December 2019 - 20

PLANT HEALTH
BIOPESTICIDES
NEW
for GREENHOUSE CROPS
Are you seeking biological controls to protect your plants? These four new products
are worth trying out.
BY A. R. CHASE
W
hen I started my career, about 40 years ago, biological control
was known and studied but not in practice in many parts of
agricultural production. Today we have come far with several
new products launched annually. In most cases, these products are as well
researched and understood as currently launched conventional fungicides.
In many cases, the companies launching the products also produce
conventional fungicides but sometimes they focus primarily on
biopesticides. In this article I have decided to focus on four of the newest
biopesticides that have reached the greenhouse/ornamentals market.
Each of the four products below are OMRI-listed. I have not placed them in
any particular order.
STARGUS BIOFUNGICIDE
Marrone Bio Innovations
The active ingredient in Stargus Biofungicide is listed as a beneficial
rhizobacterium that colonizes plant root hairs, leaves and other surfaces
to prevent establishment of fungal and bacterial plant diseases. The
active agent is Bacillus amyloliquefaciens strain F727* cells and spent
fermentation media.
The label lists disease control for Botrytis species (gray mold), powdery
and downy mildews, black spot on citrus, Phytophthora blight and late
blight. It is also registered for some soil-borne pathogens including
Fusarium, Phytophthora, Pythium, Rhizoctonia and Sclerotinia species
as well as some others. Check Table 1 for a summary of efficacy trials
that have been done on all crops (including experimental trials on
ornamentals).
Stargus is currently registered on edible field crops including a long list
of herbs and spices. As far as I can tell, it it not registered for ornamentals
specifically. It has a four-hour REI and a signal word of CAUTION.
Best disease control is achieved when Stargus is applied preventatively
in a regularly scheduled protective spray program. The manufacturer also
suggests using it in rotation or tank mix program with other registered
20 DECEMBER 2019 GPNMAG.COM
PATHOGEN
Alternaria leaf spot
Botrytis (blight)
Cercospora leaf spot
Colletotrichum
(anthracnose)
Erwinia (fire blight)
PLANT
Geranium, poinsettia, raspberry,
blueberry and strawberry fruit
Beet
Blueberry fruit
Apple
Macrophomina (charcoal rot) Strawberry
Phytophthora root rot
Powdery mildew
Pseudomonas leaf spot
Rhizoctonia root rot
Sclerotinia (white mold)
Septoria leaf spot
Verticillium wilt
Xanthomonas leaf spot
Hydrangea
Raspberry
Mum
Viburnum
Lettuce, bean
Tomato
Strawberry
Brussels sprouts, cabbage,
geranium
Table 1. Stargus efficacy trial summary for all crops.
fungicides. The label allows for application flexibility with foliar, aerial,
chemigation and soil-applied methods.
In a couple of recent trials, Stargus was tested on two soil-borne
root diseases on woody ornamental by Baysal-Gurel (Tennessee State
University). The crops were viburnum with Rhizoctonia root rot and
hydrangea with Phytophthora root rot. Stargus provided control in these
two trials that was equivalent to RootShield Plus and nearly as good as the
conventional root disease fungicides for Phytophthora (Empress, Segovis
and Subdue Max) and Rhizoctonia (Empress and Mural). It is important
to note that the application interval in these trials was weekly while the
other products were applied on a three-week interval or much longer
(RootShield Plus and Subdue Maxx).
RESULT
Brussels sprouts, tomato, potato None to very good
None to excellent
Very good
Excellent
None to some
None
Very good
Excellent
Some
Good
Some to excellent
None
None
None to very good
http://www.GPNMAG.COM
December 2019

Table of Contents for the Digital Edition of December 2019
