By Gregg Nuessly

Scout your seedlings twice weekly to protect them from the serpentine leafminer. Left unnoticed, high populations of leafminer can kill or stunt young plants.

What to look for

Adult serpentine leafminers are small, black flies with yellow markings. They deposit their eggs into leaves. Larvae emerge within four days to feed on the leaves. The yellow larvae grow to about 1/8 inch long and complete development in 10 to 14 days. Full-grown larvae then cut themselves out of the leaves and travel to the soil or leaf trash to pupate and complete their metamorphosis to adulthood.  

Serpentine leafminers are fly pests of leafy and fruiting vegetables and floricultural plants. Adult females puncture holes in leaves for feeding and egg-laying that result in raised, discolored scars. Leafminer feeding produces white- to green-colored tunnels on the leaves. Leafmining reduces photosynthesis and food availability to the growing plant.

Insecticide use can be justified when an average of more than one mine per plant is found in young leafy vegetables. Protection of wrapper leaves may require more frequent scouting and treatments.

Disk fields to destroy and cover infested crop residues as soon as possible after harvest to reduce infestation of neighboring fields by emerging adults.

Mining damage

Older plants more readily tolerate attacks by this pest. But mining on lettuce and cabbage wrapper leaves, and leaves of flowering broccoli stalks can throw the heads out of grade — even though the damage often is merely cosmetic. High levels of damage result in defoliation of fruiting vegetables.

Rotate to prevent resistance

The use of broad spectrum insecticides can eliminate natural enemies and result in leafminer outbreaks.

The serpentine leafminer developed resistance to most insecticides labeled for its control prior to 1990. Cyromazine and abamectin were labeled for its effective control during the 1990s. Leafminer resistance to these materials, as well as to similar products containing spinosad, has now developed to levels of concern in several U.S. greenhouse facilities.

It is important for growers to continue to strictly rotate these valuable insecticides according to their labels in order to manage resistance development and preserve their efficacy. Concerns about insecticide efficacy should promptly be reported for further evaluation.

Gregg Nuessly is an associate professor at the University of Florida Institute of Food and Agricultural Sciences Everglades Research and Education Center, Belle Glade, (561) 993-1559. E-mail is gsn@ifas.ufl.edu.

Center Updates

Citrus Research and Education Center

Ron Brlansky’s Lake-Alfred, Fla.-based Citrus Research and Education Center lab is conducting research on the three main exotic systemic citrus diseases: stem-pitting citrus tristeza, citrus leprosis and citrus greening. The lab has recently shown that stem-pitting tristeza is preferentially transmitted by the brown citrus aphid.

www.crec.ifas.ufl.edu

Gulf Coast Research and Education Center

The Gulf Coast Research and Education Center in Wimauma hosted the Florida Weed Science Society’s annual meeting Feb. 21-22. Guest speakers included John Wilcut from North Carolina State University, Raleigh, and Janis McFarland from Greensboro, N.C.-based Syngenta. For details, visit the GCREC Web site at http://gcrec.ifas.ufl.edu/FWSS/main.htm.

Indian River Research and Education Center

In an effort to help the citrus industry with one of its troublesome pests, Charles Powell, a professor at the Ft. Pierce-based Indian River Research and Education Center, is studying the use of protease inhibitors to decrease citrus root weevil populations.

www.irrec.ifas.ufl.edu

North Florida Research and Education Center-Quincy

A warm January 2006 was followed by a low temperature of 24 F recorded at the North Florida Research and Education Center-Quincy on Feb. 13. Peaches and nectarines were almost in full bloom, and open blossoms of most fruit crops in north Florida sustained some damage. We expect a full to partial crop of peaches and nectarines, provided that another frost or freeze does not occur.

http://nfrec.ifas.ufl.edu

North Florida Research and Education Center-Suwannee Valley

The Spring Twilight Field Day will be held at the North Florida Research and Education Center-Suwannee Valley in Live Oak, Fla., on May 23 at 5 p.m. A meeting on finding niche markets will begin at 2 p.m.

http://nfrec.ifas.ufl.edu

Southwest Florida Research and Education Center

More than 80 growers attended a citrus workshop Feb. 15 at the Southwest Florida Research and Education Center in Immokalee. The event focused on greening and canker and included “Integrated Management of Citrus Psyllid and Greening,” a presentation by professor of entomology Phil Stansly. 

http://swfrec.ifas.ufl.edu