September 2022 - 21

BIOCONTOLS & BIOPESTICIDES
Fig. 2. Trichogramma pretiosum wasp on
moth egg. Photo: Max Badgley.
parasitize pests when they are at their
larval stage, so their application should be
synchronized when the targeted pest is at
this stage. They have proven to be effective
biocontrol agent against the cranberry
fruitworm, sparganothis fruitworm,
red-headed flea beetle and the cranberry
girdler. Similarly, multiple species of
parasitic wasps in the genus Trichogramma
are available commercially and can be
easily bought by the billions. Different
indigenous species, such as T. pretiosum
(Fig. 2) in Wisconsin, have been found
naturally parasitizing different cranberry
pests. They are also typically reared on
a factice host (usually sterilized eggs of
the Mediterranean flour moth) in insect
rearing facilities. They are applied as pupae
parasitizing their factice host egg, and they
emerge as adults in the days following
their application. Freshly emerged adults
then mate and go on looking for moth
eggs. Therefore, their application should
be synchronized with the targeted pest's
flight, which is also approximately their
egg-laying period. They can either be
applied manually (stuck on cardboard
pieces spread across the fields), or
mechanically. Direct injection spraying
devices are currently being developed in
Quebec, to allow Trichogramma pupae
application in water (just like any other
pesticide), which make it possible to apply
them at a large scale quickly with limited
human resources. Their application rate is
around 1 million per acre, but their adult
lifespan is around 2 or 3 days, so they must
be applied two to three times during the
pest's flight to maximize results. Neither of
these two augmentative biocontrol agents
have a detrimental effect on the crop,
but their establishment on the marsh is
expected to be limited. Thus, they must
be reapplied year after year, similar to
insecticides, minus the risks to human
health and the environment.
Conservation
Implementing conservation biocontrol
can be accomplished via the establishment
of flower patches (such as pollinator
gardens) or allowing weeds on marsh
edges to flower, as these would provide
nutritional resources, in the form of nectar
and pollen, and habitat that would provide
nesting areas, refugia from pesticide
sprays, and hibernation sites. Reducing
the number of insecticide applications and
using reduced risk pesticides would also
greatly benefit natural enemies and should
be considered throughout the season. For
example, implementing a spring flood
helps reduce the use of insecticides. A 30hour
spring flood in late May was shown
to be as effective as a broad-spectrum
insecticide application of Chlorpyrifos
in reducing the numbers of black headed
fireworm, cranberry fruitworm, and
sparganothis fruitworm, while supporting
more biocontrol agents in the form of
spiders and parasitoids in flooded beds
compared to sprayed beds (van Zoeren
et al., 2018). Parasitism rates were also
shown to be higher on neglected marshes
where they reached close to 50% of
cranberry fruitworm egg parasitism by
the parasitic wasp T. pretiosum (Fig. 2;
Simser, 1995), with similar observations
in British Columbia with blackheaded
fireworm eggs (Li et al., 1993).
These high parasitism rates can be
linked to the fact that very little to no
insecticides were used on those marshes
since most broad-spectrum insecticides
not only kill pest species, but also natural
enemies. Marshes implementing IPM
strategies were observed to foster natural
enemy communities thereby benefiting
from natural biocontrol and minimizing
crop losses. For more information on how
to select pesticides, please see this Oregon
State publication or download the app
" Reduce bee poisoning from pesticides " .
In summary, the two biological
control strategies that are the most
relevant to cranberry at this time
are augmentation and conservation.
Augmentation biocontrol would require
purchasing commercially-available
natural enemies such as parasitoid
wasps or nematodes and releasing
them at the appropriate times and in
the right amounts to best target the
pest species. Conservation biocontrol
could be implemented with minimal
input by providing floral resources and
habitat, reducing pesticide usage, and
using reduced-risk pesticides to foster
naturally-occurring populations of
natural enemies. FGN
®
FAST & EFFECTIVE ORGANIC WEED CONTROL
SUPPRESS® Herbicide EC , the market leader
in certified organic herbicides, was the first
effective herbicide to be approved for use on
all certified organce food crops. With years
of grower-proven efficacy and university
testing, SUPPRESS Herbicide's patented and
proprietary formulation consistently provides
fast and effective burndown on a wide variety
of grasses and weeds.
SUPPRESS®
Check
ADVANTAGES
■ Excellent tool in IPM programs
■ Helps break chemical resistance
■ No pre-harvest interval or MRLs
■ Low-foaming and easy-to-use
■ Highly effective pre-harvest desiccant
Herbicide EC consistently demonstrates fast and effective
burndown in years of university and field trials.
Grower Trial, 2017
d-limonene (10%)
100
120
20
40
60
80
3
Check
Check
Check
d-limonene (10%)
100
120
20
40
60
80
WESTBRIDGE IS NOW GROWING AS SAN AGROW
Call (760) 599-8855 or visit www.san-agrow.com to learn more.
100
120
20
40
60
80
20
40
60
80
100
120
20
40
60
80
20
40
60
80
FGN | SEPTEMBER 2022 | 21
100
120
Check
d-limonene (10%)
100
120
CheckCheckHand Weeding
d-limonene (10%)
7
14
Days After Treatment
Days After Treatment
Hand Weeding
d-limonene (10%) SUPPRESS Herbicide (6%)
Hand Weeding
d-limonene (10%) SUPPRESS Herbicide (6%)
d-limonene (10%)
SUPPRESS Herbicide (6%)
Hand Weeding
SUPPRESS Herbicide EC (6%)
elargonic Acid (5%)
21
Pelargonic Acid (5%)
Pelargonic Acid (5%)
Pelargonic Acid (5%)
Hand WeedingHand WeedingPelargonic Acid (5%)Pelargonic Acid (5%)
SUPPRESS Herbicide (6%)
SUPPRESS Herbicide (6%)
Hand Weeding
Vineyard Weed Control
SUPPRESS Herbicide (6%)
Pelargonic Acid (5%)
% Control
% Control
% Control
% Control
% Control
% Control
http://www.san-agrow.com
September 2022

Table of Contents for the Digital Edition of September 2022
