Evaluation of lime products for clubroot (Plasmodiophora brassicae) management in canola (Brassica napus) cropping systems

Figures & data

Table 1. Effects of hydrated lime (Ca(OH)₂) on clubroot index of disease and plant growth parameters of the clubroot-susceptible canola ‘45H31ʹ under field conditions in Edmonton, Alberta, in 2017 and 2018.^a

Lime rate (t ha^−1)	Emergence count (plants/6 m)	Index of disease (%)	Fresh shoot weight (g) 10 plants^−1	Fresh root weight (g) 10 plants^−1	Plant height (cm)	Yield (kg ha^−1)
2017 Site 1: Initial pH 6.3
0.0	84 a	46.7 a	1936.3 a	201.3 a	95.4 a	2229.2 a
4.7	72.8 b	37.5 a	2137.5 a	246.3 a	113.9 a	2182.2 a
8.0	56.1 c	6.7 b	2391.3 a	147.5 a	123.2 a	2477.5 a
11.4	52.4 c	4.1 b	3058.8 a	176.3 a	122.4 a	2511.4 a
2017 Site 2^b: Initial pH 5.1
0.0	75.5	78.3	1490.0	210.0	58.5	268.9
6.0	65.9	66.7	1855.0	167.5	72.5	536.7
9.4	64.2	45.0	2132.5	175.0	91.8	1075.6
12.7	47.9	43.3	2625.0	240.0	87.6	1191.1
2018 Site 1: Initial pH 6.6
0.0	85.9 a	3.3 a	1862.5 a	127.8 a	130.9 a	1875.0 a
4.7	75.1 a	1.7 a	2188.0 a	150.0 a	138.8 a	1644.8 a
8.0	82.8 ab	1.7 a	1827.0 a	132.8 a	134.8 a	2032.2 a
11.4	45.3 b	4.1 a	2101.5 a	138.8 a	140.1 a	1982.8 a
2018 Site 2: Initial pH 5.0
0.0	98.3 a	60.8 a	1331.3 a	225.3 a	122.5 a	745.3 a
6.0	105.5 a	67.5 a	1308.0 a	176.8 a	121.3 a	791.9 a
9.4	97.8 a	66.7 a	1541.8 a	215.3 a	117.9 a	746.4 a
12.7	115.1 a	66.7 a	889.0 a	172.3 a	118.4 a	861.7 a

^aMeans followed by the same letter do not differ according to Tukey test at P > 0.05.

^b2017 Site 2 was not analyzed statistically, since there were only two true replicates.

Table 2. Effects of hydrated lime (Ca(OH)₂) on clubroot index of disease (ID), canola plant height, dry shoot weight and dry root weight under greenhouse conditions 8 weeks after planting, in 2017 and 2018.^a

			Index of Disease (%)				Plant Height (cm)				Shoot Weight (g)				Root Weight (g)
Cultivar^b			Resting spores g^−1 medium				Resting spores g^−1 medium				Resting spores g^−1 medium				Resting spores g^−1 medium
Year	Lime (t ha^−1)	pH	10^3	10^4	10^5	10^6	10^3	10^4	10^5	10^6	10^3	10^4	10^5	10^6	10^3	10^4	10^5	10^6
‘45H31’	0	5.3	97 a	92 a	100 a	100 a	41.3 c	32.8 a	30.8 b	28.3 b	5.5 c	3.3 b	3.9 b	3.1 d	3.4 a	3.7 a	3.6 a	3.2 a
2017	4.7	6.0	0 b	0 b	0 b	18 b	51.7 bc	42.0 a	70.6 a	58.1 a	6.5 bc	6.3 a	11.1 a	10.5 a	0.6 b	0.5 b	0.8 b	0.9 b
	8.1	6.5	0 b	0 b	0 b	0 b	69.4 a	41.1 a	60.8 a	58.3 a	8.8 a	6.3 a	10.0 a	8.5 b	0.8 b	0.6 b	0.8 b	0.6 b
	11.4	7.0	0 b	0 b	0 b	0 b	60.3 ab	40.4 a	64.8 a	60.6 a	7.3 ab	6.6 a	9.7 a	8.3 b	0.5 b	0.8 b	1.0 b	0.7 b
	14.8	7.5	0 b	0 b	0 b	0 b	61.9 ab	41.9 a	73.8 a	60.5 a	7.3 ab	2.9 b	9.9 a	5.9 c	0.6 b	0.3 b	0.8 b	0.5 b
‘9558C’	0	5.3	13 a	11 a	9 a	10 a	66.6 ab	42.6 a	68.1 a	68.5 a	9.1 a	7.3 a	10.9 a	10.4 a	0.7 a	0.8 a	0.9 a	0.8 a
2017	4.7	6.0	0 b	0 a	0 a	0 a	53.6 b	41.2 a	71.1 a	69.5 a	6.9 ab	6.8 b	9.3 a	9.1 ab	0.4 b	0.4 bc	0.8 ab	0.7 ab
	8.1	6.5	0 b	0 a	0 a	0 a	72.1 a	41.5 a	69.7 a	66.9 a	8.2 ab	5.8 b	9.4 a	6.7 bc	0.7 ab	0.5 b	0.6 b	0.4 b
	11.4	7.0	0 b	0 a	0 a	0 a	66.3 ab	44.6 a	64.8 a	72.2 a	8.2 ab	5.8 b	10.1 a	8.1 b	0.4 ab	0.4 bc	0.7 ab	0.5 b
	14.8	7.5	0 b	0 a	0 a	0 a	65.0 ab	31.8 a	76.5 a	65.0 a	5.9 b	2.7 b	8.9 a	5.6 c	0.3 b	0.2 c	0.8 ab	0.4 b
‘45H31’	0	5.3	10 a	81 a	83 a	100 a	71.0 b	70.4 b	68.1 b	45.7 b	7.3 a	5.3 c	4.4 b	2.4 b	0.5 a	1.4 b	1.4 b	2.2 b
2018	4.7	6.0	0 a	0 b	0 b	0 b	82.3 a	73.4 ab	66.2 b	73.5 a	7.6 a	5.2 bc	5.5 ab	6.6 a	0.4 a	0.2 a	0.3 a	0.4 a
	8.1	6.5	0 a	0 b	0 b	0 b	72.4 b	78.7 ab	82.3 a	74.8 a	6.9 a	7.9 a	7.7 a	6.8 a	0.3 a	0.5 a	0.4 a	0.4 a
	11.4	7.0	0 a	0 b	0 b	0 b	74.9 ab	76.0 ab	75.9 a	73.0 a	6.9 a	7.2 abc	7.4 a	6.1 a	0.4 a	0.3 a	0.4 a	0.4 a
	14.8	7.5	0 a	0 b	0 b	0 b	71.4 b	80.5 a	80.0 a	68.5 a	6.5 a	7.4 ab	6.4 ab	5.3 a	0.4 a	0.4 a	0.4 a	0.3 a
‘9558C’	0	5.3	0 a	3 a	7 a	8 a	75.2 a	81.2 a	80.3 b	84.7 a	7.8 a	6.8 a	6.1 bc	9.2 a	0.4 a	0.4 a	0.3 a	0.6 a
2018	4.7	6.0	0 a	0 a	0 a	0 b	80.5 a	78.5 a	77.7 b	74.9 b	6.4 a	6.1 a	7.9 ab	6.3 b	0.3 a	0.3 a	0.4 a	0.3 b
	8.1	6.5	0 a	0 a	0 a	0 b	83.4 a	86.9 a	94.1 a	74.2 b	8.1 a	7.4 a	8.6 a	6.4 b	0.4 a	0.4 a	0.4 a	0.3 b
	11.4	7.0	0 a	0 a	0 a	0 b	75.6 a	81.5 a	81.4 b	79.4 ab	6.2 a	7.3 a	7.0 abc	6.4 b	0.2 a	0.4 a	0.4 a	0.3 b
	14.8	7.5	0 a	0 a	0 a	0 b	77.6 a	84.3 a	75.6 b	72.3 b	5.9 a	7.0 a	4.9 c	6.3 b	0.3 a	0.4 a	0.3 a	0.4 b

^aMeans followed by the same letter do not differ at P < 0.05 within each column for each year.

^b’45H31ʹ is clubroot-susceptible; ‘9558C’ is resistant.

Table 3. Effects of limestone (CaCO₃) on clubroot index of disease (ID), canola plant height, dry shoot weight and dry root weight under greenhouse conditions 8 weeks after planting, in 2017 and 2018.^a

			Index of Disease (%)				Plant Height (cm)				Shoot Weight (g)				Root Weight (g)
Cultivar^b			Resting spores g^−1 medium				Resting spores g^−1 medium				Resting spores g^−1 medium				Resting spores g^−1 medium
Year	Lime (t ha^−1)	pH	10^3	10^4	10^5	10^6	10^3	10^4	10^5	10^6	10^3	10^4	10^5	10^6	10^3	10^4	10^5	10^6
‘45H31’	0	5.3	97 a	92 a	100 a	100 a	41.3 b	32.8 b	30.8 a	28.3 b	5.5 b	3.3 d	3.9 b	3.1 a	3.4 a	3.7 a	3.6 a	3.2 a
2017	4.7	6.0	24 b	64 b	100 a	100 a	64.0 a	40.4 ab	36.0 a	39.6 a	9.5 a	7.9 a	4.7 ab	2.9 a	1.8 ab	2.8 ab	3.7 a	2.7 a
	8.1	6.5	13 b	56 bc	100 a	100 a	59.7 a	43.2 a	33.3 a	27.2 b	9.1 a	7.3 ab	5.5 ab	3.1 a	1.0 b	2.2 ab	4.6 a	3.0 a
	11.4	7.0	11 b	40 cd	98 a	100 a	57.2 a	41.5 ab	38.0 a	27.8 ab	9.5 a	5.3 bc	5.7 a	3.4 a	0.9 b	1.0 b	4.4 a	2.9 a
	14.8	7.5	11 b	20 d	96 a	100 a	58.4 a	35.8 ab	38.6 a	30.2 ab	8.4 a	4.3 cd	5.9 a	2.9 a	1.0 b	0.6 b	4.1 a	3.0 a
‘9558C’	0	5.3	13 a	11 a	9 a	10 b	66.6 ab	42.6 a	68.1 a	68.5 a	9.1 bc	7.4 a	10.9 a	10.4 ab	0.7 a	0.8 a	0.9 b	0.8 b
2017	4.7	6.0	0 a	5 a	16 a	8 b	75.2 a	49.2 a	40.2 c	67.6 a	11.3 a	9.0 a	9.8 a	12.0 a	0.8 a	0.8 a	1.6 a	0.8 b
	8.1	6.5	1 a	4 a	13 a	20 ab	81.4 a	46.2 a	50.5 bc	55.2 a	10.6 ab	8.2 a	9.8 a	9.0 b	0.7 a	0.8 a	0.9 b	1.1 ab
	11.4	7.0	4 a	3 a	7 a	36 a	54.6 b	44.8 a	73.5 a	58.3 a	7.5 c	7.8 a	11.0 a	8.3 b	0.5 a	0.5 ab	0.9 b	1.3 a
	14.8	7.5	0 a	0 a	16 a	4 b	67.4 ab	37.1 a	60.8 ab	67.8 a	8.9 abc	4.2 b	10.6 a	10.1 ab	0.6 a	0.2 b	0.9 b	0.9 ab
‘45H31’	0	5.3	10 a	81 a	83 a	100 a	71.0 b	70.4 b	68.1 c	45.7 c	7.3 a	5.3 ab	4.4 b	2.4 b	0.5 a	1.4 a	1.4 a	2.2 c
2018	4.7	6.0	0 a	23 b	53 b	100 a	71.7 ab	72.7 ab	90.6 a	70.6 b	6.9 a	6.3 ab	9.5 a	3.6 ab	0.4 a	0.5 b	1.1 ab	1.5 bc
	8.1	6.5	0 a	3 a	28 c	73 b	78.8 b	74.1 ab	78.6 b	81.6 a	7.2 a	4.9 b	6.1 b	4.7 b	0.5 a	0.4 b	0.4 c	1.2 c
	11.4	7.0	0 a	0 a	45 bc	96 ab	75.4 ab	79.7 a	84.4 bc	79.9 a	7.2a	7.4 a	9.3 a	3.3 ab	0.3 a	0.4 b	0.9 bc	1.7 abc
	14.8	7.5	0 a	0 a	37 bc	96 ab	73.2 ab	78.8 a	85.0 bc	77.6 ab	7.2 a	6.7 ab	8.8 a	3.9 ab	0.4 a	0.3 b	0.8 bc	1.9 ab
‘9558C’	0	5.3	0 a	3 a	7 a	8 a	75.2 b	81.2 ab	80.3 b	84.7 a	7.8 ab	6.8 a	6.1 c	9.2 a	0.4 a	0.4 a	0.3 a	0.6 a
2018	4.7	6.0	0 a	11 a	0 a	12 a	71.9 b	74.4 b	92.8 ab	55.8 c	5.6 c	6.7 a	8.7 ab	5.4 b	0.3 a	0.4 a	0.3 a	0.4 ab
	8.1	6.5	0 a	0 a	3 a	3 a	74.4 b	80.4 ab	86.4 a	68.8 b	6.5 bc	6.5 a	7.4 bc	7.4 ab	0.4 a	0.3 a	0.5 a	0.4 ab
	11.4	7.0	0 a	3 a	11 a	8 a	78.4 ab	81.4 ab	92.3 a	55.2 c	7.4 abc	6.2 a	10.3 a	7.4 ab	0.3 a	0.3 a	0.6 a	0.3 b
	14.8	7.5	0 a	0 a	0 a	12 a	87.9 a	84.6 a	92.8 a	63.2 bc	8.9 a	6.6 a	9.9 a	6.5 b	0.4 a	0.3 a	0.5 a	0.5 ab

^aMeans followed by the same letter do not differ at P < 0.05 within each column for each year.

^b’45H31ʹ is clubroot-susceptible; ‘9558C’ is resistant.

Fig. 1 The effects of hydrated lime in 2017 on the amount of Plasmodiophora brassicae in the roots of 10-day-old seedlings of the canola cultivars (a) ‘45H31ʹand (b) ‘9558C’ as determined by quantitative PCR analysis. The seedlings were grown under greenhouse conditions in potting medium inoculated with 1 × 10³, 1 × 10⁴, 1 × 10⁵ and 1 × 10⁶ resting spores g⁻¹ potting medium and treated with 4.7, 8.1, 11.4 or 14.8 T ha⁻¹ of hydrated lime, which targeted a pH of 6.0, 6.5, 7.0 or 7.5, respectively. Controls did not receive any lime (pH 5.3). Means with no letters do not differ; means differences are denoted by different letters at P < 0.05.

Fig. 2 The effects of limestone in 2017 on the amount of Plasmodiophora brassicae in the roots of 10-day-old seedlings of the canola cultivars (a) ‘45H31ʹ and (b) ‘9558C’ as determined by quantitative PCR analysis. The seedlings were grown under greenhouse conditions in potting medium inoculated with 1 × 10³, 1 × 10⁴, 1 × 10⁵ and 1 × 10⁶ resting spores g⁻¹ potting medium and treated with 4.7, 8.1, 11.4 or 14.8 T ha⁻¹ of limestone, which targeted a pH of 6.0, 6.5, 7.0 or 7.5, respectively. Controls did not receive any lime (pH 5.3). Means with no letters do not differ; means differences are denoted by different letters at P < 0.05.

Fig. 3 The effects of hydrated lime in 2018 on the amount of Plasmodiophora brassicae in the roots of 10-day-old seedlings of the canola cultivars (a) ‘45H31ʹ and (b) ‘9558C’ as determined by quantitative PCR analysis. The seedlings were grown under greenhouse conditions in potting medium inoculated with 1 × 10³, 1 × 10⁴, 1 × 10⁵ and 1 × 10⁶ resting spores g⁻¹ potting medium and treated with 4.7, 8.1, 11.4 or 14.8 T ha⁻¹ of hydrated lime, which targeted a pH of 6.0, 6.5, 7.0 or 7.5, respectively. Controls did not receive any lime (pH 5.3). Means with no letters do not differ; means differences are denoted by different letters at P < 0.05.

Fig. 4 The effects of limestone in 2018 on the amount of Plasmodiophora brassicae in the roots of 10-day-old seedlings of the canola cultivars (a) ‘45H31ʹ and (b) ‘9558C’ as determined by quantitative PCR analysis. The seedlings were grown under greenhouse conditions in potting medium inoculated with 1 × 10³, 1 × 10⁴, 1 × 10⁵ and 1 × 10⁶ resting spores g⁻¹ potting medium and treated with 4.7, 8.1, 11.4 or 14.8 T ha⁻¹ of limestone, which targeted a pH of 6.0, 6.5, 7.0 or 7.5, respectively. Controls did not receive any lime (pH 5.3). Means with no letters do not differ; means differences are denoted by different letters at P < 0.05.