Whitefly Information & Control

Check Below for New Information as of July 2014

 

Update: July 11, 2014

 

The Village Arborist, John Sutton, inspected Village trees in public areas on June 23, 2014 and found no infestation of the rugose spiraling whitefly. No pest control or other preventative measures are needed.

 


 

 

A new type of whitefly infestation on trees, palms, shrubs and fruits was identified in public areas and private properties in the Village of Key Biscayne in 2011. The gumbo limbo spiraling whitefly, a leaf-sucking insect, was first observed in Miami-Dade County on a gumbo limbo tree in March 2009. The pest is believed to originate in the Caribbean/Central America.

Since the insects have been seen on several types of trees and palms in South Florida they are now referred to as rugose spiraling whiteflies. This species is different from the ficus whitefly that defoliated ficus hedges throughout the area several years ago.  According to Dr. Catharine Mannion, a University of Florida Associate Professor and Extension Specialist based in Homestead, the type and amount of damage caused by rugose spiraling whiteflies is dependent on the plant, and different plants may show different symptoms of infestation. Leaf drop occurs in some plants but others do not drop their leaves at all.

 

Follow the links below to jump to different sections of this long page for specific information and updates:

 


Update - February 10, 2012

The Public Works Department received a Rugose Spiraling Whitefly Report on January 24, 2012 from the Village Arborist and Pest Control contractor (Trugreen) that summarized observations made to assess the effectiveness of the public area treatment program initiated in August 2011 (see August 1, 2011 update below). TruGreen treated approximately 2,500 trees and palms; the Village has about 5,000 trees and palms along public rights-of-way and in parks. The systemic Neonicotinoid insecticide has been shown to be effective for approximately six months.Treated trees are identified by green dots on the trunks. Monitoring of the effectiveness of the systemic treatment has been ongoing.

The experts visited streets with Gumbo Limbos on January 12, 2012. Gumbo Limbos infested by whitefly have comprised 100% of complaints made to the Village by residents in November 2011, December 2011 and January 2012. The results of the field assessment are as follows:

 

  • Both experts observed active whitely adults flying in the air but inspections of the treated trees in January 2012 show no active, established infestations This indicates the treatment is working and is proof that the insecticide has traveled up the tree from the root area, resulting in the death of early stages of the whitefly after eggs have hatched. Adult whiteflies will continue to be observed around both treated and untreated trees. Flying adult flies originate from untreated areas and land on treated trees to lay their eggs. When the eggs hatch, the immature insect is killed when it begins to feed on the treated trees and new infestation is prevented. The larvae and juvenile whitefly suck nutrients from the trees and produce a black, sticky substance called honeydew.  These sucking stages of the whitefly were 100% dead in inspected gumbos, showing that treatment by injection in Gumbo Limbos is effective.  Injections of the systemic Niconoid anti-whitefly insecticide have been proven to be the most effective treatment for hardwood trees, not drenching. Drenching is effective for palms and hedge plants.

  • Even though active infestations were not found, the Pest Control representative met with three residents who made complaints and re-treated several trees for extra assurance at no cost to the Village.

  • Gumbo Limbos are beginning to naturally drop their old leaves that are covered with old honeydew. This is good news for residents who are filing complaints about sticky residue from the Gumbo Limbo street trees on the public right-of-way in front of their homes. Once the new leaves grow there should be no new honeydew on the street trees, assuming the treatment chemical stays active.

  • The experts do not recommend pest control application in Winter since lower temperatures slow the metabolic rate of the cells in the trees. This lowers the requirement for water and nutrients as the trees are in a quasi-dormant state. It is not the optimum time for tree to absorb the anti-whitefly chemicals applied by injection treatment and distribute them upward to the branches and leaves.

  • Recommendations:
    • The Village Arborist will conduct a Village-wide inspection in the Spring to once again identify the highest to medium-highest infected areas. If funds are approved by the Village Council the Public Works Department will continue with the systemic pest control method recommended by the experts. These treatments are by injection for hardwoods and by drenching for palms and hedge plants.

    • Since the recommended systemic treatment does not hurt whitefly predators such as the lacewing, the Village Arborist will also look for predators in his inspections. Natural predators such as the lacewing have been observed feeding on young whitefly stages in neighboring municipalities such as Coral Gables confirmed. They have not yet been idenitified in the Village. No additional information has been obtained on the wasp predator introduced by entomologist Dr. Catharine Mannion.

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Update - August 1, 2011
Treatment of gumbo limbo trees and palms in the public right-of-way and parks against rugose spiraling whitefly began on Monday, August 1. The duration of the project is estimated to be 3 weeks.

Residents are advised that personnel and trucks carrying 500-600 gallon tanks will be working throughout the Village from August 1 through the third week of the month. Personnel will be wearing TruGreen logo shirts and equipment also will be clearly marked.

The focus of the treatment program will be in areas with the highest whitefly infestations as previously identified by the Village's consulting arborist. Systemic Neonicotinoid treatment will be applied via injection or drenching to approximately 2,500 trees. Gumbo limbos will be treated via injection. This treatment method showed immediate results in a test conducted in a small area of the Village with intense infestation.  Whitefly-afflicted palms will be treated by the drench method.

TruGreen will extend the pricing schedule given to the Village to residents for treatment of vegetation on private property. Interested individuals should contact Fred Hein, TruGreen's Commercial Sales Representative, at FredHein@trugreenmail.com. Email is the preferred method of communication but Mr. Hein also can be reached at (305) 218-4861.

Should you have any questions about the scope of this project, please call the Department of Public Works at (305) 365-8945.

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Update - June 21, 2011

Follow this link to a video of a June 16, 2011 interview with Dr. Mannion at her lab in Homestead, where she answers frequently answered questions about the whitefly infestation and treatment options. The interview also aired on Channel 77, the Village's public access cable channel.

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Update - June 16, 2011

Dr. Mannion presented new data and an array of photographs of the whitefly's life stages and what they look like on affected plants at the Rugose Spiraling Whitefly Workshop held on June 7, 2011 in the Island Room of the Community Center.   Dr. Mannion's June 2011 Powerpoint presentation, "Whiteflies in the Landscape", is available here as a PDF (Warning: Large 3.4 MB file).

In addition, she discussed natural and pesticide/insecticide treatment options as well as the importance of trying to preserve natural pests of the whitefly. The most promising treatment seems to be the application of a systemic (neoniconitoid) insecticide to the trunk or soil above the root system of the affected tree. A list of neoniconitoid insecticides is given here (pg. 32 of Dr. Mannion's PDF). These treatments can be applied to the soil (via drench, granular or pellets) or to the trunk (via basal spray or injection). It may take several weeks to take effect but control lasts approximately one year.  Please be aware that some of the insecticides on this list contain a Neonicotinoid and a pyrethroid. Pyrethroids may harm beneficial garden insects as well as kill the whitefly, so it is advisable to use other formulations.

Foliar applications are another option and provide quick control instead of long-term results in most cases. A list of professional (landscape) and homeowner insecticides is given here (pg. 36-38 of Dr. Mannion's PDF). For this treatment to work, several conditions must be met. Whiteflies should be present. Some foliar insecticides (i.e., pyrethroids) may disrupt the natural enemies and should be used very selectively. Use of the same insecticide on both the foliage and in the soil is NOT recommended.

This link is to whitefly control information provided by the Public Works Division to residents' telephone and email inquiries as of June 16. This document is updated as new information is received.

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Symptoms of Whitefly Infestation and Affected Plants

Common noticeable symptoms are an abundance of white, waxy material covering leaves and fronds, a sugary substance called "honeydew" produced by the leaf-sucking insects, and excessive dark sooty mold on leaves or fronds that grows on the honeydew.  An infestation does not typically kill healthy plants, but can be disfiguring and cause some damage or plant decline. The presence of the white waxy substance, excessive sooty mold and honeydew often appears to be more of a concern or nuisance to property owners.

According to a Fact Sheet titled "Rugose Spiraling Whitefly - A New Whitefly in South Florida" (PDF), authored by Dr. Mannion and distributed by the University of Florida/Institute of Food and Agricultural Sciences (IFAS), early infestation is apparent on the underside of leaves as adult whiteflies gather to feed and reproduce. The best early sign is the highly visible eggs laid in spiral patterns on leaves and fronds. Adult whiteflies are more obvious as the infestation starts to build. The Fact Sheet (PDF) contains more detailed information as well as photos of rugose spiraling whitefly life cycles and what infestations look like on different plant species.

Village of Key Biscayne officials are monitoring public area plantings for occurrences, and have treated affected trees and palms in the Village Green and along roadways. Homeowners are encouraged to inspect their gardens and take action to control this pest.

John Sutton, the Village's Consulting Arborist, inspected plants in the Village Green and other public areas in December 2010. Spiraling whitefly was identified on Pink and Yellow Tabebuia, Gumbo Limbo, Live Oak, Pongam, Mahogany, Calophyllum, Kapok, Pigeon Plum and Pithecellobium trees. Palm hosts include Alexander, Adonidia, Coconut and Reclinata species. Shrubs with the whitefly are Barbados Cherry hedge, Gold Mound Duranta, Oleander and Clusia rosea. Please note that other plants may be affected. This list will be updated as subsequent surveys are completed. The next public area survey by the Village Arborist and a Urban Horticulture Agent from the County Extension Office will take place on May 2, 2011.

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How to Manage Whiteflies: Natural and Chemical Methods

If you have any of these plants in your garden, it is in your best interest to inspect them for early signs of rugose spiraling whitefly infestation. Pest management is easier when populations are small. If you notice the invader on a tree or shrub, check nearby plants as well since the spiraling whitefly feeds on many species. Remember to always follow the directions on insecticide labels since "the label is the law."  You may want to consult a landscaping professional for assistance in applying these products. A discussion of management techniques and lists of available treatments are included in the Fact Sheet by Dr. Catharine Mannion titled "Rugose Spiraling Whitefly - A New Whitefly in South Florida" (PDF) and distributed by the University of Florida/Institute of Food and Agricultural Sciences (IFAS).

For small infestations or on small plants, the following actions are suggested:

 

  • Wash off the eggs and immature stages of the whitefly with water.

  • Thorough coverage of infected leaves with horticultural oil or insecticidal soap also is effective.

  • Repeat treatment in 7-10 day intervals as needed.

For heavily infested trees or shrubs the Village recommends that you contact a pest control company. Treatment is usually by a contact insecticide applied to leaves as a spray, by a systemic insecticide applied to the root/trunk system as a drench, or both. Another approach is to let "nature take its course" and treat only in certain situations, as described below.

 

  • Contact (leaf spray) insecticide applications show short-term results but can kill many beneficial garden insects such as lady bugs that are natural predators of many pests. Dr. Mannion reports that the foliar treatment is not always necessary, its effectiveness does not last very long (a few weeks) and often is detrimental to natural enemies of the whitefly. She typically recommends it when the infestation is severe to help knock down the adults. Foliar sprays alone are not going to solve the problem. Follow this link to a list of foliar insecticides provided by Dr. Mannion.

  • Systemic insecticide applications to the root system are less toxic to beneficial insects but take up to four weeks to show results, as the insecticide travels through the roots and trunk to branches and leaves. Dr. Mannion states that even though tests on the effectiveness of systemic products have not been conducted, these treatments should provide a minimum of 6 months of control if not longer. Follow this link to a list of neoniconitoid systemic insecticides provided by Dr. Mannion.

  • Some municipalities in South Florida are, for the most part, letting "nature take its course" to control the infestation. Historical information shows that natural predators of newly introduced pests develop over time and then keep the pests at lower populations. Systemic insecticides are applied in certain cases where a particular plant is of high value or infested trees are located over parking areas. Control is warranted in these situations, says Dr. Mannion, since the honeydew, sooty mold and white waxy substance are high-impact nuisances.

  • Another recommendation to help plants fight off the pest is to apply an appropriate fertilizer to trees or palms when still healthy to encourage growth.

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