Black Spot of Apples

Venturia inaequalis

Names:

Apple Scab.

Description:

A fungal disease of Apples that initially shows as 3 mm diameter spots on the leaves that are darker green and soon turn black. The spots may join to form black patches and in severe cases the leaves may be small and distorted. Black spots also form on the fruit and go brown and corky with age and are usually raised and round with irregular margins. These lesions are often only surface blemishes but with early infection they may crack and distort the fruit.

Species Affected:

Apples. Granny Smith and Delicious varieties are very susceptible. Jonathon and Gravenstein are more tolerant.

Biology:

Spread by raindrop splash.
The fungus grows in leaf litter over winter and releases spores in spring.
Spores are formed on the surface of the spots.
Infection requires the leaves to be wet for about 10 hours at 150C. At higher temperatures infection can occur in a shorter time and at lower temperatures longer is required.

Life Cycle:

Origin and History:

Distribution:

Significance:

Management and Control:

Apply fungicides when infective conditions occur in Apple Black spot areas.
Destroy or burn fallen leaves in autumn.

Related and Similar Species:

References:

1291

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.