Symptoms
Dark, wet, sunken patches on the trunk and main branches that ooze reddish-brown gum and kill the bark beneath. Patches enlarge and can girdle the trunk, causing canopy decline and dieback.
Prevention
Keep the trunk dry and well-lit by pruning low branches and avoid wounding the bark. Improve drainage and do not let mulch or soil bank up against the trunk.
Treatment
Organic
Scrape out diseased bark back to healthy tissue and paint the wound with a copper paste. Drench the surrounding root zone with phosphonate as a protectant.
Chemical (last resort)
Paint or inject phosphonate, or apply metalaxyl, to active cankers and protect the trunk preventively in the wet season. Treat early and observe PHI on fruit trees.
Affects 1 crop
Sources
MARDI Durian Production Guide; DOA IPM Manual