July 2019 - 40

PLANT HEALTH
Using Biopesticides in
Conventional Operations
With their increasing popularity, many growers are looking into biopesticides
to protect their plants. Here are some things to consider.
BY A.R. CHASE
W
e are hearing more today about biopesticides (including
biological agents) than ever before. If you have crops that
are being produced organically, then you are probably aware
of all of the newly registered products coming from both biopesticide
and previously conventional product companies. But what if you are not
trying to grow crops organically? Do you wonder if you should try some
biopesticides in your operation? In this article, I will try to answer some of
your questions regarding biopesticide use as well as dispel some myths and
misconceptions that are still clinging to their use.
MYTHS AND MISCONCEPTIONS
Here are a few of the statements I hear from a variety of growers,
researchers and manufacturer representatives regarding biopestcides
(especially biologicals).
* They do not work as well as synthetic/conventional products.
* They do not have a good shelf life.
* They are not compatible with synthetic/conventional products.
* Applying them once is enough.
* We don't know what they are doing - they are magic!
* They are never phytotoxic and are inherently safe for the environment,
the plant and us.
* You don't have to rotate/alternate products for resistance management.
These statements are each wrong at least as applied to some of the
biopesticides we have registered today. I will share some alternate truths as
supported by research below.
* Some biologicals/biopesticides must be used before the pest pressure
arrives (at seedling, at planting in plugs trays).
* They should be used following (or sometimes with) chemical fungicides.
* Under high disease pressure, they may not perform well.
Many things affect their efficacy, including fertilizer, host plant, pathogen
and even pathogen species.
* Being a better grower makes using biologicals more likely to succeed.
BIOLOGICALS, BIOPESTICIDES AND ORGANIC PRODUCTS
Although some products are biologicals, biopesticides and organic,
not all biopesticides are biological and not all organic products are
biopesticides. Table 1 lists a few of the multitude of organic biopesticide
products including some biologicals (highlighted in column 1). I decided
not to include organic products that are best described as conventional (like
copper and peroxide).
40 JULY 2019 GPNMAG.COM
HOW BIOPESTICIDES WORK
Biopesticides that are not biological control agents (BCA) act more
like synthetic products making them simpler to use in many cases. The
products are typically a combination of a variety of chemicals they make
in culture or are extracted from them. They can be simple but are more
likely to provide a variety of direct and indirect effects. Direct effects would
be lipopolysaccharides that destroy bacterial and fungal cell was (for
example Bacillus). Indirect effects are those that these products trigger in
the host - often referred to as SAR (systemic acquired resistance) factors.
Trichoderma, Bacillus and some plant extracts have been shown to trigger
these plant defense responses.
One of the best examples of how much our knowledge has improved over
the past 20 years is the understanding of T-22 (one of the biologicals in
RootShield PLUS+). Here is a summary of the ways that researchers (often
at universities here and internationally) have discovered they work. This
particular summary was prepared by BioWorks Inc.
* Excludes pathogens. RootShield PLUS+ takes up space in the
rhizosphere and crowds out pathogens. It not only overtakes that
space, it eats nutrients as well - causing pathogens to starve.
* Shields roots. Not only does RootShield PLUS+ grow on the roots, it
shields them from pathogens. It acts as a barrier that pathogens cannot
get through.
* Hunts and eats pathogenic fungi. RootShield PLUS+ seeks out, attacks
and eats fungal pathogens.
* Antagonizes pathogens. RootShield PLUS+ releases anti-pathogen
substances creating a zone that is inhospitable to pathogens.
* Induces host resistance. RootShield PLUS+, with its presence in the
rhizosphere, signals the plant to accumulate defensive compounds,
which give the plant a better defense response in subsequent
encounters with pathogens.
WHAT FACTORS AFFECT USE OF BIOPESTICIDES?
The answer is exactly everything that affects how conventional products
work including: timing, rate and interval, inoculum pressure and crop, tank
mixing or alternation with conventional/synthetic fungicides, the potting
medium, irrigation method and fertility regime, and finally even the exact
species of the pathogen causing the disease.
Mary Hausbeck and her team at Michigan State University performed
extensive research with a few biologicals and a few conventional
fungicides. They tested ability of each product to control several species
http://www.GPNMAG.COM
July 2019

Table of Contents for the Digital Edition of July 2019
