Impact of Pecan Leafroll Mite (Acari: Eriophyidae) on Pecan Foliage

Authors: Pisani, Cristina; Cottrell, Ted

Submitted to: Journal of Entomological Science
Publication Type: Research Notes
Publication Acceptance Date: 9/26/2023
Publication Date: 2/16/2024
Citation: Pisani, C., Cottrell, T.E. 2024. Impact of Pecan Leafroll Mite (Acari: Eriophyidae) on Pecan Foliage. Journal of Entomological Science. 59(1)/86-89. https://doi.org/10.18474/0749-8004-59.1.86.
DOI: https://doi.org/10.18474/0749-8004-59.1.86

Interpretive Summary: Pecan leaf roll mites feed on the edges of leaves causing leaf edge to assume a rolled appearence. Their damage is generally cosmetic and not a significant problem for pecan trees. However, in some orchards the abundance of affected leaves appears to be problematic. Therefore we assessed whether damage by pecan leaf roll mite would impact tree health as determined by affected leaf area, leaf chlorophyll content, and gas exchange parameters. Mite damage did not affect chlorophyll and carbon assimilation rate, but there was a significant difference in leaflet area from compound leaves with mite damage versus without mite damage. However, this difference was only observed during the first sampling date in late July and diminished to non-detectable levels during late August and late September.

Technical Abstract: There are many species of leaf roll mites and most are host specific. Visual symptoms of their feeding damage depend on both the mite and host species but can include galls, stunting, blisters, leaf curl, rust, silvering, russeting of fruit, witches’ broom, stunting and deformities of seedlings. On pecan in early spring, the leaf roll mite, Aceria caryae, feeds on the lateral edge of the upper leaf surface of young, expanding leaflets. Such feeding causes cells on the adaxial surface to grow slower than those cells on the abaxial side, hence forming a gall-like deformation along the lateral leaf margin causing them to curl up in a tight roll. Damage is generally cosmetic and not a significant problem for the host plant. The objective of this study was to assess whether damage by pecan leaf roll mite would impact tree health as determined by affected leaf area, leaf chlorophyll content, and gas exchange parameters. Mite damage did not affect chlorophyll and carbon assimilation rate, but there was a significant difference in leaflet area from compound leaves with mite damage versus without mite damage. However, this difference was only observed during the first sampling date in late July and diminished to non-detectable levels during late August and late September.