Reactions of some citrus rootstock and varieties to citrus gummosis (Phytophthora citrophthora) and effects of some fungicides on infection

In this study, against Phytophthora citrophthora susceptibility of 33 citrus varieties and 14 citrus rootstocks were examined. In addition the efficacy of Fosetyl-Al, metalaxyl, oxadixyl and cymoxanyl against mycelial growth of pathogen in vitro and pathogenesis on kütdiken lemon seedlings were also studied.The most susceptible variety was Ortanique, the most resistant was Napolitana among mandarin varieties. Apart from the other orange varieties, Navelina and Fukumoto that are early navels showed highest susceptibility, the less infection development occurred on Washington navel and Valencia. Kütdiken, among lemon varieties showed the highest level of susceptibility. Comparison between grapefruit varieties, the red ones Star ruby and Riored, were more susceptible to than others. Although infection development was rarely on rootstocks, Mexica laym and Orlando tangelo were the most susceptible ones beside Sour orange was determined as a most resistant rootstock.According to experiments in vitro, Metalaxyl had given the highest level of efficacy on micelial growth of pathogen.The fungicide application a week before pathogen inoculation gave the highest effect in the study which effects of fungicides upon pathogenesis of P. citrophthora on Kütdiken lemon seedlings tested. In this application, while Fosetyl-Al and metalaxyl inhibited the infection development completely, the oxadixyl and cymoxanyl applications some infections occurred rarely. In case of fungicide applications with pathogen inoculation, Fosetyl-Al efficacy reached to 100 %., however, with the other fungicide applications a week after pathogen inoculation the efficacy level was obtained at 96 %.