Annals of Applied Biology (1997) 130, 439-451

G.A. Kong, G.B. Simpson, J.K. Kochman and J.F. Brown (1997)
Components of quantitative resistance in sunflower to Alternaria helianthi
Annals of Applied Biology 130 (3), 439-451
Abstract: Components of quantitative resistance, spore production, incubation period, infection frequency and mean lesion size were measured in 17 sunflower accessions inoculated with conidia of Altemaria helianthi under controlled conditions. The same accessions were also rated for disease reaction in the field in 1994 and 1995 using a generated epidemic and varied in their disease reactions from highly susceptible to highly resistant. Spearman's ranking of accessions was highly correlated (r = 0.9) for both years; however, the ranking of components measured under controlled conditions with field severity was generally poor. Regression analysis of components with field severity ratings of the accessions showed that mean lesion size was highly correlated (r = 0.74) and infection frequency was moderately correlated (r = 0.58) with the field severity ratings taken over the two years. Infection frequency was also well correlated (r = 0.75) with mean lesion size. Spore production and incubation period were poorly correlated with the field severity ratings for both years. An index based on infection frequency and mean lesion size gave a better correlation with the 1995 field severity ratings than either component alone, but in 1994 the index was not as well correlated with field severity as mean lesion size alone. It is suggested that mean lesion size, determined from plants 7-9 days after inoculation could be used to select for resistance to A. helianthi in the greenhouse. Infection frequency could also be used as a predictor of resistance, but to a lesser degree.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Gary A. Kong

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Alternariaster helianthi	Sunflower (Helianthus annuus)	Australia (South+SE)