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An Amazing Discovery
Preferal Microbial Insecticide is a naturally-occurring fungus that infects both foliage and soil dwelling insects such as whiteflies, aphids, thrips, weevils, psyllids, leafminers, spider mites, mealybugs, and other pests.  Lance S. Osborne, Ph.D. and Professor of Entomology, University of Florida, Mid-Florida Research and Education Center in Apopka, discovered the Isaria fumosorosea Apopka 97 strain which is the active organism in Preferal.  Preferal is registered by the EPA and is labeled for use in the greenhouse, nursery, landscape and turf markets.

Preferal Microbial Insecticide Benefits

  • Biological insecticide that provides efficacy as good or better than traditional insecticides
  • Broad-spectrum activity on both foliar and soil insects
  • Patented, highly virulent and effective strain
  • Submerge fermented in the U.S.A. under highest QC and process control
  • Contains blastospores which germinate and infect faster
  • Unique mode of action—highly effective for resistance management
  • Easy to use and mix 20% WDG formulation
  • Little or no effect on beneficial insects
  • OMRI listed
  • 4 hour Restricted Entry Interval (REI)

Laboratory culture of Isaria fumosorosea.  Photos courtesy of Dr. Z. Landa, Univ. of S. Bohemia, Czech Rep.

Biological Mode of Action
Preferal is different than other mycoinsecticides in that it is comprised of blastospores of the fungal species Isaria fumosorosea.  Blastospores provide faster germination and infection than mycoinsecticide comprised on conidia.  When blastospores of Preferal are sprayed onto the insect, these spores attach to the insect and then germinate.  The germinated spores will penetrate the outer skin of the insect and grow into and inside the insect.  As the fungus continues to grow inside the insect, the insect will die and will have a darker appearance.  Under optimum conditions white fungal growth may appear outside the dead insect.  The fungus then emerges from the dead insect to release more spores to infect other insects.

Optimizing Preferal Results
The best results can be obtained by using Preferal in an Integrated Pest Management Program, which includes scouting, monitoring (e.g. yellow sticky cards) and early detection of target insects.  Monitoring of pest pressure is critical to the effective use of Preferal.  Efficacy results from germination and growth of the beneficial fungus over several days, so applications should start before pest numbers have reached crisis levels.  Preferal is most effective when application is initiated just before or at the first signs that target pests are present.

Optimal Environmental Conditions
Preferal is most effective when relative humidity is 80% or higher for 8 - 10 hours and temperature is between 68° and 82°.  Watering (irrigating) walkways, operating sprinklers, misters or cooling pads will increase humidity levels.  Apply in the late afternoon or evening to avoid drying from sun and when air movement is lower to retain wetness on foliage surface as long as possible.

Application Techniques
Apply to plants with pressurized spray equipment (such as backpack sprayer, tractor-mounted spray boom, hand-held spray gun or wand, mist blower, cold fogger, electrostatic spray or other application equipment).  Spray sufficient volume to achieve thorough coverage of the plant foliage while minimizing run-off.  Typical spray volumes would be 20 - 50 gallons per acre on small plants material and 80 - 100 gallons per acre on larger or denser plants. 

Preferal has little to no effect on beneficial insects such as bees, ladybeetles, parasitic wasps, predatory mites, and other insect predators (e.g. Orius).  Studies to determine compatibility with other pesticides are on going.  Preferal should not be tank-mixed with fungicides and fungicide applications should be avoided within 5 days of a Preferal application.  Preferal appears to be compatible with most insecticides.  Rotations and tank-mixes with insecticides that are compatible with beneficial insects such as Insect Growth Regulators (IGRs) like Talus® (buprofezin) have proven to be good partners.

Preferal is very stable and will last unopened for 1 year if refrigerated at 40°.  If an application does not require the use of a full 1 lb bag, then squeeze our all air, reseal, store at 40°and use within one month.  DO NOT ALLOW Preferal to FREEZE.

Plant Tolerance
Preferal 20% WDG formulation has exhibited very good plant tolerance.  Before treating plant on a large scale, the user should trial the product under their growing conditions to ensure acceptable crop tolerance.

Characteristics of Preferal Microbial Insecticide


Where to buy: To purchase Preferal Microbial Insecticide, contact your SePRO sales rep or distributor.  May not be registered in all states.  Always read and follow label directions.


Preferal Compatability with Benefits (PDF)

Preferal Application Guide (PDF)

Preferal Specimen Label (PDF)

Preferal Material Safety Data Sheet (PDF)

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