Phytotoxicity and Efficacy of Florel (Ethephon) for Defoliation of

Japanese Rose (Rosa rugosa ‘Hansa’)

By

Heiner Lieth, Director Linda Dodge Shannon Still

Ron Lane

Project: USDA Interregional Research Project #4 Project Number 18815A – September 30, 2003

Acknowledgements: Donors/Supporters: CDFA Minor Crops Research Grant, Project 2: Enhancement of the Western

Region IR-4 Program to Address California Needs High Ranch Nursery, Loomis CA

UC Davis Environmental Horticulture IR4 Center Department of Environmental Horticulture University of California One Shields Ave. Davis, CA 95616 http://envhort.ucdavis.edu/ir4

PR.NO.: 18815A TRIAL: 1 DATE: 9-30-03

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IR-4 ORNAMENTAL DATA REPORTING FORM (Please type or print) 1. INVESTIGATOR (Name, Address, Phone#):

Dr. Heiner Lieth Department of Environmental Horticulture University of California One Shields Ave. Davis, CA 95616 Ph 530-752-7198 FAX 530-752-1819 Email: jhlieth@ucdavis.edu

LOCATION OF TRIAL: Environmental Horticulture Dept., University of California, TRIAL TYPE: FIELD CONTAINER

2. PESTICIDE:

COMMON NAME: ethephon FORMULATION: 3.9% ai BATCH NO.: 3030193 Item 5105 PRODUCT: Florel EPA REG. NO. 54705-8 MFG: Monterey Lawn and Garden Products, Inc.

3. USE INFORMATION: COMMON NAME SCIENTIFIC NAME

PLANT: Japanese or Turkestan Rose Rosa rugosa cv ‘Hansa’ REASON: Defoliation SOIL TYPE OR TYPE OF POTTING MIX: organic container mix from grower

% SAND % SILT % CLAY % OM % pH SEEDING DATE EMERGENCE DATE TRANSPLANTING DATE PLANT OR POT SPACING 12 inches ROW SPACING 24 inches POT SIZE one gallon PLOT SIZE 110 sq. ft EXPERIMENTAL DESIGN randomized complete block (3) NO.OF REPS 4X3=12

4. APPLICATION PARAMETERS:

TYPE OF APPLICATION: foliar spray NO. OF APPLICATIONS one APPLICATION TYPE NOZZLE TYPE/SIZE NOZZLE PRESSURE DELIVERY RATE CALIBRATION DATE (S)

5. APPLICATION SUMMARY:

APPL.DATE

RATES (a.i./A)*

GROWTH STAGE

8-19-03

0, 1.6, 3.2, 6.4 fl. oz./gal.

Full leaf, mature buds

(0, 500, 1000, 2000 ppm)

*Be sure to provide units

PR.NO.: 18815A TRIAL: 1 DATE: 9-30-03

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IR-4 ORNAMENTAL DATA REPORTING FORM (Please type or print) 6. RAINFALL/IRRIGATION RECORDS: Plants were irrigated as needed with tap water

INCLUDE RAINFALL/IRRIGATION INFORMATION (printouts, IR-4 forms, etc.) See Table 1

7. OTHER PESTICIDES, FERTILIZER, LIME AND ADJUVANTS USED:

PRODUCT unknown slow-release fertilizer AMOUNT unknown DATE unknown PRODUCT AMOUNT DATE PRODUCT AMOUNT DATE PRODUCT AMOUNT DATE

8. NARRATIVE SUMMARY OF METHODS AND RESULTS: (Use more pages if needed) Materials and Methods Plant Material and Culture. Fifty one-gallon plants of Rosa rugosa cv. ‘Hansa’ were received at UC Davis on 7-29-03 from High Ranch Nursery in Loomis, CA. Each plant had three or four shoots and all were in bloom. The plants were held in a greenhouse at 75°F (24°C) for two weeks and then transferred to the outdoor nursery on 8-12-03, where they remained until the end of the experiment on 9-30-03 (six weeks). The plants were watered as needed with tap water and temperatures ranged from 50°F (10°C) to 102°F (39°C) during the course of the experiment (Table 1). Experimental Procedure. Forty-eight one-gallon plants of Rosa rugosa cv. ‘Hansa’ were randomly assigned to four treatment groups (12 replicates per treatment). The plants were sprayed to runoff with 0, 500, 1000 or 2000 ppm ethephon and then randomized into three blocks on 8-19-03 (Figure 1). The leaves on two branches of each plant were counted the day after treatment (8-20-03) and 16 days later (9-04-03) (Figure 2). The plants were rated for phytotoxicity at the same time. The plants remained in the nursery until 9-30-03 (six weeks). Additional Observations. During the experiment, it was observed that basal buds on some plants were initiating shoot growth. As this is a known effect of ethephon on roses, these basal breaks were counted on all plants on day 16. Statistical Analysis. The data were analyzed using Proc GLM of the Statistical Analysis System (SAS). The plants were arranged in a randomized complete block design. Increases in the mean from the starting number of leaves were analyzed for significant differences using t-tests. Increases in the number of bud breaks were analyzed for significant differences using t-tests. Results Phytotoxicity. Ethephon had no phytotoxic effects on Rosa rugosa cv. ‘Hansa’ plants (Appendix A). Efficacy. The number of leaves per stem increased over the two-week counting period (Appendix B, Figure 3). Additional Observations. Two weeks after treatment, the control plants showed no bud break while the plants treated with 1000 ppm ethephon averaged one break per plant and those treated with 2000 ppm ethephon averaged 2.5 breaks per plant (Appendix C, Figure 4). The 2000 ppm treatment had a significantly higher number of bud breaks than the other treatments. There was no significant difference in bud breaks between the control, 500, and 1000 ppm treatments. Discussion The objective of this experiment was to evaluate the usefulness of ethephon as a defoliating agent prior to harvest and cold storage of Rosa rugosa plants. Under the experimental conditions imposed here, rapid defoliation did not occur and the numbers of leaves per stem actually increased over the two-week counting period (Appendix B, Figure 3). The plants were still in full leaf six weeks after the ethephon applications were made. It was speculated that the warm temperatures

PR.NO.: 18815A TRIAL: 1 DATE: 9-30-03

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during the experiment might have led to volatilization of the ethephon before affecting leaf abscission. This is unlikely, however, as spray applications were made early in the morning when cool air temperatures prevailed. The average maximum air temperature for the nearest CIMIS station over the six-week experimental period was 90°F (32°C); the average minimum air temperature was 56°F (13°C) and the overall average temperature was 70°F (22°C) (Table 1). Volatilization of ethephon is also unlikely due to the significant occurrence of basal budbreak on treated plants (Figure 4), a known response of roses to treatment with ethephon. 9. GOOD RESEARCH PRACTICE STATEMENT:

I acknowledge that I have read and followed the IR-4 Research protocol and completed this trial following good agricultural practice, or reported any deviations (note any changes from authorized protocol in narrative).

SIGNATURE DATE

Dr. Heiner Lieth PRINCIPAL INVESTIGATOR

PR.NO.: 18815A TRIAL: 1 DATE: 9-30-03

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Table 1. Weather data for Davis CIMIS station from 8-19-03 to 9-30-03 during Rosa rugosa experiment. (Data taken from http://www.cimis.water.ca.gov/) Date CIMIS

ETo (mm) Precip (mm)

Sol Rad (W.sq.m)

Avg Vap (kPa)

Max Air Temp (°C)

Min Air Temp (°C)

Avg Air Temp (°C)

Max Rel Hum (%)

Min Rel Hum (%)

Avg Rel Hum (%)

Dew Pt (°C)

Avg wSpd (m/s)

Wnd Run (Km)

Avg Soil Temp (°C)

8/19/03 5.94 0 301 1.5 31.7 13 21 87 25 59 12.6 2.6 226.3 19.68/20/03 6.13 0 299 1.5 34.8 13.1 24.1 87 24 49 12.6 1.8 157.7 19.68/21/03 3.25 1.4 153 1.7 30.4 17 21.7 92 33 65 15 2.6 221 19.78/22/03 4.47 3.4 240 1.7 25.4 15.4 20.3 94 49 71 14.8 2.7 232.2 -- 8/23/03 5.38 2 291 1.8 31.3 13.2 22.2 94 39 65 15.4 1.5 128.6 19.48/24/03 5.7 1.3 298 1.7 35.2 15.8 25.2 92 26 54 15.1 1.4 122.8 20.28/25/03 6.02 0.6 293 1.6 37 17 26.9 83 22 45 14 1.5 133.1 20.88/26/03 6.49 0.1 271 1.5 36.8 16.4 25.9 75 19 44 12.7 2.6 224.9 21.18/27/03 5.65 0 291 1.5 31.9 -- 24.4 89 30 48 12.8 2.9 249.5 20.88/28/03 5.61 0 300 1.4 29.3 11 19.6 89 35 61 12 2.5 212.5 19.88/29/03 5.49 0 296 1.4 33.8 11.2 21.1 92 24 56 12 1.8 159 19.78/30/03 5.38 0 287 1.4 33.3 12.2 21.6 89 28 56 12.5 1.8 152 208/31/03 5.75 0 285 1.5 37.5 12.5 24.2 87 19 49 12.7 1.6 139.4 20.2

9/1/03 5.6 0 279 1.5 37.2 14 24.5 83 22 50 13.4 1.6 136.3 20.59/2/03 5.88 2.3 274 1.5 39.4 13.8 25.6 89 14 46 13 1.9 166.4 18.49/3/03 5.57 0.5 229 1.5 36.2 18.2 25.6 71 20 46 13.2 2.5 213.2 19.99/4/03 5.45 0 250 1.6 32.2 16.3 22.9 80 37 57 13.9 2.7 234.1 20.19/5/03 5.72 0 282 1.2 30.8 13.3 21.3 85 20 49 10 2.5 213.7 19.89/6/03 5.39 0 280 1.3 27.4 12.7 18.8 82 36 58 10.4 3.1 266.8 19.19/7/03 4.46 0 226 1.4 28.7 10.1 19.6 88 38 61 12 2.4 205.4 18.79/8/03 5.52 0 258 1.2 28.8 11.6 20 91 24 50 9.2 2.6 225.6 18.79/9/03 3.31 0 168 1.4 26 13.4 19.1 87 36 64 12.1 2.5 216.2 18.3

9/10/03 6.84 0 263 1.2 31.1 14.4 22.7 90 19 43 9.4 4.1 357.5 18.59/11/03 5.79 0 260 1.1 34 14.3 24.3 62 18 37 8.5 2.1 185.2 18.69/12/03 7.68 0 262 1 36.2 18.7 27.1 52 12 29 7.5 3.6 314.8 199/13/03 8.39 0 259 0.6 35.2 17.6 27.6 39 12 18 0.8 5.5 478.1 18.89/14/03 5.98 0 258 0.9 36.4 13 25.3 66 11 27 4.8 2.1 180.3 18.69/15/03 5.03 0 243 1.3 30.3 14.2 21 75 32 53 11 2.9 250.5 18.69/16/03 4.62 0 247 1.1 28 12 18.9 76 26 52 8.9 2.5 219.7 189/17/03 7.82 0 251 0.7 28.4 12.4 21.1 77 14 28 1.9 5.7 493.9 -- 9/18/03 6.19 0 254 0.6 31.7 13.6 22.7 40 12 21 -0.5 2.7 232.8 -- 9/19/03 5.04 0 246 0.8 34.4 10 22.2 53 13 29 3.2 1.3 116.5 16.59/20/03 6.39 0 247 0.9 37.4 11.4 24.4 59 13 30 5.8 2.5 218.2 179/21/03 4.83 0 242 1.1 37.8 12.4 24.4 64 14 35 8 1.2 101.9 17.49/22/03 5.08 0 235 1 39.3 16.2 26.1 52 11 29 6.7 1.3 112.8 17.99/23/03 4.78 0 229 1.3 34.8 13 22.9 73 22 45 10.3 1.8 156.6 18.19/24/03 4.58 0 227 1.4 29.5 12 19.6 86 36 61 11.8 2.7 235.1 -- 9/25/03 3.88 0 225 1.4 27.5 11.2 18.4 86 42 66 11.9 1.8 157.9 16.59/26/03 3.77 0 224 1.4 28.5 9.6 18.3 89 38 65 11.7 1.5 131.1 16.89/27/03 3.78 0 221 1.4 30.5 9.4 18.8 90 37 65 12 1.4 118.5 179/28/03 4.28 0 217 1.4 27.3 10.1 18.6 89 45 66 12.2 2.9 246.7 179/29/03 3.67 0 221 1.3 28.1 10 18.4 89 33 61 10.7 1.6 141.4 16.89/30/03 4.06 0 209 1.2 30.4 11.4 19.8 80 28 52 9.8 1.8 152.2 16.8

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Figure 1. Rosa rugosa cv. ‘Hansa’ plants were sprayed to runoff with 0, 500, 1000 or 2000 ppm ethephon and then randomized into three blocks in an outdoor nursery and held for six weeks to evaluate defoliation.

Figure 2. The leaves on two branches of each Rosa rugosa cv. ‘Hansa’ plant were counted the day after treatment (8-20-03) and 16 days later (9-04-03). Branches to be counted were identified with colored tape.

PR.NO.: 18815A TRIAL: 1 DATE: 9-30-03

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0

2

4

6

8

10

12

14

Control 500 ppm 1000 ppm 2000 ppm

Ethephon concentration

num

ber o

f lea

ves

per s

tem

week 0week 2

Figure 3. The average number of leaves per stem for Rosa rugosa cv. ‘Hansa’ plants treated with 0, 500, 1000 or 2000 ppm ethephon on the day after treatment (week 0) and 16 days later (week 2) (n = 12).

0.00

0.50

1.00

1.50

2.00

2.50

3.00

Control 500 ppm 1000 ppm 2000 ppm

ethephon concentration

Num

ber o

f bas

al b

reak

s pe

r pla

nt

Figure 4. The average number of basal bud breaks per plant for Rosa rugosa cv. ‘Hansa’ plants 16 days after treatment with 0, 500, 1000 or 2000 ppm ethephon (n = 12).

PR.NO.: 18815A TRIAL: 1 DATE: 9-30-03

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Appendix A: PHYTOTOXICITY REPORT FORM

TREATMENT

RATE

*fl oz/gal

PHYTO REP.

Block A PHYTO

RATE #1 8-20-03

Block A PHYTO

RATE #2 9-04-03

Block B PHYTO

RATE # 1 8-20-03

Block B PHYTO

RATE #2 9-04-03

Block C PHYTO

RATE # 1 8-20-03

Block C PHYTO

RATE #2 9-04-03

CONTROL

0

1

0

0

0

0

0

0

CONTROL

0

2

0

0

0

0

0

0

CONTROL

0

3

0

0

0

0

0

0

CONTROL

0

4

0

0

0

0

0

0

CONTROL

0

MEAN

0

0

0

0

0

0

1X (500 ppm)

1.6

1

0

0

0

0

0

0

1X (500 ppm)

1.6

2

0

0

0

0

0

0

1X (500 ppm)

1.6

3

0

0

0

0

0

0

1X (500 ppm)

1.6

4

0

0

0

0

0

0

1X (500 ppm)

1.6

MEAN

0

0

0

0

0

0

2X (1000 ppm)

3.2

1

0

0

0

0

0

0

2X (1000 ppm)

3.2

2

0

0

0

0

0

0

2X (1000 ppm)

3.2

3

0

0

0

0

0

0

2X (1000 ppm)

3.2

4

0

0

0

0

0

0

2X (1000 ppm)

3.2

MEAN

0

0

0

0

0

0

4X (2000 ppm)

6.4

1

0

0

0

0

0

0

4X (2000 ppm)

6.4

2

0

0

0

0

0

0

4X (2000 ppm)

6.4

3

0

0

0

0

0

0

4X (2000 ppm)

6.4

4

0

0

0

0

0

0

4X (2000 ppm)

6.4

MEAN

0

0

0

0

0

0

NOTE: DEFINE MEASUREMENT OF PHYTOTOXICITY, OR INDEX OF INJURY (0=NO INJURY, 10=COMPLETE KILL)

*Be sure to provide units

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Appendix B: EFFICACY REPORT FORM for Rosa rugosa Block A

TREATMENT

RATE

*fl oz/gal

REP.

8-20-03 Number of leaves on

branch one

8-20-03 Number of leaves on

branch two

9-04-03 Number of leaves on

branch one

9-04-03 Number of leaves on

branch two

CONTROL 0

1 13 10 14 18

CONTROL

0

2 6 8 12 14

CONTROL

0

3 15 6 16 6

CONTROL

0

4 10 11 15 14

CONTROL

0

MEAN

11.0

8.8

14.3

13.0

1X (500 ppm)

1.6

1 13 9 21 11

1X (500 ppm)

1.6

2 9 9 9 11

1X (500 ppm)

1.6

3 8 16 7 18

1X (500 ppm)

1.6

4 7 26 5 29

1X (500 ppm)

1.6

MEAN

9.3

15.0

10.5

17.3

2X (1000 ppm)

3.2

1 10 9 12 12

2X (1000 ppm)

3.2

2 11 9 13 12

2X (1000 ppm)

3.2

3 15 11 14 22

2X (1000 ppm)

3.2

4 12 9 13 10

2X (1000 ppm)

3.2

MEAN

12.0

9.5

13.0

14.0

4X (2000 ppm)

6.4

1 13 14 14 12

4X (2000 ppm)

6.4

2 7 11 10 22

4X (2000 ppm)

6.4

3 10 11 15 12

4X (2000 ppm)

6.4

4 15 12 16 14

4X (2000 ppm)

6.4

MEAN

11.3

12.0

13.8

15.0

NOTE: DEFINE MEASUREMENT OF PEST POPULATION AND EFFICACY SCALE (0=NO CONTROL, 10=COMPLETE CONTROL)

Measurements taken were the number of leaves on each of two branches per plant.

**In herbicide trials report for both weedy check and weed-free check. *Be sure to provide units 07/94

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Appendix B: EFFICACY REPORT FORM for Rosa rugosa Block B

TREATMENT

RATE

*fl oz/gal

REP.

8-20-03 Number of leaves on

branch one

8-20-03 Number of leaves on

branch two

9-04-03 Number of leaves on

branch one

9-04-03 Number of leaves on

branch two

CONTROL 0

1 7 8 10 10

CONTROL

0

2 8 7 10 5

CONTROL

0

3 10 9 19 14

CONTROL

0

4 16 13 14 14

CONTROL

0

MEAN

10.3

9.3

13.3

10.8

1X (500 ppm)

1.6

1 9 10 16 20

1X (500 ppm)

1.6

2 8 8 16 11

1X (500 ppm)

1.6

3 10 14 14 13

1X (500 ppm)

1.6

4 10 8 16 10

1X (500 ppm)

1.6

MEAN

9.3

10.0

15.5

13.5

2X (1000 ppm)

3.2

1 15 11 14 13

2X (1000 ppm)

3.2

2 21 12 29 10

2X (1000 ppm)

3.2

3 7 9 12 12

2X (1000 ppm)

3.2

4 10 7 18 12

2X (1000 ppm)

3.2

MEAN

13.3

9.8

18.3

11.8

4X (2000 ppm)

6.4

1 8 14 13 15

4X (2000 ppm)

6.4

2 9 7 16 9

4X (2000 ppm)

6.4

3 15 12 17 12

4X (2000 ppm)

6.4

4 10 14 16 12

4X (2000 ppm)

6.4

MEAN

10.5

11.8

15.5

12.0

NOTE: DEFINE MEASUREMENT OF PEST POPULATION AND EFFICACY SCALE (0=NO CONTROL, 10=COMPLETE CONTROL)

Measurements taken were the number of leaves on each of two branches per plant.

**In herbicide trials report for both weedy check and weed-free check. *Be sure to provide units 07/94

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Appendix B: EFFICACY REPORT FORM for Rosa rugosa Block C

TREATMENT

RATE

*fl oz/gal

REP.

8-20-03 Number of leaves on

branch one

8-20-03 Number of leaves on

branch two

9-04-03 Number of leaves on

branch one

9-04-03 Number of leaves on

branch two

CONTROL 0

1 8 9 9 9

CONTROL

0

2 7 11 13 7

CONTROL

0

3 14 11 12 12

CONTROL

0

4 9 9 16 15

CONTROL

0

MEAN

9.5

10.0

12.5

10.8

1X (500 ppm)

1.6

1 8 7 13 11

1X (500 ppm)

1.6

2 7 8 2 9

1X (500 ppm)

1.6

3 10 7 10 6

1X (500 ppm)

1.6

4 12 11 6 11

1X (500 ppm)

1.6

MEAN

9.3

8.3

7.8

9.3

2X (1000 ppm)

3.2

1 13 7 10 5

2X (1000 ppm)

3.2

2 12 7 14 15

2X (1000 ppm)

3.2

3 9 8 11 11

2X (1000 ppm)

3.2

4 8 11 3 10

2X (1000 ppm)

3.2

MEAN

10.5

8.3

9.5

10.3

4X (2000 ppm)

6.4

1 10 10 12 13

4X (2000 ppm)

6.4

2 10 8 12 8

4X (2000 ppm)

6.4

3 10 10 14 10

4X (2000 ppm)

6.4

4 10 8 9 11

4X (2000 ppm)

6.4

MEAN

10.0

9.0

12.7

10.3

NOTE: DEFINE MEASUREMENT OF PEST POPULATION AND EFFICACY SCALE (0=NO CONTROL, 10=COMPLETE CONTROL)

Measurements taken were the number of leaves on each of two branches per plant.

**In herbicide trials report for both weedy check and weed-free check. *Be sure to provide units 07/94

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Appendix C: Number of Basal Bud Breaks per plant for Rosa rugosa on 9/04/03

TREATMENT RATE (fl. oz./gal.) Rep. Block A Block B Block C

CONTROL 0 1 0 0 0 CONTROL 0 2 0 0 0 CONTROL 0 3 0 0 0 CONTROL 0 4 0 0 0 CONTROL 0 MEAN 0 0 0 1X (500 ppm) 1.6 1 0 0 0 1X (500 ppm) 1.6 2 0 0 0 1X (500 ppm) 1.6 3 0 1 0 1X (500 ppm) 1.6 4 0 1 1 1X (500 ppm) 1.6 MEAN 0 0.5 0.25 2X (1000 ppm) 3.2 1 0 0 3 2X (1000 ppm) 3.2 2 0 5 1 2X (1000 ppm) 3.2 3 0 1 3 2X (1000 ppm) 3.2 4 0 1 0 2X (1000 ppm) 3.2 MEAN 0 1.75 1.75 4X (2000 ppm) 6.4 1 0 2 4 4X (2000 ppm) 6.4 2 5 3 0 4X (2000 ppm) 6.4 3 8 0 3 4X (2000 ppm) 6.4 4 1 3 1 4X (2000 ppm) 6.4 MEAN 3.5 2 2