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Registration and Certification of Propagative Materials in California

E. C. Catavan

Summary

A registrationprogram for apparentfreedom from psorosiswas established by the NurseryService of California in 1937,4 yearsafter Dr. H. s. Fawcett discoveredpsorosis to be a graft-transmissibledisease. Since that time the programhas undergone ~eral revisionsand now (late 1973)it is againbeing very extensivelyrevised. The main purposeof the programwill remain,as always,the provision,to growersand nurserymen,of true-to-nameplants that are free of important pestsand pathogensand which havesuperior production potential.

The California Citrus RegistrationProgram

The original registrationprogram provided for in.field inspectionof all registeredtrees for young-leafsymptoms of psorosis and for other important symptoms,but containedno provisionfor indexing. Following the developmentof an index for psor- osisby Dr. J. M. Wallace,an index wassometimes made by Dr. Wallacein a University of Californiagreenhouse. Later in the 1950'sthe NurseryService developed its own indexingfacilities in Sacramentoand Riverside.At first psorosiswas the only in. dex madeon candidatetrees, most of which were in privately owned orchards. Then,asit becamepractical to index for more diseases,tristeza, vein enation and exocortis indexeswere includedin the nurseryservice indexing for everycandidate tree.

Sincethe mid-1960'sthe overall program for citrus improvement,including registrationand certification, hashad 2 parts:

a) The interim programwhich is the expandedcitrus psorosisregistration program begun in 1937and

b) The long-rangecitrus registrationand certification programwhich utilizes foundation stock from the University Citrus Variety ImprovementProgram (CVIP) which startedin 1958 on the Riversidecampus at the requestof .

The vast majority of citrus treesgrown in Californiaduring the decadeof 1963-1913have been propagated from orchardtrees registeredin the interim program. In the past few yearsa substantialnumber of treeshave come from materialsin the long-range program. It had beenexpected that the long-rangeprogram would soon provide budwoodfor a majority of the citrus treespro- ducedin California. The developmentof stubborn diseasein a substantialportion of the mother treesand in their bud progeny hasprecluded very extensiveuse of this programin its presentform.

The long.rangeprogram provided for completeindexing, including cachexiaand impietratura, of all selectionsentered in the program. Candidatetrees of selectionsfound entirely clean of bud transmissiblepathogens and all disorderswere planted in a foundation block at Lindcove,near Visalia in the SanJoaquin Valley. After foundation treesfruited satisfKtorily budwood from them was releasedto nurserymenfor propagationof mother block treesto be grown on private property. Requirements for participation wereso restrictivethat few mother blockswere established. Those which were establishedhad considerab!e trouble with stubborn diseaseinfection. The percentageof stubborn diseaseinfection in nurserytrees propagated from regis- tered mother block treeswas also unacceptably high for sweetoranges and . The infections appearto haveoccurred at sometimeduring the long period (10 yearsor more) of outdoor exposureto the presumedleafhopper vectors of stubborn.

Now we plan to combinethe interim and long-rangeprograms into a singleregistration and certification programthat will greatly reduce the hazard from stubborn in certified stock while combining the best features of both programs. Details of the proposed new program will be discussedlater.

Responsibilitiesfor the operationof citrus registrationprograms in Californiawill be asshown below:

1) California Department of Food and Agriculture Nursery and Seed Services assistedby County Departments of Agriculture. a) Supervision of preparation of nursery sites, budwood cutting and maintenance of identity. .138-

b) Inspectionand indexing of trees. c) Registrationof eligible scionand seedtrees and cancellationof registrationwhen necessary. d) Certification of eligible nurseryplants. e) Maintenanceof statistical records.

2) Universityof California, Riverside,assisted by specialistsin the Agricultural ExtensionService and d1eUSDA.

a) Obtainclean material of desiredclones by selection,indexing, therapy, and culturing. b) Maintainfoundation material of desiredclones indoors and outdoors. c) Makefoundation materialavailable to nurserymen. d) Provideconsultation, information and training asnecessary.

3) Nurserymenand groMrs

a) Grow protected blocks indoorsand nurseryincrease blocks and nurserystock indoors or outdoors. b) Grow or locateorchard trees for registration. c) Maintain identity records. d) Support programby participatingin it andby payingfees to supportthe program.

The proposedprogram will upgradethe presentinterim programby provision of annualinspection of all candidateor regis- tered treesduring the mature fruit season.In addition annualindexing for tristezaand triennial indexingfor exocortiswill be providedfor all registeredtrees being used for budwood. Indexingfor psorosiswill normally be done only every sixth year. The main improvementsin the programare more careful inspectionfor stubborn symptomsin sourcematerials and nursery trees,better availability of completely testedfoundation stock from the lindcove foundation block and from an indoors foun- dation block at Riverside,and provisionfor indoor protectedfacilities to be operatedby nurserymen.

The CVIP will continue to be responsiblefor indexing,maintenance, and protection of materialsunder its jurisd;ction and hasfacilities for heat therapy of exocortis-freebudlines that are desirablebut infected with psorosisor another heat.'abilepath ogen. CVIP alsois equippedto handleforeign selectionsreceived from USDA Plant Quarantinefacilities at Glenn Dale Mary- land. OccasionallyCVIP cooperatesin obtainingmeristem-tip or nucellar-tissuecultures from budlinescontaining pathogens that cannot be eliminatedby heat treatment

The CVIP hasindexed and processedmore than 300 selectionsof citrus. Of thesemore than 200 remainin the program. The otherswere droppedmostly becauseof infection though somewere discardedfor chimeras,poor quality, etc.

Selectionsretained in the program have been indexed or are under index for all known virus diseasesof citrus and for stub- born disease. Short-term indexing is now done on seedlings of 'Troyer' , Citrusexcelsa, 'Mexican' , 'Kara' man- darin, 'Madam Vinous' and/or 'Pineapple' sweet , standard sour orange and 'Dweet' and on '' and 'Parsons Special' mandarin budlings.

Detailsof the indexinghave been reported in variousplaces. Basicallyhealthy index plants free of nutritional imbala"1ce and pestsare graftedwith buds,leaf patches,side- or shoot-tip grafts,then cut back and forced into new growth which IS,n- spectedperiodically for symptoms. Bark is peeledfrom 'Mexican' lime plants to detect tristezapitting and from 'Parsons Special'on 'Rough' to detect cachexiagumming. At least4 plants are usedfor eachindex and 2 or more piecesof in- oculum are grafted into eachplant.

Charts showingflow patternsof the existingand proposedprograms are shownin Figures1-3. It must be emphasizedthat the proposedscheme has been developed especially for the Californiasituation and environmentand that certain parts of it may be of no value or unworkableunder other cireumstancesin other areas. .139-

The approximateform of certain definitions and regulationsare givenbelow:

Definitions: Wordsdefined in the Food and Agricultural Codehave the samemeanings in this article and in addition:

(a) "Virus-infected" means infected by a seriousviras or graft-transmissible diseaseor manifestingsymptoms or behavior characteristicof a seriousvirus or other graft-transmissibledisease. (b) "Index" meanstesting a plant for infection by graftingwith tissuefrom it to an indicator plant or by other approved means. (c) "Virus-free" meansplants producedunder terms of this regulationand free of seriousvirus or other graft-transmissible diseaseas determinedby index testing and inspectionprocedures outlined in this article. (d) "Off type" means different from the variety, strain, or selectionlisted on the applicationfor registrationor certification. (e) NSelectedtree" meansa tree for which registrationis intendedwhen inspectionand testing arecompleted. (f) "Testedtree" meansa tree testedfor virus infection and found to be in compliancewith specificquarantine requirements but not eligible for registrationunder the terms of this regulation. (g) "Registered" means a registrationnumber has boon assigned by the Departmentto a tree that hasbeen inspected and test- ed in accordancewith the provisionsof this article to selVeas a sourceof propagatingmaterial for certified nurserystock. (h) "Foundation block" meansa planting, maintainedby state or federal agencies,in which treesmay be registeredto selVe as a primary sourceof propagatingmaterial. (i) "Protectedblock" meansa planting of treesin an;approved glasshouse or screenhouse,propagated and grown there with foundation stock scions,which are to be register. and maintainedby an applicantas a sourcefor growingcertified nur- sery stock. ij) "Nursery increase block" means a planting of citros nurserystocks, propagated directly from registeredtrees. Treesin . nurseryincrease block which are 18 months old or lessfrom buddingmay be usedas a supplementarysou rce of sc:ons for growingcertified nurserystock. (k) "Certified block" means a planting of citrus nur.ry stock for the production of certified nurserystock. (I) °Foundation stock" means propagating materialproduced from a registeredtree in a foundation block or from properly indexedmaterial propagated and grown in an approvedstate, federal, or university glasshouseor screenhouse. (m) "Registeredstock" meanspropagating material from a registeredtree or a nurseryincrease block. (n) "Certified citrus nursery stock" means treesprofMgated by usingscions from registeredstock, and certified in accordance with the provisionsof this article.

GeneralProvisions: Participationin this programshaH be voluntary and may be withdrawn at the optionof the applicant. Registration or certification shall not imply any warranty on the part of the Department or of any employee thereof. Registra- tion, certification, approvals, and supervision mentioned herein shall be conducted by the Department.

(a) Responsibilityof applicant: The applicantshall be responsiblefor the: (1) Selectionof the tree for testing. (2) Selectionof the location and of the proper maintenanceof any plants beinggrown under the provision of th:s article. (3) Application for the registry or re-registryof plants beinggrown under the provision of this article. (4) Identity of all plants enteredin this program. (b) Location of plantings: Eachplanting location shall be subjectto approvaland shall be in an areahaving minimal risks for spreadof infectious pestsby drainage,ffoodi~, irrigation, or by other means.

A protectedblock, nurseryincrease block, and certified block shall be locatednot lessthan 50 feet distant from any establishedcitrus tree. Eachnursery increase blook and certified block shall be a separateplanting sufficiendy apart from any other planting to maintain its identity.

Selected trees for registration, other than those grown in a protected block, may be selected from any location with the approval of the Department.

(c) Maintenanceof plants: All plants enteredin this programshall be kept in a thrifty growingcondition and pestsshall be effectively controlled. Suitableprecautions shall be taken in cultivation, irrigation, movementand useof equipmeff' and in otherfarming and nursery practices to guardagainst spread of peststo plantsentered in this program. -140.

To assurethat the inspectionsrequired herein may be madeproperty and to provideclose working knowledgeof field operations,the applicantshall notify the Departmentin advanceof any planting, propagatingor pruning operation or removalof nurserystock or treesin any planting enteredin this pro{fram.

All pruning shears,saws or other implementsshall be disinfectedin an approvedmanner prior to any fruit picking or cuttingof anyselected or registeredtree, or anyclonal selection Vtrithin an increase block or certifiedblock.

Any plant found to be off-type, showing symptoms characteristic of stubborn disease,or infected with a virus, may be required to be removed immediately from any planting. Approval may be given to remove off-type parts of a registered tree without revoking registration of the tree.

Labeling of eachselected or registeredtree and~f nurserystock growingin planting enteredin the programto identity it asto rootstockand as to its scionsource shall be donein anapproved manner.

(d) Eligibility and Planting Requirements;

(1) RootstockPropagation: The rootstock of any plant enteredin the programmay be grown from seedor it may be vegetativelypropagated providing the propagatingwood meetsthe samerequirements as the scion to be usedfor the plant.

(2) Foundation Block: A selectedtree may be planted in a foundation block when propagatedwith a scion from a regis- tered tree in a foundation block or when propagatedfrom a greenhouse- or screenhouse- grown scion that haspassed the short-terminspection and testing proceduresrequired in this article and hascompleted or is under the cachex;a- xyloporosisindex. The tree may be registeredwhen inspectionand testingprocedures prescribed in this article have beencompleted with satisfactoryresults and, if an outdoor planting, when the tree hasproduced sufficient fruit to give acceptableevidence that it is not off-type. A selectedtteefound to be ineligible for registrationshall be removed from a foundation block.

(3) ProtectedBlock: Treesin a protected block shall be grown in an approvedmanner and the rootstock for eachtree shall be horticulturally suited to the scionvariety.

At 1east1 duplicatetree propagatedfrom eachbudstick usedto produceprotected block treesshall be planted out. doors,in a climate suitablefor the variety, for visual inspectionsof growth habits,trueness to variety, and disease symptoms.

A protectedblock treemay be registeredwhen it is at least9 months old and hasshown good normal growth free of diseasesymptoms. A tree shall be removedfrom a protected block when it is found to be ineligiblefor registration. Registrationof a protected block tree may be cancelledif the duplicate outdoor tree producesan excessiveamount of off-type fruit and off-type growth.

(4) SelectedOutdoor Trees: Any individual orchard,yard; or containertree may be selectedfor inspectionand index- ing for registrationunder the terms of this regulation..

(5) NurseryIncrease Block: Scionsused to propagatethe nurserystock therein shall be from registeredtrees. Within . 18 months of propagation,scions may be taken from the block for usein growingcertified nurserystock. TreesIn a nursery increaseblock alsomay be certified.

(6) Certified Block: Scionsused to propagate the nurserystock therein for certification shall be from registeredtrees or from a nurseryincrease block. .' "

Inspectionand TestingProcedures: Inspectionand indexingprocedures prescribed in this article may be madeby the Universityof California,the United StatesDepartment of AgricaJture,orthe Departmentand shall be conductedin an approvedmanner at times determinedas suitable by the Department.'In the indexingprocedures required in this sect:on, the Departmentmay approvethe substitution of other indicator plants, if equally suitable,or may approveindexing on a -141.

feMr number of indicator plants, or may approveother proceduresfor testing for virus infection if determinedequally suitable.

Additional inspectionsor indexing other than providedin this sectionmay be requiredby the Departmentif seasonal conditions or other factors tend to obscurevirus symptomsor makeadequate inspection impossible, or when virus in. fectionis suspected,or whenvirus symptoms may be masked in a particularvariety.

The Departmentshall assigna numberto a selectedtree pendingregistration.

(a) Treesin a Foundation Block: The scion parent of any tree planted in a foundation block shall have been indexed for and not found to be infected with the viruses of citrange stunt, concave gum, exocortis, psorosis, tatterleaf, seedling yellows tristeza, tristeza, vein-enation and yellow vein by short-term indexing on Citrus excelsa, 'Oweet' tangor, 'Etrog' citron, 'Mexican' lime, sour orange, sweet orange and 'Troyer' citrange plants. The scion parent or the selected tree must be indexed for c.:hexia-xyloporosis virus in 'Parsons Special' mandarin plants in a warm glasshouseand these indicator plants must remain free of cachexia symptoms for at least 1 year before the selec'ed tree may be registered. Only the tristeza and exocortis indexes shall be required if the scion parent of the sclected tree is a registered tree in a foundation block. Trees to be planted in a foundation block must be grown in an a- pproved glasshouseor screenhouse.

Following planting in a foundation block, a tree shall be indexedon 'Mexican' lime for tristezaand vein-enation virusesand on suitableindicators for psorosisand exocortis viruseswithin the 12-monthperiod before registration. In subsequentyears after registration,tristeza indexing shall be repeatedwithin 1 year prior to budwood coll~c~l(\n from a registeredtree. Eachregistered tree shall be reindexedfor exocortisvirus everythird year and for psorosls virus everysixth year. Eachfoundation block tree shall receive1 or more visual inspectionseach year. The fruit of bearingtrees, except lemonsand limesshall also be inspectedeach year after color break.

(b) Treesin 8 Protected Block: Each tree in a protected block shall be indexedfor exocortis everythird year and for tristezaevery sixth year. In addition, annualvisual inspectionis requiredfor eKh tree.

(c) Non-Protected,Selected Trees of Participants:A selectedtree and treesadjacent to it shall be givenat least 1 vlsu21 inspectionprior to registration. The selectedtree alsoshall be indexedon 'Mexican' lime and 'Etrog' citron and a suitableindicator host for psorosisprior to the initial registration. Suchselected trees shall be of good vigor and free from apparentmutations, or disorderswhich may obscuredisease symptoms or makethe tree undesirableas a propagatingsource.

Indexing for tristezavirus is requiredfor a registeredoutdoor tree eachyear in which approvalfor cutting budwnod is requested; for exocortis indexing is required every third year. and for psorosis every sixth year.

Eachtree shall be given 1 visual inspectioneach year. For fruiting treesoutdoors, inspection shall be during the period that maturefruits are on the tree after color break,except for lemonsand limes.

(d) Order of Indexing: Indexing shall be made in the order in which applications are received and as indicator host plants Ire available.

(8) Registration shall be for a period of 3 years from June 30 in the calendar year in which indexing is commenced

(f) Registration may be continuous provided application for inspection and testing is filed with the Department prirf to the expiration dIu of registration.

(g) NurseryIncrease Block, Certified Block: Onevisual inspectionshall be madeeach year of plants in a certif:ed blo:;l, or in a nurseryincrease block. .142.

(h) Refusal or Cancellation of Registration or Certification: Registration or certification may be refused or canceled for any plants in part or all of a planting if:

(1) The requirements of this article have not been met.

(2) A selectedor registeredplant is found to be off-type or virus-infected. At the discretionof the Department,a plant growingoutdoors, determined to be infected with vein-enationvirus or tristeza,may be registeredor cer tified when it is growingin an areawhere such virus is known to be prevalent.

(3) A tree is found to be within the rangeof possibleroot graft of anothertree found to be virus-infected.

(4) The pestcleanliness requirements for nurserystock in the nurseryinspection regulations of the California Administration Codehave not beenmet

(5) For any reason the identity of a plant becomesuncertain or hasnot beenproperly maintained.

(6) A registrationnumber is misusedor misrepresented.

(7) An ~cumulated percentageof more than 1/2 percentof the treesof the samevariety on the samekind of root- stock are found virus-infectedin a nurseryincrease block or more than 2 percentvirus infected or stubborn affec- ted treesin a certified block. Either visualinspections or the resultsof indexing or both may be usedas a basIs for calculatingthe numberof treesthat may be infected.

Application and Fees:

(a) Application: The applicantshall furnish information requestedand shall givehis consentto the Departmentto take plant materialsfrom any planting for inspectionor indexingpurposes. An applicationsubmitted for the accepta!ice of any plant or planting and for subsequentinspections, approvals, registration or certification may be refusedunless madesufficiently in advanceof time of plantino to permit the Departmentto establishthe origin of the stock, LOde- termine the suitability of the location, and to superviseany treatment that may be required.

(b) Fees: Fees establishedin this article are payablein advanceof the work to be done and are for the sole purposeof defrayingexpenses incurred in the inspection,indexing, approval, registration and certification proceduresherein providedand are not to obtain any right or privilege.

Feesshall not be chargedthe Universityof Californiaor the United StatesDepartment of Agriculture for registration or for the inspectionand testing of treesproviding there shall be no expenseto the Departmentother than for obs~r. vation of the inspectionand indexing requiredin this article and for the keepingof records. Whenthe procedures areconducted by the University of Californiaor by the United StatesDepartment of Agriculture, they shall not be lessthan provided in this article and the Departmentshall be notified eachyear of me treesto be enteredor contin- ued in the program.

(1) Fees: The Departmentshall establisha scheduleof feesfor servicesprovided in this article. The fee shall be basedupon the approximatecost of the servicesrendered.

(2) Refunds: Feespaid for servicesthat are not renderedshall be refundedto the applicant.

Detailsof the aboveproposal are tentative at this time. Somedefinitions and regulationsmay be modified, addedor deleted. It seemsdesirable to add anothercategory "protected foundation block" to coverfoundation materialkept in an insect.free facility operatedby the University,State or the USDA. -143.

In addition to the programsfor registrationof treesto be usedprimarily assources of scion material, Californiahas a programfor registrationof seedsource trees for truenessto type and freedomfrom all kinds of psorosis. In this program treesmay be registeredas seed source trees after beinginspected and found apparentlytrue to nameand healthy and after beingindexed for psorosis.

Considering the importance,the destructivenessand easeof transmissionof severalgraft-transmitted and bud-perpetuated citrus diseasesit seemsunlikely that a large and viable citrus industry can survive more than a few decadeswithout employing some organized registration system for reducing the spread and preventing the incidence of graft-transmissible diseasessuch as stubborn, greening and certain severeforms of tristeza. In addition, special measuresmay have to be taken to prevent 1 of these 3 diseases from becoming established in new areasor of causing catastrophic lossesin areasalready infested. -144-

CaliforniaInterim RegistrationProgram for Citrus

RegisteredTrees

~ rees now in field M.B., trees now registered in interim program-free from psorosis, GO, exocortis, vein-

Mustbe indexedfor psorosis, - - no, exocortisvein.enation, Must be visually inspected Tested Trees for stubborn

Figure 1. Interim registrationprogram in effect 1963-1973.

_:- _C---ccc-,-

CaliforniaCitrus Registrationand Certification Program(Long-Range)

r-- ~ . U.C.Q~-;'~~e Outdoor Mother Block I Field Mother ~~.Idi~~ -, ~ iel~fj~ r-u:-c~~~~-;;1- ~) Block .., Block 1 Screenhoose ~L-~~~~~eJJ .} Candidate Trees Block.. -

Figure2. Long-rangeprogram in effect1968-1973. -145-

ProposedCalifornia Citrus Registrationand Certification Program1973

Figure3. Proposedcombination of interim and long-rangeregistration and certification programs.