INTEGRATED SYSTEMS TO MANAGE PESTS OF CITRUS AND FRUITING VEGETABLE CROPS IN FLORIDA

The objectives of this project are to develop, evaluate and extend to stakeholder integrated programs for management of pests and vectored diseases in citrus and fruiting vegetables. While considerable effort will be focused on insecticides: efficacy, resistance, thresholds, biological and cultural controls will not be ignored. Metalized UV reflective plastic mulch will figure large in both citrus and vegetables. Plasticulture is standard practice for vegetable production in Florida and elsewhere in the Southeast and the use of metalized mulch is widespread. Nevertheless, there are important details that still merit investigation such as effectiveness against pepper weevil, effects on natural enemies and effects of different bed width and height. In contrast to vegetables, use of UV reflective mulch in citrus is totally new. Nevertheless, we have demonstrated good repellence of Asian citrus psyllid (ACP) and reduced incidence of huanglongbing (HLB) in large scale trials and the product tested is still intact after 3 years. Furthermore, early yields have increased 45-90% compared to bare ground. However, many details remain to be worked out regarding bedding equipment, irrigation, fertigation, etc. Biological control is little used in Florida vegetables but we have seen excellent results using predaceous mites for controlling whiteflies, thrips and mites on everything but tomato and mirid predators for whiteflies on tomato. Unfortunately, heavy insecticide use to control ACP has taken a heavy toll on natural enemies in citrus and secondary pest outbreaks are more and more common. One must look toward more efficient use of insecticides by employing economic thresholds and more selective products to promote conservation of beneficial insects and mites, bolstered by releases of Tamarixia radiata. A major outreach effort will also be continued to bring these strategies to stakeholders.

Objective 1 Vegetables Seedlings are transplanted on raised beds covered with white, black or metalized polyethylene film in replicated plots. Insecticides to be tested are either sprayed with a high clearance tractor, drenched soon after planting or applied through drip later in the crop. Pests are monitored weekly in the field and immature stages counted under a stereoscopic microscope. Virus incidence is evaluated by rating all plants from 0 to 4 based on symptoms. Number, size, and weight of marketable fruit are from 6 plants per plot. Data are subjected to ANOVA and means separated by LSD (P = 0.05).Citrus Treatments and an untreated check are randomly distributed in an RCBD with 4 replicates in 5-tree plots with untreated buffers between plots and rows. Foliar treatments are applied to both sides of the trees using an air blast speed sprayer at 100 gpa or low volume "Proptec" at 5-10 gpa.. ACP nymphal populations are monitored on 10 randomly selected shoots per plot examined under a stereomicroscope/ Adults are monitored by 4 "stem tap" samples per tree, 3 trees per plot, taken from randomly chosen branches struck 3 times and counting individuals falling on a white clipboard. Data is subjected to ANOVA and means separated using LSD (P = 0.05).Objective 2 Contingent on funding. additional replicated experiments will be run in highly infected mature citrus blocks to test 4 levels of ACP control: (1) "calendar" insecticide sprays (10-11 per year), (2) sprays based on a high, and (3) low threshold,and (4) an untreated check (no sprays). Treatments (2) and (3) also receive 1 or 2 dormant sprays respectively regardless of counts. ACP numbers will be monitored as above and yields and fruit quality per treatment assessed annually. An economic analysis is will document costs and benefits. Preliminary results indicate that yields increase with intensity of insecticide use profits were greatest for trees treated at the 0.2 ACP/tap threshold. Therefore a conservative 0.1 ACP/tap threshold was adopted for extension purposes. Upon further validation, the threshold system will be promoted for use for regional decision making as part of the Citrus Health Management Area (CHMA) program.Objective 3 Nursery grown grafted citrus trees are planted in commercial groves in beds covered or not with UV reflective mulch 72-90 inches wide 3.5 mil thick. The three layer low-density black polyethylene is metalized on top and covered with a clear polyethylene coat to protect from foliar sprays and UV breakdown. Drip irrigation is by punch in drip emitters or drip tape installed under the mulch which also serves for application of fertilizers and systemic insecticides. ACP is monitored as above, incidence of HLB using qPCR, and tree growth by trunk girth. All fruit is weighed at harvest and juice quality is tested by standard procedures. Costs and benefits are subjected to economic analysis. Stakeholders are engaged directly in the research development and documentation process focusing on field trials in their orchards.Objective 4a Replicated field evaluations of insecticidal programs usable in organic citrus for ACP suppression and products plus releases of parasitoid Tamarixia radiata is being conducted in two commercial blocks of mature orange. Treatments compare organic insecticides alone, or tank mixed and rotated with either horticultural mineral oil or insecticidal soap a conventional standard and an untreated check. ACP populations and HLB incidence and yield are monitored as above. T. radiata from our colony or the FDACS-DPI colony in Dundee is released periodically in all plots. Yellow sticky traps are used to track psyllid movement between plots. Costs and benefits will be subjected to economic analysis at the end of the study.Objective 4b The potential of Nesiocoris tenuis (Hemiptera: Miridae) to control B. tabaci and surrogates of two invasive Lepidoptera will be evaluated in laboratory, field cage and open field tomato crops in Florida. Keiferia lycopersicella, the tomato pinworm, and Helicoverpa zea, the tomato fruitworm will be used as surrogate species for the potential invasive pests Tuta absoluta and Helicoverpa armigera respectively. The objectives would thus be to develop viable biological control alternatives which can be employed now to control B. tabaci in tomato and would then be in place should the two invasive Lepidoptera become widespread and threaten tomato production in the US and neighboring countries. N. tenius is reared on tomato and tobacco plants in bug dorms and fed with eggs of moth Ephestia kuehniella offered ad libitum.Field studies will be conducted in tomato crops interplanted or not with sesame, a preferred plant that supports N. tenuis reproduction in the absence of prey. Mirids are released as adults onto seedlings in cages for a 7 d oviposition period. Whitefly adults and mirid adults and nymphs and plant damage are monitored at weekly intervals. Fruit of marketable size will be harvested from 6 plants and culled for defects. Data will be subjected to ANOVA and means separated using LSD (P = 0.05).Cage studies will be conducted in parallel with field experiments using the same plants and treatments to evaluate effects under confinement.Objective 4c Predaceous mites Amblyseius swirskii and Neoseiulus californicus are often sufficient to control whiteflies, spider mites, broad mites and thrips on pepper, eggplant, and cucurbit crops in Florida. This technology is ready for use by growers but requires adaptation to their methods and conditions. Nevertheless, compatible tools are needed to control pepper weevil. Cultural controls for pepper weevil include shortened crop cycles, crop rotation, field sanitation, and control of nightshade, an alternate host. Natural enemies include the native ectoparasitoid Catolaccus hunteri attacking 3rd instars and a species from Mexico, Triaspis eugenii that attacks the egg but will require renewed permit to bring back into the US. The female wasp homes the anal deposit used by the female weevil to plug the oviposition puncture. It can access the weevil in any size fruit whereas C. hunterii is limited flower buds and small fruit such as nightshade berries. Nevertheless, augmentative release of C. hunteri has been shown to reduce pepper weevil populations and damage. It will be reared using the cowpea weevil Callosobruchus maculatus reared on cowpea as a host. Contingent on funding we would undertake to obtain colonies of C. hunteri and T. eugenii for study, field release and evaluation and develop an artificial diet for pepper weevil based on the boll weevil system.Outreach Field days demonstrating insecticidal, biological and cultrual control in vegetables will be organized at SWFREC with the assistance of Multi-county Cooperative Extension toward the end of fall and spring crops, November and May respectively. Stakeholders will be notified through SWFREC and County Extension websites and directly by email. Field days will feature vegetable research being conducted at SWFREC including field experiments with mirids. Extension articles will be prepared for the UF-IFAS Electronic Data Information Service (http://edis.ifas.ufl.edu/) describing recent advances in biological control of whiteflies in open field vegetable crops. The article will also be reformatted for Trade Journal Publication.