Significance of seed infection on epidemics of mycosphaerella blight in field pea

Figures & data

Table 1.  Dates of important operations at the four sites in 2005 and 2006

Year & location	Seeding date	Seedling counts	Assessment dates, foliar symptoms					Stem ratings	Lodging	Harvest
			1	2	3	4	5
2005
Saskatoon	May 18	June 20	July 08	July 28	Aug.10	Aug. 30	–	Sept. 09	–	Sept 09
Vegreville	May 30	July 07	July 06	July 13	July 22	July 29	Aug 03	Aug 03	July 29	Sept 08
Morden	May 24	–	–	–	–	–	–	–	–	–
Bradford	May 26	June 17	June 28	July 18	July 29	–	–	–	–	Aug 26
2006
Saskatoon	May 12	June 29	July 19	July 25	Aug.14	–	–	Aug 14	Aug 17	Aug 18
Vegreville	May 11	June 14	July 05	July 21	Aug.14	–	–	–	–	Aug 24
Morden (1)	May 11	June 14	July 06	July 14	July 21	July 28	Aug 06	–	Aug 05	Aug 09
Morden (2)	May 23	June 14	July 17	July 23	July 31	Aug 07	Aug 13	–	Aug 13	Aug 29
Bradford	May 10	May 25	June 28	–	–	–	–	–	–	Aug 18

Table 2.  Impact of seed infection on seedling establishment (seedlings m⁻²) of two field pea cultivars across all four sites in 2005 and 2006

Cultivar	Seed infection	Saskatoon		Vegreville		Morden 2006		Bradford
		2005	2006	2005	2006	Site 1	Site 2	2005	2006
Keoma	High	25 c	59 a	42 cd	17 d	38 cd	45 a	33 e	59 d
	Intermediate (I)	25 c	57 a	36 de	34 abc	46 bc	50 a	59 cd	73 d
	I  +  Crown	32 abc	57 a	45 bc	29 bc	53 ab	49 a	43 de	92 c
	Low	45 a	67 a	56 a	36 a	53 ab	52 a	100 a	155 a
Carneval	High	24 c	52 a	33 e	19 d	32 d	44 a	43 de	73 d
	I	28 bc	60 a	39 cde	34 ab	57 a	52 a	56 cde	109 c
	I  +  Crown	25 c	60 a	41 cd	29 c	56 a	50 a	73 bc	102 c
	Low	40 ab	63 a	51 ab	37 a	51 ab	50 a	96 ab	125 b
Notes: (a–d) Means in a column followed by the same letter do not differ at P  =  0.05 based on the Waller–Duncan k-ratio t test.

Fig. 1. Disease progress in station-years where seed infection treatment (H  =  high infection, I  =  intermediate, C  =  I  +  Crown fungicide, L  =  low infection) for two field pea cultivars had an impact on severity of mycosphaerella blight. Capped lines represent standard errors.

Fig. 2. Mean disease progress on two field pea cultivars in three station-years where seed infection treatment did not affect the severity of mycosphaerella blight. Standard errors were smaller than the symbols in the graphic and are not presented. Note: In addition, only trace levels of blight developed at Bradford in either year.

Table 3.  Monthly mean temperature and precipitation for the test sites in 2005 and 2006 compared with the long-term (30-year) mean (LTM) values

Location	Month	Mean temperature (°C)			Rainfall (% of LTM)
		LTM	2005	2006	LTM	2005	2006
Saskatoon	May	11.5	10.2	12.0	42 mm	55	123
	June	15.2	14.7	17.0	61 mm	272	164
	July	18.2	18.0	20.8	57 mm	73	82
	Aug	17.3	15.7	18.9	35 mm	193	95
Vegreville	May	10.5	9.9	11.2	34 mm	103	162
	June	14.5	13.8	15.5	64 mm	86	44
	July	16.3	15.9	18.3	80 mm	108	69
	Aug	15.8	13.4	15.7	55 mm	117	71
Morden	May	11.9	10.8	13.0	63 mm	130	74
	June	17.3	18.0	19.1	81 mm	205	52
	July	20.4	20.6	22.2	73 mm	88	23
	Aug	19.2	18.5	20.1	65 mm	51	61
Bradford	May	12.7	10.8	13.8	73 mm	19	89
	June	17.7	21.2	18.4	76 mm	81	83
	July	20.3	21.8	21.9	76 mm	40	91
	Aug	19.2	19.9	19.2	78 mm	67	50

Table 4.  Impact of seed infection on seed yield (Mg/ha) of two field pea cultivars across all four sites in 2005 and 2006

Cultivar	Seed infection treatment	Saskatoon		Vegreville		Morden		Bradford
		2005	2006	2005	2006	2006–1	2006–2	2005	2006
		Seed yield (Mg/ha)
Keoma	High	1.1 c	1.0 a	1.7 ab	0.19 a	3.5 b	2.5 a	2.2 a	2.2 a
	Intermediate (I)	1.4 bc	1.3 a	1.8 a	0.55 a	4.1 ab	2.9 a	2.0 a	2.5 a
	I  +  Crown	1.7 ab	1.3 a	1.7 ab	0.31 a	4.0 ab	2.9 a	1.5 a	3.0 a
	Low	1.9 a	1.1 a	2.0 a	0.39 a	4.3 ab	2.9 a	1.1 a	2.9 a
Carneval	High	1.1 c	0.9 a	1.4 bc	0.26 a	4.1 ab	3.0 a	3.6 a	3.0 a
	I	1.2 c	1.8 a	1.3 c	0.35 a	4.5 a	3.0 a	1.5 a	2.7 a
	I  +  Crown	1.1 c	1.8 a	1.5 bc	0.42 a	4.3 ab	3.6 a	2.3 a	3.1 a
	Low	1.9 a	1.5 a	1.8 a	0.40 a	4.4 a	3.4 a	3.3 a	3.1 a
Notes: (a–d) Means in a column followed by the same letter do not differ at P  =  0.05 based on the Waller–Duncan k-ratio t test.

Table 5.  Impact of seed infection on lodging (0–9 scale, where 0  =  no lodging and 9  =  completely lodged) in two field pea cultivars at Vegreville in 2005, Saskatoon in 2006, and two sites at Morden in 2006

Cultivar	Seed infection treatment	Vegreville 2005	Saskatoon 2006	Morden 2006
				Site 1	Site 2
Keoma	High	2.8 a	3.5 a	3.5 abc	4.3 b
	Intermediate (I)	3.0 a	1.0 bc	4.8 a	7.5 a
	I  +  Crown	2.8 a	2.0 abc	4.3 ab	6.5 a
	Low	2.5 a	1.3 bc	4.3 ab	7.5 a
Carneval	High	2.8 a	2.5 ab	0.8 d	0.8 c
	I	2.5 a	1.0 bc	1.0 cd	1.3 c
	I  +  Crown	2.8 a	0.5 c	0.8 d	1.0 c
	Low	2.0 a	0.5 c	1.8 bcd	1.0 c
Notes: (a–d) Means in a column followed by the same letter do not differ at P  =  0.05 based on the Waller–Duncan k-ratio t test.