of Grape Diseases
5A) Fungicides for Use in
Organic Production Systems
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
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 85F)
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,
Specific comments on fungicide use will be made in the
text for each crop where applicable.
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
- -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) 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. It provides little or no control of the other grape
diseases. 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
- -Kaligreen (potassium bicarbonate)
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 crops.
- -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. It's efficacy for control of grape diseases has not been
- -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 appropriate.
5C) Fungicide Use Strategies for Organic Production
Unfortunately, there are not many options to choose
from when one considers current fungicide use strategies. The current
1. Do Not Use Fungicides
This is always an option, but may not be a wise
decision for commercial grape plantings in the Midwest. This option
should not be confused with "organic" production. Grape growers in
"organic" production systems will most probably use Sulfur or Copper to
some extent for disease control. Sulfur and Copper are fungicides.
Growers that choose not to use fungicides must rely completely on
cultural practices, disease resistance, or biological control agents or
products for disease control.
2. Protectant Fungicide Program
In a protectant program, fungicides are used as a
protective barrier on the plant surface. This chemical barrier prevents
the fungus from entering the plant. It works much like paint on a piece
of wood to keep out water. Protectant fungicides (such as sulfur and
copper) are not systemic and cannot move into plant tissues. Once the
fungus penetrates into the plant, protectant fungicides will not
control it. As the protective barrier breaks down or new foliage is
produced, additional applications are required to maintain the
Protectant fungicide programs have been, and still are
very effective; however, they generally result in a fairly intensive
use of fungicide. On grapes, protectant fungicides are usually applied
on a 7-10 day schedule early in the growing season and on a 10-14 day
schedule later in the season. Obviously, maintaining a protective
barrier on the plant surface throughout the growing season requires
several applications. It is important to note that the most critical
period for disease control on grapes with fungicides is from immediate
prebloom through 3 to 4 weeks after bloom. It is during this period
when protection of fruit is most critical. Cover sprays later in the
season may also be required to protect foliage and cluster stems
(rachis) from infection by powdery and downy mildew.
5D) Fungicides for Organic
Grape Disease Control
Due to the complex of grape diseases in the Midwest
(black rot, powdery mildew, downy mildew, Phomopsis cane and leaf spot,
Botrytis bunch rot) some use of fungicide within the organic production
system will probably be required. The use of sulfur and copper
fungicides on grapes has a long history, and these fungicides are
commonly used in conventional grape production systems today. The
challenge for the organic producer is to develop a program using only
these fungicides that will provide simultaneous control of the entire
disease complex. Especially in wet growing seasons, all of the above
mentioned diseases can develop within the vineyard simultaneously. The
exclusive use of sulfur and copper, even in combination, may not
provide acceptable disease control of all the diseases under moderate
to heavy disease pressure.
Liquid Lime Sulfur
Lime sulfur is recommended for control of anthracnose
as a dormant application in the spring. It is recommended at the rate
of 10 gallons per acre. The dormant application is generally not
recommended unless anthracnose is a problem. Some growers routinely
make a dormant application of lime sulfur or copper, and feel they are
getting some benefits for control of other diseases as well. University
research indicates that a dormant application alone will not provide
season long control of any grape disease; thus, foliar applications
through the growing season will probably be required.
Sulfur is highly effective against
powdery mildew if used in a protectant program with a minimum of 7 to
10 days between applications. Sulfur provides very good control of
powdery mildew, but has little or no effect on all the other grape
diseases. Under moderate to heavy powdery mildew disease pressure, a
minimum of 7 to 10 days between spray intervals will probably be
There are many formulations of sulfur (wettable
powders, dusts, dry flowables and flowables). The flowable formulations
appear to most effective and result in much less applicator exposure
when preparing sprays.
Note: On sulfur tolerant varieties that
are susceptible to PM (Table 2),
Sulfur will be a major component of
the fungicide program. On highly susceptible varieties, spray intervals
shorter than 14 days (7-10 days) will probably be required.
Although Sulfur is highly effective for PM control, it
has little or no effect on the other grape diseases. It is important to
remember that Sulfur can cause severe injury on some varieties. Sulfur
should only be used varieties known to be sulfur tolerant (Table 2).
Note: Concord grapes are extremely
sensitive to Sulfur. Sulfur injury may occur even on sulfur-tolerant
varieties when temperatures of 80 to 85F or higher are experienced
during or immediately after application.
Copper fungicides are highly
effective against downy mildew and are moderately effective against
powdery mildew. Copper fungicides are weak for controlling black rot,
Botrytis Bunch, and Phomopsis Cane and Leaf Spot. A concern with the
use of copper fungicides is the potential they have for phytotoxicity
or "vine damage".
The following summary of recommendations are intended
to reduce the danger of phytotoxicity when using copper:
1. Do not make a complete season-long spray program with
any copper fungicides.
2. Use fungicides other than copper whenever possible.
3. When using copper fungicides, delay their use as late
in the growing season as possible.
4. When using copper fungicides, avoid the use of copper
sulfate. Always us a "fixed" copper formulation.
5. Use the full recommended rate of lime. Never
eliminate the use of lime completely, unless the pesticide label
indicates that lime should not be used.
6. Remember that cool, wet weather enhances the risk of
copper injury. Be especially certain to use adequate lime levels during
such periods or switch to other fungicides.
7. Make sure that any material you tank mix with copper
is compatible. Many materials are
incompatible (cannot be tank-mixed) with copper.
8. Avoid copper and lime sprays on fruit destined for
for Powdery Mildew
Powdery mildew is different from most other grape
diseases, 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
other diseases that colonize deeper into infected plant tissues, such
as black rot. 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 season. These 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
phosphate); Kaligreen and Armicarb (potassium
bicarbonate-baking soda); oils such as Stylet Oil and Trilogy; and
dilute solutions of hydrogen peroxide (Oxidate). In Australia,
dilutions of milk and whey (the dairy by-product) have been effective
for controlling powdery mildew.
Unfortunately, these materials have very little or no
effect on the other grape 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 as organic.
Table 3 in section 5E shows the
relative effectiveness of organically
approved fungicides for control of the major grape diseases. It should
be noted that none of the materials or highly effective against black
rot, phomopsis cane and leaf spot, and Botrytis bunch rot. These
diseases will be a major concern on susceptible varieties in organic
production systems. Whereas, most varieties do not have complete
resistance to these diseases, varieties differ greatly in their level
of susceptibility. Organic growers should at least AVOID varieties that
are highly susceptible to these diseases (Table 2). In addition, the
use of cultural practices mentioned in these guidelines must be
There are many biocontrol materials and other products
such as oils and salts currently registered for use on grapes. Most of
these are registered for control of powdery mildew and Botrytis bunch
rot, and their effectiveness under moderate to severe disease pressure
needs to be determined. As information on these materials becomes
available, they will be included in these guidelines.
Table 3: Relative
effectiveness of organically
approved fungicides for controlling grape diseases.
cane and leaf spot
Botrytis bunch rot
|Horticulture grade spray oils
|Hydrogen peroxide (oxidate)
H= highly effective
M= moderately effective
W= weak or not effective