Indian River County Extension Service
1028 20th Pl, Suite D
Vero Beach, FL 32960
5 March 2002
FOR RELEASE:10 March 2002
Daniel F. Culbert, County Extension Director
HOMEOWNERS CAN KEEP CITRUS FLY-FREE
Ths past week was the annual meeting of Indian River Citrus growers, who met to learn about the latest trends in their industry. And as most local persons are aware, what happens to this important industry effects our local economy. Besides implementing best management practices to improve water quality, growers are now concerned with an amazing array of marketing and pest management challenges.
One of the perpetual pests that local commercial citrus growers worry about is the Caribbean fruit fly. While it is not as threatening as its Mediterranean cousin, citrus canker disease, or the Diaprepes rootstock weevil, the Caribfly represents a threat to growerís ability to sell their fruit to foreign markets. And, the presence of certain landscape plants in our landscapes can encourage this pest. Todayís column will describe how the Caribfly effects us all, and identify these host plants that should be avoided in local landscapes. Information for this column comes to us from University of Florida Entomologists James L. Nation and Thomas R. Fasulo and from Florida Department of Agriculture sources.
Fruit flies damage Citrus
The Caribbean fruit fly (Anastrepha suspensa) is one of several West Indian fruit fly species.. It has also been called the Greater Antillean fruit fly, the guava fruit fly and the Caribfly. While the larvae of this insect can attack several kinds of tropical and subtropical fruits, guavas, roseapples, and Surinam cherries are severely attacked by this fly when present.
In Florida, only very ripe citrus has been attacked. However, because strains of invasive pests can often act differently outside of their native area, Caribflies are viewed with some concern as a potential pest of commercial citrus, mangoes, and peaches in Florida. The Sunshine state battled with the Caribfly in the 1930's and won the battle. The war was lost in the mid 1960's when another infestation rapidly spread over the state. Today, the known range of this insect stretches southwards from Volusia and Citrus counties.
The adult Carib fly is Ĺ to 2 times larger than a house fly, with rather long, patterned wings. Itís overall color is yellow-brown, with yellow brown wing bands. (The dreaded Medfly is more grey to black in color.) Eggs are laid singly in mature to overripe fruits and hatch in about two to three days. The maggots feed for 10 to 14 days, and pupation for another week or so. The adults emerge, seek a mate, and complete the life cycle. Several generations can occur in a year.
Caribfly has many hosts
Nearly 100 different host plants s have been recorded for Caribbean fruit fly, including several Citrus species. However, the preferred hosts include common guava (Psidium guajava), Surinam cherry (Eugenia uniflora), roseapple (Syzygium jambos), peach (Prunus persica) and tropical almond (Terminalia catappa). Since 1965, Department of Agriculture officials have found that this fly also is highly attracted to cattley/strawberry guava (Psidium cattleianum), Barbados cherry (Malpighia glabra) and the balsamapple (Momordica balsamina).
Many of these hosts plants are not commonly found growing in our area, but there are adventuresome backyard gardeners who try their hands at the unusual and unique. Several are cold sensitive and would normally freeze in our area. Letís learn a bit about these host plants:
Who can resist the temptation of growing a "Florida Cherry" hedge that can produce edible red cherry-like fruit in an exotic landscape? This is the moniker sometimes used to market the Surinam Cherry. I like to tell people about its other common name, pitanga, which approximates the sound made when a sour fruit is spit out. Their one-inch leaves allow for easy shearing, and its small puff-ball flowers are in bloom right now. Because it grows easily from seed, it is a highly invasive weed, is prohibited by some local ordinances. It is not recommended by the University of Florida as a landscape plant where its spread is not preventable.
The roseapple is uncommon in our area, but there are a few around. It is a fast growing tree with 4 to 6 inch long leaves. It is also blooming right now, and produces a delicious summer fruit that, are you ready, tastes like a rose smells. The plant grows easily from seed, and can also invade natural habitats.
Common and cattley guava are large shrubs that are native to tropical America. Thickened evergreen leaves may make them attractive as a landscape plant, and their pear shaped fruits that ripen in the summer are relished by people and wildlife. Considered highly invasive by park rangers and land managers, they also are not recommended by the University of Florida.
Topical Almond trees can be found in some of our warmer locations. Their large spreading habit and rapid rate of growth makes them a questionable choice for most local landscapes. These trees have large red leaves in the fall and the edible fruit that covers an almond-like nut is a novelty. Its seed make it invasive.
Loquat or Japanese Plum trees are also know to harbor these fruit flies. These large-leaved evergreen trees flower in the winter and give rise to yellow-fruited berries that are quite delicious to people and birds, depending upon the individual tree. An impressive landscape tree, the Loquat is not a citrus relative despite its name. Nurseries sell Loquat trees.
Balsam Apple is weedy vine that most homeowners would be happy to be rid of. Their small cucumber-like fruit splits open to reveal a mass of red seed. Despite its rapid growth, it is not listed as an invasive plant, but is considered and undesirable visitor to our landscapes.
Barbados Cherry produces fruit all year round, but is much more prolific in warmer months. Their attractive lacy pink blossom give rise to red skinned "cherries" that are very rich in vitamin C. This shrub is not as aggressive as the rest of these host plants.
Given a subtropical climate, the urge to grow the unusual may encourage these plants to be placed into our landscapes. The result is that the seasonal spread of ripe fruit available for Caribfly egg laying has now been extended well beyond the citrus season. When such host plants are present, the populations of Medflys can expand all year long.
Protecting our Groves
If you were a citrus grower in a country or state that did not have Caribbean fruit flies, would you like it if fruit could be imported into your area and possibly infest your groves with this insect pest? This is exactly the attitude of several foreign countries, including Japan, China, and New Zealand, and is also the reason that our fruit is restricted when being sent to California, Hawaii and Texas.
Local growers who wish to sell their fruit in these markets must show there are no Caribflies near their groves. This certification can be achieved in two ways: fruit growing areas must be maintained under certain sanitary conditions, including the removal of preferred hosts plants from in and around the groves. Second, insect trap surveys are routinely conducted to make sure there are no Caribbean fruit flies in the area.
If either of these two conditions can not be met, citrus groves must be treated with aerial applications of bait sprays that will kill the Caribflies. The area to be treated and the frequency of application will depend on how close a citrus grove is to host plants. Bait sprays are an additional production cost that allow our fruit to be sold abroad. Export fruit sales help to bring profits back to our local economy. And because of this Caribfly protocol, citrus growers need your help.
For new development adjacent to citrus growing areas, developers are prohibited by our County from including these host plants into newly installed landscapes. However, after the homeowner moves in, there are no regulations that prohibit the planting of these host plants. Likewise there is no law that calls for the removal of Caribfly host plants. The fly-free protocol states that it is the responsibility of the grower to negotiate with the property owner for host plant removal. Growers regularly contact property owners to ask for voluntary removal of host plants.
If you have any of these host plants in your landscape, and you are within three miles of a producing grove, consider removing and replacing them with other landscape ornamentals. The actual distance may be less than that in some cases. Our office can help you identify these plants and can suggest alternatives. Our citrus growers are currently making considerable investments in improving our environment and generating a substantial part of our local economy. Will you join them by maintaining a Florida friendly yard and contributing to a vibrant local economy?
You can find the Caribbean Fruit Fly bulletin on the Internet (Featured Creatures ifas.ufl.edu) or come by our office for a printed copy and more information about this profit killing pest. If you need additional information on the Caribbean fruit fly or their host plants, visit our Master Gardeners, or call or stop by our office. For those with other questions about Florida Yards, our office holds Master Gardener Clinic hours at the Extension office (1028 20th Place, Suite D, Vero Beach) every weekday morning and most afternoons, Wednesday morning at the North County Library in Sebastian, and the first Saturday of the month at the Environmental Learning Center. Our phone number is 770-5030, and you can e-mail us at Indian@mail.ifas.ufl.edu .