Phloemia

Phloemia is a historical or obscure term referring to diseases of the phloem tissue in vascular plants. The phrase appears in older botanical and plant pathology literature, but it is not widely used in modern terminology, where more specific names are preferred for different phloem-related disorders.

The phloem is responsible for transporting sugars and other organic nutrients from photosynthetic tissues to growing or storage organs. When phloem function is disrupted, the distribution of photoassimilates is impaired, which can limit growth and weaken the plant.

In affected plants, symptoms may include stunted growth, chlorosis, leaf mottling, vein clearing, leaf scorch, dieback, or girdling of stems. These signs result from impaired transport rather than from a single uniform pathogen, making diagnosis challenging and often necessitating tissue examination for confirmation.

Causes are diverse and include bacterial, fungal, and phytoplasmal pathogens; nematodes; and abiotic stresses such as drought, cold, or salinity that hinder phloem transport. Phloem diseases can lead to carbohydrate starvation in sinks, reduced vigor, and, in severe cases, plant death.

Diagnosis relies on symptom patterns and direct examination of phloem tissue, with molecular assays or pathogen Identification used to determine the exact etiologies where possible. Management focuses on prevention and containment, including sanitation, resistant cultivars where available, vector control, and cultural practices that reduce stress and encourage overall plant health.

Historically, phloemia appears in older botanical literature; in modern plant pathology, terms like phloem necrosis, sieve-tube degeneration, or vascular wilt are generally preferred. See also: Phloem, Phloem transport, Vascular wilt.