Table 2.

Preventative treatment. Comparison of selected inducing resistance (IR) agents applied as root drenches for the control of Venturia inaequalis and V. pirina on leaves of apple (Malus cv. Crown Gold) and pear (Pyrus communis ‘Williams Bon Chrétien’), respectively, as measured by an observed scab severity index.

Treatment	Time and number of applications					Scab severity
	9 March	8 April	16 May	9 June	Apple		Pear
	9 March	8 April	16 May	9 June	Leaves^{^z}	Fruit^{^z}	Leaves^{^z}	Fruit^{^z}
Water (control)	−	−	−	−	4.8e	2.5ef	3.1cde	2.2de
HP	+	−	−	−	4.7e	2.1cdef	3.3e	2.0cde
HP	+	+	−	−	4.3de	2.3def	3.2e	2.1de
HP	+	+	+	−	3.2bcd	1.7bcde	2.7c	1.6cd
HP	+	+	+	+	2.4ab	1.3abc	2.0b	1.6cd
PP	+	−	−	−	4.6de	2.5ef	3.2e	2.4e
PP	+	+	−	−	4.6de	2.5ef	2.7cde	1.8cde
PP	+	+	+	−	3.3bcd	1.5bcd	2.1bcd	1.4c
PP	+	+	+	+	2.8bc	1.1ab	1.8bc	1.1b
SA	+	−	−	−	4.9e	2.6f	3.3e	2.4e
SA	+	+	−	−	4.5de	2.5ef	2.4cde	1.8cde
SA	+	+	+	−	3.3bcd	1.4bc	1.9bc	1.1b
SA	+	+	+	+	2.5b	1.2ab	1.6b	0.7ab
Chitosan	+	−	−	−	4.4de	2.6f	3.0de	2.4e
Chitosan	+	+	−	−	4.4de	2.3def	2.9de	2.4e
Chitosan	+	+	+	−	2.8bc	1.9bcde	1.7b	1.6cd
Chitosan	+	+	+	+	2.8bc	1.5bcd	1.7b	1.1b
Penconazole	+	−	−	−	4.4de	2.1cdef	3.1e	2.0cde
Penconazole	+	+	−	−	4.0cde	2.0cdef	2.8d	1.6cd
Penconazole	+	+	+	−	2.0ab	1.3abc	1.8b	0.7ab
Penconazole	+	+	+	+	1.1a	0.5a	0.6a	0.3a
Treatment (T)					< 0.001	< 0.001	< 0.001	< 0.001
No applications (NA)					< 0.001	< 0.001	< 0.001	< 0.001
T*NA					< 0.001	< 0.001	< 0.001	< 0.001

HP = harpin protein; PP = potassium phosphite; SA = salicylic acid.
+ = root drench/spray applied; − = no root drench/spray.
↵^zMean of six randomised complete blocks with a single tree per block.
Lower case letters indicate significant differences between means for each evaluation date by Tukey’s honest significance test (P = 0.05).