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

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

EUROPEAN JOURNAL OF PLANT PATHOLOGY

SPRINGER

Lugar: Holanda; Año: 2019 p. 975 - 982

0929-1873

Citrus Brown Rot (BR), caused byPhytophthora spp., provokes important economicallosses mainly in periods of high rainfall. The management of this disease in Florida and Brazilian citrus areas,main orange growers worldwide, includes chemicalcontrol using phosphite salts. In Argentina, the worldleader in lemon production, these compounds are registered only as fertilizers. In this work, the effect ofpotassium phosphite on different Phytophthora sp. cellular structures and the conditions to control lemon BRby it application at pre and post-harvest stages wereevaluated. Phosphite inhibited in vitro the mycelialgrowth, the sporangia production, and the motility andgermination of zoospores of a local isolate ofPhytophthora citrophthora. In postharvest applicationson artificially inoculated lemons, the phosphites exerteda moderate curative activity, reducing BR incidences~25% in respect to controls. When this salt was applieda week before inoculation, BR incidences were 50?60%lower than those of controls, denoting a significantpreventive activity. The application of phosphite withfungicides in commercial packingline prevented BRdisease in fruit inoculated at 96 h post-treatment. Inpre-harvest, two phosphite applications reduced incidences ~40?60% in lemons harvested and inoculatedup to 75 d after treatment. Our data confer valuabletechnical information towards the use of phosphite saltsagainst lemon BR, contributing to the pre- and postharvest management strategies of this disease.