Wednesday, December 12, 2001 -

Citrus root weevil and tree decline in Texas citrus

J. Victor French and Mani Skaria. Texas A&M University-Kingsville, Citrus Center, 312 N. International Blvd, Weslaco, TX

Orange trees in several citrus orchards in the Lower Rio grande Valley (LRGV) showed rapid decline and death this past season. Investigations are underway to identify the cause(s) of this very serious problem. Affected trees first show leaf wilt, yellowing and defoliation—followed by tree death in 4 to 5 weeks. Many of the affected trees were removed and the roots washed with a handgun sprayer. Roots showed extensive insect feeding injury (channeling), together with symptoms of severe Phytophthora root rot. The channels varied from 1.25 cm to more than 30 cm in length, and up to 1.5 cm wide. Legless white larvae (grubs) subsequently identified as the ‘golden-headed weevil,' Compsus auricephalus (Say), and the sugarcane root stalk weevil, Diaprepes abbreviatus (L.), were identified from the soil. Adult root weevil species are being monitored by special ‘Tedders traps' placed in 18 orchards across the 3 county LRGV citrus growing area. C. auricephalus and another indigenous weevil species, Epicaerus mexicanus Boheman, are being trapped in high numbers. To date, D. abbreviatus have been identified in only 2 orchards (near Edinburg,TX) which are under quarantine, with an intensive chemical weevil eradication program therein and coordinated by the Texas Department of Agriculture.

Species 1: Coleoptera Curculionidae Diaprepes abbreviatus (L.) (sugar cane root stalk borer weevil)
Species 2: Coleoptera Curculionidae Compsus auricephalus (Say) (golden headed weevil)
Species 3: Coleoptera Curculionidae Epicaerus mexicanus Boheman (Mexican root weevil)
Keywords: root weevil/disease complex, phytophthora root rot

The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA