BIOLOGY AND CONTROL OF CONIOPHORA-EREMOPHILA ON LEMON TREES IN ARIZONA

A survey of mature lemon trees showed an average of 30% oi trees with symptoms of brown heartrot caused by Coniophora eremophila. Growth of C. eremophila inoculated into branches of Valencia orange, Marsh grape fruit, Orlando tangelo, or Lisbon lemon on rough lemon rootstock was s ignificantly higher in lemon than fn other types of citrus. C. eremoph ila inoculated into Lisbon lemon branches on trees established on roug h lemon, volkameriana, macrophylla, Cleopatra mandarin, sour orange, o r Troyer citrange rootstocks showed no significant differences in grow th. Somatic incompatibility tests oi isolates from one mature orchard demonstrated that isolates from different trees were incompatible. In vitro fungicide trials showed that NECTEC P paste and NECTEC blank pas te effectively reduced decay on lemon blocks 15 weeks after inoculatio n with C. eremophila. Field fungicide trials showed that NECTEC P past e with fungicides, as well as the blank paste without fungicides, sign ificantly inhibited the advance of the fungus 7 months alter inoculati on. Also, propiconazole al 10,000 mu g/ml, imazalil at 20,000 mu g/ml, or propiconazole at 10,000 mu g/ml in combination with imazalil at 20 ,000 mu g/ml significantly inhibited the advance of the fungus.