dieback

Dieback is a plant condition characterized by progressive death of tissue, typically starting at the tips of shoots or at roots, while the main stem or healthier sections may remain alive for some time. It can affect trees, shrubs, and herbaceous plants, and may involve only a portion of the crown or root system.

Dieback results from stress or damage that disrupts the plant’s ability to supply water, nutrients, or assimilates to growing points. Causes include abiotic stress such as drought, waterlogging, frost, nutrient deficiency or toxicity, soil compaction, and pollution, as well as biotic factors such as pathogens (fungi and oomycetes), pests, and root disorders. In forests, dieback often arises from multiple interacting factors, creating a decline syndrome rather than a single disease.

Common signs include wilting, chlorosis, browning or necrosis of shoots starting at the tips, thinning of the crown, dieback along branches, and exposure of inner wood. Dieback may be partial or progress to encompass larger portions of the plant; roots may show necrosis if the damage is severe.

Diagnosis relies on the pattern of symptoms, history, and often laboratory testing. Management focuses on reducing stress and preventing spread: remove and destroy severely infected material, improve site conditions (adequate irrigation, drainage, and soil structure), avoid mechanical damage and soil compaction, minimize pruning wounds, and, where available, use resistant varieties. In forests, management emphasizes resilience and sanitation, with thinning to reduce stress and prevent spread; chemical controls are limited. Notable forms include ash dieback caused by Hymenoscyphus fraxineus, and other diseases such as Phytophthora-induced root and crown rot, oak decline, and pine wilt disease.