Susceptibility to Stemphylium vesicarium of asparagus, onion, pear, and rye in Canada

Figures & data

Table 1. Isolates of Stemphylium vesicarium, collected from asparagus and onion fields in Canada, used to assess pathogenicity on onion, asparagus, pear and rye. Checkmarks indicate which isolates were used in DNA sequencing and for each host assessment.

Isolate information							Hosts
Code^1	Year	Collection location	Crop	Source	DNA sequenced	Asparagus	Onion	Pear	Rye
OA20	2012	Norfolk County, ON	asparagus	J.M. Foster	✓			✓
OA46	2013	Norfolk County, ON	asparagus	J.M. Foster	✓	✓	✓		✓
OA48	2014	Essex County, ON	asparagus	J.M. Foster	✓	✓		✓	✓
OA56	2014	Norfolk County, ON	asparagus	J.M. Foster		✓		✓
NA51	2014	Kings County, NS	asparagus	J.M. Foster	✓	✓
NA52	2014	Kings County, NS	asparagus	J.M. Foster		✓
OO27	2013	Simcoe County, ON	onion	J.M. Foster	✓	✓	✓
OO31	2013	Simcoe County, ON	onion	J.M. Foster	✓			✓
OO54	2014	Norfolk County, ON	onion	F. Shi			✓
OO55	2014	York Region, ON	onion	C.S. Tayviah		✓	✓		✓
NO35	2013	Kings County, NS	onion	P. Hildebrand	✓		✓	✓
NO36	2013	Kings County, NS	onion	P. Hildebrand	✓	✓		✓

¹Isolates with first letter ‘N’ are from Nova Scotia, those with ‘O’ are from Ontario. The second letter indicates host ‘A’ for asparagus and ‘O’ for onion.

Fig. 1 (Colour online) Conidia of the five isolates of Stemphylium vesicarium assessed in a growth room study of pathogenicity and aggressiveness on onion.

Table 2. Differences in final disease severity index (DSI) on detached spears of asparagus inoculated with eight isolates of Stemphylium vesicarium from asparagus and onion. The experiment was repeated twice.

Isolate^1	DSI^2
	Repetition 1	Repetition 2
First assay^3
NA52	77a^4	84a
OA46	76a	81a
OA56	76a	71ab
OA48	68a	78a
NA51	77a	72ab
OO55	68a	59b
NO36	54b	38c
Standard error	1.5	2.0
P value	<0.001	<0.001
Second assay^5
OA46	58a	49a
OO27	18b	36b
Standard error	2.1	2.3
P value	<0.001	0.0023

¹Isolates with first letter ‘N’ are from Nova Scotia, those with ‘O’ are from Ontario. The second letter indicates host ‘A’ for asparagus and ‘O’ for onion.

²The repeated experiments could not be combined since a significant interaction was observed between isolate and repeated experiment in the first (P = 0.0046) assay and second (P < 0.0001) assay. Data from six hybrids were combined as no interaction was observed between hybrid and isolate for the first (P = 0.1489) and second assay (P = 0.6662).

³The hybrids used were ‘Guelph Millennium’, ‘Guelph Equinox’, ‘Guelph Eclipse’, UG010 and UG009.

⁴Means in a column followed by the same letter do not differ using Tukey’s multiple range test at P ≤ 0.05.

⁵The hybrids used were ‘Guelph Millennium’, ‘Guelph Equinox’, ‘Jersey Giant’, ‘Tiessen’, UG010 and UG023.

Table 3. Differences in disease severity index (DSI) on asparagus spears of several cultivars and lines hybrids inoculated with Stemphylium vesicarium. The experiment was repeated twice.

	DSI^1
Hybrid cultivar	Repetition 1	Repetition 2
First assay^2
Guelph Eclipse	59b^3	61b
UG020	71a	67ab
Guelph Millennium	73a	67ab
UG010	73a	77a
UG009	78a	73ab
Standard error	1.5	2.0
P value	<0.0001	0.0233
Second assay
UG010	36	54a
Jersey Giant	37	48ab
UG023	37	46ab
Guelph Millennium	38	40ab
UG020	38	34ab
Tiessen	41	33b
Standard error	2.1	2.3
P value	0.9108	0.0023

¹The repeated experiments could not be combined since a significant interaction was observed between isolate and repeated experiment in the first (P = 0.0046) assay and second (P < 0.0001) assay. Data from several isolates were combined as no interaction was observed between hybrid and isolate for the first (P = 0.1489) and second assay (P = 0.6662).

²The isolates used were NA51, NA52, OA46, OA56, OA48, OO55, and NO36.

³Means in a column followed by the same letter do not differ using Tukey’s multiple range test at P ≤ 0.05, based on data combined from two repetitions.

⁴The isolates used were OA46 and OO27.

Table 4. Lesions per leaf and final leaf dieback (%) on seedlings of 12 onion cultivars¹ inoculated with Stemphylium vesicarium by isolate. The experiment was repeated twice.

	Lesions per leaf ^2		Leaf dieback^3 (%)
Isolate	Repetition 1	Repetition 2	Repetition 1	Repetition 2
OO27	9a^4	10a	70a	66a
OO55	7b	7b	44b	41b
OO54	5b	6bc	41b	38b
OA46	9a	9a	31c	29c
NO35	4c	4c	28c	26c
Standard error	0.3	0.3	1.6	1.4
P value	<0.001	<0.001	<0.001	<0.001

¹Onion cultivars were ‘Pontiac’, ‘Hendrix’, ‘Milestone’, ‘LaSalle’, ‘Madras’, ‘Stanley’, ‘Genesis’, ‘Prince’, ‘Trailblazer’, ‘Patterson’, ‘Hamlet’ and ‘Highlander’.

²There was a significant cultivar *isolate interaction when repeated experiments were pooled (P < 0.0001), so each experiment is presented separately. There was no interaction between cultivar *isolate for individual repetitions (Rep1 P = 0.2553, Rep2 P = 0.1756).

³There was a significant cultivar *isolate interaction when repeated experiments were pooled (P = 0.0069), so each experiment is presented separately. There was no interaction between cultivar *isolate for individual repetitions (Rep1 P = 0.8868, Rep2 P = 0.7029).

⁴Means in a column followed by the same letter do not differ using Tukey’s multiple range test at P ≤ 0.05, based on data combined from two repetitions.

Table 5. Lesions per leaf and final leaf dieback (%) of 12 onion cultivars inoculated with Stemphylium vesicarium (isolates OA46, OO27, OO54, OO55 and NO35). The experiment was repeated twice.

	Lesions per leaf^1		Leaf dieback (%)
Cultivar	Repetition 1^2	Repetition 2	Repetition 1	Repetition 2
Highlander	6ab^2, 3	7	59a	56a
Hamlet	6ab	7	51ab	52ab
Trailblazer	8ab	8	45abc	44abc
Patterson	8a	9	50abc	43abc
Prince	7ab	8	46abc	42abc
Madras	7ab	7	41bc	41abc
Stanley	6ab	6	41bc	40bc
Genesis	6ab	6	47abc	40bc
Hendrix	7ab	7	33cd	34cd
LaSalle	7ab	7.	38bcd	33cd
Milestone	8ab	9	37bcd	31cd
Pontiac	5b	6	23d	23d
Standard error	1.6	1.4	0.3	0.3
P value	0.0161	0.2740	<0.0001	<0.0001

¹No significant interactions were observed between repeated experiments, cultivar and isolate (P = 1.0000, 1.0000), repeated experiments and isolate (P = 0.9585, 0.9925), or repeated experiments and cultivar (P = 0.9977, 0.9569) for lesions or dieback, respectively.

²The data were pooled as no significant interactions between isolate and cultivar were observed when sorted by experiment for lesions (Rep 1 P = 0.2553, Rep 2 P = 0.1756) or dieback (Rep 1 P = 0.8868, Rep 2 P = 0.7029).

³ Means in a column followed by the same letter do not differ using Tukey’s multiple range test at P ≤ 0.05, based on data combined from two repetitions.

Table 6. Incidence (%) and disease severity index (DSI) on spears of six asparagus hybrids at two field locations in Ontario in 2014, 2015 and 2016.

	Simcoe^1
		DSI			Plattsville^2
Hybrid cultivar	Incidence (%)^1	2014	2015	2016	Incidence (%)	DSI
Guelph Millennium	37a^3	6a	15ab	14a	74	31
Guelph Equinox	38a	8a	11a	18ab	71	32
Tiessen	37a	7a	16ab	16ab	73	32
UG010	44b	7ab	14ab	19b	66	25
UG023	56b	19bc	22b	25c	69	28
Jersey Giant	62b	23c	18ab	27c	72	29
Standard error	3.3	2.4	1.9	1.3	2.5	1.7
P value	<0.0001	0.0002	0.0155	<0.0001	0.2077	0.1220

¹Incidence data 2014 to 2016 data were pooled as no interaction between cultivar and year was observed (P = 0.0545). DSI data could not be pooled as the interaction was significant (P = 0.0337).

²Data from 2014 to 2016 were pooled as interaction was observed between cultivar and year for incidence (P = 0.9742) and DSI (0.9997).

³Means in a column followed by the same letter do not differ using Tukey’s multiple range test at P ≤ 0.05.

Table 7. Incidence (%) and standardized area under the disease severity index (DSI) on ferns of six asparagus hybrids at two field locations in Ontario in 2015 and 2016.

	Simcoe^1
	Incidence (%)			Plattsville
Hybrid cultivar	2015	2016	DSI	Incidence (%)	DSI
Guelph Millennium	100	68a^2	32a	59	19
Guelph Equinox	100	76a	30ab	54	16
UG023	100	70a	30ab	55	19
UG010	100	30b	24abc	58	15
Tiessen	100	8b	20bc	54	16
Jersey Giant	98	10b	18c	62	19
Standard error	0.4	43.8	2.1	19.1	6.6
P value	0.4430	<0.0001	0.0018	0.7276	0.7733

¹Data were separated between sites as an interaction between year, and location were observed. (P < 0.001), and year and cultivar for Simcoe incidence(P < 0.001).

²Means in a column followed by the same letter do not differ using Tukey’s HSD at P ≤ 0.05, n = 5.

Fig. 2 Reaction of onion cultivars to Stemphylium leaf blight at the MCRS, Holland Marsh, ON in 2015 and 2016: (a) leaf lesions and (b) leaf dieback. Bars topped with the same lower case letter (2015) or upper case letter (2016) do not differ based on Tukey’s HSD at P ≤ 0.05.