Controlling Pests While Staying 'Green'

Each decade we seem to come up with a new theme to live by.  The latest are maintaining a “reduced carbon footprint” and being “green”.  It’s time for cut flower growers to jump on the bandwagon and learn to use these themes to sell more cut flowers.  What is more environmentally sound than cut flowers?  Especially if you can grow them without using chemicals that the public perceives as “anti-green”.  Now, if we could just eliminate all of the disease, insect and weed problems this business could really be “green”.  As in cash.

Microbial Pesticides

Microbial insecticides have come a long way and now you as grower have several choices to use in your cut flower production.  What are microbial insecticides?
Microorganisms, including bacteria, fungi, and viruses, are the active ingredient of microbial pesticides.  Some microbials control plant pathogens, usually on a preventative basis, and some control insects and mites.  In some cases the microbial insecticide may be specific, such as Bacillus thuringiensis  (Bti), which controls fungus gnat larvae and mosquito larvae. Others, such as the fungus Beauveria bassiana, control several species of insects including whiteflies, aphids, and some caterpillars.  The most widely known microbial pesticide is Bacillus thuringiensis (Bt), which is used to control a variety of early-stage caterpillars.  Most cut flower growers can readily obtain Bt under several brand names such as Dipel, Thuricide, or Caterpillar-Attack, to name a few on the market.  Bt is very effective on the early life stages of several lepidopterous caterpillars that feed on cut flower crops.

Pathogens That Attack Thrips

In 2007 we started working with Novozymes Biologicals Inc. of Salem, Virginia, to evaluate a fungus called Metarhizium anisopliae, strain F52, for potential control of thrips.  In the first phase of our trial we evaluated different sprayers to see if we could get an even spore count in a growing area.  We placed out petri dishes and cover slips to collect spores applied to the plants by the growers. Our next phase is to evaluate what sort of reduction can we obtain with thrips populations feeding on plants.  A representative of Novosymes expects to have EPA approval by spring of 2008.  We’ll keep you posted.

Reduced-Risk Pesticides

Starting in 1993 the federal EPA has expedited the registration of conventional pesticides that had very low toxicity to humans and nontarget organisms including fish and birds, low risk of groundwater contamination or runoff,  and a demonstrated efficacy and compatibility with IPM.  EPA refers to materials meeting these criteria as “reduced risk”.  The reduced-risk designation applies only to certain uses of a particular pesticide, which may not include all label uses for that product.  Reduced-risk products/uses must be registered with EPA and labels will bear EPA registration numbers.  Manufacturers, however, aren’t permitted to label materials as “reduced risk.”
Floramite (bifenazate) (EPA# 400-481) , Akari (fenpyroximate), and Shuttle (acequinocyl) are three low-risk miticides.  Reduced-risk insecticides include Endeavor (pymetrozine) (100-613), Tristar 70 WSP (acetamiprid), Flagship (thiamethoxam), Celero 16 WSG (clothianidin), Aria (flonicamid), and Pedestal (novaluron).
Dow AgroSciences’ Tebufenozide (Confirm), an insect growth regulator (IGR) for caterpillars, is also a reduced-risk pesticide for ornamentals.  Some insecticides such as spinosad (Conserve) are considered reduced risk for certain non-ornamentals applications only.  Conserve is not presently classed as a reduced-risk pesticide.  Other reduced-risk pesticides for use on ornamentals include Heritage fungicide (azoxystrobin) (10182-408), Decree (fenhexamid),   Subdue (mefenoxam) 2X WSP (100-795), and Subdue Maxx (100-796) for ornamentals, and Compass (trifloxystrobin) (100-920) for ornamentals.

Stay Green

Keep making the green that you can spend this summer and try to stay on the green side with your pesticide selection.

Stanton Gill

Extension Specialist

Stanton Gill is an extension specialist (professor-ranked principal agent) in IPM and entomology with the University of Maryland Extension, based at the Central Maryland Research and Education Center in Ellicott City. He is also a professor in the Landscape Technology Program at the Germantown Campus of Montgomery College. Contact him at [email protected]

Shannon Wadkins


Shannon Wadkins is Technician at CMREC, University of Maryland Cooperative Extension. Contact them at [email protected]