Angular Leaf Spot -
Pseudomonas syringae p.v. lachrymans

Angular Leaf Spot     Angular Leaf Spot
Clemson University, USDA Cooperative                          R.J. Reynolds Tobacco Co. Slide Series,
Extension Slide Series, www.ipmimages.org                    www.ipmimages.org


HOSTS: Cucurbits (cucumber, squash), a similar strain infects beans.

DESCRIPTION: This is a bacterial disease causing dark, angular spots between leaf veins; tear shaped droplets ooze from infected tissue. As the leaf dries, leaf tissue tears and shrinks.  Fruit may exhibit circular spots or rotted areas.

LIFE CYCLE: The bacteria over winters in plant debris and can persist for more than two years on dry leaves. It enters the plant through wounds or natural openings under wet conditions, then can be spread mechanically. Angular leaf spot is also seed borne (treat seed for 20 minutes with 120°F. water).

CONTROLS: Use 2 year rotations between cucurbit crops. Avoid wetting foliage with irrigation water. Use resistant cultivars when possible. Plant on raised beds.
Copper can be sprayed to protect leaves when weather is wet and warm.  Excessive nitrogen fertilizer increases disease severity.


Missoula County Extension Office; Missoula, MT 59808 - Updated for 2006