Resource Guide for Organic Insect and Disease ... - Cornell University

FORMULATION AND APPLICATION GUIDELINES:
Both liquid and powder formulations are available. In one study, an ES (emulsifiable
suspension) formulation showed better ability to withstand rain than the comparable
WP (wettable powder) form. Read labels for specific application guidelines, including
determination of reentry interval (REI) and pre-harvest interval (PHI).
For some pest species, a baited formulation may be most effective (Bextine and Thorvilson
2002); however, no baited formulations are currently OMRI Listed.
GENERAL GUIDELINES: Range of efficacy will depend on the susceptibility of the species in
question, pest population levels, and environmental conditions at time of application; however,
there are several important considerations for this product:
1. Look before spraying.
Apply only when the insect is seen on the plant, and do not apply as a preventative
spray because the residue may be gone in a few days.
2. A single application may not be sufficient.
Since the fungus is rapidly broken down by sunlight and washed off the plant by rain,
multiple applications may be required to provide adequate control. The product is
best used as a suppressant rather than an eradicant, and thresholds (i.e., treatment
guidelines) developed for other products may not be appropriate. There is evidence
that the fungus can overwinter in insects and may suppress pest populations over the
long term, especially with repeated applications (Groden et al. 2002).
3. Use against earlier stages of the insect.
B. bassiana is more effective on younger stages of insects than on older stages (e.g.,
large larvae or adults).
4. Consider compatibility.
Do not tank mix with any fungicides not allowed on the label (note: the Mycotrol label
states that it is compatible with “some fungicides”). Applying subsequent fungicide
sprays within 4 days after a B. bassiana application may also reduce its efficacy. Note
other label cautions about tank-mixing with adjuvants or other materials.
5. Humidity is a factor.
Beauveria is likely to be more effective in farm microclimates with high relative
humidity, such as valley bottoms (Lo et al. 1999).
6. Watch for phytotoxicity.
There have been some reports of phytotoxicity to young tomato greenhouse
transplants with an ES formulation, so testing prior to large-scale application is
advisable.
AVAILABILITY:
B. bassiana is widely available from garden and farm supply mail order companies. Be sure to
verify registration status in the state where it will be used.
OMRI LISTED PRODUCTS:
Mycotrol O (Laverlam International Corp.) Beauveria bassiana strain GHA
References to OMRI listed products in this Guide are based on the 2012 edition of the OMRI
Product List. Please consult www.omri.org for changes and updates in the brand name product
listings.
EFFECT ON HUMANS AND THE ENVIRONMENT:
Humans: There are no expected health risks to humans who apply this insecticide
or to people who eat the crops that have been treated with the fungus. The two
commercial strains of B. bassiana (GHA and ATCC 74040) have been tested against
rats and rabbits, and the results indicate they are not considered to be pathogenic,
infective, or toxic. Precaution should be taken, however, as they can be skin, eye, and
lung irritants.
114 Organic Resource Guide