The following is a brief
description of some disease control materials that are commonly
or traditionally used in organic production systems. Copper
fungicides, elemental sulfur and liquid lime sulfur are the old
“standard” fungicides, and have been used for many years in
organic production systems.
Note: Prior to using any material in the organic system,
it is important that the grower consult his/her organic
certification agency or program to be positive that use of the
material is permitted.
When different formulations of copper are dissolved in water,
copper ions are released into solution. These copper ions are
toxic to fungi and bacteria because of their ability to destroy
proteins in plant tissues. However, because copper can kill all
types of plant tissues, the use of copper fungicides carries the
risk of injuring foliage and fruit of most crops. Factors
promoting this injury include: 1) the amount of actual copper
applied, and 2) cold, wet weather (slow drying conditions) that
apparently increases the availability of copper ions and, thus,
increases the risk of plant injury. Because of the potential to
injure plants and to accumulate in soil, the use of copper
fungicides in conventional production systems has largely been
replaced with conventional fungicides that are generally safer
to plant tissues and often more effective.
Several terms are used when discussing copper as a fungicide.
The original material used was copper sulfate (also known as
blue vitriol or bluestone). When this material was combined with
lime in the French vineyards, the combination became known as
Bordeaux mixture is a mixture of copper sulfate and hydrated
lime in water. It has long residual action and has been used for
years to control many diseases, including downy mildew and
powdery mildew of grape. It can be made (mixed) on site by
combining copper sulfate with spray grade lime. It is also
commercially available as a dry wettable powder.
Fixed Copper Fungicides
Following the discovery and use of Bordeaux mixture, several
relatively insoluble copper compounds or fixed coppers were
developed. Fixed copper formulations release less copper ions
and are generally less injurious to plant tissues (safer to use)
than Bordeaux mixture, but their use is still limited because of
their potential to injure plants and lack of compatibility with
other pesticides. Some of the more common commercial
formulations of fixed copper include C-O-C-S, Kocide 101,
Tribasic Copper sulfate, Champ, and Tenn-Copp 5E. There are
several fixed copper fungicides registered for use on small
Sulfur is available as liquid lime sulfur and as dry wettable
powders or liquid (flowable) formulations of elemental sulfur.
Liquid Lime Sulfur
Liquid lime sulfur can be used at high concentrations as a
dormant spray on raspberries and blackberries for control of
cane blight, spur blight and anthracnose and on grapes for
control of anthracnose. At high concentrations, it should be
used only when plants are dormant. It can cause severe damage if
applied after green foliage appears. Lime sulfur has a foul odor
that many people dislike. It is also registered for use on
grapes and caneberries as a more dilute concentration for use
during the growing season.
Dry Wettable Sulfurs or Flowable Sulfurs
Sulfur for use as a fungicide is available under many trade
names. The microfine wettable sulfurs or flowable sulfurs are
usually much less injurious to foliage and fruit than liquid
lime sulfur, but their use during hot weather (above 85°F)
may result in some leaf burning and fruit damage. Sulfur
fungicides are very effective for control of powdery mildew on
most fruit crops, but are not highly effective for control of
most other fruit crop diseases. Sulfur is very toxic to foliage
of certain grape varieties (mainly American grapes) including
Concord, Chancellor, DeChaunac and Foch. Sulfur is relatively
safe on most other varieties see Table 6, page 68. Applications
after the fruit begins to ripen may pose problems during
fermentation if the grapes are intended for wine making.
Growers should note that sulfur is lethal to some beneficial
insects, spiders and mites. These beneficial insects are natural
predators of harmful insects and mites that affect fruit crops.
Killing these beneficial insects may increase certain pest
problems, especially mites.
Specific comments on fungicide use will be made in the text
for each crop where applicable.
“New Alternative” Disease Control
Materials for Small Fruit
Many products are currently available or currently being
introduced as “biological control agents” or “biopesticides”.
These include living microorganisms, “natural chemicals
such as plant extracts, and “plant activators” that induce
resistance in plants to disease. For most of these products,
independent evaluations are currently being conducted; however,
their effectiveness under moderate to high disease pressure is
uncertain. Although many of these new products have great
potential for use within organic production systems, their
effectiveness needs to be determined in field tests. It is
important to remember that registration of these materials for
control of a specific disease on a crop is no guarantee that
they will provide effective control under moderate to heavy
disease pressure. In addition, many products may be effective
for only one or a few diseases and most have very limited
residual activity (they have to be applied often). It is also
important to remember that these are registered pesticides and
growers need to be certain that their use is permitted within
their organic certification program.
The IR-4 project is a federally funded program that facilitates the registration
of sustainable pest management technology for specialty crops and minor uses. IR-4
has a very helpful searchable database for all registered biopesticide products. I
think the following web sites probably have the best information on biopesticides
that are avilable nationally and in your state.
For background go to:
For the searchable database on biopesticies go to:
Also, the Biopesticide Industry Alliance recently updated their web site. On it there
is some general information about biopesticides that should be useful to organic growers.
These web pages list all the products currently available along with information such as
registered crops and diseases controlled. It also lists the name of the company that
manufacturers or distributes the product along with phone numbers and web site addressess. These
sites are updated regularly and should be a valuable resource for growers interested in these
The following are a few of the most common "alternative"
disease control products currently registered for use on small
AC10 (Ampelomyces quisqualis) is a
biofungicide registered for control of powdery mildew in
grapes, strawberries, blueberries, raspberries,
currants, and gooseberries. A. quisqualis is a
fungus, that parasitizes powdery mildew fungi.
Preliminary results in grapes in Michigan show moderate
disease control. Adding an adjuvant such as Nufilm
(0.02% v/v) enhances its efficacy. Application should
start as soon as susceptible tissue becomes available
and continue on a 7 to 14 day schedule. A minimum of 2
sequential applications if needed to maintain the
population of A. quisqualis. The following
chemicals cannot be tank-mixed with AQ10: sulfur and
potassium salts of fatty acids.
Armicarb 100 (potassium bicarbonate=baking
powder) is a reduced-risk, protectant (contact)
fungicide. Armicarb 100 is registered for control of
powdery mildew and other diseases in grapes,
blueberries, strawberries, and brambles. Preliminary
results in grapes in Michigan indicate moderate control
of powdery mildew. Start applications at the first sign
of disease and continue on a 7-14 day schedule. The
preharvest interval (PHI) on all crops is 0 days.
Galltrol (Agrobacterium radiobactor strain 84) is
a biological control product for control of crown gall,
caused by Agrobacterium tumifaciens on several tree
fruit and nut crops. The active ingredient is the
bacterium, Agrobacterium radiobactor strain 84. On small
fruits it is effective for control of crown gall on
raspberry and blueberry. It is not effective for
controlling crown gall on grapes. It is purchased as a
pure culture grown on agar in petri plates. The
bacterial mass from one plate is diluted into one gallon
on non-chlorinated water and plants are treated with a
pre-plant dip in the solution or as a soil drench.
Kaligreen (potassium bicarbonate = baking powder)
is a reduced-risk protectant (contact) fungicide.
Kaligreen is registered for control of powdery mildew on
grapes, strawberry, brambles (raspberry and blackberry)
and blueberry. It provides good control of powdery
mildew when applied on a frequent-protectant program of
7 to 10-day intervals. It has little or no efficacy
against most other fungal diseases on small fruit. It is
formulated as a micro-encapsulated powder that is mixed
in water and sprayed directly on the crop. Kaligreen has
a preharvest interval (PHI) of 1 day on all small fruit
Messenger (harpin) is a reduced risk product
registered for use on grapes, blueberries, cranberries,
strawberries, brambles, and currants. The active
ingredient is derived from a protein produced by certain
bacteria. This protein stimulates natural plant
defenses. Messenger has no direct effect on pathogens.
The efficacy of this material for disease control or
suppression has not been sufficiently confirmed.
Messenger has a 0 day PHI.
Mycostop (Streptomyces griseoviridis strain K61)
is a biocontrol product registered for use on all fruit
crops for control of several important pathogenic fungi
that cause seed, root, and stem rot and wilt diseases.
The active ingredient is the bacterium, Streptomyces
griseoviridis strain K61. It is sold as a powder
formulation that is mixed with water and applied as a
spray or a drench.
Oxidate (hydrogen dioxide) is a broad-spectrum
bactericide/fungicide registered for use in grapes,
blueberries, cranberries, strawberries, and brambles. It
is a rather corrosive material and works by oxidizing
fungal and bacterial cells. The efficacy of the material
for disease control has not been sufficiently confirmed
on several diseases. In one Ohio fungicide evaluation,
it provided no control of grape black rot.
Serenade (Bacillus subtilis) is a
biocontrol product registered for control of powdery
mildew, Botrytis bunch rot and sour rot in grapes.
Serenade is also reported to provide some suppression of
downy mildew. This product needs further evaluation, but
preliminary results show a moderate level of control of
Botrytis bunch rot and powdery mildew. Serenade did not
control grape black rot in Ohio. Good coverage is
important for control. Applications are recommended on a
7-10 day schedule. Serenade has no maximum seasonal
application rate and has a 0 day PHI.
Trichodex (Trichoderma harzianum) is a
biofungicide registered for use on all small fruit crops
for control of a wide range of diseases, but primarily
for control of Botrytis fruit rot. It is sold as a
wettable powder formulation that is mixed with water and
sprayed directly onto the plants.
Trilogy (Clarified Hydrophobic Extract of Neem
Oil). The label states that Trilogy is a broad spectrum
fungicide of certain diseases and controls mites in
citrus, deciduous fruits and nuts, vegetable crop,
cereal grains and other miscellaneous crops. The label
does not state what diseases are controlled on specific
crops. Trilogy is registered for use on grapes,
strawberry, brambles (raspberry and blackberry), and
blueberry. Trilogy is a liquid that is applied for
diseases as a 1% solution in sufficient water to achieve
complete coverage of the foliage.
As the efficacy of these new materials is tested and
validated, they will be included in these guidelines where
Efficacy of Disease Control Materials
for Powdery Mildew
Powdery mildew is different from most other plant diseases
caused by fungi, because the fungus that causes it lives almost
entirely on the surface of infected plant parts. The fungus may
penetrate only one cell layer deep into the plant. Thus, it is
exposed to eradication following topical treatment with a range
of products that do not affect many other pathogenic fungi that
colonize deeper into infected plant tissues. Research in New
York and other locations has demonstrated that many new and “alternative
materials can provide effective control of powdery mildew if
applied often enough (7 day schedule) through the growing
materials burn out the fungus growing on the surface, but do
not provide protection against new infections; thus, repeated
applications are important. These materials include: Nutrol (manopotassium
phosphate); Kaligreen and Armicarb (potassium bicarbonate-baking
soda); oils such as Stylet Oil and Trilogy; and dilute solutions
of hydrogen peroxide (Oxidate).
Unfortunately, these materials have little or no effect on
many other small fruit diseases. In addition, organic growers
need to consult with their certification agency or program to be
sure that any material they use is “certified” or acceptable