PEST MANAGEMENT DECISION GUIDE: GREEN LIST Citrus tristeza virus (CTV) Citrus tristeza virus Grapefruit stem pitting Prevention Monitoring Direct Control

l The disease is spread by virus-infected l The following three syndromes and the severity of their symptoms vary l Control strategies for CTV differ budwood or plants; use only disease-free depending on the CTV isolate, environmental conditions and hosts: according to the incidence and propagation material from certified l Stem pitting (mostly grapefruit): it does not kill trees, but causes a thin severity of the isolates in a particular nurseries. Use tolerant scions if available canopy, fewer fruits of reduced size and quality, deep pits in the trunk area and with the cultivars and such as Mandarin and Valencia orange and stem and, in severely affected trees, dieback rootstocks used. No single strategy is applicable to all situations l When using budwood, ensure that they are l Seedling yellowing (inoculated grapefruit, lemon and sour orange Dieback of sweet orange budded onto rootstocks that are resistant/ seedlings): dwarfing and general chlorosis l Remove infected trees immediately to grafted on sour orange (L. tolerant to CTV such as sweet orange, avoid spreading the disease and Navarro, Instituto Valenciano Cleopatra mandarin, rough lemon, Rangpur l Decline (sour orange rootstock): in slow decline, wilting and chlorosis of maintain surveillance de Investigaciones Agrarias, lime and trifoliate orange the canopy, an abnormal crop of small fruits persisting after death of the Bugwood.org) tree and many small conical pits on the face of the bark surface l Chemical control of aphids in the field l It is also spread by several species of (honeycombing). Trees affected by quick decline lack honeycombing, is not recommended as it is an aphids, but the most efficient vector is but frequently show a yellow-brown stain at the bud union unproven strategy for CTV control Toxoptera citricidus, the brown citrus aphid: and insecticides may not act quickly l Roots: necrotic streak or lesions, deterioration l In nurseries, maintain good aphid control enough to prevent infection and keep trees under a screen to help l Remove a patch of bark across the bud union from declining trees to look l There are no treatments available to keep the vector out of the planting for small pits (honeycombing) reverse the decline in affected trees material l Inspect the orchards regularly for symptoms if the area is susceptible or at on sour orange rootstocks l Control weeds under trees and in the risk to the CTV, and more often during high aphid population periods Stem pitting (Florida Division of field to eliminate host plants for the l Plant Industry Archive, Florida CTV can be confused with diseases such as citrus blight (no bud union Department of Agriculture and aphids symptoms) and citrus greening (no stem pitting) Consumer Services, Bugwood.org)

Honeycombing on lemon rootstock (S.D. Sawant)

Note: Pesticides may be available to control this pest. Please check with the Ministry of Agriculture in your country to find out which pesticides are registered in your country and the local restrictions for their use.

CREATED/UPDATED: October 2014 LOSE LESS, FEED MORE PRODUCED BY: Plantwise Plantwise is a CABI-led global initiative www.plantwise.org