Symptoms
Yellowing, sparse canopy and dieback of branches as the root and lower trunk rot; bark at the collar oozes dark gum and the wood beneath turns brown. Trees decline over one or more seasons and can die.
Prevention
Plant on raised mounds with excellent drainage and graft onto tolerant rootstocks where available. Keep the collar dry, avoid trunk wounds and do not pile mulch against the trunk.
Treatment
Organic
Expose and scrape out cankered bark, then paint with a copper paste. Drench the root zone with phosphonate and Trichoderma and fix the drainage.
Chemical (last resort)
Apply phosphonate (potassium phosphite) as a trunk paint, soil drench or injection, or use metalaxyl drenches. Treat early and correct drainage — observe PHI on fruit trees.
Affects 1 crop
Sources
MARDI Durian Production Guide; DOA IPM Manual