Title: Evaluation of some bactericides and biopesticides for suppression of bacterial diseases on landscape ornamental plants
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Title: Evaluation of some bactericides and biopesticides for suppression of bacterial diseases on landscape ornamental plants
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Language: English
Creator: Strandberg, James O.
Publisher: Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville, Fla.
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University of Florida
Institute of Food and Agricultural Sciences
Mid Florida Research and Education Center
Apopka, Florida

Evaluation of Some Bactericides and Biopesticides for Suppression of
Bacterial Diseases on Landscape Ornamental Plants

James 0. Strandberg1


Plant Pathology Research Report 2006 2 October, 2006



Bacterial diseases of woody ornamental plants occur sporadically during nursery
production, but when they occur, major production problems and losses often result.
Several plant pathogenic bacteria incite disease of woody ornamental, but bacteria in
the genera Xanthomonas and Pseudomonas probably cause the greatest losses,
particularly in humid climates. Diseases incited by Pseudomonas spp. such as P.
syringae, and P. chicorii, and P. marginalis occur frequently, affect many nursery crops.
Xanthomonas species, especially various pathovars of X. campestris, are especially
common, cause frequent epidemics (especially in warm, humid regions), and are
particularly destructive pathogens on numerous ornamental species. Presently, there
are few options for control or suppression once such diseases appear. Copper
compounds and antibiotics provide mostly unsatisfactory results in disease-favorable
climates. Most growers attempt to suppress or control bacterial plant pathogens after
disease has appeared when control is particularly difficult. Preventative applications of
compounds based on neutral salts of phosphonic acid have shown some promise for
control of both Xanthomonas and Pseudomonas spp. and modest levels of biological
control with antagonistic bacteria has also been obtained.

This project evaluated some new biopesticide products (and mixtures) with the
potential for suppression and control of plant pathogenic bacteria. As these materials
have minimal environmental impact, they were applied frequently to prevent or suppress
disease damage. It is not feasible to test these materials on numerous ornamental
species, but the results obtained are likely transportable to similar crops. Successful
suppression or control (or lack of it) of four typical and representative pathogens (two
Pseudomonas and two Xanthomonas spp.) on four species representative of popular
woody ornamental plants will be evaluated to identify, or exclude new opportunities for
the use of biopesticides to control plant pathogenic bacteria in ornamental production.

1 Professor, Plant Pathology


Page 1









MATERIALS AND METHODS


Two Xanthomonas spp. representative of those frequently impacting woody
ornamental production were evaluated on two representative woody ornamental
plants: Prunus umbellata or P. incisa x campanulata cv. 'Okame' infected with
Xanthomonas campestris pv pruni, and Wax myrtle (Myrica cerifera infected with a
Xanthomonas species (currently being identified to species). Two species
representative of the genus Pseudomonas: Pseudomonas chicorii and P. marginalis
were evaluated on Hibiscus (Hibiscus rosa-sinensis), and Hydrangea (Hydrangea
quercifolia) respectively. Also, an unknown Xanthomonas species (which is currently
being identified) was isolated from some Hydrangea plants, so there was likely a mixed
infection on this host.

Treatments were applied at 14-day intervals during May through early November.
Plants were quantitatively evaluated by periodic (14-day interval) leaf sampling and
estimating percent leaves infected and percent leaf area damaged. The tests were
done at the University of Florida, Mid-Florida Research and Education Center, Apopka,
Florida.

There were four replicates for each treatment in a randomized complete block design.
Plot size was 4 ft X 12 ft (0.0011 acre). Each plot originally contained 16 plants of each
of the four species placed in adjacent closely-spaced rows. A few plants were lost from
causes not related to the treatments. Plots were separated by at least six feet on all
sides from adjacent plots.

Treatments were applied with a compressed air-powered sprayer maintained at 40 Ib/in2
pressure at the nozzle (TeeJet 8004 tip Spraying Systems Co, Wheaton, IL 60189) to
deliver 50 gal/acre. Treatments and application rates Plants were obtained as large
liners and were transplanted into 1-gallon pots in a peat-sand-pine bark potting mix with
minor elements and dolomite. Osmocote fertilizer 19-6-12 was added (18 g per pot).
Plants were watered nightly with an automatic, overhead sprinkler irrigation system.

Abundant disease damage was present on Japanese Plum, when the plants were
obtained, but Hydrangea, and Wax myrtle had minimal levels of disease; Hibiscus had
none. Therefore these plants were inoculated with bacteria cells produced in culture.
One liter of nutrient broth was inoculated with the pathogen, and grown at 24 C for 24 hr
with continuous shaking. Bacterial cells were then centrifuged, re-suspended in 1 L of
tap water, and sprayed on appropriate test plants early in the morning when plants were
wet with dew and from irrigation.

All treatments were applied to all test plants (on the same day) at 14-day intervals. Plots
were evaluated for disease incidence and damage during alternate weeks from spraying.
Results were evaluated by sampling 10 leaves at random from each replicate of each
species of test plants throughout the experiment. Leaf samples were evaluated for
percent of leaves diseased and average percent leaf area damaged (LAD) using


Page 2









specially-prepared pictorial disease damage keys. For each sampling date, average
percent LAD and the percent of leaves infected were calculated. Final results were
determined by obtaining the average of the area under the disease progress curves
(AUDPC). Data were analyzed with a 2-way ANOVA (block, treatment) and means were
separated with Student-Newman-Keuls method. Results are provided as AUDPC for
percent LAD and percent leaves infected (Tables 2 5, Figures 1 4) and for percent
LAD and percent leaves infected on the final sampling day (Tables 2 5).


RESULTS AND DISCUSSION

Disease damage progressed normally on Japanese Plum, Hydrangea, and Wax Myrtle,
but much more slowly on Hibiscus, so fewer sampling days were obtained for Hibiscus.
However, there was sufficient disease damage to evaluate the chemicals tested. on all
four host species. Another issue was the impressive and rapid flush of new foliage
growth that occurred on Wax Myrtle near day 250 (Figure 2); this had the apparent effect
of greatly reducing LAD because of the dilution effect of the new and uninfected leaves.
Of the data collected, the area under disease progress curves provided the best
information for determining efficacy. Of all the treatments, only the Actinovate plus Tricon
treatment consistently suppressed disease, but the levels of disease were not always
significantly different than the controls or from other treatments (Tables 2 5, Figures 1 -
4). The tank mixtures used in this experiment were specifically suggested for evaluation.
Unfortunately the results obtained did not determine if Tricon, Actinovate, or the
combination was responsible for the results obtained, so additional work is needed with
the individual components of this mixture. With the possible exception of the Rapsody-
Kocide-Vital, BioPhos with chelated copper, and Kocide treatments (Treatments 3, 6
and 8), none of the other treatments appeared to have significant potential for controlling
the diseases used in this experiment when applied at 14-day intervals. It is likely, that
under the conditions of the test, a 14-day application interval is not frequent enough to
provide acceptable control of the diseases used in this study. No phytotoxicity was
noted in this experiment.


Page 3









Table 1. Biopesticide treatments and application rates evaluated for control of bacterial
disease on four woody ornamental species at Apopka, Florida, Summer, 2006.

Trt # Product Application 1 Active Ingredient
Rate
1 Physpe 450 ml / 100 liters / Seaweed extract
A derivative
2 Kasumin 32 oz /50 gal / A Kasugamycin 2%

3 Rhapsody, 1% by volume Bacillus subtillis
+ Kocide 2000 1.5 Ib/A Copper hydroxide
+ Vital 4 pints/A Phosphorous acid
4 K-Phite 5 qts / 100 gal / A Phosphorous acid

5 Tanos, 50% WG 8 oz./A Famoxadone (25%) + Cymoxanil
+ Kocide 2000 1.5 Ib/A (25%)
Copper hydroxide
6 BioPhos + 2% by volume Phosphorous acid
Chelated copper 0.1 Ib ai/A Chelated copper

7 Actinovate + 3.4 g / gal Streptomyces lydicus
Tricon, 0.4% 15 ml/gal Sodium tetraborate
decahydrate
8 Kocide 2000 1.75 lb/acre Copper hydroxide

9 Control --


1 All rates were re-calculated
experiment.


for application in 50 gal/acre of water per acre in this


Page 4









Table 2. Summary of data for Japanese Plum (Prunus incisa x campanulata cv Okame)
plants infected with Xanthomonas campestris pv. pruni following application of some
bio-pesticides at 14-day intervals at Apopka, Florida, Summer and Fall, 2006.


Treatment
number


Product


1 Physpe


Kasumin


Rhapsody
+ Kocide 2000
+ Vital

K-Phite

Tanos, 50% WG
+ Kocide 2000P

BioPhos +
Chelated copper

Actinovate + Tricon

Kocide 2000

Control


F= 4.479
P = 0.001 **


3.215
0.013 **


1.389
0.251 NS


1.796
0.1281 NS


1 Calculated mean area under the disease progress curves in arbitrary units for percent leaf area damaged. Value is
average for four replications. Means separated by Student-Newman-Keuls method based upon 2-way analysis of
variance. Values followed by the same letter are not significantly different at the P = 0.05 level.
2 Percent LAD on last sampling day. Value is average for four replications. Means separated by Student-Newman-
Keuls method based upon 2-way analysis of variance of Arc Sin of percentage values. Values followed by the same
letter are not significantly different at the P = 0.05 level.
3 Calculated mean area under the disease progress curves in arbitrary units for percent of leaves infected. Value is
average for four replications. Means separated by Student-Newman-Keuls method based upon 2-way analysis of
variance. NS = not significant at P = 0.05 level.
4 Percent of leaves infected on last sampling day. Value is average for four replications. Means separated by Student-
Newman-Keuls method based upon 2-way analysis of variance of Arc Sin of percentage values. NS = not significant at
P = 0.05 level.


Page 5


AUDPC1
Percent
LAD
1908.7 b

2014.5 b


1417.2 ab



2229.1 b

1842.6 b


1681.4 b


934.2 a

1800.1 b

1986.4 b


Last 2
Percent
LAD
29.2 b

31.6 b

33.3 b



32.4 b

27.4 b


29.3 b


12.3 a

34.1 b

32.4 b


AUDPC 3
Percent
Infected
79.3

76.5


75.5



77.5

73.8


74.0


69.0

76.8

78.8


Last 4
% leaves
Infected
90.0

97.5


95.0



97.5

97.5


97.5


82.5

100

95.0































- TREATMENT 1
o.-- TREATMENT 2
-- TREATMENT 3
--v- TREATMENT 4
TREATMENT 5
--o- TREATMENT 6
-- TREATMENT 7
--- TREATMENT 8
...A... CONTROL


. 0:*


I I I I I
200 220 240 260 280 300 320

DAY OF YEAR, 2006
















/ \2



B

200 220 240 260 280 300 321


DAY OF YEAR, 2006



Figure 1. Disease Progress curves for Xanthomonas campestris pv. prunii on Japanese
Plum. A) Percent of leaf area damaged;. B) Percent of leaves infected.


Page 6


".- ''4;











Table 3. Summary of data for Wax Myrtle (Myrica cerifera) plants infected with a
Xanthomonas spp. following application of some bio-pesticides at 14-day intervals at
Apopka, Florida, Summer and Fall, 2006.

Treatment Product AUDPC1 Last 2 AUDPC3 Last 4
Number Percent Percent % leaves % leaves
LAD LAD Infected Infected
1 Physpe 605.0 0.7
67.1 ab 50.0
2 Kasumin 595.0 1.1 65.3 ab 62.5

3 Rhapsody 545.7 0.7 59.8 a 47.5
+ Kocide 2000
+ Vital

4 K-Phite 628.9 1.0 71.8 b 65.0

5 Tanos, 50% WG 599.2 0.9 63.8 ab 52.5
+ Kocide 2000

6 BioPhos + 604.6 0.5 63.2 ab 52.5
Chelated copper

7 Actinovate + Tricon 506.6 0.6 57.2 a 52.5

8 Kocide 2000 522.4 0.9 60.5 a 57.5

9 Control 731.5 1.1 73.2 b 60.0

F= 1.412 0.995 4.442 1.500
P = 0.242 NS 0.465 NS 0.002 ** 0.209 NS
1 Calculated mean area under the disease progress curves in arbitrary units for percent leaf area damaged. Value is
average for four replications. Means separated by Student-Newman-Keuls method based upon 2-way analysis of
variance. NS = not significant at P = 0.05 level.
2 Percent LAD on last sampling day. Value is average for four replications. Means separated by Student-Newman-
Keuls method based upon 2-way analysis of variance of Arc Sin of percentage values. NS = not significant at P = 0.05
level..
3 Calculated mean area under the disease progress curves in arbitrary units for percent of leaves infected. Value is
average for four replications. Means separated by Student-Newman-Keuls method based upon 2-way analysis of
variance of ArcSin of percentage values. Values followed by the same letter are not significantly different at the P =
0.05 level.
4 Percent of leaves infected on last sampling day. Value is average for four replications. Means separated by Student-
Newman-Keuls method based upon 2-way analysis of variance of ArcSin of percentage values. NS = not significant at
P = 0.05 level.


Page 7































0


200


220 240 260 280 300


DAY OF YEAR, 2006


TREATMENT
TREATMENT 2
TREATMENT 3
TREATMENT 4
TREATMENT 5
TREATMENT 6
TREATMENT 7
TREATMENT 8
TREATMENT 9


220 240 260 280 300


DAY OF YEAR, 2006


Figure 2. Disease Progress curves for a Xanthomonas spp on Wax Myrtle. A)
Percent of leaf area damaged; B) Percent of leaves infected.


Page 8


/V FLUSH OF NEW GROWTH

/ox


K. ..-


-0-
O-.

-a--
-v -

-A.-

A--


\ s









Table 4. Summary of data for Hibiscus (Hibiscus rosa-sinensis) plants infected with
Pseudomonas chicorii following application of some bio-pesticides at 14-day intervals at
Apopka, Florida, Summer and Fall, 2006.

Treatment Product AUDPC 1 Last 2 AUDPC 3 Last 4
Number Percent Percent Percent % leaves
LAD LAD Infected Infected
1 Physpe 110.2 bc 2.0 23.4 52.5

2 Kasumin 155.2 c 2.0 25.2 55.0

3 Rhapsody 93.2 ab 2.6 21.1 52.5
+ Kocide 2000
+ Vital

4 K-Phite 126.7 bc 1.6 24.4 50.0

5 Tanos, 50% WG 145.7 c 2.3 27.7 70.0
+ Kocide 2000

6 BioPhos + 141.1 bc 2.5 25.9 67.5
Chelated copper

7 Actinovate + Tricon 64.8 a 1.4 24.1 50.0

8 Kocide 2000 112.0 bc 2.7 25.2 57.5

9 Control 132.4 b 2.0 28.0 57.5

F= 6.409 0.385 1.577 0.849
P = 0.000 ** 0.765 NS 0.184 NS 0.481 NS
1 Calculated mean area under the disease progress curves in arbitrary units for percent leaf area damaged. Value is
average for four replications. Means separated by Student-Newman-Keuls method based upon 2-way analysis of
variance. Values followed by the same letter are not significantly different at the P = 0.05 level.
2 Percent LAD on last sampling day. Value is average for four replications. Means separated by Student-Newman-
Keuls method based upon 2-way analysis of variance of Arc Sin of percentage values. NS = not significant at P = 0.05
level.
3 Calculated mean area under the disease progress curves in arbitrary units for percent of leaves infected. Value is
average for four replications. Means separated by Student-Newman-Keuls method based upon 2-way analysis of
variance. NS = not significant at P = 0.05 level.
4 Percent of leaves infected on last sampling day. Value is average for four replications. Means separated by Student-
Newman-Keuls method based upon 2-way analysis of variance of Arc Sin of percentage values. NS = not significant
at P = 0.05 level.


Page 9






























285 290 295 300 305 310 315 320


DAY OF YEAR, 2006


-*- TREATMENT 1
-o TREATMENT
-v- TREATMENT 3
---- TREATMENT
-U- TREATMENT
---- TREATMENT 6
-4 TREATMENT 7
--- TREATMENT 8
A..- TREATMENT


285 290 295 300 305 310 315 320


DAY OF YEAR, 2006





Figure 3. Disease progress curves for Pseudomonas chicorii on Hibiscus. A) Percent of
leaf area damaged; B) Percent of leaves infected. The disease was slow to develop, so
fewer data points were obtained.


Page 10









Table 5. Summary of data for Oak Leaf Hydrangea (Hydrangea quercifolia) plants
infected withPseudomonas chicorii and an unknown Xanthomonas spp following
application of some bio-pesticides at 14-day intervals at Apopka, Florida, Summer and
Fall, 2006.

Treatment Product AUDPC1 Last 2 AUDPC 3 Last4
Number Percent Percent Percent % leaves
LAD LAD Infected Infected
1 Physpe 5.10 80.2 b 87.5
657.7 bc
2 Kasumin 612.1 bc 5.30 81.63 b 90.0

3 Rhapsody 641.2 bc 5.90 79.3 a b 95.0
+ Kocide 2000
+ Vital

4 K-Phite 653.7 bc 2.90 78.6 a b 87.5

5 Tanos, 50% WG 676.8 bc 5.70 79.0 a b 92.5
+ Kocide 2000

6 BioPhos + 499.4 b 3.50 75.0 a b 85.0
Chelated copper

7 Actinovate + Tricon 346.6 a 2.20 66.7 a 77.5

8 Kocide 2000 541.9 bc 5.30 75.3 a b 87.5

9 Control 707.4 c 4.20 80.7 b 97.5

F= 7.242 1.563 2.410 1.495
P = 0.000 ** 0.188 NS 0.046 NS 0.211 NS
1 Calculated mean area under the disease progress curves in arbitrary units for percent leaf area damaged. Value is
average for four replications. Means separated by Student-Newman-Keuls method based upon 2-way analysis of
variance. Values followed by the same letter are not significantly different at the P = 0.05 level.
2 Percent LAD on last sampling day. Value is average for four replications. Means separated by Student-Newman-
Keuls method based upon 2-way analysis of variance of the Arc Sin of percentage values. NS = not significant at P =
0.05 level..
3 Calculated mean area under the disease progress curves in arbitrary units for percent of leaves infected. Value is
average for four replications. Means separated by Student-Newman-Keuls method based upon 2-way analysis of
variance. Values followed by the same letter are not significantly different at the P = 0.05 level.
4 Percent of leaves infected on last sampling day. Value is average for four replications. Means separated by Student-
Newman-Keuls method based upon 2-way analysis of variance of the Arc Sin of percentage values. NS = not
significant at P = 0.05 level..


Page 11















































TREATMENT 1
TREATMENT 2
TREATMENT 3
TREATMENT 4
TREATMENT 5
TREATMENT
TREATMENT 7
TREATMENT 8
TREATMENT 9


.*- -


II I I1
200 220 240 260 280 300 32C

DAY OF YEAR, 2006







-
/. \




..


DAY OF YEAR, 2006

Figure 4. Disease Progress curves for Pseudomonas chicorii and an
unknown Xanthomonas spp. on Hydrangea. A) Percent of leaf area
damaged; B) Percent of leaves infected.


Page 12


-"O-"

-0-

-G --




A---




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