INSECT-PLANT PATHOGEN INTERACTIONS: PRELIMINARY STUDIES OF DIAPREPES ROOT WEEVIL INJURIES AND PHYTOPHTHORA INFECTIONS

ROGERS, STEVEN

Abstract


It has been speculated that larval injuries by Diaprepes abbreviatus L. serve as preferred infection courts for root rot diseases caused by soil pathogens such as Phytophthora spp. A completely randomized block experiment was performed in the greenhouse where roots of young Cleopatra mandarin (C. reticulata Blanco) and trifoliate orange (Poncirus trifoliata L.) were first exposed to D. abbreviatus larvae of known density and then later inoculated with Phytophthora nicotianae Breda de Haan. Results suggest that the incidence and severity of root rot disease on Phytophthora-susceptible seedlings generally increased in relation to the amount of root damage caused by D. abbreviatus larvae. Phytophthora-tolerant seedlings, however, showed little or no increase in disease severity with increasing insect injury. Infection of root tips dis- tal to D. abbreviatus damaged roots suggest that root wound exudates serve as nutritional substrates for developing P. nicotianae populations. This paper presents the first study describing an interaction between soil insect injuries and the subsequent infection by a plant pathogen in the citrus rhizosphere.

Keywords


citrus rootstocks; root weevil; cleopatra mandarin; trifoliate orange; root rot

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283