Articles
Protective and curative ability of postharvest potassium phosphite treatment to control Phytophthora brown rot of citrus fruit
Article number
1451_8
Pages
59 – 68
Language
English
Abstract
Brown rot is a postharvest disease of citrus caused by Phytophthora spp.
The objectives of this study were to evaluate the curative and protective efficacy of potassium phosphite (1500 µg mL‑1) as an aqueous dip treatment for the postharvest management of Phytophthora brown rot on different citrus types (lemons, oranges and mandarins). Curative ability of potassium phosphite was determined by dipping fruit in the potassium phosphite solution 6, 12, 24 or 48 h after Phytophthora nicotianae zoospore inoculation.
The preventative ability of the treatment was evaluated by dip treating the fruit in the potassium phosphite solution 6, 12, 14 or 48 h before zoospore inoculation.
Results indicated that the potassium phosphite dip treatment had good curative action, reducing brown rot incidence significantly when the fungicide was applied 12 h after inoculation.
Applications done 24 h after inoculation also provided some curative action but not as effective as earlier applications.
Potassium phosphite furthermore provided very good protection against infection if inoculations were done up to 48 h after application on all three fruit types.
Interestingly, the protective ability of potassium phosphite was better the longer the fungicides remained on the fruit before inoculation.
The data obtained from this study can add additional value to the already registered preharvest potassium phosphite usage.
The objectives of this study were to evaluate the curative and protective efficacy of potassium phosphite (1500 µg mL‑1) as an aqueous dip treatment for the postharvest management of Phytophthora brown rot on different citrus types (lemons, oranges and mandarins). Curative ability of potassium phosphite was determined by dipping fruit in the potassium phosphite solution 6, 12, 24 or 48 h after Phytophthora nicotianae zoospore inoculation.
The preventative ability of the treatment was evaluated by dip treating the fruit in the potassium phosphite solution 6, 12, 14 or 48 h before zoospore inoculation.
Results indicated that the potassium phosphite dip treatment had good curative action, reducing brown rot incidence significantly when the fungicide was applied 12 h after inoculation.
Applications done 24 h after inoculation also provided some curative action but not as effective as earlier applications.
Potassium phosphite furthermore provided very good protection against infection if inoculations were done up to 48 h after application on all three fruit types.
Interestingly, the protective ability of potassium phosphite was better the longer the fungicides remained on the fruit before inoculation.
The data obtained from this study can add additional value to the already registered preharvest potassium phosphite usage.
Authors
J.M. van Niekerk, E. van der Merwe, C.L. Lennox
Keywords
Phytophthora nicotianae, phosphonate, aqueous application, zoospores
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