Ecological Archives E088-076-A3

Ingrid M. Parker and Gregory S. Gilbert. 2007. When there is no escape: the effects of natural enemies on native, invasive, and noninvasive plants. Ecology 88:1210–1224.

Appendix C. Detailed description of fungicide experiments.

This section includes: (1) Table C1. Effect of fungicide on infection and disease symptoms, (2) Table C2. Effect of Daconil fungicide application on aboveground biomass for each species individually in Year 3, (3) Table C3. Effect of Dithane 45 fungicide application on aboveground biomass for each species individually in Year 4, (4) Fungicide phytotoxicity experiments, and (5) Fungicide effects on mycorrhizal colonization.

Fungicide treatment effects

Here we show data on the efficacy and side effects of fungicide applications.

TABLE C1. Effect of fungicide on infection and disease symptoms. Fungicides were successful in reducing, but not eliminating, infection and disease symptoms in the two years they were applied (Year 3 and Year 4). Here species were used as replicates and analyses were done on the proportion infected or the proportion leaf tissue damaged, arcsine-square-root transformed before analysis. We report one-tailed P values (fungicide < control) for paired t tests.

 

Measure

Control mean (SD)

Fungicide mean (SD)

t

df

P

Year 3

Infection%

90.9 (12.8)

84.3 (18.6)

2.89

15

0.0056

Year 4

Infection%

89.1 (10.7)

70.1 (16.9)

6.28

16

<0.00001

Year 3

Symptom%

3.80 (4.21)

1.32 (2.30)

2.44

15

0.014

Year 4

Symptom%

1.29 (1.98)

0.61 (1.07)

2.58

16

0.010


TABLE C2. Effect of Daconil fungicide application on aboveground biomass for each species individually in Year 3. Means (± standard deviation) are provided. Paired t tests were performed on log-transformed values; two-tailed P values are presented. Bold indicates species that are invasive in the Bodega Marine Reserve.

Origin

Species

Control biomass (g)

Fungicide biomass (g)

t

df

P

Introduced

M. arabica

0.597 (0.520)

0.561 (0.705)

1.72

36

0.09

Introduced

M. lupulina

0.068 (0.176)

0.047 (0.083)

0.34

35

0.73

Introduced

M. polymorpha

0.648 (0.698)

0.68 (1.082)

0.70

35

0.49

Introduced

T. campestre

0.022 (0.057)

0.020 (0.035)

0.14

22

0.89

Introduced

T. dubium

0.014 (0.025)

0.014 (0.026)

1.08

25

0.29

Introduced

T. glomeratum

0.007 (0.012)

0.004 (0.003)

0.78

12

0.45

Introduced

T. repens

0.005 (0.003)

0.011 (0.012)

2.90

33

0.007

Introduced

T. subterraneum

0.071 (0.148)

0.089 (0.137)

1.21

30

0.24

Native

T. barbigerum

0.113 (0.086)

0.105 (0.097)

0.12

25

0.91

Native

T. bifidum

0.124 (0.129)

0.103 (0.076)

0.57

30

0.57

Native

T. fucatum

0.569 (0.386)

0.509 (0.675)

1.10

27

0.28

Native

T. gracilentum

0.124 (0.118)

0.103 (0.085)

0.47

28

0.64

Native

T. macraei

0.123 (0.112)

0.186 (0.152)

1.45

24

0.16

Native

T. microcephalum

0.072 (0.071)

0.050 (0.065)

0.55

20

0.59

Native

T. microdon

0.145 (0.131)

0.134 (0.146)

1.44

28

0.16

Native

T. wormskjoldii

0.053 (0.050)

0.053 (0.048)

0.48

32

0.63


TABLE C3. Effect of Dithane 45 fungicide application on aboveground biomass for each species individually in Year 4. Means (± standard deviation) are provided. Unpaired t tests assuming unequal variances were performed on log-transformed values, two-tailed P values are presented. Bold indicates species that are invasive in the Bodega Marine Reserve.

Origin

Species

Control biomass (g)

Fungicide biomass (g)

t

df

P

Introduced

M. arabica

0.104 (0.049)

0.104 (0.049)

0.07

9.8

0.95

Introduced

M. lupulina

0.057 (0.042)

0.093 (0.064)

0.49

9.7

0.63

Introduced

M. polymorpha

0.137 (0.108)

0.125 (0.073)

0.11

9.0

0.91

Introduced

T. campestre

0.083 (0.058)

0.053 (0.033)

0.68

8.7

0.52

Introduced

T. dubium

0.112 (0.059)

0.074 (0.057)

1.10

6.4

0.31

Introduced

T. glomeratum

0.169 (0.038)

0.123 (0.090)

1.05

3.1

0.37

Introduced

T. repens

0.062 (0.046)

0.048 (0.029)

0.25

6.9

0.81

Introduced

T. subterraneum

0.124 (0.069)

0.111 (0.064)

0.14

9.7

0.89

Native

T. barbigerum

0.143 (0.077)

0.108 (0.077)

0.79

7.2

0.46

Native

T. bifidum

0.195 (0.24)

0.137 (0.073)

0.35

6.7

0.73

Native

T. fucatum

0.300 (0.213)

0.519 (0.749)

0.16

7.4

0.88

Native

T. gracilentum

0.189 (0.232)

0.181 (0.239)

0.65

6.4

0.54

Native

T. macraei

0.345 (0.237)

0.213 (0.181)

0.61

9.4

0.56

Native

T. microcephalum

0.162 (0.201)

0.167 (0.186)

0.19

9.5

0.85

Native

T. microdon

0.208 (0.163)

0.242 (0.152)

0.29

8.2

0.78

Native

T. willdenovii

0.372 (0.198)

0.412 (0.217)

0.22

9.9

0.83

Native

T. wormskjoldii

0.097 (0.033)

0.124 (0.091)

0.42

4.3

0.69

 

Fungicide phytotoxicity experiments

We tested for phytotoxicity of DaconilTM in the summer of 2001 and of Dithane F45TM in the fall of 2002. We used all 17 clover species, with N = 12 per species for Daconil and N = 16 per species with DithaneTM. We germinated seeds on moistened filter paper and then planted seedlings into Conetainers (2.5 cm × 16.5 cm) filled with double autoclaved Premier brand Pro-Mix PGXTM growth medium. Plants were maintained in a growth chamber with 14-h days and 15°C/10°C day/night temperatures until they developed 3 leaves. Then one of each species was placed into eight split-block replicates. Blocks were racks split horizontally into spray and control treatments (randomly assigned), with dividers to prevent chemical drift between them. Species were randomized within each treatment. The blocks were transferred to the greenhouse and maintained with 16-h days and 75°C/65°C day/night temperatures and minimal fertilizer. Plants were sprayed once a week for four weeks according to manufacturer instructions. One week after the final spray, the plants were harvested and the roots and shoots separated. The roots and shoots were oven dried and weighed. We performed one-tailed t tests assuming unequal variances on the data (JMP 5.1.1). DaconilTM application did not decrease plant size either above ground (t = 0.035, df = 123, P = 0.51) or belowground (t = 1.2, df = 112, P = 0.11) for all species combined. Dithane F45TM application did not decrease plant size either above ground (t = 1.81, df = 262, P = 0.96) or belowground (t = 0.99, df = 263, P = 0.84) for all species combined. Of the 68 comparisons made (two fungicides, 17 species, above- and below-ground), one showed a significant negative effect of the fungicide at alpha< 0.05 but not at the Bonferroni-adjusted alpha< 0.0007 (DaconilTM, T. subterraneum belowground, t = 3.8, df = 4.2, P = 0.009).

Fungicide effects on mycorrhizal colonization

In Year 4, we tested for effects of Dithane F45TM fungicide on mycorrhizal infection of roots. We randomly selected 8–12 plants (equal numbers of fungicide and control) of each species from the common garden experiment. After harvest, we washed and cut roots into 1-cm pieces and cleared them in 10% KOH for 24–28 h at room temperature. We then rinsed roots 3 times in tap water and stained them for 15 min with 0.05% trypan blue in lactoglycerine (1:1:1 water: lactic acid: glycerol) (Brundrett et al. 1996). Roots were destained and stored in lactoglycerine. Counts of mycorrhizal colonization were made by a modified gridline intersection procedure (Giovannetti and Mosse 1980). We performed one-tailed t tests assuming unequal variances on the data, which were log-transformed to improve normality (JMP 5.1.1). Mycorrhizal colonization (units of relative abundance, Mean ± SD) was not less common in fungicide plants (0.11 ± 0.08) than in control plants (0.12 ± 0.09) when all species were combined (t = 0.80, df = 183, P = 0.21). When considered independently, two of the 17 species showed significantly lower mycorrhizal infection in the fungicide plants at alpha< 0.05 but not significantly lower at the Bonferroni-adjusted alpha< 0.0029 (T. glomeratum, t = 4.19, df = 5.5, P = 0.0035; T. willdenovii, t = 3.75, df = 7.6, P = 0.0031).

LITERATURE CITED

Brundrett, M., N. Bougher, B. Dell, T. Grove, and N. Malajczuk. 1996. Working with mycorrhizas in forestry and agriculture. Australian Centre for International Agricultural Research, Canberra, Australia.

Giovannetti, M., and B. Mosse. 1980. An evaluation of techniques for measuring vesicular-arbuscular infection in roots. New Phytologist 84:489–500.



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