Isaria fumosorosea Apopka Strain 97

Paecilomyces fumosoroseus Apopka Strain 97 has been reclassified and is now known as Isaria fumosorosea Apopka strain 97. It is a naturally occurring fungus that infects and kills several kinds of insects. 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 is a biological insecticide that provides efficacy as good or better than traditional insecticide with broad-spectrum activity on both foliar and soil insects. It is patented, highly virulent and effective strain whereas the submerge is fermented in the U.S.A. under highest QC and process control. It contains blastospores which germinate and infect faster. The unique mode of action of Preferal makes it highly effective for resistance management. Preferal is easy to use and mix, has 20% WDG formulation and has little or no effect on beneficial insects. Preferal OMRI listed and has only 4 hour Restricted Entry Interval (REI).


Target Pests: whiteflies • aphids • thrips • spider mites • broad mites • rust mites • leafminers • citrus leafminers • mealybugs •psyllids • black vine and other root weevils • rootworms • wireworms • Coleoptera grubs and larvae • Japanese beetle • Lepidoptera caterpillars and larvae • symphylans.

Mode of Action: Isaria fumosorosea, the active component in PFR-97, is a naturally occurring fungus which infects many insect and mite pests that occur on foliage and other above ground plant, as well as many soil-dwelling pests. Under proper environmental conditions, spores of the fungus attach to and penetrate the cuticle of the target pest. The fungus grows inside the insect causing its death. The fungus then emerges from the dead insect to release more spores to infect other insects.

Monitoring of pest pressure is critical to the effective use of PFR-97. Efficacy results from germination and growth of the beneficial fungus over several days, so applications should start before pest numbers have reached crisis levels. PFR-97 is most effective when application is initiated just before or at the first signs that target pests are present.

Application Tips: Mix Isaria fumosorosea in clean water at a rate of 14 to 28 ounces of product per 100 gallons of water. Agitate for 20-30 minutes before application to ensure a well-dispersed suspension.

Product may be premixed with 5 gallons of water per pound and agitated continuously for 20-30 minutes to completely suspend and hydrate the spores. Dilute this suspension to the final volume for application. This suspension can also be metered (injected) into a chemigation system without further dilution if desired.

Maintain agitation during application. Apply the suspension using one of the methods below, depending on target pest and application site (foliar or soil).

Optimal Environmental Conditions: Isaria fumosorosea is most effective when relative humidity is 80% or higher for 8-10 hours. Irrigating will increase humidity levels. Application at times of low air movement and moderate temperature (70-90°F) will reduce drying conditions and maintain the effectiveness of the fungus.

Compatibility: Isaria fumosorosea can be used in conjunction with most other pesticides and is compatible with beneficial arthropods. It can be mixed with copper-based fungicides without impacting performance. However, do not mix with other fungicides, or apply within 5 days of fungicide applications other than copper. Isaria fumosorosea can be mixed with most insecticides for which such mixing is permitted by the label, in accordance with the most restrictive label limitations and precautions of all products used in the mixture. Do not exceed any label dosage rates. However, physical compatibility should be checked by mixing small quantities of each tank mix partner in correct proportions (“jar test”) prior to the first time such a mixture is attempted.

Precautions and Safety Equipment: Minimize your exposure to pesticides.  Avoid contact with eyes.  Wear eye protection, long pants, a long-sleeved shirt, and a hat that can be washed after each use.  Always read label of individual product for additional directions.

Personal Protective Equipment:

Applicators and other handlers must wear:  Long-sleeved shirt and long pants. Shoes plus socks.

Mixers, loaders, applicators and other handlers must wear a dust/mist filtering respirator (MSHA/NIOSH approval number prefix TC-21C), or a NIOSH approved respirator with prefix N-95, R-95, or P-95.

Follow manufacturer’s instructions for cleaning and maintaining PPE. If no such instructions for washables, use detergent and hot water. Keep and wash PPE separately from other laundry.

Selected References

Isaria fumosorosea (formerly Paecilomyces fumosoroseus) Apopka Strain 97 (115002) Fact Sheet