Vol 107 (1994): Proceedings of the Florida State Horticultural Society

Quality Tree Program for Florida Citrus

Published June 1, 1995


In order to provide the best possible nursery material to the Florida citrus industry, the Florida Citrus Nurserymen's Association (FCNA) and the Florida Citrus Production Managers' Association (FCPMA) have worked together to develop a Quality Tree Program (QTP). This QTP would provide for changes in the current Florida Citrus Budwood Registration Program (FCBRP) by making it mandatory that all citrus nursery tree stock grown in Florida be propagated from registered sources, with required recurring testing to be made of registered sources for severe strains of citrus tristeza virus (CTV) yearly and for psorosis and viroids every six years. Seed source trees for Poncirus trifoliata and P. trifoliata hybrids would be indexed only for psorosis once every six years un less they were propagated from foundation material. Use of nursery increase blocks would be encouraged with virus-test ed budwood for these blocks being provided by the FCBRP, and the increase blocks would be tested for presence of severe CTV between the 12th and 18th month of their life span (24 months in the field or 30 months if screened). The need to have a mandatory FCBRP has been recognized: Florida faces the imminent threat of invasion of the brown citrus aphid, Toxoptera citricida, the most efficient vector of CTV. This would greatly increase the risk that stem pitting strains of CTV would be transmitted from possible "sleeping source trees" in the state into cultivars enabling more efficient aphid transmission and introduction in budwood source trees. Also, recent indexing has indicated the presence of psorosis-like agents in some registered sources. The Florida Division of Plant Industry (DPI) would have the responsibility for enforcement of the mandato ry QTP, but the QTP would be governed by an Advisory Committee composed of members from FCNA, FCPMA, and research scientists. Once the law is passed making the QTP mandatory, enforcement of the law would begin after a three-year grace period. This grace period would allow time for the existing non-qualified citrus nursery stock to be sold or con sumed, and to allow sufficient time for an ample amount of reg istered screenhouse scion/seed start material to be available to nurserymen. The disease testing of registered sources be longing to nurserymen and private owners would be done by commercial and private diagnostic labs which would be certified by DPI. It should be encouraged that all scion and seed source material currently being used be tested now with the approved testing techniques. This testing would be considered to fulfill the recurring indexing requirements once the QTP becomes law and is enforced.