CHAPTER 3: EFFECTS OF A NEEM-AMENDED PRODUCT ON PLANT-PARASITIC
3.3 RESULTS
3.3.1 Plant-parasitic nematode data from 250 ml soil
Plant-parasitic nematodes observed in the trial included individuals belonging to the genera Meloidogyne, Pratylenchus, Helicotylenchus (Steiner, 1945), Paratrichodorus (Siddiqi, 1974), Tylenchorhynchus (Cobb, 1913), Rotylenchulus (Linford & Oliveira, 1940), Xiphinema (Cobb, 1913) and Hemicycliophora (de Man. 1921) as well as from the family Criconematidae (Taylor, 1936). However, only data for Meloidogyne, Pratylenchus, Hoplolaimidae (Filipjev, 1934) and Criconematidae is discussed, as the other PPN population densities were detected in low numbers (<100 individuals/250 ml soil during all sampling intervals).
3.3.1.1 Root-knot nematodes
No significant differences were evident among the treatments per sampling interval, nor did a significant interaction exist for treatments x sampling times (Table 3.6) indicating that RKN population densities were similar for all treatments and sampling times although it did increase over the sampling times.
Population densities for RKN in 250 ml soil samples were low before the commencement of treatment applications and planting activities (Pre-plant sampling interval), ranging from zero to 13 (Table 3.6). At 10 weeks after crop emergence (WAE; Sampling interval 2), the average RKN population densities slightly increased (ranging from zero to 44/250 ml soil). This was evident for the untreated control, treatment 4 and 5 plots, but remained unchanged in treatment 8 plots. By the harvest sampling date (19 WAE; Sampling interval 3), all the treatments showed a substantial increase in RKN counts but still did not differ significantly from each other.
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Table 3.6: Root-knot nematode (Meloidogyne) second-stage juvenile (J2) population densities in 250 ml soil for three sampling intervals. (Significance level for Repeated measures ANOVA in capital letters indicating that different letters indicate significant differences across rows for sampling intervals; different small letters per column indicate significant differences among treatments per individual sampling interval).
Treatment Treatment name Sampling
interval 1:
Pre-plant
Sampling interval 2:
10 WAE
Sampling interval 3:
19 WAE (Harvest) 1 Untreated control 0.211 (6)2 aA 0.73 (44) aA 2.23 (994) aAB 2 Nemacur® 400 EC, Fenamiphos
@ 400 g / L, IRAC: 1B
0.0 (0) aA 0.0 (0) aA 0.79 (56) aA 3 Nemacur® 400 EC + Kalahari 3:1 0.0 (0) aA 0.0 (0) aA 1.91 (363) aA 4 Nemacur® 400 EC +Velum®
Prime 400 SC
0.25 (13) aA 0.21 (6) aA 0.82 (363) aA 5 Nemacur® 400 EC +Velum®
Prime 400 SC + Kalahari 3:1
0.25 (13) aA 0.32 (44) aA 1.57 (338) aA 6 Velum® Prime 400 SC, Fluopyram
@ 400 g / L, IRAC: 25; FRAC: 7
0.0 (0) aA 0.0 (0) aA 1.51 (1081) aAB 7 Velum® Prime 400 SC + Kalahari
3:1
0.0 (0) aA 0.0 (0) aA 1.97 (500) aAB 8 Kalahari 3:1, organic fertiliser 0.21 (6) aA 0.21 (6) aA 2.61(1650) aB
F-ratio: 0.575 1.588 1.919
P-value: 0.773 0.158 0.083
Interaction: Treatments x Sampling intervals
F-ratio: 1.51
P-value: 0.21
1Log-transformed mean of nematode population density; 2Real means of nematode population density.
3.3.1.2 Lesion nematodes
Statistically significant differences were evident between the untreated control (treatment 1) and treatments 2 and 5 at the 10 WAE sampling date (sampling interval 2) only (Table 3.7). No significant differences were evident among the treatments at the pre-plant or harvest sampling dates (sampling intervals 1 and 3), nor did any significant interactions exist for treatment x sampling times. This indicates that LN population densities were similar for treatments and sampling times.
Population numbers for LN in 250 ml soil samples were fairly uniform in all the plots at the pre- plant sampling date (>100 but <200 individuals/250 ml soil). At 10 WAE (sampling interval 2), the population counts for the untreated plots differed significantly from treatments 2-5, which all showed reduced LN population densities at this sampling date. By the harvest sampling date (19 WAE; sampling interval 3), most of the treatments showed an increase in population numbers when compared to the 10 WAE sampling interval, but not to the pre-plant sampling interval.
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Table 3.7: Lesion nematode (Pratylenchus) population densities in 250 ml soil for three sampling intervals. (Significance level for Repeated measures ANOVA in capital letters; different letters indicate significant differences across rows for sampling intervals; different small letters per column indicate significant differences among treatments per individual sampling interval).
Treatment Treatment name Sampling interval 1:
Pre-plant
Sampling interval 2:
10 WAE
Sampling interval 3:
19 WAE (Harvest) 1 Untreated control 1.131 (106)2 aA 1.86 (238) bA 1.30 (200) aA 2 Nemacur® 400 EC, Fenamiphos @
400 g / L, IRAC: 1B
1.34 (119) aA 0.21 (6) aA 1.56 (100) aA 3 Nemacur® 400 EC + Kalahari 3:1 1.36 (131) aA 0.43 (13) abA 0.60 (75) aA 4 Nemacur® 400 EC +Velum® Prime
400 SC
1.15 (106) aA 0.51 (38) abA 1.13 (119) aA 5 Nemacur® 400 EC +Velum® Prime
400 SC + Kalahari 3:1
1.39 (138) aA 0.32 (44) aA 1.52 (94) aA 6 Velum® Prime 400 SC, Fluopyram
@ 400 g / L, IRAC: 25; FRAC: 7
1.63 (163) aA 0.83 (81) abA 1.11 (88) aA 7 Velum® Prime 400 SC + Kalahari
3:1
1.63 (181) aA 1.01 (56) abA 0.84 (69) aA 8 Kalahari 3:1, organic fertiliser 0.89 (100) aA 0.52 (44) abA 0.27 (19) aA
F-ratio: 0.377 2.377 1.284
P-value: 0.912 0.034 0.275
Interaction: Treatments x Sampling intervals
F-ratio: 1.375
P-value: 0.177
1Log-transformed mean of nematode population density; 2Real means of nematode population density.
3.3.1.3 Spiral nematodes
No significant differences were evident among the treatments per sampling interval, nor did a significant interaction exist for treatments x sampling times (Table 3.8) indicating that spiral nematode population densities were fairly similar for all treatments and sampling times.
Population densities for spiral nematodes in 250 ml soil samples were high before the commencement of treatment applications and planting activities (Pre-plant sampling interval), ranging from 219 to 1163. At 10 WAE (Sampling interval 2), the average spiral nematode population densities decreased in all treatments and the untreated control (ranging from six to 200/250 ml soil). By the harvest sampling date (19 WAE; Sampling interval 3), most of the treatments showed a slight decline in spiral nematode counts but did not differ significantly from each other.
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Table 3.8: Spiral nematode (Hoplolaimidae) population densities in 250 ml soil for three sampling intervals. (Significance level for Repeated measures ANOVA in capital letters; different letters indicate significant differences across rows for sampling intervals; different small letters per column indicate significant differences among treatments per individual sampling interval).
Treatment Treatment name Sampling
interval 1:
Pre-plant
Sampling interval 2:
10 WAE
Sampling interval 3:
19 WAE (Harvest)
1 Untreated control 1.601 (350)2
aAB
1.72 (194) aAB 1.27 (106) aAB 2 Nemacur® 400 EC, Fenamiphos @
400 g / L, IRAC: 1B
1.52 (219) aAB 1.04 (69) aAB 0.54 (38) aAB 3 Nemacur® 400 EC + Kalahari 3:1 1.50 (407) aAB 1.17 (188) aAB 0.50 (31) aAB 4 Nemacur® 400 EC +Velum® Prime
400 SC
2.17 (963) aAB 0.21 (6) aA 0.80 (69) aAB 5 Nemacur® 400 EC +Velum® Prime
400 SC + Kalahari 3:1
1.87 (269) aAB 0.79 (106) aAB 0.90 (94) aAB 6 Velum® Prime 400 SC, Fluopyram @
400 g / L, IRAC: 25; FRAC: 7
1.75 (725) aAB 1.20 (100) aAB 0.95 (181) aAB 7 Velum® Prime 400 SC + Kalahari 3:1 2.56 (1163) aB 1.49 (200) aAB 1.78 (200) aAB 8 Kalahari 3:1, organic fertiliser 2.21 (800) aAB 1.35 (169) aAB 1.03 (256) aAB
F-ratio: 0.648 1.373 0.975
P-value: 0.714 0.235 0.458
Interaction: Treatments x Sampling intervals
F-ratio: 0.890
P-value: 0.569
1Log-transformed mean of nematode population density; 2Real means of nematode population density.
3.3.1.4 Ring nematodes
No significant differences were evident among the treatments per sampling interval (Table 3.9).
The only significant difference evident for interactions between treatments x sampling times was between treatment 1 at pre-plant sampling versus treatment 7 at 10 WAE (sampling interval 2).
This indicates that, overall, the ring nematode population densities were similar between all treatments and sampling intervals.
Population densities for ring nematodes in 250 ml soil samples generally showed a decrease in population numbers at 10 WAE (sampling interval 2). Only treatment 1 showed a steady increase in ring nematode population densities over time, although this increase was not statistically significant.
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Table 3.9: Ring nematode (Criconematidae) population densities in 250 ml soil for three sampling intervals. (Significance level for Repeated measures ANOVA in capital letters; different letters indicate significant differences across rows for sampling intervals; different small letters per column indicate significant differences among treatments per individual sampling interval).
Treatment Treatment name Sampling
interval 1:
Pre-plant
Sampling interval 2:
10 WAE
Sampling interval 3:
19 WAE (Harvest) 1 Untreated control 0.01 (0)2 aA 1.74 (194) aAB 1.92 (306) aAB 2 Nemacur® 400 EC, Fenamiphos @ 400
g / L, IRAC: 1B
0.97 (169) aAB 1.12 (106) aAB 1.06 (76) aAB 3 Nemacur® 400 EC + Kalahari 3:1 0.68 (25) aAB 0.59 (56) aAB 0.87 (88) aAB 4 Nemacur® 400 EC +Velum® Prime 400
SC
1.09 (94) aAB 0.77 (50) aAB 1.22 (163) aAB 5 Nemacur® 400 EC +Velum® Prime 400
SC + Kalahari 3:1
1.35 (131) aAB 0.77 (56) aAB 0.65 (113) aAB 6 Velum® Prime 400 SC, Fluopyram @
400 g / L, IRAC: 25; FRAC: 7
0.95 (44) aAB 0.95 (181) aAB 0.93 (119) aAB 7 Velum® Prime 400 SC + Kalahari 3:1 0.93 (288) aAB 2.21 (206) aB 0.55 (63) aAB 8 Kalahari 3:1, organic fertiliser 1.64 (481) aAB 0.86 (75) aAB 0.99 (294) aAB
F-ratio: 1.439 2.091 0.938
P-value: 0.208 0.059 0.485
Interaction: Treatments x Sampling intervals
F-ratio: 2.238
P-value: 0.010
1Log-transformed mean of nematode population density; 2Real means of nematode population density.