An enhanced trunk injection formulation of potassium phosphite against chestnut ink disease

Abstract

Chestnut ink disease, caused by Phytophthora cinnamomi and P. cambivora, is one of the most destructive diseases affecting Castanea sativa. Currently, disease control requires careful integrated chemical and agronomic measures. Trunk injection with potassium phosphite was proven to be effective in reducing symptoms but little is known about the ideal formulation. In this research, potassium phosphite at different concentrations and with some other bio stimulants was injected into sweet chestnuts which had been inoculated with a local strain of P. cinnamomi. The most effective formulation, potassium phosphite mixed with a micronutrient solution, was then tested with a preventive approach; as a result, the trunk injection treatments completely ceased the development of the disease in planta in most cases. In order to consider the importance of each component of the solution, potassium phosphite and the bio stimulant elements were tested in vitro singly and in an isobolographic analysis of interactions. The results broaden the knowledge base on endotherapic treatments as an effective measure for the management of chestnut ink disease with potential for many other diseases.