THE PEACH REPLANT PROBLEM IN ONTARIO: VII. THE PATHOGENICITY OF PRATYLENCHUS PENETRANS (COBB, 1917) FILIP. & STEK. 1941

Abstract

Experiments were carried out to determine the role of Pratylenchus penetrans (Cobb, 1917) Filip. & Stek. 1941 in the peach replant problem. It is shown that this nematode is a true plant pathogen since it invades and causes necrosis of peach roots in the absence of bacteria and fungi. Necrosis of the root tissue occurs rapidly and appears to take place in advance of the invading nematode. The main mechanism involved in the formation of the lesion is the production of phytotoxic substances through hydrolysis of the cyanophoric β-glucoside, amygdalin. P. penetrans is capable of hydrolyzing this substance in vitro. It is concluded that, although P. penetrans is the most important primary parasite and a true plant pathogen, its main role in peach replant failure appears to be its ability to incite root degeneration by providing extensive infection courts for soil microorganisms.