Control of Phytophthora brown rot of lemons by pre- and postharvest applications of potassium phosphite

RAMALLO, A. C.; CERIONI, L.; OLMEDO, G. M.; VOLENTINI, S. I.; RAMALLO, J.; RAPISARDA, V. A.

EUROPEAN JOURNAL OF PLANT PATHOLOGY

SPRINGER

Lugar: Berlin; Año: 2019 vol. 154 p. 975 - 982

0929-1873

Article is protected by copyright and all rights are held exclusively by Koninklijke Nederlandse Planteziektenkundige Vereniging. The e-offprint is for personal use only and shall not be self-archived in electronic repositories. To deposit the accepted manuscript version in any repository, provided it is onlymade publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer´s website. The link must be accompanied by the following text: "The final publication is available at link.springer.com? Citrus Brown Rot (BR), caused by Phytophthora spp., provokes important economical losses mainly in periods of high rainfall. The management of this disease in Florida and Brazilian citrus areas, main orange growers worldwide, includes chemical control using phosphite salts. In Argentina, the world leader in lemon production, these compounds are registered only as fertilizers. In this work, the effect of potassium phosphite on different Phytophthora sp. cellular structures and the conditions to control lemon BR by it application at pre and post-harvest stages were evaluated. Phosphite inhibited in vitro the mycelial growth, the sporangia production, and the motility and germination of zoospores of a local isolate of Phytophthora citrophthora. In postharvest applications on artificially inoculated lemons, the phosphites exerted a moderate curative activity, reducing BR incidences ~25% in respect to controls. When this salt was applied a week before inoculation, BR incidences were 50?60% lower than those of controls, denoting a significant preventive activity. The application of phosphite with fungicides in commercial packingline prevented BR disease in fruit inoculated at 96 h post-treatment. In pre-harvest, two phosphite applications reduced incidences ~40?60% in lemons harvested and inoculated up to 75 d after treatment. Our data confer valuable technical information towards the use of phosphite salts against lemon BR, contributing to the pre- and postharvest management strategies of this disease.