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Table 1. Effects of short-term fallowing and fumigation on subsequent performance of peach trees used to replant a cleared peach orchard site in 1998; Parlier, CA; data from Trout and Ajwa

 

 

Trunk diameter (mm)d

Marketable yield (kg/tree) d

Pre-plant treatmenta

11/98

12/99

11/00

11/01

10/02

8/00

8/01

8/02

0-year fallow, non-fumigated

22 c

40 c

63 c

81 c

104 c

6.7 b

17.1 a

32.8 a

1-year fallow, non-fumigated

27 bc

50 b

74 bc

88 bc

113 bc

7.2 b

18.4 a

35.5 a

1-year fallow, Telone + Vapamb

29 b

53 b

80 ab

97 ab

116 ab

9.1 a

20.4 a

38.2 a

0-year fallow, methyl bromide c

37 a

63 a

89 a

104 a

126 a

9.9 a

18.8 a

38.2 a

 

aFor the fallow treatments, trees were removed in fall, either 0 year (4 mo) or 1 year (16 mo) before replanting. After tree removal, fallow plots were ripped to 76 cm depth and planted to Merced rye, which was mowed in spring. All treatments were planted simultaneously in February 1998.

b35 gal/A Telone II EC (310 lb/A 1,3-D) was applied by sub-drip in 100 mm water in fall 1997 with Vapam (26 gal/A) microsprayed on the soil surface.

cMethyl bromide (350 lb/A) was shank-injected in fall 1997, under HDPE plastic.

dMeans within a column and with letters in common are not significantly different (P=0.05).

 

 

 

Table 2. Effects of short-term fallowing and fumigation on subsequent performance of peach trees used to replant an old peach orchard site in 1999; Parlier, CA; data from Trout and Ajwa

 

 

Trunk diameter (mm)d

Marketable yield,7/02 (kg/tree) d

Pre-plant treatmenta

12/99

11/00

11/01

10/02

0-year fallow, non-fumigated

17 c

42 c

61 b

88 c

22.6 c

1-year fallow, non-fumigated

19 b

49 b

69 b

94 bc

26.2 bc

1-year fallow, Inline + Vapamb

22 a

58 a

80 a

106 a

32.8 a

0-year fallow, methyl bromide c

23 a

58 a

79 a

104 ab

30.1 ab

 

aFor the fallow treatments, trees were removed in fall, either 0 year (4 mo) or 1 year (16 mo) before replanting. After tree removal, fallow plots were ripped to 76 cm depth and planted to Merced rye, which was mowed in spring. All treatments were planted simultaneously in February 1998. b35 gal/A Inline (Telone C-35 EC) (320 lb/A 1,3-D+130 lb/A chloropicrin) was applied by sub drip in 76 mm water in fall 1998 with Vapam (13 gal/A) microsprayed on the soil surface.

cMethyl bromide (350 lb/A) was shank-injected fall 1998, covered with HDPE plastic.

dMeans within a column and with letters in common are not significantly different (P=0.05).

 

 


Table 3. Effects of short- to long-term pre-plant fallowing and pre-plant fumigation on performance of plum trees used to replant an old plum orchard site in 2000; Parlier, CA; after Trout and Ajwa

 

 

Trunk diameter (mm)d

 

Pre-plant treatmenta

10/00

11/01

10/02

Marketable yield (kg/tree) d

0-year fallow, non-fumigated

25 c

52 c

92 b

4.7 b

1-year fallow, non-fumigated

29 b

64 b

108 a

5.9 ab

1-year fallow, non-fumigated, herbicide treatment of stumps b

28 bc

63 b

109 a

6.4 ab

2-year fallow, non-fumigated

30 ab

67 ab

111 a

8.3 ab

3-year fallow, non-fumigated

34 a

71 a

115 a

12.7 a

0-year fallow, methyl bromide c

34 a

71 a

115 a

11.8 a

 

aFor the fallow treatments, trees were removed in fall, either 0, 1, 2, or 3 year before replanting. After old tree removal, fallow plots were ripped to 76 cm depth and planted to Merced rye, which was mowed in spring. All plots were planted on the same day in February 2000.

bStumps of old trees treated with Roundup (50 ml/tree) immediately after cutting off tops in September, 16 mo before replanting.

cMethyl bromide (350 lb/A) was shank-injected fall 1999, covered with HDPE plastic.

dMeans within a column and with letters in common are not significantly different (P=0.05).

 

 

 

Table 4. Effects of short- to long-term pre-plant fallows and pre-plant fumigation on subsequent performance of peach trees used to replant an old peach orchard site in 2000; Parlier, CA; after Trout and Ajwa

 

 

Trunk diameter (mm)c

 

Pre-plant treatmenta

11/00

10/01

10/02

Marketable yield (kg/tree) c

0-year fallow, non-fumigated

20 b

42 d

62 c

8.0 d

1-year fallow, non-fumigated

20 b

44 cd

72 b

10.4 cd

2-year fallow, non-fumigated

22 b

48 bc

76 b

14.0 bc

3-year fallow, non-fumigated

23 b

50 b

80 b

16.0 b

0-year fallow, methyl bromide b

29 a

58 a

90 a

18.2 a

 

aFor the fallow treatments, trees were removed in fall, either 0, 1, 2, or 3 year before replanting. After old tree removal, fallow plots were ripped to 76 cm depth and planted to Merced rye, which was mowed in spring. All treatments & plots were planted on the same day in February 2000.

bMethyl bromide (350 lb/A) was shank-injected fall 1999, covered with HDPE plastic.

cMeans within a column and with letters in common are not significantly different (P=0.05).

 

 


Table 5. Effects of pre-plant cover crop and fumigation treatments on subsequent growth of peach seedlings in soil collected from an old peach orchard site near Parlier, CA

Pre-plant soil treatmentsa

 

Performance of Nemaguard peach seedlingsb

 

Fumigation status

 

Cover crop / fallow conditions

Cover crop residue incorporated per 2-liter pot (range, g)

Top fresh weight (g)

Root fresh weight (g)

Percentage of discolored rootsc

Non-fumigated

Bare fallow, moist soil

0

115

75

46

Non-fumigated

Bare fallow, dry soil

0

118

98

46

Bucket-fumigatedd

Bare fallow, moist soil

0

113

82

26

Field-fumigatede

Bare fallow, dry soil

0

92

66

36

Non-fumigated

Castor bean, Ricinus communis

233-306

130

111

48

Non-fumigated

Crotolaria

107-141

117

78

52

Non-fumigated

Sesbania, Sesbania exaltata

88-131

107

76

52

Non-fumigated

Sudangrass, Sorghum sudanensis

134-182

117

80

42

Non-fumigated

Sudex, Sorghum bicolor x sudanese

124-206

122

94

41

Non-fumigated

Sword bean, Canavalia ensiformis

87-95

115

70

40

Non-fumigated

Velvetbean, Mucuna pruriens var. utilis

102-135

120

97

44

Non-fumigated

Vetch, Vicia sativa

3-26

110

75

44

Non-fumigated

Wheat, Triticum aestivum, cv. ÔDawsÕ

118-124

110

85

41

Non-fumigated

Wheat, Triticum aestivum, cv. ÔSpragueÕ

148-151

122

92

47

L.S.Df:

 

 

NS

NS

14

 

aSoil was collected in summer 1999 from replicate MBr-fumigated and non-fumigated plots near Parlier, screened through a 1-cm mesh screen, placed in 2-liter pots in a greenhouse, and subjected to the cover crop / fallow treatments. The cover crops were allowed to grow 4 months, uprooted, chopped with a shredder, weighed, incorporated into the soil, and allowed to decompose for 2 months.

bAfter the decomposition period, three Nemaguard peach seedlings were planted per 2-liter pot (May 2000). Three months after transplanting, total top and root fresh weight was determined for the peach seedlings in each pot, and the roots were washed free from the soil and inspected for symptoms of disease. There were four replicate pots per treatment combination.

cVisual estimate of the percentage of total root length with brown-discolored cortex tissue or decay extending through the root cortex.

dFumigated 3 weeks before transplanting with peach seedlings (MBr : chloropicrin 67:33, 0.8 g per liter soil; in a sealed 19-liter bucket).

eFumigated fall 1998, approx. 9 mo before collection of soil (MBr, 350 lb/A, shank injected in the field under HDPE plastic).

fLeast significant difference among means, based on 95% confidence intervals; NS indicates no significant difference.



Table 6. Effects of pre-plant cover crop and fumigation treatments on subsequent growth of peach seedlings in soil collected from an old plum orchard site near Parlier, CA

Pre-plant soil treatmentsa

 

Performance of Nemaguard peach seedlingsb

 

Fumigation status

 

Cover crop / fallow conditions

Cover crop residue incorporated per 2-liter pot (range, g)a

Top fresh weight (g)

Root fresh weight (g)

Percentage of discolored rootsc

Non-fumigated

Bare fallow, moist soil

0

113

55

42

Non-fumigated

Bare fallow, dry soil

0

106

64

44

Bucket-fumigatedd

Bare fallow, moist soil

0

81

64

30

Non-fumigated

Castor bean, Ricinus communis

233-306

127

63

36

Non-fumigated

Crotolaria

107-141

108

54

48

Non-fumigated

Sesbania, Sesbania exaltata

88-131

111

60

44

Non-fumigated

Sudan grass, Sorghum sudanensis

134-182

123

84

39

Non-fumigated

Sudex, Sorghum bicolor x sudanese

124-206

121

84

42

Non-fumigated

Sword bean, Canavalia ensiformis

87-95

114

63

43

Non-fumigated

Velvetbean, Mucuna pruriens var. utilis

102-135

116

61

47

Non-fumigated

Vetch, Vicia sativa

3-26

111

48

42

Non-fumigated

Wheat, Triticum aestivum, cv. ÔDawsÕ

118-124

129

75

39

Non-fumigated

Wheat, Triticum aestivum, cv. ÔSpragueÕ

148-151

125

59

36

L.S.D.f:

 

 

NS

NS

NS

 

aSoil was collected in summer 1999 from replicate non-fumigated plots near Parlier, screened through a 1-cm mesh screen, placed in 2-liter pots in a greenhouse, and subjected to the cover crop / fallow treatments. The cover crops were allowed to grow 4 months, uprooted, chopped with a shredder, weighed, incorporated into the soil, and allowed to decompose for 2 months.

bAfter the decomposition period, three Nemaguard peach seedlings were planted per 2-liter pot (May 2000). Three months after transplanting, total top and root fresh weight was determined for the peach seedlings in each pot, and the roots were washed free from the soil and inspected for symptoms of disease. There were four replicate pots per treatment combination.

cVisual estimate of the percentage of total root length with brown-discolored cortex tissue or decay extending through the root cortex.

dFumigated 3 weeks before transplanting with peach seedlings (MBr : chloropicrin 67:33, 0.8 g per liter soil; in a sealed 19-liter bucket).

fLeast significant difference among means, based on 95% confidence intervals; NS indicates no significant difference.

Table 7. Effects of pre-plant cover crop and fumigation treatments on incidence of fungal genera associated with peach seedling roots grown in soil collected from an old peach orchard site near Parlier, CAa

 

Fumigation status

 

Cover crop / fallow conditions

Incidence of selected fungal genera on roots of Nemaguard peach seedlings (%)

Cylindrocarpon

Fusarium

Mortierella

Papulospora

Pythium

Rhizoctonia

Trichoderma

Non-fumigated

Bare fallow, moist soil

0

50

5

3

0

3

20

Non-fumigated

Bare fallow, dry soil

0

50

3

3

0

3

30

Bucket-fumigatedb

Bare fallow, moist soil

3

15

3

0

0

13

23

Field-fumigatedc

Bare fallow, dry soil

8

33

0

0

0

0

20

Non-fumigated

Castor bean

15

20

0

3

0

3

23

Non-fumigated

Crotolaria

8

83

8

0

3

0

8

Non-fumigated

Sesbania

5

40

15

3

0

0

13

Non-fumigated

Sudangrass

0

53

0

0

13

0

8

Non-fumigated

Sudex

23

15

3

0

0

0

38

Non-fumigated

Sword bean

5

43

3

0

3

0

20

Non-fumigated

Velvetbean

8

63

3

0

3

3

10

Non-fumigated

Vetch

0

55

8

3

0

0

8

Non-fumigated

Wheat, cv. Daws

0

45

15

5

0

0

13

Non-fumigated

Wheat, cv. Sprague

3

58

3

0

3

3

5

L.S.D.f:

 

NS

21

NS

NS

NS

NS

NS

 

aSoil was collected in summer 1999 from replicate MBr-fumigated and non-fumigated plots near Parlier, screened through a 1-cm mesh screen, placed in 2-liter pots in a greenhouse, and subjected to the cover crop / fallow treatments. The cover crops were allowed to grow 4 months, uprooted, chopped with a shredder, weighed, incorporated into the soil, and allowed to decompose for 2 months. After the decomposition period, three Nemaguard peach seedlings were planted per 2-liter pot (May 2000). Three months after transplanting, total top and root fresh weight was determined for the peach seedlings in each pot, the roots were washed free from the soil and inspected for symptoms of disease, and 10 Nemaguard root pieces (1 cm length) were cultured per replicate pot to determine incidence of the fungi listed above. There were four replicate pots per treatment combination.

bFumigated 3 weeks before transplanting with peach seedlings (MBr : chloropicrin 67:33, 0.8 g per liter soil; in a sealed 19-liter bucket).

cFumigated fall 1998, approx. 9 mo before collection of soil (MBr, 350 lb/A, shank injected in the field and covered with HDPE plastic).

dLeast significant difference, based on 95% confidence intervals; NS indicates no significant difference.


Table 8. Effects of pre-plant cover crop and fumigation treatments on incidence of fungal genera associated with peach seedling roots grown in soil collected from an old plum orchard site near Parlier, CAa

 

 

Fumigation status

 

Cover crop / fallow conditions

Incidence of selected funal genera on roots of Nemaguard peach seedlings (%)

Cylindro-carpon

Fusarium

Mortierella

Papulos-pora

Pythium

Rhizoctonia

Tricho-derma

Non-fumigated

Bare fallow, moist soil

7.5

27.5

0

0

2.5

0

40

Non-fumigated

Bare fallow, dry soil

2.5

42.5

12.5

0

0

10

12.5

Bucket-fumigatedb

Bare fallow, moist soil

2.5

12.5

2.5

0

0

20

42.5

Non-fumigated

Castor bean

12.5

27.5

0

0

0

2.5

25

Non-fumigated

Crotolaria

5

52.5

0

0

0

0

20

Non-fumigated

Sesbania

0

45

2.5

0

2.5

0

45

Non-fumigated

Sudangrass

22.5

17.5

2.5

0

0

2.5

15

Non-fumigated

Sudex

10

25

5

2.5

5

10

17.5

Non-fumigated

Sword bean

10

30

5

0

12.5

2.5

27.5

Non-fumigated

Velvetbean

15

60

0

7.5

5

2.5

2.5

Non-fumigated

Vetch

12.5

32.5

2.5

5

0

5

15

Non-fumigated

Wheat, cv. ÔDawsÕ

2.5

30

2.5

10

0

0

37.5

Non-fumigated

Wheat, cv. ÔSpragueÕ

15

30

2.5

2.5

7.5

0

15

L.S.Dc:

 

NS

NS

NS

NS

NS

NS

NS

 

aSoil was collected in summer 1999 from replicate non-fumigated plots near Parlier, screened through a 1-cm mesh screen, placed in 2-liter pots in a greenhouse, and subjected to the cover crop / fallow treatments. The cover crops were allowed to grow 4 months, uprooted, chopped with a shredder, weighed, incorporated into the soil, and allowed to decompose for 2 months. After the decomposition period, three Nemaguard peach seedlings were planted per 2-liter pot (May 2000). Three months after transplanting, total top and root fresh weight was determined for the peach seedlings in each pot, the roots were washed free from the soil and inspected for symptoms of disease, and 10 Nemaguard root pieces (1 cm length) were cultured per replicate pot to determine incidence of the fungi listed above. There were four replicate pots per treatment combination.

bFumigated 3 weeks before transplanting with peach seedlings (MB : chloropicrin 67:33, 0.8 g per liter soil; in a sealed 19-liter bucket).

cLeast significant difference, based on 95% confidence intervals; NS indicates no significant difference:

 


Table 9. Design of experiment on effects of short-term pre-plant fallowing and cover crops on incidence and severity of replant disease, Parlier

 

Treatment

Summer crop (2002)

Fall fumigation (2002)

Fall/winter cover crop (2002/03)

Micro plots per treatmenta

1

Almond on Nemaguard peach

None

None

5

2

None

None

Wheat

5

3

Piper sudan grass

None

Wheat

5

4

Piper sudan grass

None

None

5

5

Almond on Nemaguard peach

MB/chloropicrin (50/50), 400 lb/A

None

5

6

None

none

None

5

7

None

MB/chloropicrin (50/50), 400 lb/A

None

5

8

Field corn

none

None

5

aArranged in randomized complete blocks

 


Table 10. Lack of specificity between grape and peach replant disorder in a greenhouse test

 

 

Previous crop at field sitea

 

Fumigation trt.b

 

 

Heat trt.c

 

Assay plantd

 

Shoot fresh wt. (g)

 

Root fresh wt. (g)

 

Root discoloration (%)

Root infection by Pythium (%)e

 

 

Root Flour. Pseudomonad count (cfu/g root)f

 

 

 

 

 

 

 

 

 

Grape

-

-

grape

0.7

1.3

97

83

222

 

-

+

 

14.6

2.6

27

0

0.3

 

+

-

 

2.8

1.1

55

73

148

 

+

+

 

11.8

3.7

25

0

6

 

-

-

peach

8.7

6.0

37

50

0.02

 

-

+

 

12.1

7.9

0

0

0.14

 

+

-

 

13.0

7.4

0

16

0

 

+

+

 

13.3

9.4

0

0

0.05

Peach

-

-

grape

2.7

1.3

61

100

82

 

-

+

 

13.0

2.8

26

0

0.22

 

+

-

 

4.2

0.8

69

82

69

 

+

+

 

9.2

2.9

11

0

4

 

-

-

peach

7.0

4.1

51

97

0.13

 

-

+

 

12.7

7.0

0

0

0.02

 

+

-

 

10.2

5.8

20

50

0.6

 

+

+

 

12.9

8.6

0

0

0

Min. Sig. Dif. (Waller-Duncan k ratio):

4.7

1.8

25

33

198

 

aSoil samples were collected in the spring from replicated plots several months after fall removal of the indicated commercial crop.

b"+" indicates that soil was fumigated in the field (MBr, 350 lb/A, tarped) in the fall before sampling, "-" indicates that no fumigation occurred.

c"+" indicates that soil was autoclaved after collection from the field, "-" indicates that no heat treatment occurred.

dNemaguard peach or Carignane grape seedlings were planted into the test soils, one seedling per 500 ml pot of soil. Eight replicate seedlings were used per treatment.


Table 11. Effects of pre-plant fumigation treatments on performance of almond on Marianna 2624 rootstock, Chico replant Experiment 1a

 

 

Pre-plant fumigation treatment

Increase in trunk diameter (mm)

Tree height (m)

Disease rating (0-5 scale)b

Acceptable trees (%)c

None (control)

1 a

1.0 a

3.4 a

2 a

MBr (360 lb/A)

4 b

1.2 a

2.1 b

21 a

Chloropicrin (374 lb/A)

10 c

1.7 b

0.3 c

96 b

Telone (360 lb/A)

2 a

1.1 a

2.9 a

1a

 

aThe pre-plant treatments were imposed 10/21/01 after old tree removal about 1 month earlier. The fumigants were shank injected without tarping; there were four replicate 19 x 22 m plots per treatment. The plots were replanted in January 2001 to almond on Marianna 2624 rootstock (18 trees per replicate plot). All data are based on final measurements taken 8/13/01. Means without letters in common are significantly different according to 95% confidence intervals.

bRating scale: 0=vigorous shoot growth, no stunting evident; 1=little active shoot growth, but canopy volume near normal; 2=no new shoot growth occurring, tree stunted; 3= no new shoot growth occurring, leaves reduced in number or small in size, defoliation may be evident, tree obviously stunted; 4=more than 50% of the foliage dead, tree appears irreversibly diseased; 5=tree dead.

cOnly trees that had grown more than 5 ft (1.5 m) tall were considered commercially acceptable

 

 

 

Table 12. Effects of pre-plant fumigation treatments on performance of almond on Marianna 2624 rootstock in Chico replant Experiment 2a

 

Pre-plant treatment

Rootstock

Increase in trunk diameter (mm)

Tree height (m)

Disease rating (0-5) b

Acceptable trees

(%)c

None (control)

Mar.2624

1 a

0.9 a

3.5 a

0

None (control)

Lovell

6 b

1.3 b

1.2 b

33

MBr (1 lb / tree site)

Mar.2624

7 b

1.4 b

0.9 b

58

Telone (1 lb / tree site)

Mar.2624

8 b

1.3 b

1.4 b

67

 

aThe non-fumigated control, MB (1 lb per tree site), and Telone (1.8 lb per tree site) treatments were each applied to tree sites in replicate plots on 10/21/01by shank injection (one per tree site) without tarping; there were four replicate three-tree plots per treatment. The plots were replanted in January 2001 to almond trees on the indicated rootstocks. All data based on final measurements taken 8/13/01. Means with letters in common are not significantly different.

bRating scale: 0=vigorous shoot growth, no stunting evident; 1=little active shoot growth, but canopy volume near normal; 2=no new shoot growth occurring, tree stunted; 3= no new shoot growth occurring, leaves reduced in number or small in size, defoliation may be evident, tree obviously stunted; 4=more than 50% of the foliage dead, tree appears irreversibly diseased; 5=tree dead.

cOnly trees that had grown more than 5 ft (1.5 m) tall were considered commercially acceptable

 


Table 13. Effects of rootstock and pre-plant fumigation treatments on severity of almond replant disease, Chico Experiment 3

 

Rootstock

Fumigation treatment

(rate per tree site)a

Increase in trunk diameter (mm)b

Final tree height (m)c

Final disease severity ratingd

Acceptable trees (%)e

Lovell peach

Control

7

1.7

1.7

67

 

MB:Pic 75:25 (1 lb)

15

2.2

0.3

94

 

Pic (1 lb)

17

2.3

0.0

100

Marianna 2624

Control

4

1.2

2.9

6

 

MB:Pic 75:25 (1 lb)

15

2.0

0.4

94

 

Pic (1 lb)

14

1.9

0.6

83

LSD from 95% confidence intervals:

4

0.3

1.1

--

 

aMB:Pic= methyl bromide / chloropicrin mixture; Pic= chloropicrin; fumigants injected with a single probe per tree site at 30 to 45 cm depth

bFrom 2/27/02 to 10/11/02

cOn 10/11/02

dOn 10/11/02; on a scale where 0 = healthy tree with good growth, 5= dead tree and 1, 2, 3, and 4 were intermediate gradations

eOnly trees taller than 5 ft (1.5 m) on 10/11/02 were considered acceptable.

 

 

 

Table 14. Effects of scion/ rootstock combination and pre-plant fumigation treatments on severity of almond replant disease, Chico Experiment 4

 

Scion/ rootstock combination

Fumigation treatment

(rate per tree site)a

Increase in trunk diameter (mm)b

Final tree height (m)c

Final disease severity ratingd

Acceptable trees (%)e

Carmel almond / Mar. 2624 (bare root)

Control

0

1.0

4.3

0

 

MB:Pic 75:25 (1 lb)

14

1.9

0.7

100

Carmel almond / Mar. 2624 (potted)

Control

3

1.0

3.8

0

 

MB:Pic 75:25 (1 lb)

13

1.8

1.0

67

French prune / Mar. 2624 (bare root)

Control

3

1.2

2.8

17

 

MB:Pic 75:25 (1 lb)

13

2.1

0.2

100

LSD from 95% confidence intervals:

6

0.4

1.6

--

 

aMB:Pic= methyl bromide / chloropicrin mixture; one probe per tree site at 30 to 45 cm depth

bFrom 2/27/02 to 10/11/02

cOn 10/11/02

dOn 10/11/02; on a scale where 0 = healthy tree with good growth, 5= dead tree and 1, 2, 3, and 4 were intermediate gradations

eOnly trees taller than 5 ft (1.5 m) on 10/11/02 were considered acceptable.

 


Table 15. Effect of tree-site fumigation treatments on severity of replant disease, Chico

 

Fumigant

(and rate per tree site)

Increase in trunk diameter (mm)a

Final tree height (m)b

Final disease severity ratingc

Acceptable trees (%)d

Control

8

1.4

2.0

37

Methyl bromide (1 lb)

12

1.8

1.0

81

Telone (1.8 lb)

12

1.8

1.0

81

Chloropicrin (0.5 lb)

17

2.0

0.4

89

Chloropicrin (1 lb)

17

2.0

0.5

93

Chloropicrin (2 lb)

12

1.7

2.0

63

LSD from 95% confidence intervals:

6

0.4

1.4

--

 

aFrom 2/27/02 to 10/11/02

bOn 10/11/02

cOn 10/11/02; on a scale where 0 = healthy tree with good growth, 5= dead tree and 1, 2, 3, and 4 were intermediate gradations

dOnly trees taller than 1.5 m (5.5 ft) on 10/11/02 were considered acceptable.

 

 

 

 

Table 16. Effect of history of planting hole soil on severity of replant disorder, Chico

 

Soil used to refill planting hole

Increase in trunk diameter (mm)a

Final tree height (m)b

Final disease severity ratingc

Acceptable trees (%)d

Resident soil from hole

2

1.0

3.9

0

Soil from adjacent alfalfa field

8

1.4

2.2

40

LSD from 95% confidence intervals:

9

0.5

1.1

--

 

aFrom 2/27/02 to 10/11/02

bOn 10/11/02

cOn 10/11/02; on a scale where 0 = healthy tree with good growth, 5= dead tree and 1, 2, 3, and 4 were intermediate gradations

dOnly trees taller than 1.5 m (5.5 ft) on 10/11/02 were considered acceptable.

 


Table 17. Incidence of selected fungi on roots sampled on 5-14-01 from replanted almond trees on Marianna 2624 rootstock in Chico Experiment 1a

 

 

 

 

Incidence of isolation from roots (%)

Pre-plant fumigation treatment

Status of root sample

Root trt.

Aspergillus

Cylindroarpon

Fusarium

Mortierella

Penicillium

Rhizoctonia

Trichoderma

None

Healthy

None

0

0 b

0 c

0 b

0

0

0

 

 

Bleach

0

0 b

0 c

0 b

0

0

0

 

Diseased

None

4

4 b

75 a

4 b

17

0

4

 

 

Bleach

4

33 a

67 a

0 b

0

4

0

Chloropicrin

Healthy

None

0

8 b

25 bc

25 a

17

0

8

 

 

Bleach

0

0 b

0 c

0 b

8

0

0

 

Diseased

None

8

21 ab

8 bc

25 a

13

8

29

 

 

Bleach

0

13 ab

33 b

0 b

0

8

0

 

aRoots were sampled from trees planted in plots given the indicated pre-plant treatments, categorized as being healthy (relatively white cortex and no obvious decay) or diseased (dark, damaged cortex), and either rinsed in sterile water or surface sterilized in 10% commercial bleach adjusted to pH 7.2 before culturing on water agar amended with ampicillin (100 ppm). Twenty-four root pieces were cultured for each combination of field treatment, root health, and root surface sterilization treatment. All fungi growing from cultured roots were identified according to morphology. Mean separation letters were assigned only in columns where there were significant differences among the means; those within a column and without letters in common differ significantly according to the Waller-Duncan k-ratio test.

 

 

 

 

 





 

 

Table 18. Incidence of selected fungi on roots sampled on 8-13-01 from replanted almond trees on Marianna 2624 rootstock in Chico Experiment 1a

 

 

 

 

Incidence of isolation (%) from roots

Pre-plant soil fumigation treatment

Status of root sample

Root sample trt.

Alternaria

Basidomycetes

Cylindrocarpon

Fusarium

Rhizoctonia

Mortierella

Penicillium

Pythium

Peyroniella

Trichoderma

Gliocladium

Wardomyces

Other

Chloropic.

Healthy

None

9

3

0 b

22 b

13

13 ab

3

0

0

3

0

6

3

Chloropic.

Diseased

None

16

0

3 b

16 b

13

22 a

6

0

0

3

6

3

0

None

Diseased

None

6

0

14 b

80 a

2

2 bc

2

2

2

0

5

0

6

Chloropic.

Healthy

Bleach

0

0

0 b

22 b

3

0 c

0

0

0

3

0

0

3

Chloropic.

Diseased

Bleach

0

0

6 b

16 b

6

0 c

0

0

0

0

0

0

13

None

Diseased

Bleach

2

8

34 a

48 ab

3

0 c

6

0

0

0

0

0

8


Roots were sampled from trees planted in plots given the indicated pre-plant treatments, categorized as being healthy (relatively white cortex and no obvious decay) or diseased (dark, damaged cortex), and either rinsed in sterile water or surface sterilized in 10% commercial bleach adjusted to pH 7.2 before culturing on water agar amended with ampicillin (100 ppm). Thirty-two to 64 root pieces were cultured for each combination of field treatment, root health, and root surface sterilization (root sample) treatment. All fungi growing from cultured roots were identified according to morphology. Mean separation letters were assigned only in columns where there were significant differences among the means; those within a column and without letters in common differ significantly according to the Waller-Duncan k-ratio test.


Table 19. Nematode counts from experimental plots in Chico trials


 

 

Avg. number of nematodes per 250 cc soil

Date of sampling

Pre-plant fumigation treatment

Lesion (Pratylenchus sp.)

Stunt

(Tylenchorhynchus sp.)

Spiral

(Helicotylenchus sp.)

8/13/01

None

8

0

2

 

Chloropicrin

(374 lb per acre broadcast)

7

0

4

10/11/02

None

1

1

0

 

Methyl bromide:chloropicrin (75:25, 1 lb per tree site)

1

0

0

 

 


Table 20. Effects of semi-selective soil chemical treatments and pre-plant soil autoclaving on growth and health of Marianna 2624 and Nemaguard cuttings planted in the greenhouse in potted samples of soil from the replant disorder study near Chicoa

 

Chemical treatmentb

Soil heating

Top weight (g)

Root weight (g)

Percentage of discolored roots

Control

None

4.8

5.7

49

 

Autoclaved

4.7

7.1

18

Chloramphenicol + streptomycin

None

4.6

6.1

48

 

Autoclaved

3.9

5.6

21

Difenoconozole

None

4.7

6.5

47

 

Autoclaved

4.2

5.8

13

Fludioxonil

None

3.8

6.6

17

 

Autoclaved

3.7

6.5

7

Mefenoxam

None

4.0

6.5

49

 

Autoclaved

5.1

7.2

18

Fenamiphos

None

4.7

5.4

43

 

Autoclaved

4.5

6.2

20

L.S.D.c:

 

NS

NS

12

 

aSoil was collected from methyl bromide-fumigated and non-fumigated plots in Chico Experiment 1. Effects of fumigation and rootstock did not interact significantly with chemical or soil heating treatments above, so the data were combined across the former two factors for presentation above.

bTreatments of difenoconazole (Dividend 3MG, 20 mg a.i./kg soil), fludioxonil (Maxim 4 FS, 20 mg ai/ kg), and chloramphenicol + streptomycin (each antibiotic at 10 mg/kg) were applied 3 days before planting by atomization into mixing soil samples, and the treatments were repeated at 1 and 2 mo after planting by soil drenching. Ridomil Gold EC (mefenoxam, 10 mg a.i./kg) and Nemacur 3 (fenamiphos, 30 mg ai/kg) were applied only pre-plant by the atomization method. Controls received water alone.

cLeast significant difference according to 95%confidence interval for means, NS indicates there was no significant difference



Table 21. Incidences of selected fungi on roots of Marianna 2624 and Nemaguard rootstock plants grown in the greenhouse in potted samples of soil from the Chico replant disorder studya

 

 

 

 

Incidence of isolation per root piece (%)

Pre-plant soil heat treatment

Apparent status of root sample

Root sample surface sterilization treatment

Cylindrocarpon

Fusarium

Mortierella

Rhizoctonia

Trichoderma

None

Healthy

None

17.2

77

8.5

3.1

9.7

 

 

Bleach

37.0

46

0.2

0.0

2.9

 

Diseased

None

5.2

87

4.3

7.8

11.3

 

 

Bleach

22.4

82

0.2

10.9

2.9

Autoclavingb

Healthy

None

0.0

77

20.3

0.0

9.4

 

 

Bleach

0.0

41

1.6

0.0

1.6

 

Diseased

None

0.0

80

15.6

0.0

18.8

 

 

Bleach

0.0

95

0.0

1.6

4.7

Significant statistical effectsc

 

 

Heat x surf. ster. (P=0.005); heat x root health (P=0.04)

Root health x surf. ster. (P=0.02)

Surf. ster. (P<0.0001)

Heat x root health (P=0.01)

Surf. ster. (P=0.009)

aFor each treatment combination, four healthy and four discolored root segments (0.5 to 1 cm length, <1 mm dia) were sampled from eight replicate plants of Marianna 2624 plum and Nemaguard peach that had grown for 3 months in potted 0.6-liter samples of soil from the Chico replant trial. The root segments were rinsed in sterile water or bleached (10% commercial bleach, pH 7.0 to 7.2) and cultured on water agar amended with tetracycline 100 mg/liter. Three days after culturing the roots, all fungal isolates were transferred individually to one-fifth strength PDA + tetracycline (100 ppm) and identified to genus according to morphology. Additional fungi, not listed above, were isolated at low incidence (generally less than 5%) and had no statistical association with root health.

bAutoclaved for 1 hr on 3 successive days at 110¡ C

cAccording to analysis of variance, SAS Version 8.


 

 

Table 22. Incidence of Pythium spp. on roots of Marianna 2624 and Nemaguard rootstocks grown in the greenhouse in potted samples of soil from the Chico replant studya

 

 

 

Plant selection

Soil fumigation treatment

Soil heat treatment c

Apparent status of root sample

Incidence of Pythium (%)

 

 

 

 

 

Marianna 2624

Non-fumigated

None

Healthy

6

 

 

 

Diseased

19

 

 

Autoclaved

Healthy

0

 

 

 

Diseased

0

 

MBr-fumigatedb

None

Healthy

0

 

 

 

Diseased

0

 

 

Autoclaved

Healthy

0

 

 

 

Diseased

0

 

 

 

 

 

Nemaguard

Non-fumigated

None

Healthy

38

 

 

 

Diseased

69

 

 

Autoclaved

Healthy

0

 

 

 

Diseased

0

 

MBr-fumigated

None

Healthy

0

 

 

 

Diseased

13

 

 

Autoclaved

Healthy

0

 

 

 

Diseased

0

 

 

 

 

 

Significant statistical effectsd

 

 

 

Rootstock x fumig. x heat (P=0.01); heat x roothealth (P=0.04)

 

aFor each treatment combination, four healthy and four discolored root segments (0.5 to 1 cm length, <1 mm dia) were sampled from eight replicate plants of Marianna 2624 plum and Nemaguard peach that had grown for 3 months in potted 0.6-liter samples of soil from the Chico replant trial. The root segments were rinsed in sterile water or bleached (10% commercial bleach, pH 7.0 to 7.2), and cultured on water agar amended with tetracycline 100 mg/liter. Three days after culturing the roots, all fungal isolates were transferred individually to one-fifth strength PDA + tetracycline (100 ppm) and identified to genus according to morphology.

b360 lb/A, pre-plant shank injected on 10/21/01, no tarp.

cApplied before planting in the greenhouse, after soil collection from Chico plots. Autoclaved on 3 successive days at 110 C.

dAccording to analysis of variance, SAS Version 8.


Table 23. Effects of pre-plant fumigation treatments on performance of Nemaguard peach seedlings in Parlier micro plots in 2002a

 

Date of plant sampling

Pre-plant fumigant

 

Fumigant rateb

Shoot height (cm)

Shoot weight (g)

Root weight

(g) c

Root rot (%)c

8/14/02

None (control)

None

32

8

3

46

 

Methyl bromide

Low

41

13

5

42

 

 

High

66

60

13

13

 

Chloropicrin

Low

64

53

14

18

 

 

High

64

56

13

11

 

LSD from 95% conf. intervals:

10

18

10

30

 

 

 

 

 

 

 

9/24/02

None (control)

None

31

11

--

--

 

Methyl bromide

Low

49

62

--

--

 

 

High

92

218

--

--

 

Chloropicrin

Low

75

166

--

--

 

 

High

92

225

--

--

 

LSD from 95% conf. intervals:

38

128

--

--

 

 

 

 

 

 

 

11/22/02

None (control)

None

31

18

17

--

 

Methyl bromide

Low

46

34

28

--

 

 

High

92

211

162

--

 

Chloropicrin

Low

93

187

130

--

 

 

High

90

219

182

--

 

LSD from 95% conf. intervals:

9

64

40

--

aData for each date of sampling from four replicate micro plots per treatment. Each micro plot was 18Ó in diameter and 4 ft deep.

bFor both methyl bromide and chloropicrin, the low rate was 400 lb per acre (micro plot area basis) and represented a ÒbroadcastÓ treatment, and the high rate high rate was 2700 lb per acre (micro plot area basis) and represented a typical concentrated dose delivered by a Òtree site treatmentÓ when 1 lb of fumigant is delivered to a 4-ft. x 4-ft. tree site area.

cBased on roots in extracted sample cores (each core 5Ó diameter x 18Ó deep, centered around the root system crown). Ó--Ò indicates data points that were not taken.


Table 24. Incidence of selected fungi from roots of Nemaguard peach, Parlier short-term fallow field trial, February 2000a

 

 

Incidence of isolation per root piece (%)

Pre-plant soil fumigation treatment

Cylindrocarpon

Fusarium

Pythium

Trichoderma

Other Fungi

None

3.0

33.2

2.3

5.3

6.3

Methyl Bromideb

0.1

14.0

2.0

6.9

4.9

L.S.D.c:

1.0

9.7

NS

NS

NS

 

aRoot samples were collected on 2/9/00 from trees replanted in spring 1998. Ten root pieces were cultured on water agar amended with tetracycline from each of four trees in each of four replicate field plots. The trees were from interplanted rows that had been dug from the planting sites just before sampling.

bInjected by shank pre-plant (350 lb/A, covered by HDPE plastic).

cLeast significant difference according to 95%confidence interval for means, NS indicates there was no significant difference.

 

 

 

 

Table 25. Incidence of selected fungi from roots of peach and plum trees on Nemaguard rootstock, Parlier long-term fallow field trials trial, July 2000 a

 

 

Incidence of isolation per root piece (%)

Pre-plant soil fumigation treatment

Cylindro-carpon

Fusarium

Mortierella

Pythium

Rhizoctonia, Moniliopsis

Trichoderma

None

2.3

53.5

0.4

0.0

12.1

2.7

Methyl Bromide

0.0

14.4

6.6

0.8

25.8

8.6

L.S.D.c:

NS

16.7

NS

NS

NS

NS

 

aRoot samples were collected on 7/27/00 from trees replanted in January 2000. Ten root pieces were cultured on water agar amended with tetracycline from each of four trees in each of four replicate field plots. The trees were from interplanted rows that had been dug from the planting sites just before sampling.

bInjected by shank pre-plant (350 lb/A, covered by HDPE plastic).

c Least significant difference according to 95%confidence interval for means, NS indicates there was no significant difference.


Table 26. Incidence of selected fungi from roots of peach and plum trees on Nemaguard peach rootstock, Parlier short and long-term fallow field trials, January 2001a

 

 

 

 

Incidence of root infestation (% of roots infested)

Pre-plant soil fumigation treatment

 

Appearance of root sample

Root sample surface sterilization treatment

Alternaria

Cylindro-carpon

Fusarium

Rhizoctonia, Moniliopsis

Mortierella

Penicillium

Pythium

Trichoderma

None

Healthy

None

3.8

0.6

9.4

0.0

0.6

1.3

0.0

1.3

 

 

Bleach

10.3

0.0

4.4

1.6

25.3

5.3

3.4

9.7

 

Diseased

None

3.1

0.6

26.9

1.3

2.5

1.3

0.6

8.1

 

 

Bleach

5.6

0.3

10.3

2.5

32.5

1.6

2.8

12.2

Methyl Bromide

Healthy

None

3.1

0.6

20.0

1.9

0.6

3.1

0.6

1.9

 

 

Bleach

3.1

0.0

11.3

2.8

23.1

5.6

5.3

10.9

 

Diseased

None

3.1

0.6

34.4

3.1

1.3

3.1

1.3

6.9

 

 

Bleach

3.1

0.0

12.2

2.5

24.4