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Weather Conditions Increasing Likelihood of Sour Rot Development

Our Pace Field Technicians in California are accustomed to treating sour rot of mandarins; however, this year, Pace’s team is also seeing a high incidence in Navel oranges. The decay is also appearing in storage much sooner than in previous years. Instead of treatment applications taking place in March or April, our California team is advising its customers to begin treatments earlier.

Sour rot of citrus, caused by Geotrichum candidum var. citri-aurantii, can be a distressing storage disease. Although less common than green mold and more sporadic in occurrence, sour rot can cause significant economic losses during high rainfall years. This yeast-like fungus naturally survives in soil and can be disseminated onto fruit by rain splash, irrigation, wind, and insects. The fungus can readily colonize wound sites on injured fruit, resulting in a soft, juicy decay with a noticeably sour odor. Infection can spread rapidly during postharvest storage through contact with juices leaking from nearby rotting fruit.

How to control Sour Rot development?

Fungicide treatments applied after harvest are crucial in preventing fruit decay and sporulation of pathogens during storage, transit, and marketing. Alongside these treatments, incorporating various sanitation practices to minimize inoculum levels is vital for an integrated decay management program.

Pace’s propiconazole-based fungicide, PacRite® Propi 155 EC, stands out as an effective fungicide for controlling sour rot. However, its resistance potential is high due to its single-site mode of action.

BioSpectra® – The Natural Solution

BioSpectra is the latest biorational fungicide to be organically listed for postharvest applications. It controls broad-spectrum decay against several major fungal postharvest diseases, including sour rot.

BioSpectra is an effective postharvest fungicide with a unique mode of action, capable of controlling isolates resistant to conventional fungicides, making it an ideal rotation or mixture partner.

Broad-Spectrum Activity

Targeting all major fungal postharvest diseases, BioSpectra provides a broad-spectrum solution for comprehensive protection against threats such as Blue Mold, Gray Mold, Mucor Rot, Green Mold, and Sour Rot. At present, no other fungicide can simultaneously and effectively address all major diseases.

Resistance Control

BioSpectra effectively controls strains resistant to Thiabendazole, Imazalil, Pyrimethanil, and Fludioxonil, with no evidence of resistance development.

Propiconazole Replacement

In contrast to propiconazole treatments, BioSpectra has exhibited no development of resistance and has demonstrated remarkable efficacy in sour rot control.

Proven Preservative in the Food Industry

BioSpectra effectively controls strains resistant to Thiabendazole, Imazalil, Pyrimethanil, and Fludioxonil, with no evidence of resistance development.

Exempt from Tolence in the U.S.

Rest easy knowing that BioSpectra complies with U.S. regulations, making it exempt from tolerance and a safe choice for your postharvest needs.

View the BioSpectra® 100 SC product overview page.


If you would like more information, please contact our Regional Sales Manager, Curtis Koga, at (559) 329-2909.

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