IDENTIFICATION OF JUGLONE IN PECAN AS A POSSIBLE FACTOR OF RESISTANCE TO FUSICLADIUM-EFFUSUM

Juglone (5-hydroxy-l, 4-naphthoquinone) was isolated from pecan (Carya illinoensis Koch) and shown to be inhibitory to Fusicladium effusum Wint., the incitant of pecan scab. The content of juglone in pecan leaves and nuts was found to be low in June and increased through July. The level in nuts continued to increase to a maximum in August while that in leaves decreased to near zero. The content in nuts was consistently higher than that in leaves except in early season. The level of juglone in several species of the Juglandaceae family and in several cultivars of pecan was measured. There was some indication that those species and cultivars less affected by F. effusum in nature had higher levels of juglone. © 1979, American Chemical Society. All rights reserved.