Damage by Infestations of Texas Citrus Mite (Acari: Tetranychidae) and Its Effect on the Life of ‘Valencia’ Leaves in an Irrigated Citrus Grove

Authors

  • David G. Hall
  • Michael K. Simms

Abstract

Studies were conducted during 1996-1999 to evaluate damage to citrus leaves by the Texas citrus mite, Eutetranychus banksi (McGregor), and its impact on leaf longevity in irrigated citrus. Natural mite infestations were followed in a citrus orchard (‘Rhode Red Valencia’) under irrigation management, and damage to leaves and leaf abscission were assessed periodically. The number of feeding stipples per cm2 on the upper leaf surface was used as an index of feeding damage. A variable ‘mite-days’ [average number of mites per leaf multiplied by the number of days of infestation] was used to characterize infestation densities over time. Increases in average numbers of stipples per cm2 per leaf (Y) across different mite-day values (X) were described by the equation Y = 44.08 + 0.59X (r2 = 0.57). A model including temperature was marginally better. The final mean density of feeding stipples on infested leaves for the 1996, 1998 and 1999 evaluation periods averaged 327, 134 and 873 per cm2, respectively, with an overall mean of 470. Leaf life from the date of full expansion until abscission averaged 443, 387 and 380 days for the respective periods, with an overall average of 399 days. The observed life of the leaves was typical to what has been observed in Florida citrus. Overall, no significant negative relationship was found between leaf life and mite damage. The study indicated that damage by Texas citrus mites to ‘Valencia’ citrus leaves promoted little or no premature leaf abscission in irrigated trees.

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Published

2003-03-01

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Section

Literature Review Articles