Use of Landscape Fabric to Manage Diaprepes Root Weevil in Citrus Groves

Abstract

Experiments were conducted at 3 sites in Florida to determine whether landscape fabric, used as soil mulch, can reduce damage to citrus trees by Diaprepes abbreviates. The mulches were intended to prevent newly hatched weevil larvae from entering the soil to feed on roots and to prevent teneral adult weevils from exiting the soil to initiate egg-laying. The weight of aboveground parts of trees at a site heavily infested by D. abbreviatus on the east coast was 70% larger (P = 0.05) for trees grown for 3 years on mulched compared to unmulched soil. Mulching did not affect the amount of feeding damage to roots at the east coast site, suggesting that mulched trees tolerated the damage better than trees in bare soil. Small plot size and relatively narrow fabric dimensions at the east coast site may have facilitated the entry of neonate larvae into soil. At a site on the Central Ridge with low weevil population density, average trunk cross-sectional area of 5-year-old mulched trees was 31% greater (P < 0.02) than trees in bare soil. At both this site and a central flatwoods site, the number of adult weevils captured in ground traps that catch weevils emerging from soil was reduced by up to 99% when traps were installed next to trees on mulch compared to bare soil. Adult weevils did not appear to migrate beneath fabric to emerge at the edges because mean numbers of weevils trapped at the edges of the fabric (2.75 ± 1.01) did not differ (P > 0.05) from those trapped at the same position on unmulched trees (4.38 ± 1.95). Additional work is needed to demonstrate the effect of fabric mulches on weevil population density. Nevertheless, fabric mulches were shown to consistently increase tree growth in weevil-infested orchards. Fabric mulches also eliminate the need for herbicides and potentially insecticides or other IPM tactics to manage root weevil pests.

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