Cucurbits angular leaf spot (Pseudomonas syringae pv. lachrymans) – identify and control

cucurbits-angular-leaf-spot-control

Cucurbits angular leaf spot Pseudomonas syringae pv. Lachrymans are a common and damaging disease of cucumber crops in the field and protected areas.

Symptoms – Cucurbits angular leaf spot

The disease manifests itself on all above-ground organs of the plant throughout the growing season. On the cotyledons, immediately after the seedlings emerge, small circular or colored spots appear, dark green and watery at first, then turning brown. Dark green angular spots appear on the leaves, arranged between the veins and surrounded by a greenish-yellow area.

Under favorable conditions, the spots merge and a whitish, mucilaginous bacterial exudate appears on the underside of the leaves in the form of a droplet. In dry weather, the bacterial ooze dries and forms a greyish-white crust. Subsequently, the attacked tissues necrotize, detach and fall off, and the leaves appear pitted, ragged.

Similar spots appear on stems and leaf petioles. Infected flowers wither and fall off. Small (1-3 mm), deep, whitish spots appear on fruit.
In wet weather, these spots are covered with whitish bacterial ooze. If the attack occurs on young fruit, they become deformed. The pathogen penetrates the seeds and infects them.

The pathogen is Pseudomonas syringae pv. Lachrymans. The pathogen is transmitted through the infested seeds and plant debris from diseased plants and is spread during vegetation by rainwater or irrigation, insects, tools.

The pathogen enters the plant through natural openings or wounds.

Prevention and control. As preventive measures, it is recommended to respect 3-4 years crop rotation system, to use healthy seeds, to gather and burn plant debris, to remove attacked plants from the crop. When the attack is detected, it is recommended to apply specific fungicide treatments.

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Cucurbits angular leaf spot (Pseudomonas syringae pv. lachrymans) – identify and control
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