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ENY623 2002 Florida Citrus Pest Management Guide: Citrus Leafminer1 H.W. Browning, P.A. Stansly and J. Pea2 1. This document is Fact Sheet ENY-623, part of the 2002 Florida Citrus Pest Management Guide, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Date printed: December 1995. Date revised: October 2001. For a copy of this handbook, request information on its purchase at your county extension office. Please visit the EDIS Web site at http://edis.ifas.ufl.edu. 2. H.W. Browning, center director, Citrus REC, Lake Alfred, Florida; P.A. Stansly, professor, entomologist, Southwest Florida REC, Immokalee, Florida; J. Pea, professor, entomologist, Tropical REC, Homestead, Florida; Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611. The use of trade names in this publication is solely for the purpose of providing specific information. It is not a guarantee or warranty of the products named, and does not signify that they are approved to the exclusion of others of suitable composition. The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Service/Institute of Food and Agricultural Sciences/University of Florida/Christine Taylor Waddill, Dean. Citrus leafminer (CLM) can occur on new flush throughout the growing season but typically affects little of the important spring flush. Since subsequent flushes do not account for significant portions of the total leaf crop on mature trees, CLM damage generally does not significantly affect growth and yield except on young trees. Under southwest Florida conditions, the cutoff point has been shown to be about 4 years of age. Less damage could be expected in more northerly locations. Nursery stock and young resets are most affected by CLM injury. Leafminer populations build on flush growth. Thus, grove practices that will deter winter flushes should be encouraged. A strong synchronized spring flush should offset the loss of small sporadic winter flushes. Climatic conditions will ultimately determine flushes; however, irrigation and fertilization during the winter should be restricted to the maintenance of tree health. Mechanical hedging should be delayed if possible until cooler winter temperatures prevail, thus limiting regrowth. Irrigation and fertilization should be initiated in early to mid January, slightly in advance of the anticipated spring flush. Natural enemies already present in Florida have responded to CLM infestations, causing in excess of 50% mortality of larvae and pupae in some areas. The introduced parasitoid Ageneaspis citricola has established throughout most of Florida, with rates of apparent parasitism reaching 90% or more. Thus, biological control makes a significant contribution, even where chemical control may be required, and therefore should be conserved by avoiding unwarranted pesticide use, especially of broad spectrum insecticides. The citrus leafminer development period from egg to adult is as short as 14 days. Within this cycle the susceptible larval stage may occupy only 4-5 days. Thus, pesticidal applications for control of CLM will only affect a small proportion (larvae) of the population. Furthermore, residual activity of pesticides is limited by rapid appearance of new and unprotected flush, so that 14-21 days control is the best that can be expected, even under ideal conditions. Scouting is therefore necessary to determine peak periods of larval activity during flushing periods when chemical suppression might be
2002 Florida Citrus Pest Management Guide: Citrus Leafminer 2 justified. A scouting program should be initiated to monitor CLM development when 50% of the trees are producing flush. Pesticidal control should be considered only when the new flush is anticipated to constitute about 20% of the entire leaf area. Under these conditions, application should begin when about 30% of the flush leaves show active mines to maximize the susceptibility of larvae and thus have the greatest impact on CLM populations. Pesticides should be rotated to reduce selection for resistance. Since CLM affects only developing leaves, coverage of peripheral leaves in the canopy should be adequate to exert suppression when applying pesticides for CLM. The products listed in Table 1 for CLM management have consistently been shown to be the most effective. To be consistent with other tables, per acre rates are based on fully mature trees. Therefore, the rate shown in 250 gallons of water should treat several acres of small trees. Recommended Chemical Controls READ THE LABEL. Rates for pesticides are given as the maximum amount required to treat mature citrus trees unless otherwise noted. To treat smaller trees with commercial application equipment including handguns, mix the per acre rate for mature trees in 250 gallons of water. Calibrate and arrange nozzles to deliver thorough distribution and treat as many acres as this volume of spray allows.
2002 Florida Citrus Pest Management Guide: Citrus Leafminer 3 Table 1. Recommended Chemical Controls for Citrus Leafminer (Nonbearing/Young Bearing Citrus) Pesticide Mature Trees Rate/Acre Comments Other Pests Controlled Agri-Mek 15 EC + Petroleum Oil 97+% (FC 435-66, FC 455-88, or FC 470-01) 5 oz + Min of 1 gal Do not apply within 7 days of harvest. Do not apply within 30 days of last treatment. Do not make more than 3 applications or apply more than 40 fl oz/growing season. No more than 1 application per year recommended to avoid pest resistance. Always apply with horticultural spray oils as directed. Do not apply in citrus nurseries. Do not apply by aircraft. FC 470-01 has not been evaluated for effects on fruit coloring or ripening. These oils are more likely to be phytotoxic than lighter oils. Citrus rust mite, citrus bud mite, broad mite Micromite 25 WP + Petroleum Oil 97+% (FC 435-66, FC 455-88, or FC 470-01) 1.25 lb + Min of 1 gal One application per season. See restrictions on the label. Do not apply when temperatures exceed 94F. FC 470-01 has not been evaluated for effects on fruit coloring or ripening. These oils are more likely to be phytotoxic than lighter oils. Citrus root weevils, citrus rust mites Micromite 80 WG + Petroleum Oil 97+% (FC 435-66, FC 455-88, or FC 470-01) 6.25 oz + Min of 1 gal Micromite 4 L + Petroleum Oil 97+% (FC 435-66, FC 455-88, or FC 470-01) 10 oz + Min of 1 gal Petroleum Oil 97+% (FC 435-66, FC 455-88, or FC 470-01) 5 gal Do not apply when temperatures exceed 94F. FC 470-01 has not been evaluated for effects on fruit coloring or ripening. These oils are more likely to be phytotoxic than lighter oils. 1 Lower rates may be used on smaller trees. Do not use less than the minimum label rate.