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, CA^a

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, CA^a

 

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 1^a

 

 

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 2^a

 

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 1^a

 

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 1^a

 

^{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 Chico^a

 

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 study^a

 

			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 study^a

 

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 2002^a

 

^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 2000^a

 

	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 2001^a

 

			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