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Citrus

Lemon Sieve Tube Necrosis

(Reviewed 7/03, updated 7/03)

In this Guideline:

Symptoms
Management

SYMPTOMS
Lemon sieve tube necrosis is an inherited disorder of lemon trees in coastal areas. Eureka budlines and Frost Lisbon lemons are affected. In intermediate areas the disease is less severe, and in the San Joaquin and Coachella valleys, lemon sieve tube necrosis does not result in noticeable decline.

Trees with lemon sieve tube necrosis go through a cyclic decline. About 4 or 5 years after planting, the older food-conducting sieve tubes near the bud union die. Several years later, younger sieve tubes also die, severely restricting food transport to the roots. Many feeder roots starve, fruit ripen prematurely, shoots grow poorly, and some leaves turn yellow and drop. The dieback stimulates new cambium and phloem production, and the tree recovers temporarily. Once the new sieve tubes also become necrotic, the decline process starts again. Only a microscopic analysis can reveal the collapsed sieve tubes.

MANAGEMENT
Only certain budlines are affected by this inherited disorder. Eureka lemons that have this disorder could potentially die in 8 to 15 years. Before planting this variety, obtain the most recent recommendations from your farm advisor.

PUBLICATION

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Diseases
H. D. Ohr, Plant Pathology, UC Riverside
J. A. Menge, Plant Pathology, UC Riverside

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