The evaluation of alternative materials

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Research Project
The evaluation of alternative materials for the
control of Venturia inaequalis, the apple scab
fungus
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Objective 1 To obtain a local source of V.
inaequalis from infected leaves
Objective 2 To produce a continuous supply of
apple seedlings for
inoculations
Objective 3 To develop a method to produce
consistent, continuous inoculum of the
fungus for plant inoculations
Objective 4 To establish infection of apple
leaves by V. inaequalis
Objective 5 To identify alternative materials
that inhibit the
development of scab on leaves
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Objective 1 To obtain a local source of V.
inaequalis from infected
leaves
On June 2, 2004, scabby leaves of Golden
Delicious and York were collected from an
abandoned orchard in Adams Co, PA.
leaves were stored by
Placing them on layers of paper towels, 5 layers
thick
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Layers were wrapped in waxed paper then placed in
cold storage until spores (conidia) were needed
for the inoculation of apple leaves.
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Objective 2
To produce a continuous supply of apple seedlings
for inoculations
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remove seeds
surface sterilize w/10 Clorox, 10 m wash 3X
w/water
place in sterile sand and/or peat at 4C
2-3 months germination
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Objective 3
To develop a method to produce consistent,
continuous inoculum of the fungus for plant
inoculations
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collect scabby leaves
cut out sporulationg lesions
place lesions in beaker with known volume of water
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Stir lesions for approx 20 min
Take sample for spore count 1-5 x 104
conidia/ml
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Objective 4 To establish infection of apple
leaves by V. inaequalis
On June 7, 2004 apple seedlings were inoculated
with spores of the apple scab fungus.
spores were sprayed onto leaf surfaces
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Plants were placed in a dew chamber in the dark
for 48 h, 20C, 100 RH
inside dew chamber
..then removed and placed in a growth chamber
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Growth Chamber
14h daylight, 10h dark photoperiod, 20C at 85 RH
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3 weeks after inoculation, plants were rated for
scab infection
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In June 25, 2004, began testing alternative
fungicides for the control of apple scab
Cultivars being tested include Red and Golden
Delicious, Gala, Cortland, McIntosh
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plants are grown in an incubator
12h daylight, 12h dark photoperiod, 20C, no RH
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One treatment one alternative fungicide
Treatments were applied once a week for 2-3
weeks Plants receiving treatments were returned
to the incubator One week after treatment
application, plants were inoculated with conidia
of the apple scab fungus, placed in a dew chamber
for 48h in the dark, 20C, 100 RH, then into a
growth chamber for 3 weeks Controls will
include a treatment check (treatment
alone) plants sprayed with just the pathogen
(scab control) plants receiving no sprays
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Alternative Materials Being Tested

• VAPOR GARD (Miller Chemical)
• Vigor Cal (AGRO-K)
• Vigor Cal Boron (AGRO-K)
• S-DX (AGRO-K)
• NUFILM 17 (Miller Chemical)
• Calexin (Miller Chemical)
• Phostrol (NewFarm)

• Bacillus subtilis, Serenade
• (AGRA Quest)
• Mirosphaeropsis ochracea (Agro-Engage)
• Pyola (purchased from Gardens Alive)
• Armicarb (Helena Chemical)
• Storox (BioSafe Systems)
• JMS Stylet Oil
• (JMS Flower Farms)

These materials are being tested alone and in
combinations with each other. We thank the
chemical companies for their donations of these
materials.
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NU-FILM- 17 and VAPOR GARD are antitranspirants
In the literature, it is suggested that
antitranspirants may exhibit some suppression of
apple scab
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Vigor-Cal and Vigor Cal Boron are foliar
nutrients
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Controls
scab control plants sprayed with spores of the
apple scab fungus only
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An example of treatments on leaves in one
experiment
The alternative fungicides Calexin and Vapor Gard
did not suppress the development of scab lesions
on leaves at the percentages used.
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An example of an alternative treatment that may
have potential for reducing scab on leaves.
Analyses Experiment 8
Treatments of plants infected Total plants incidence
2 Serenade ASO 0.5 NU-FILM-17 scab 9 26 35
Scab control 20 21 95
of plants represent both high and low scab
concentrations used
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Experiment 8 Results
Scab -inoculated controls
The biological alternative Serenade showed some
suppression of scab on leaves when compared to
the scab-inoculated controls.
The experiment has been repeated and results have
not been consistent.
We are still in the process of screening this
bacterial antagonist using various percentages
and in combination with other alternative
materials.
2 Serenade 0.5 NU-FILM-17 scab
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Working with Biologicals
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We are still in the process of looking for and
screening alternative products that will
suppress the apple scab fungus