm and 1000ppm natamycin treatments reduced the average percent of fruit infected by 53% and 72% respectively. The fungicide Mentor 45WP combined with the highest label rate of BioSpectra 100SC reduced Mucor rot by 22% in a small preliminary trial. Further testing of BioSpectra 100SC in combination with other post-harvest chemicals is proposed for 2025-2026. This research has improved our understanding of the efficacy of natamycin for controlling Mucor rot on ‘d’Anjou’ pears in a laboratory setting. BioSpectra 100SC is currently the only commercially available postharvest fungicide that we are aware of that has been shown to help reduce Mucor rot incidence. Aside from the Mucor rot control, BioSpectra 100SC can be used as a rotational fungicide to help reduce fungicide resistance as according to the label BioSpectra 100SC also helps to control blue and grey mold.
