2007 Extension Research Report
Disease Management
NUFARM SOIL DRENCH AND FOLIAR APPLICATIONS FOR
MANAGEMENT OF PHYTOPHTHORA CAPSICI
A.S. Csinos, Scott Monfort, Unessee Hargett, and Lara Lee Hickman, Department of Plant
Pathology, University of Georgia-CPES, P.O. Box 748, Tifton, Ga. 31793
complete block (RCBD) with
8 treatments and 5 replications.
Each plot was inoculated with P. capsici
infested vermiculite on 9 August and again on 25
September by placing 1/8 teaspoon of P. capsici
infested beet seed (approximately 15-20 seed per
location) in the crown of the plant in three
locations, beginning, middle and end of plot.
Fungal inocula was produced by plating pure
cultures of Phytophthora capsici on V8-agar
plates and incubating for 7-10 days.
Inoculum of P. capsici vermiculite was
produced by adding 250ml of V8 broth (200ml of
V8, 800 ml of distilled water, 2g of CaCO3 per
liter) to 500 cm3 of vermiculite. Flasks containing
V8 vermiculite were autoclaved for one hour.
After autoclaving, flasks containing V8
vermiculite medium were allowed to cool and
then inoculated with V8 agar plugs of P. capsici
(approximately 1/4”x 1/4” diameter plugs) under
a laminar flow hood using aseptic techniques.
Flasks were allowed to incubate at 26 degrees
Celsius for 10-14 days before field inoculation.
P. capsici on beet seed (Detroit Medium
Top variety) was produced by soaking beet seed
in distilled water in aluminum pans for 24 hours.
Soaked beet seed was decanted and then poured
into 500ml flasks to the 250-300ml mark, plugged
with Identi-plug™ foam plugs, covering plugs
with foil and securing with autoclave tape. Flasks
were then autoclaved for 30 minutes. After
autoclaving, flasks were allowed to cool and then
inoculated with V8 agar plugs of P. capsici
(approximately 1/4”x 1/4” diameter plugs) under
a laminar flow hood using aseptic techniques.
Flasks were allowed to incubate at 26 degrees
Celsius for 10-14 days before field inoculation.
Introduction
Phytophthora capsici is a soilborne
disease that has become a serious threat in the
production of cucurbits, pepper and tomato crops.
The disease affects all parts of the plant including
roots, stems, plant crowns, and fruit. The disease
can cause heavy crop losses and may even force
growers to move production to other areas due to
the ability of the fungus to persist in the soil for
several years. To date there is no effective
method of controlling Phytophthora capsici and
further research needs to be done to develop better
strategies for managing the disease. This trial
evaluates the effectiveness of several chemical
control agents, including a standard commercial
chemical application, being applied at strategic
times during the growing season for management
of the disease.
Methods and Materials
The study was located at the Black Shank
Farm, Tifton, Georgia in Block 1240- Pcap area 3
of the Phytophthora capsici nursery. The test area
was fertilized on 31 July with a 10-10-10
formulation applied at 500lb/A. Fertilizer was
applied and then roto-tilled into the soil. On 09
August, test area was prepared and beds were
shaped and covered with 1 mil black polyethylene
film mulch and plumbed with drip tape installed
simultaneously in the center of the bed
approximately 1-inch deep. The drip tape was
Aquatraxx™ brand with a 12-inch emitter
spacing, and a flow rate of .45 gal/min/100ft with
a 12-PSI regulator. Plastic mulch covered plots
were 30 inches wide, 30 feet in length with 5 foot
alleys between plots with an average of 28 squash
plants per plot. The plot design was a randomized
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The test was planted with yellow summer
squash variety ‘Payroll’ in the first four reps and
the fifth rep being planted with zucchini.
Approximately 30 squash plants and 30 zucchini
plants per plot were transplanted on17 August.
Plant spacing for squash was 12". Yellow squash
and zucchini seedlings were transplanted using a
mechanical transplanter that cuts holes in the
center of the plastic and adjacent to the drip tape
just ahead of the planters.
Additional fertilizer was applied through
the drip lines to all plots throughout the growing
season at a rate. Pesticide applications were
made weekly to control aphids and whitefly.
Admire Pro at the rate of 4oz/A was applied
through the drip tape on 18 and 25 August, and
01, 08, 14, and 28 September. Phaser at the rate of
1qt/A was applied through the drip tape on
25 August, 11, 20, and 27 September, and 02
October. Intruder was applied through the drip
tape on 05, 15, 22 and 29 September.
plants, any diseased or dead plants and to
determine if any phytotoxicity was occurring on
plants. Counts were conducted on 25 and 28
August, 05, 12, 20 and 25 September.
Plots were irrigated with additional
overhead water twice a day beginning on
29 September and ending on 06 October. Each
irrigation time was fifteen minutes long with 1/4"
of water being applied equaling ½" additional
irrigation water per day.
The squash and zucchini crop were hand
harvested with each harvest being separated into
marketable and cull fruits, counted, and weighed.
Five separate harvests were conducted on 20 and
26 September and 02 and 06 October with the
final harvest being taken on 12 October. Yellow
squash and zucchini fruits are considered
harvestable when the blossom has fallen off.
All data was collected and analyzed using
SAS 9.1 with an analysis of variance (P=0.05) and
means were separated using LSD.
Individual drip treatments were made at
transplanting (17 August-Treatments 2-8). All soil
drench treatments were applied through the drip
line simultaneously using the Hickey Injection
System, with an injection period of four hours.
Foliar treatments were made at 3 weeks after
transplanting (08 September-Treatments 5 and 7),
and 6 weeks after transplanting
(29 September- Treatments 5 and 7).
Plant vigor ratings were conducted on 08
September and 20 September. Vigor ratings were
conducted on a 1-10 scale with 10 representing
live and healthy plants and 1 representing dead
plants. Stand counts were made to record live
Summary
The year 2006 was a very dry year and in
particular very little rain fell in September and
October. Even though we inoculated the plots and
irrigated frequently, very little disease developed.
In addition, very little disease occurred within the
state of Georgia on growers fields as a result of
the low rainfall.
There were no differences among
treatments for vigor, number of fruit/plot, yield,
cull fruit, and cull weight at P=0.05. Disease
incidence however, was lower in the non-treated
control and Ridomil treated plots than in plots
treated with Admire Pro.
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Table 1. Nufarm Soil Drench and Foliar Applications for Management of Phytophthora capsici
M arketable Fruits
Treatment1
Cull Fruits
Total Yield
Vigor 2
Number 3
Yield 4
(lbs/plot)
Number 5
Yield 6
(lbs/plot)
Total Number of
harvested fruit 7
Total weight of
harvested fruit 8
Percent 9
Disease
1. Untreated Control
7.3 a
182.2a
93.2ab
6.8a
1.5ab
189 a
94.7 ab
5.9 b
2. Admire Pro
7.0 a
140.8a
66.1b
5.0a
2.0ab
146 ab
68.1 b
14.9 a
3. Nufarm NUP06063
7.4 a
159.8a
99.2a
10.0a
4.7a
170 ab
103.9 a
12.5 ab
4. Nufarm NUP06024
7.5 a
159.4a
93.2ab
4.0a
1.2b
163 ab
94.4 ab
12.2 ab
5. Nufarm NUP06024 + Phostrol
7.2 a
160.0a
91.0ab
6.4a
0.95b
166 ab
92.0 ab
11.1 ab
6. Nufarm NUP06024 + Ultra Flourish
7.0 a
138.4a
77.4ab
5.2a
2.0ab
144 b
79.5 ab
7.8 ab
7. Nufarm NUP06024 + Ultra Flourish
+ Phostrol
7.0 a
161.6a
91.2ab
4.4a
1.7ab
166 ab
93.0 ab
13.2 ab
8. Ridomil Gold
7.4 a
160.0a
85.4ab
4.4a
1.4ab
164 ab
86.9 ab
5.7 b
1
Data are means of five replications. Means in the same column followed by the same letter are not different (P=0.05) according to Duncan’s multiple range test. No
letters indicate non-significant difference.
2
Vigor was done on a scale of 1-10 with 10= live and healthy plants and 1 = dead plants. Average is of three vigor ratings conducted on 05and 20 September & 03 October.
3
The fruit collected from each individual plot that was considered to be marketable and showed no symptoms of disease was separated and counted on 15, 22, and 28 September
with the final harvest being conducted on 06 October.
4
The fruit was collected from each individual plot and the fruit considered marketable and showed no symptoms of disease was weighed (in lbs.) on 15, 22, and 28
September with the final harvest being conducted on 06 October.
5
The fruit collected from each individual plot that was considered diseased and non-marketable was separated and counted on 15, 22, and 28 September with the final
harvest being conducted on 06 October.
6
The fruit was collected separately by each plot and the fruit diseased and non-marketable was weighed (in lbs.) on 15, 22, and 28 September with the final harvest
being conducted on 06 October.
7
Equals total number of fruits harvested both marketable and culls
8
Equals total weight (in lbs.) of fruits harvested both marketable and culls.
9
Percent Disease was calculated by dividing the total dead plants by the initial stand count and multiplying by 100. Stand counts were conducted on 25and 28 August,
05, 12, 20, and 25 September and 11 October.
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