Bacterial Leaf Spot of Cucurbits

Xanthomonas campestris pv. cucurbitae

Description:

A bacterial disease that leaves holes and large pieces missing from leaves. Initially it shows as small water soaked patches on the underside of the leaves with a corresponding light yellow area on the topside of leaves. These develop over a few days into round to angular spots up to 7 mm diameter with translucent brown centres and wide yellow rims. Spots may merge to form large dead patches. Lesion may also appear on petioles and stems and often crack with age. On Pumpkin fruit spots have a water soaked appearance with a light brown ooze and dries to a pale yellow with a rough centre and a dark green greasy rim. The flesh and seeds beneath may be infected.

Species Affected:

Cucurbits

Biology:

Spread by raindrop splash, equipment and workers.
Seed may carry the disease from one crop to the next.
Favoured by warm humid conditions.

Life Cycle:

Origin and History:

Distribution:

Significance:

Management and Control:

Use healthy seed.
Destroy plant debris.
Rotate to resistant species.
Destroy volunteer cucurbits.
Don't work in wet crops.
Apply bactericides.

Related and Similar Species:

Angular Leaf Spot of Cucurbits - tends have tearing along the spots rather than dead patches on the leaf that falls away.

References:

1291

Acknowledgments:

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