Professor, Center Director Texas A&M University Weslaco, Texas
The South Texas citrus industry must contend with increasing populations of the citrus leafminer (CLM), Phyllocnistis citrella (Lepidoptera: Gracillariidae), in recent years. Damage to citrus trees by CLM results from larval feeding and formation of mines on young leaves, stems, and even immature fruit. Currently, P. citrella is not considered a key pest in mature citrus groves but large populations can cause serious damage to young trees. In South Texas, patterns of CLM invasion and dispersion in young citrus groves is not well understood. Seasonal variation in leafminer damage to citrus groves could result from increased P. citrella immigration into groves, changes in moth dispersion patterns within groves, and response of ovipositing females to temporal or spatial distribution of preferred young citrus shoots (flush) among grove trees. From February to October 2022, we monitored populations of P. citrella infesting a citrus grove in the Rio Grande Valley that consisted of young (4-year old) Valencia orange trees. During this study, infestations of CLM adults were monitored by AlphaScents PHYCIT lures deployed in Delta traps uniformly distributed throughout the grove. Availability of different flush stages and infestations of immature CLM were assessed by sampling flush shoots of sentinel trees next to the traps. Mortality of immature leafminers and distribution of mines were evaluated at different times following soil-applications of Admire Pro insecticide during the growing season. Based on our findings, we provide recommendations on treatment thresholds for CLM in young citrus groves.
