Kontrola lista vinove loze - savjeti za upravljanje simptomima lista vinove loze -


Napisala: Mary Ellen Ellis

Virus lista vinove loze je složena i destruktivna bolest. Gotovo 60 posto gubitaka usjeva u vinovoj lozi širom svijeta svake se godine pripisuje ovoj bolesti. Prisutan je u svim regijama uzgoja grožđa na svijetu i može utjecati na bilo koju sortu ili podlogu. Ako uzgajate vinovu lozu, morate biti svjesni listanja listova i što možete učiniti s tim u vezi.

Šta je vinova loza?

Listanje grožđa je virusna bolest koja je komplicirana i teško je prepoznati. Simptomi nisu uvijek očigledni do duboke sezone rasta, ali ponekad nema vidljivih simptoma koje uzgajivač može prepoznati. Druge bolesti uzrokuju simptome koji mogu biti slični onima kod listanja, što još više komplicira situaciju.

Simptomi su izraženiji kod crvenog grožđa. Mnoge bijele sorte grožđa uopće ne pokazuju znakove. Simptomi se mogu razlikovati u zavisnosti od starosti vinove loze, okoline i sorte vinove loze. Jedan od najčešćih znakova listanja je kotrljanje ili oblikovanje lišća. Na crvenoj vinovoj lozi lišće također može postati crveno u jesen, dok žile ostaju zelene.

Vinova loza pogođena bolešću takođe je uglavnom manje energična. Plod se može kasno razviti i biti lošeg kvaliteta sa smanjenim udjelom šećera. Ukupni prinos voća na zaraženim vinovim lozama obično je značajno smanjen.

Upravljanje listovima vinove loze

Virus lista vinove loze uglavnom se prenosi zaraženim biljnim materijalom, kao što je upotreba alata za obrezivanje zaražene loze, a zatim i zdrave loze. Može doći do određenog prenošenja i preko brašnastih stenica i mekih kamenaca.

Kada se bolest uspostavi, kontrola lista je izazovna. Nema liječenja. Alate koji se koriste na vinovoj lozi treba dezinficirati izbjeljivačem kako bi se spriječilo širenje virusa.

Jedini način da osigurate da se ostaci vinove loze ne drže izvan vašeg vinograda je korištenje samo certificiranih, čistih vinovih loza. Bilo koja loza koju stavite u svoje dvorište i baštu trebalo je, između ostalih, testirati na virus. Jednom kada je virus u vinogradu, nemoguće ga je eliminirati bez uništavanja vinove loze.

Ovaj je članak posljednji put ažuriran


Bolest crvene mrlje

Bolest može odgoditi ili otežati sazrijevanje plodova, što dovodi do smanjenog kvaliteta vina za neke sorte i u nekim regijama.

Bolest crvene mrlje uzrokuje virus poznat kao virus crvene mrlje vinove loze (GRBV). Prvi je put opisan na Cabernet Sauvignonu u dolini Napa 2008. godine, ali je od tada identificiran u mnogim američkim vinogradarskim regijama, uključujući CA, ID, NC, NY, MO, OH, OR i WA. Poznato je 86 različitih virusa koji zaraze vinovu lozu, više nego bilo koja druga višegodišnja kultura, a GRBV je samo jedan od njih. Iako je nedavno identificiran, GRBV je vjerovatno prisutan desetljećima. Bolest uzrokuje da krošnje postanu crvene i mrljaste (kod crvenoplodnih sorti) ili klorotične i žute (kod bijelih plodnih sorti). Bolest može odgoditi ili otežati sazrijevanje plodova, što dovodi do smanjenog kvaliteta vina za neke sorte i u nekim regijama. Dodatni opisi simptoma dostupni su u daljnjem odjeljku za čitanje u nastavku.


Bolest crvene mrlje i status virusa kod CDFA certificiranih zaliha vinove loze

Otkriće virusa vinove loze crvene mrlje (GRBaV, Red Blotch) 2012. godine usredotočilo je industriju na bolest crvene mrlje - nepoznato stanje sa prepoznatljivim simptomima kojeg su uzgajivači bili svjesni već neko vrijeme. GRBaV je pronađen u novom sadnom materijalu, kao i u etabliranim vinogradima u Kaliforniji i nekoliko drugih vinorodnih država u SAD-u. Tokom proteklih 18 mjeseci, u nastojanju da zaustave širenje bolesti, ključne zainteresirane strane iz opskrbe „od stoka do stola“ lanca uložili su značajno vrijeme i novac kako bi bolje razumjeli GRBaV. Univerziteti, rasadnici, uzgajivači, profesionalna udruženja, lideri industrije i laboratoriji za ispitivanje odigrali su presudnu ulogu u rješavanju ovog novog izazova za vinsku industriju.

Slika 1: Crvena mrlja u CS04. 7. novembra 2012.

"Otkriće virusa Red Blotch bit će glavni faktor u poboljšanju programa i smanjenju problema s virusima u rasadniku", rekla je dr. Deborah Golino, direktorica UC Davis Foundation Plant Services. „Dugi niz godina uzgajivači, rasadnici i istraživači bili su frustrirani gledajući vinove loze na terenu sa simptomima crvenih listova koji su negativni na svim dostupnim laboratorijskim testovima na viruse vinove loze. Prema mom iskustvu, svake godine su pronađeni slučajevi gdje su laboratorijski testovi bili negativni, ali vinova loza nije izgledala normalno i sumnjalo se na infekciju virusom lista. Sada znamo da su mnoge od tih loza zaražene virusom Red Blotch. "

Rastuća prevalencija bolesti vidljiva je iz nedavne oznake Kalifornijskog odjela za hranu i poljoprivredu (CDFA) Pierceove bolesti / staklastog krilca (GWSS) odbora GRBaV, brašnaste loze i smeđeg marmoriranog smrada kao štetočine vinove loze. Ova oznaka postavlja odbor da brzo reaguje na određene epidemije naporima u obrazovanju i informiranju i cilja istraživačke projekte za dugoročne napore u kontroli. Daljnje dokaze o rastućem značaju Red Blotcha i njegovom potencijalnom ekonomskom utjecaju izvijestila je Lucie Bell iz Australijske radiodifuzne korporacije Rural 14. aprila 2014, koja je primijetila da je poslanik zapadnoaustralskih državljana Vince Catania pozvao na hitno zaustavljanje uvoza američkog stonog grožđa kako bi se omogućilo razmatranje novog istraživanja o Red Blotchu. Catania je pisala ministru poljoprivrede zapadne Australije Kenu Bastonu i saveznom ministru poljoprivrede Barnabyju Joyceu, pozivajući na provođenje moratorija i potpune analize rizika od štetočina. Catania je rekla da su nova istraživanja pokazala da su dijelovi biljke koji nose GRBaV rašireniji nego što se prvobitno mislilo i da se virus može naći u voću. Procjenjuje se da će industrija grožđa zapadnoj Australiji do 2015. vrijediti 900 miliona dolara.

Slika 2: Chardonnay sa GRBaV. Foto: Rhonda Smith, savjetnik za vinogradarstvo, UCCE.

Simptomi crvene mrlje kod crvenih sorti uključuju razvoj karakterističnih ružičasto-crvenih mrljavih regija na listiću lista, koje nalikuju onima povezanim sa virusom bolesti listanja (Slika 1). Za razliku od bolesti listanja, žile vinove loze zaražene crvenim mrljama postaju crvene. Vrijeme pojave simptoma može ovisiti o sorti, sezoni i klimatskim uvjetima. Neki su uzgajivači izvijestili da su u lipnju uočili svijetložute nijanse u Cabernet Francu zaraženom Red Blotchom. Iako je GRBaV dobio ime po pojavi simptoma kod crvenih sorti, prisutan je i kod bijelih sorti. Bijele sorte ne pokazuju crveno lišće, ali umjesto toga listovi mogu razviti žutu ili hlorotičnu nijansu sličnu onoj koja se viđa kod vinove loze zaražene listovima (slika 2). Neke bijele sorte, poput sauvignona Blanc, mogu izgledati asimptomatski. Asimptomatske loze mogu ostati produktivne, ali u njima se kriju virusi i djeluju kao potencijalni rezervoar za širenje virusa na osjetljive loze.

Ovaj članak slijedi članak iz ožujka 2013. o utjecaju virusa vinove loze Red Blotch. Cilj je ovdje istaknuti najnoviji razvoj našeg razumijevanja bolesti crvene mrlje i skrenuti pažnju na prisustvo virusa listanja koji se nalazi u certificiranim rasadnicima vinove loze.

Ovaj članak prvobitno je objavio dr. James Stamp i dr. Alan Wei u Wine Business Monthly, avgust 2014.

Doktor James A. Stamp je znanstvenik iz Sebastopolja u Kaliforniji koji se specijalizirao za kritičku procjenu problema performansi vinograda i kvaliteta i razmnožavanja biljnog materijala vinove loze. Ima više od 25 godina vinogradarskog iskustva i osnovao je Stamp Associates nakon što je osnovao rasadnik vinove loze Novavine, radio u biljnoj biotehnološkoj industriji i završio doktorat na UC Davis. Stamp Associates savjetuje uzgajivače i vinare u SAD-u i inozemstvu u osnivanju i upravljanju visokokvalitetnim vinogradima testiranim na patogene. Kontaktirajte doktora Stampa na [email protected]

Dr. Alan Wei generalni je direktor kompanije Agri-Analysis LLC, smještene u zapadnom Sacramentu. Ima više od 25 godina industrijskog iskustva u razvoju tehnologija za otkrivanje mikroba, u rasponu od ELISA-e visoke osjetljivosti, PCR-a, qPCR-a, skrininga velike propusnosti i metoda na terenu. Ima više od 20 izdanih patenata Sjedinjenih Država u ovom i srodnim oblastima. Dr. Wei uživa u interakciji i radu s uzgajivačima kako bi naučio od njih i pomogao im identificirati i riješiti probleme. Agri-Anlysis je laboratorij koji ispituje viruse crvene mrlje i druge viruse vinove loze kako bi uzgajivačima pomogao da zaštite svoja ulaganja. Obratite se dr. Wei na [email protected]

Najnovija dostignuća u našem razumijevanju crvene mrlje

Tabela 1: Korelacija između simptoma i prisustva GRBaV u susjednim vinovim lozama.

Od identifikacije i karakterizacije GRBaV krajem 2012. godine, postalo je razumljivo sljedeće:

  • GRBaV je široko rasprostranjen u CDFA-certificiranim blokovima za povećanje vinove loze, posebno u blokovima sjemena.
  • GRBaV se takođe nalazi u blokovima podloga sa certifikatom CDFA, ali na nižoj frekvenciji nego u otpadnim materijalima.
  • GRBaV se često nalazi u selekcijama i klonovima neovlaštenih CDFA.
  • Bele sorte takođe mogu biti kontaminirane GRBaV-om.
  • Red Blotch u bijelim sortama podsjeća na listanje: vinova loza postaje klorotična, ali valjanje lišća nije često uočeno (Slika 2).
  • Kod crvenih sorti postoji snažna korelacija između prisutnosti simptoma crvene mrlje i GRBaV (Tabela 1). To sugerira da uklanjanje simptomatskih trsova može pomoći u kontroli bolesti.
  • GRBaV je virus blizanaca koji se sastoji od kružne DNK u njegovom genomu. Kao takav, ovaj virus je znatno stabilniji od virusa vinove loze na bazi RNK, kao što su lisnati listići, lisnati listići i vitivirusi (uključujući GVB, uzročnika bolesti plutaste kore).
  • Utvrđene su dvije različite varijante GRBaV.
  • Dokazani su Kochovi postulati za bolest Red Blotch, tj. Pokazano je da je GRBaV uzročnik (Marc Fuchs, Univerzitet Cornell).
  • Bolest i virus se mogu prenijeti cijepljenjem, a najizgledniji izvor kontaminacije novih vinograda je zaraženi biljni materijal.
  • Neki uzgajivači izvještavaju da se virus može prenijeti između utvrđenih biljaka vinove loze, ali mi ne znamo mehanizam. Međugodišnja anegdotska zapažanja sugeriraju da je vinova loza potencijalno kontaminirana iz žarišnog izvora - koji može biti povezan s obalnim staništima - i da vinova loza koja je uvijek udaljena od izvora može biti kontaminirana nepoznatim mehanizmom.
  • Izvještaj istraživača sa državnog univerziteta u Washingtonu sugerira da je puzavac iz Virginije vektor za GRBaV. Iako se ovaj insekt nalazi u sjevernim dijelovima doline Napa, nema dokaza da je ovaj insekt vektor za GRBaV u Kaliforniji.
  • Do danas nema izvještaja o Red Blotchu u drugim zemljama, osim u SAD-u i Kanadi.
  • Testiranje kalifornijskog rasadničkog proizvoda namijenjenog vinogradima izvan države sugerira da bi Red Blotch u drugim državama mogao proizaći iz kupovine kontaminirane vinove loze iz Kalifornije (Tabela 2).
  • AVF je finansirao 388.700 američkih dolara u istraživanjima u 2013. i 2014. Dodatnih 29.500 američkih dolara finansirala je Komisija CA Rootstock.

Učinak crvene mrlje na biljke vinove loze i produktivnost

Sada se široko razumije da GRBaV može imati negativan učinak na kvalitetu voća i vina. Da li virus i bolest utječu na prinos, manje je jasno. Nagomilavanje šećera može značajno utjecati, s smanjenjem Brix-a od 5 do 6 stupnjeva, primijećenom u vinima pogođenih sorti. Također je zabilježeno povišenje kiselosti s titracijom, smanjenje pH i promijenjene taninske i fenolne komponente. Nedovoljno sazrelo voće može napraviti veliku razliku u dnu crteža za vrhunske vinarije, a kad se matematika ne zbroji, rješenje je za neke da se u potpunosti istrgnu novi blokovi i potraga za čistim biljnim materijalom (tablica 3). Generalno postoji vrlo dobra korelacija između prisutnosti virusa, prisutnosti folijarnih simptoma (lako uočljivih kod crvenih sorti) i značajno smanjenog Brixa u zaraženim lozama. Tabela 3 ukazuje na predviđeni utjecaj GRBaV na „dno dna“ u ultra premijskoj vinariji u dolini Napa (podaci proizvođača su od voća prikupljenog u četverogodišnjem vinogradu dobivenom od certificiranih zaliha). Vinar je primijetio da je 25 ° Brix u plodu Red Blotch u 2013. godini bilo neobično - u prethodne dvije godine plod Red Blotch postigao je samo 23 ° Brix.

2013. godine Univerzitetska saradnja Kalifornije procijenila je učinke GRBaV-a kako bi razjasnila razvoj simptoma u lišću, zrelosti voća i rastu vinove loze u Chardonnayu, Cabernet Sauvignonu i Merlotu. Na svakom od tri mjesta, vinove loze odabrane za ispitivanje utvrđene su kao pozitivne ili negativne na GRBaV pomoću qPCR testa, kao i negativne na sve viruse, vitiviruse i nepoviruse povezane s listanjem. U sve tri sorte, plod vinove loze zaražen GRBaV-om smanjio je ukupne topive krutine u uzorcima bobica uzetih tokom zrenja i u berbi u odnosu na vinove loze negativne na GRBaV. Uzorci bobica prikupljeni iz vinove loze Chardonnay pozitivne na GRBaV imali su značajno veći pH tokom berbe. U sve tri sorte, plod vinove loze zaražen GRBaV-om imao je povišenu titrabilnu kiselost u svim datumima uzorkovanja i u berbi.

Uklanjanje hardvera prije uklanjanja četvrtog olovnog vinograda zaraženog Red Blotchom u dolini Napa.

Demonstracija transmisije grafta GRBaV

Porijeklo i put prijenosa GRBaV-a i dalje su neizvjesni, osim što znamo da je transplantatan. Agri-Analiza je testirala zelene presadnice CS08 / 110R iz sezone 2013. koje je uzgajivač dostavio nakon samo tri tjedna razmnožavanja u stakleniku. Uzorci tkiva prikupljeni su iz četiri različita područja matičnih kalemova: 1) novo zeleno tkivo izdanaka 2) izvorno drvo potomaka 3) podloga uz kalemljenje i 4) podloga udaljena od spoja kalemljenja. Uzorci su analizirani i konvencionalnom PCR i kvantitativnom PCR (qPCR), a utvrđeno je da (slika 1):

  • To zeleno tkivo izdanaka imalo je relativno nizak nivo GRBaV. Utvrđeno je da je relativni broj virusne DNK kopije 290 +/- 89.
  • Originalno drvo potomaka imalo je najviši nivo GRBaV. Utvrđeno je da je relativni broj virusne DNK kopije 5.450 +/- 861.
  • Temelj za uzimanje kalema imao je skroman nivo GRBaV. Utvrđeno je da je relativni broj kopije virusne DNK 1.840 +/- 914.
  • Podloga udaljena od kalemljenja nije sadržavala GRBaV.
  • Relativni nivo virusa u zelenom izdanku, drvenastom izdanku i gornjem i donjem tkivu matičnjaka (Slika, Slika 1.) iznosio je 1: 19: 6: 0, respektivno. Drugim riječima, GRBaV u zelenom rastu je oko 5 posto od onog u sjemenskom drvetu. Ovaj rezultat sugerira da je drvo potkoljenika CS08 zaraženo prije kalemljenja. Razina GRBaV u gornjem dijelu matičnjaka iznosila je 17 posto u odnosu na potomstvo. Očekujemo da će se virusne kopije povećavati kako se rast nastavlja.

Slika 1: Razine virusa u uzorkovanom tkivu ilustrirane na fotografiji desno.

Odgovor rasadnika na Red Blotch

Većina kalifornijskih rasadnika prepoznala je da je Red Blotch ekonomski problem i pokrenuli su programe internih ispitivanja kako bi se procijenio opseg kontaminacije u njihovim blokovima porasta. Ovaj pristup je nastao općenito kao rezultat opsežnog testiranja proizvoda od strane kupaca prije ili prije isporuke. Kupci su izvještavali rezultate vrtićima koji koriste ove informacije kako bi odredili koji od njihovih blokova povećanja treba testirati.

Neki su rasadnici bili proaktivniji od drugih, potičući velika ispitivanja blokova porasta kada je utvrđeno da su gotovi proizvodi izvedeni iz njih kontaminirani. Općenito, međutim, veći dio ispitivanja blokova porasta još uvijek se temelji na uzorkovanju, gdje je mali postotak svih trsova testiran na GRBaV. Obično se ovo dodatno ispitivanje odnosi samo na GRBaV, budući da drugi virusi koji zabrinjavaju uzgajivače teoretski nisu u CDFA certificiranim zalihama. Autorski radovi pokazali su, međutim, da postoji opravdana vjerojatnost da će se virus 3 povezan s vinom vinove loze (LR3) naći u certificiranim blokovima za povećanje potomstva, iako na niskom nivou kontaminacije. Slijedom toga, kupci rasadnika vinove loze koji provode vlastite istrage trebali bi testirati LR3 zajedno s GRBaV pod pretpostavkom da je vjerovatnoća da će LR3 biti prisutan kao i GRBaV.

Diskusije sa osobljem jaslica ukazuju na želju za općim poboljšanjem CDFA programa certifikacije rasadnika. Najbolja opcija za vrtiće je kontinuirano objavljivanje novih materijala iz Protokola 2010. Ovi materijali za podloge i potomke postaju dostupni i zamjenjuju postojeće standardne („klasične“, kako ih naziva FPS) materijale koji se šire više od jedne decenije. Materijali iz Protokola iz 2010. pušteni su iz FPS u rasadnike, nakon širenja kulture tkiva, kako bi se uklonili svi poznati virusi vinove loze i Agrobacterium vitis (bakterija krunskog žuči) i Xylella fastidiosa (uzročnik Pierceove bolesti).

Iako je GRBaV otkriven nakon uspostavljanja zbirke vinove loze FPS Protocol 2010 na ranču Russell, naknadnim testiranjem svih zasađenih vinovih loza nije uspjelo otkriti GRBaV3.

Rasadnici ulažu velika sredstva u uspostavljanje novog bloka za povećanje protokola 2010 udaljenog od postojećih blokova i drugih vinograda. Ovi blokovi povećanja teoretski će osigurati čiste reznice matičnjaka i potomka za buduće generacije zasada vinograda.

Međutim, mora se riješiti nekoliko zabrinutosti kako bi se osiguralo da industrija dobije najbolje od ovih novih zasada:

  • Iako su klasični blokovi FPS Foundation na UC Davis minimalno kontaminirani GRBaV-om, prema priopćenju FPS-a, ovo nije spriječilo da standardni blokovi za povećanje rasadnika postanu kontaminirani. Kao što je zabilježeno na jesenskom godišnjem sastanku FPS 2013. godine, 3.068 trsova u klasičnom vinogradu testirano je na GRBaV, a samo devet je utvrđeno pozitivnim na virus. Preostale vinove loze u klasičnom temeljnom bloku testirat će se na jesen 2014
  • Novoosnovani vinograd zaklade Protocol 2010 u Davisu nije zatvoren i nalazi se u blizini potoka i komercijalnog rasadnika - hoće li ovo postati kontaminirano ljudskom aktivnošću ili nepoznatim vektorima?
  • Hoće li vrtići držati sve materijale iz Protokola 2010 odvojeno od klasičnih materijala? To bi uključivalo odvojene objekte za razmnožavanje i staklenike i odvojene lokacije za završnu obradu polja.
  • Vinova brašnasta kukac lako prenosi LR3. Hoće li materijali iz Protokola 2010 postati zagađeni ovim virusom reguliranim CDFA-om baš kao i standardni materijali?

Kako postupati s potencijalno kontaminiranim biljnim materijalom GRBaV

  1. Testirajte sve nove proizvode za vrtić koristeći statistički ispravne metode.
  2. Ispitajte vinove loze početkom jeseni da li ima listova i kasno jeseni za Red Blotch.
  3. Uklonite pojedine kontaminirane loze kada simptomi postanu vidljivi.
  4. Uklonite cijele blokove ako je stopa onečišćenja dovoljno visoka. Ovo je teška odluka, a složena je i zbog nedostatka znanja o prenošenju virusa.
  5. Sačekajte sa sadnjom dok se ne prepoznaju čisti biljni materijali.

Kontaminacija certificiranog rasadnika vinove loze GRBaV i LR3

* -1 i * -2: Različiti izvori povećanja blokova.
POS: Pozitivan na virus

Efikasan PCR-zasnovan test za GRBaV postao je dostupan u oktobru 2012. godine, omogućavajući efikasno otkrivanje GRBaV u biljkama vinove loze i rasadnicima. Analiza završetka sezone mirovanja vinove loze 2013. (zasađene u tipičnoj gustoći od 17.000 vinove loze po hektaru u rasadničkom redu) pokazala je da je GRBaV bio prisutan u CDFA certificiranom rasadniku. U trenutku kad se industrija već početkom 2013. upoznala s problemom, mnogi su blokovi matičnjaka i rasada povećani za reznice. To je dovelo do razvoja postupaka uzimanja uzoraka i ispitivanja ubranih podloga i reznica sjemena5, a ne do efikasnije prakse ispitivanja pojedinačnih blokova vinove loze.

Istovremeno, zapažanja CDFA-certificiranih potomaka povećavaju blokove i završavaju uspavane zalihe na nekim lokacijama, pokazala su prisutnost simptoma listanja u materijalima koji su se ranije činili zdravima i / ili negativno testiranima na ekonomski važne viruse. Ograničena ispitivanja ovih vinovih loza utvrdila su da su neki materijali kontaminirani LR3, pa je Stamp Associates smatrao razboritim testiranje svih reznih materijala za sezonu 2013. predviđenih za razmnožavanje zelene i neaktivne vinove loze u sezoni 2014 za ekonomski važne viruse lista i GRBaV.

U bloku porasta, svaku lozu CDFA pregledava u svakoj vegetacijskoj sezoni. Blokovi povećanja testiraju se najmanje jednom u pet godina na virusu grenastog ventilatora, virusu rajčice paradajza i virusima povezanim sa vinom vinove loze. Praktično, međutim, otkrili smo da je vrijeme pregleda vinove loze presudno. Simptomi lista i crvene mrlje u blokovima povećanja potomstva uvelike se razlikuju, ovisno o sorti, sezoni, klimi i ostalim uvjetima okoline. Nadalje, blokovi matičnjaka možda neće pokazivati ​​očite simptome.

Slika 2: Udio svih uzoraka testiranih na agroanalizi kontaminiranim GRBaV ili LR3. Napomena: Jesen do kraja sezone mirovanja je normalno prihvaćeno vrijeme za testiranje na viruse vinove loze. Jesen je također vrijeme kada su simptomi Red Blotcha i listanja očigledni.

Gore navedena inspekcija od strane osoblja CDFA uključuje inspekcije za opštu čistoću štetočina, uključujući slobodu od bolesti kao što je crvena mrlja. Kada se pronađu simptomatske biljke, osoblje dostavlja uzorke laboratoriju CDFA na identifikaciju. Sve biljke koje imaju pozitivan test na GRBaV ne bi zadovoljile standarde čistoće štetočina za rasadnike, a njihova prodaja bila bi zabranjena u Kaliforniji. Osoblje CDFA-e može izvršiti dodatno uzorkovanje razgraničenja oko pozitivnog nalazišta sljedeće godine. Tokom posljednjih 20 mjeseci LR3 je često pronađen u CDFA certificiranim zalihama (Tabela 4). Autori preporučuju da u najmanju ruku sve biljne materijale sa certifikatom CDFA treba nezavisno testirati na ova dva virusa prije nego što se kupe vinova loza. Ostali ekonomski važni virusi pronađeni su u CDFA certificiranim zalihama u posljednjih 20 mjeseci, ali sa nižom učestalošću, uključujući leafroll-2 i leafroll-9 (Tabela 4). Detaljna studija o statusu virusa CDFA certificiranih materijala, koja je procijenjena između 2000. i 2010. godine, objavljena je u Wine Business Monthly 2010. godine.

Smatra se da je najizgledniji izvor onečišćenja LR3 zaraza brašnom u vrtićima. Sumnjamo da se blokovi i vinova loza u certificiranim vrtićima mogu zaraziti, nakon razmnožavanja, hranjenjem od brašnastih buba. Iako rasadnici obično prakticiraju strogu profilaktičku hemijsku kontrolu mućnjaka, dokazano je da se LR3 može prenijeti na vinove loze već nakon nekoliko minuta hranjenja. Nadalje, neki blokovi za uzgajanje rasadnika nalaze se u blizini komercijalnih vinograda i voćnjaka, koji su potencijalne rezerve za populacije mušica.

Kako prepoznati čisti materijal za razmnožavanje vinove loze

  • Vizuelno pregledajte blokove za povećanje šuma u jesen. Ispitajte svaku lozu koja je potencijalni izvor pupolja.
  • Odbacite cijele blokove ako bilo koja loza unutar bloka izgleda nezdravo.
  • Ispitajte sve susjedne loze loze potrebne za pupoljke u zdravim blokovima.
  • Ispitajte sve podloge vinove loze potrebne kao izvori za reznice.

Praktične implikacije onečišćenja dionica certificiranih CDFA-om GRBaV i LR3

  • Prilikom procjene utvrđenih blokova porasta potomka u jesen, može biti vrlo teško pronaći dovoljno naizgled zdravih susjednih trsova kako bi se osiguralo dovoljno pupova za razmnožavanje. Na primjer, tokom posljednjih 20 mjeseci pokazalo se vrlo teškim pronaći certificirane klonove Cabernet Sauvignona koji imaju negativan test i za GRBaV i za LR3 (Tabela 4).
  • Oduvijek se pretpostavljalo da bi uzgajivači trebali koristiti certificirane zalihe. Međutim, nalazi ekonomski važnih virusa u certificiranim rasadnicima učinili su neke uzgajivače manje sigurnim u upotrebu certificiranih materijala.
  • Zbog toga je vrijednost vlastitog odgajivačkog bloka uzgajivača sve važnija. Smatra se da podaci iz povijesnih izvora i terenska promatranja svake sezone, potkrijepljena rigoroznim ispitivanjima vinove loze, mogu pružiti čisti materijal za razmnožavanje potomaka višeg kvaliteta nego što se može pretpostaviti iz nekih certificiranih blokova porasta.

Izazov i prilika

Slika 3: Sedam terenskih LR3 pozitivnih uzoraka dosljedno je testirano negativno pomoću BIOREBA reagensa, koji se široko koristi u programima certificiranja. Novi reagens za otkrivanje koji je razvio Agri-Analysis sposoban je dosljedno detektirati sve njih (AA1, AA2).

Kada uzgajivači kupuju dionice s certifikatom CDFA, pretpostavljaju da kupuju „čiste“ materijale. Ali podaci prikupljeni u posljednjih 15 godina pokazuju da se to ne može pretpostaviti 1,6. Neprihvatljivo je da se bezbrojni upravitelji vinograda i vinarije moraju suočiti s financijskim gnječenjem mladih vinograda zbog loše fitosanitarne kontrole kvalitete. Jasan je jaz između očekivanja uzgajivača i stvarnosti.

Materijali izvedeni iz Protokola 2010. postaju sve dostupniji u većini rasadnika. Ovo nudi kratkoročni popravak za krizu. Međutim, kratkoročno, klasični blokovi porasta i dalje su izloženi potencijalnoj infekciji, dok će novoosnovani blokovi Protokola 2010 biti izloženi bezbroju vektora insekata i gljivičnih patogena koji trenutno utječu na rasadnike i mlade i etablirane vinove loze. Za dugoročnu dobrobit naših vinograda potreban je robustan i učinkovit program certificiranja.

Prije svega, vjerujemo da učinkovita certifikacija rasadnika zahtijeva snažan statistički pristup kako bi se osiguralo da su rezultati statistički značajni. Strategije uzorkovanja i statistika za ispitivanje vinove loze vrlo su složene dok je proučavanje ove teme rijetko. Potrebne su dubinske studije kako bi se razvio robustan statistički model na koji se mogu osloniti regulatori i uzgajivači. Na ovom polju naša industrija zaostaje za ostalim robnim grupama, poput sjemenske industrije u kojoj postoji rigorozan protokol uzorkovanja.

Slika 3: Simptomi crvene mrlje kod različitih trsova u novembru 2013.

Drugo, budući da je poznato da je LR3 genetski vrlo varijabilan, određeni sojevi možda nisu uspjeli biti otkriveni. "Takva genetska varijabilnost ima značajne implikacije na otkrivanje LR3 molekularnim sredstvima i serološkim testovima", rekla je dr. Tefera Mekuria, biljni virolog, Agri-Analysis. Napredak u novim metodama ispitivanja potreban je za rješavanje ovog problema. Finansirana iz USDA-ovog granta za inovacije malih preduzeća (SBIR), Agri Analysis nedavno je razvila novi reagens zasnovan na ELISA-i koji pruža širu pokrivenost sojeva LR3 od komercijalnog reagensa koji se trenutno koristi u većini programa certifikacije. Od jeseni 2013. godine, Agri-analiza identificirala je niz LR3 pozitivnih uzoraka iz vinograda Napa i Sonoma koji su bili negativni, koristeći trenutni komercijalni reagens. Slika 3 je skup podataka koji pokazuju sedam takvih uzoraka koji su prvi put testirani u decembru 2013. (AA1), a nedavno su ponovo testirani, koristeći uzorke peteljki (AA2).

Da li su neki sojevi GLRaV-3 mogli izbjeći otkrivanje tokom certifikacije? Doktorica Monica Cooper, savjetnica na farmi, UC Cooperative Extension, proučava epidemiologiju LR3 već niz godina. Kad su je pitali za mišljenje zašto se virus LR3 nalazi u certificiranim materijalima, dr. Cooper je komentirao da bi „reagensi za otkrivanje mogli biti jedno od objašnjenja. 2010. godine radio sam s uzgajivačem koji je imao LR3 (+) vinove loze s jasnim simptomima koji su stalno bili negativni. ” Kasnije je istraživački laboratorij dr. Rodriga Almeide na UC Berkeley uspio izolirati novu varijantu LR3 iz uzoraka. „Sve što možemo učiniti za poboljšanje reagenasa sigurno će nam olakšati dugoročno čišćenje vinograda i rasadnika. Nadam se da su programi certificiranja u Kaliforniji i drugim državama u toku sa svojim metodama i protokolima za testiranje virusa ”, rekao je dr. Cooper.

Jednako važni kao i ispitivanje reagensa i statistika uzorkovanja su svijest uzgajivača i budnost potencijalnih problema s virusima. Opsežne studije su pokazale da brašnarice mogu vrlo brzo proširiti LR3 u poljskim uvjetima, bilo u blokovima za uzgoj, dovršavanju rasada u rasadnicima ili utvrđenim vinogradima. Ohrabruje nedavna odluka odbora CDFA / GWSS da crvenu mrlju i brašnaste bube odredi štetočinama.

Propisi o certificiranju rasadnika vinove loze u Kaliforniji manje su strogi od onih u drugim zemljama, poput Australije i Njemačke, te bi ih trebalo preispitati i ažurirati. Na primjer, CCR § 3024.5 predviđa da „Odjel primarne i sekundarne blokove porasta mora testirati na virus lopatica vinove loze, virus prstenaste rajčice paradajza i viruse povezane sa listanjem najmanje jednom u pet godina“ i da „Certifikovane sadnice rasadnika mogu se testirati za virus vinove loze vinove loze, virus prstenaste rajčice i viruse povezane sa listanjem vinove loze od strane odjela. " Međutim, ne postoji detaljna odredba koja se odnosi na: a) broj uzoraka koji će se testirati b) nivo pouzdanosti i statističku značajnost potrebnih rezultata ispitivanja i c) maksimalnu nepodnošljivu stopu zaraze. Za usporedbu, DIREKTIVA KOMISIJE 2005/43 / EZ Europske unije zahtijeva da se „u rasadnicima namijenjenim proizvodnji osnovnog razmnožavajućeg materijala utvrdi da nemaju štetnih organizama ... na osnovu rezultata testova zdravstvenog stanja biljaka koji se odnose na sve biljke . Stopa kvarova u rasadnicima koji se pripisuju štetnim organizmima ... neće prelaziti 5 posto. "

Trebalo bi uspostaviti odbor na visokom nivou svih dionika, uključujući one koji proizvode vinove loze, certificiraju ih i sade, kako bi se ispitao postojeći program CDFA. Autori smatraju da ovom izazovu mora postojati višeslojni pristup. Na primjer, na državnom nivou, CDFA bi trebao provesti ispitivanje i inspekciju povećanih blokova i zaliha polja kako bi postigao minimalni nivo čistoće na osnovu 95 posto bez zaraze s 95 posto nivoa pouzdanosti i 5 posto margine greške. Tehnički, ovo bi trebalo biti relativno lako ostvariti i ne bi trebalo biti neprikladno za većinu dionika. Dodatna strogost mogla bi se uvesti na županijskoj razini s uzgajivačima dodajući daljnju strogost prema potrebi. Ovaj višeslojni pristup široko se primjenjuje u Europi gdje Europska unija postavlja minimalne standarde fitosanitarne inspekcije. Svaka zemlja može povisiti standard EU po potrebi. Slično tome, regioni u državi mogu dalje povisiti nacionalni standard, ali ga ne i sniziti.


Deratizacija

Hipoteza o koncentraciji resursa razmatra kako je pojava moderne poljoprivrede kao monokulture stvorila okruženje u kojem štetnici mogu brže rasti jer je njihov resurs, usjev, rasprostranjeniji. Biodiversity is fundamental for pest management and Daniel Paredes, Postdoctoral Fellow at the University of California Davis, in the department of Wildlife Fish and Conservation Biology, is studying how sustaining natural habitat around vineyards can increase biodiversity.

Once a vineyard manger has found disease there is often not much to be done, they are merely mitigating loss. The Lab at Cornell has launched several projects utilizing imaging spectroscopy (also known as hyperspectral imaging) deployed at all scales, from autonomous rovers to spacecraft with the goal to detect disease earlier when management is going to be both minimal and successful.

The Spotted Lanternfly (SLF) is the newest agricultural invasive species in the United States. Originally from Asia, this insect feeds on plant sap from a broad range of hosts. Dr. Heather Leach, Extension Associate at the Department of Entomology at Penn State University is focused on researching this insect and educating the public on how to manage the pest. Although it appears that SLF has been in the United States for some years, growers are now seeing adverse effects and report extreme vine decline and death.

Leading expert Dr. Andrew Landers of Cornell University discusses his more than thirty years of research and development on pesticide sprayer technology to reduce pesticide use through accurate, efficient delivery of the product to the plant.

Dr. Charlotte Decock, Assistant Professor Cal Poly - Earth & Soil Sciences talks about soil management with the goal of capturing greenhouse gasses from the atmosphere and sequestering them in the soil. Her teaching and research focus on sustainable fertilizer and soil management in California’s specialty crops.

Mealybugs, especially the vine mealybug, excrete a white waxy substance in clusters that is unacceptable to wineries. They also excrete a sweet honeydew that is a substrate for black sooty mold. Black sooty mold covers the fruit and the rest of the vine with a black coating. In addition, mealybugs spread Grapevine Leafroll-associated Virus 3 (GLRaV-3). Between damage to fruit and vine decline from virus, the economic impacts of the pest are substantial.

Some 25 to 30 percent of vineyards in Washington state have nematode population densities that are considered damaging. Inga Zasada, Research Plant Pathologist with the USDA Agricultural Research Service is particularly interested in nematode management because Washington is mostly own rooted vines. Inga and her team are working on practical research for growers including identifying where different types of nematodes are in relation to the vine and a degree day model for nematode life stages so if chemical becomes available it can be used property.

Steven Lindow, Professor of Plant Pathology at the University of California Berkley is a plant pathologist and microbial ecologist. He and his team are researching other bacteria that can grow in the grapevine that mysteriously sensitize them to the Pierce’s Disease pathogen. Once inoculated with the new bacteria the plant induces its innate immune system to combat Pierces Disease. This process works like a vaccine although the bacteria itself does not cause a direct action.

Bruce Reisch, Professor of Grapevine Breeding and Genetics at Cornell University, specialized in the development of new wine and table grape varieties, as well as new grape breeding techniques. Of the more than 60 grape species available, most of the grapes we are familiar with come from European vitis vinifera. Unfortunately, this species offers little disease resistance, but other species have better sources.

Beginning at version, grapes become a very attractive food for pest birds, particularly Sparrows and Starlings. Initially the vineyard is explored by small flocks of scouting birds. If those birds like the fruit, and if there is no obvious danger, the entire flock will follow. Falcons terrify pest birds, herding them away from the grapes, but not killing them.

Dr. Michelle Moyer, Assistant Professor and Statewide Viticulture Extension Specialist at Washington State University uses the age old fairytale of Goldilocks and the Three Bears to explain powdery mildew. Like Goldilocks, powdery mildew likes the weather conditions to be just right. Dr. Moyer explains these ideal conditions and two key ways to avoid disease in your vineyard by making things “not right”.

Wayne Wilcox, Professor Emeritus of Plant Pathology and Plant-Microbe Biology at Cornell University, spent his career on the applied biology and integrated management of grapevine fungal diseases. His applied research sought to discover what makes a “disease tick” and use that knowledge to learn how to better target the disease.

Grape vine trunk diseases are prevalent in mature vineyards, shortening the vineyard’s life and productivity. Akif Eskalen, Cooperative Extension Specialist and Plant Pathologist at the Department of Plant Pathology at the University of California Davis, is researching naturally occurring microorganisms to use as biocontrol against these fungal pathogens.

Lauren Noland-Hajik, Attorney and Lobbyist at Kahn, Soares & Conway gives an update on new policies that affect the wine industry including the Water Resiliency Plan and how it affects Sustainable Groundwater Management Act regulating power shutoffs to prevent wildfires anticipated regulations on pesticides and impending labor law changes.

Scott Steinmaus, PhD - Horticulture and Crop Science Department, California Polytechnic State University San Luis Obispo

John A. Roncoroni is the UC Cooperative Extension Weed Science Farm Advisor and UCIPM affiliate advisor in Napa County. In this podcast, John talks about his specialty weed management in California’s Coastal and Foothill premium winegrape growing regions and why weeds should play a more important role in pest control programs.

Gerhard (Gerry) Pietersen is a plant virologist with an interest in solving problems in South African agriculture related to plant viruses. In this interview Gerry discusses the severe plant health and economic impacts seen in South Africa from Grapevine leafroll disease, the importance of regional buy in to establish a control program including a very successful collaboration of 50 adjoining farms in New Zealand, and new techniques to detect the virus including loop-mediated isothermal amplification (LAMP) and grafting sensitive red cultivars on white cultivars to use the shoot as an indicator.

Dr. Scott Steinmaus is a professor of Biological Sciences at California Polytechnic State University in San Luis Obispo. His interview covers the complexities of herbicide resistance including challenges seen in glyphosate research around resistance, information bias, and environmental and social impacts. Scott highlights the importance of “mixing it up” – reducing use, preserving the limited modes of action available, and finding alternatives.

Dr. Luca Brillante from the Department of Viticulture and Enology at California Fresno State University discusses his current research and teaching on efficient management solutions through digital viticulture, improved accuracy and cost reduction with automation, and how he is teaching the next generation of viticulturists about sustainable wine production.

Dr. Michelle Moyer of Washington State discusses recent research on integrated pest management for grapevine powdery mildew, how short term weather patterns impacts farming decisions, why clean plants may have made red blotch virus more detectable, controlling wine quality with water stress and “Farming by Excel” – how fewer people working in the field has increased growers reliance on data and technology.

Dan Rodrigues, Owner of VinaQuest, talks about how the loss of materials impacts farming disease management for mildew, sour rot, and weeds the effects of a wet winter and what trends he sees for the future.

Dr. Stephanie Bolton, Sustainable Winegrowing Director, Lodi Winegrape Commission, talks about sustainable farming in the Lodi winegrowing region.

Mark Browning, owner, Barn Owl Box Company and Head Researcher, Barn Owl/Rodent Project discusses barn owls and their role on the farm.

Fritz Westover, viticulturist with Westover Vineyard Advising and Virtual Viticulture Academy describes growing conditions and challenges in multiple states in the Southeastern United States.

Mark Chien shares highlights from his career helping grapegrowers in some of the most difficult growing regions in the world. From his years as a vineyard manager to Penn State viticulture extension agent, and now Program Coordinator for the Oregon Wine Research Institute.

Dr. Cliff Ohmart, owner/operator of Ohmart Consulting Services, shares insights from his career in sustainability research and education in winegrapes and other crops.

Andrew Landers, Ph.D., Director, Effective Spraying & Faculty Fellow, Atkinson Centre for a Sustainable Future, Cornell University, discusses what goes into spraying pesticides efficiently and effectively to reduce environmental impacts, improve safety, and reduce costs.

Kris Beal, M.S., Executive Director of Vineyard Team, recounts some of the history of the organization, it’s current activities and what the future holds in store.

A comprehensive overview of what is known about the presence of viral, bacterial, and fungal pathogens in nursery stock including Foundation Plant Services mother blocks.

Dr. Kari Arnold talks about Grapevine Leaf Roll-associated Virus 3, its vector the vine mealybug, and how growers can manage the spread of viruses both within and between vineyards.

Dr. Kari Arnold talks about Grapevine Leaf Roll-associated Virus 3, its vector the vine mealybug, and how growers can manage the spread of viruses both within and between vineyards.

The Brown Marmorated Stink Bug and Spotted Lantern Fly are serious pests of winegrapes in Pennsylvania and NewYork. They have the potential to spread far beyond there in the future.

Walt Mahaffee, Ph.D., Research Plant Pathologist, USDA-Agricultural Research Service, Corvalis explains how and why Grape Powdery Mildew populations become resistant to certain fungicides.

Marc Lea, Deputy Agricultural Commissioner, San Luis Obispo County Ag and Lottie Martin, Deputy Agricultural Commissioner, Santa Barbara County Agricultural Commissioner’s Office talk about using pesticides safely and recycling pesticide containers.

Recommendations for control of stinkwort.

Description of the weed stinkwort (Dittrichia graveolens), its rapid spread through California, and its life cycle.

Two articles on the spread, biology, and control of stinkwort (Dittrichia graveolens).

Ashley Poupart explores why sustain practices are important to the wine and winegrape industries followed by an overview and comparison of the major sustainability certifications available to vineyards.

Bart Haycraft, Vineyard Manager for Jackson Family Wines Los Alamos, walks through all of the vineyard operations he has mechanized on his ranches including weed control, canopy management and efficient harvesting. Q&A for this session is found here: https://youtu.be/nC1gSjtU1QM

Bart Haycraft, Vineyard Manager for Jackson Family Wines Los Alamos, answers questions about the vineyard operations he has mechanized on his ranches including weed control, canopy management and efficient harvesting. The full session is found here: https://youtu.be/ItFu_50H0og

Vineyard Manger Lucas Pope describes how he farms 281 acres of winegrapes situated on a 2,000+ ranch of undisturbed oak woodland where he and his team regularly come across deer, coyotes, mountain lion, and rattlesnakes.

Check out some favorite episodes Here are ten episodes of the Sustainable Winegrowing podcast you don’t want to miss.

Steve McIntyre, Owner, Monterey Pacific Inc. and Board Member, Pierce’s Disease/Glassy-winged Sharpshooter Board talks about the PD/GWSS Board, its function, and how the board works to reduce the impacts and spread of this disease.

Bart Haycraft, Vineyard Manager, Jackson Family Wines- Los Alamos describes some of the techniques he uses in his vineyards for managing vineyard pests.

This chart shows the relative impacts on beneficial insects of 36 common insecticides.

Dan Rodrigues, Owner/Viticulturist of Vina Quest LLC, takes questions about ways to reduce the environmental impacts of vineyard development and preventing future pest problems through careful planning and paying attention to the unique topography and ecosystems of individual parcels of land.

Dan Rodrigues, Owner/Viticulturist of Vina Quest LLC talks about ways to reduce the environmental impacts of developing a vineyard and preventing future pest problems through careful planning and paying attention to the unique topography and ecosystems of individual parcels of land.

Dan Rodrigues, Owner/Viticulturist of Vina Quest LLC talks about ways to reduce the environmental impacts of vineyard development and preventing future pest problems through careful planning and paying attention to the unique topography and ecosystems of individual parcels of land.

Principal Biologist, Terra Verde Environmental Consulting talks about regulatory agency reviews, permit requirements, road/culvert designs, permitting strategies, and ecological considerations for vineyard development and management at the 2017 Sustainable Ag Expo.

A brief summary of the key points made by Dr. Tim Miles during his talk at the February 23, 2018 Fungicide Resistance Tailgate.

Reflections, insights, and advice on the 2017 powdery mildew season by Dr. Walt Mahaffee, Research Plant Pathologist, USDA-ARS Horticulture Crops Research Unit . Topics include timing, coverage, vine microclimate, canopy management and more.

These excerpts from the 2017 edition of this UCIPM text describe and explain fungicide resistance and include tables listing fungicides registered for grapes with their known efficacy against various diseases and their resistance risk as of 2017.

Amy Wolfe, President/CEO of AgSafe, discusses changes to the Worker Protection Standard including worker training, decontamination, and emergency response training.

Contacts, definitions, and processes for disposing of pesticides (hazardous waste in San Luis Obispo County.

Dr. Kendra Baumgartner, Research Plant Pathologist, USDA Agricultural Research Service, Crops Pathology and Genetics Research Unit- UC Davis, provides an update on the state of our knowledge about trunk pathogens in young vines both in the nursery and the field. She also discusses management techniques to prevent infections and manage vines if they are infected.

Dr. Kendra Baumgartner, Research Plant Pathologist, USDA Agricultural Research Service, Crops Pathology and Genetics Research Unit- UC Davis, takes questions from the audience after providing an update on the state of our knowledge about trunk pathogens in young vines both in the nursery and the field. She also discusses management techniques to prevent infections and manage vines if they are infected.

This podcast is an excerpt of the talk Dr. Pete Goodell delivered at the 2016 Sustainable Ag Expo on the history of IPM and what IPM is as a philosophy and practice.

This podcast is an excerpt of the talk Dr. Kent Daane delivered at the 2017 Sustainable Ag Expo on which insecticides are best for controlling mealybug.

Twenty years ago it was believed that dead arms and diebacks were cause by a single organism- Eutypa lata. It is now known that many fungi all cause the same symptoms and eventually kill the vine.

The annual meeting of the Association of Applied IPM Ecologists took place November 29 to December 1 at the Visalia Marriott at the Convention Center in Visalia, California. Here are some highlights.

Dr. Marc Fuchs researches the biology and ecology of the Grapevine Red Blotch associated Virus.

A scientific study of prey consumption by nesting barn owls over a three year period.

A fact sheet about cover crops and tillage.

The develop of fungal diseases on grapes is a progression from powdery mildew in the spring to Botrytis in the late summer.

The research of Megan Hall and others has advanced our knowledge of the etiology, epidemiology, and management of sour rot from what we knew four years ago. Her research sheds light on the role of fruit flies in this disease complex.

The crop looks good and canopy growth is strong.

After an epidemic of Pierce’s Diseases devastated the Temecula Valley wine industry in the 1990s, grape growers and scientist are working together to prevent that from happening again.

Although rarely seen in coastal California, when conditions are right this devastating fungal disease can make an appearance.

Sustainability rests on the principle that we must meet the needs of the present without compromising the ability of future generations to meet their own needs.

Greg Pennyroyal discusses the appearance of vine mealybug in the Temecula Valley, Integrated Pest Management (IPM), and how the community came together to monitor and manage this pest.

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Viral Diseases in the Fall:

Grapevine Leafroll and Red Blotch

As the fall season progresses, symptoms of virus infection become more pronounced in the vineyards. Arguably, leafroll and red blotch are the most notorious and important viral diseases that manifest in the fall season. Often, it is difficult to distinguish leafroll from red blotch disease symptoms in the vineyard. This is especially true on red-fruited grapevine varieties. In this article I will summarize and update information on the biology, symptoms, and transmission of the viruses responsible for these important diseases.

The Viruses responsible forLeafroll and Red blotch Diseases

There are four different virus species associated with grapevine leafroll disease. The viruses belong to one taxonomic family (Closteroviridae) and are named Grapevine leafroll associated virus followed by a number (GLRaV-1 to -4). Because it has not been possible – to date – to complete Koch’s postulates with GLRaVs, the word “associated” is added to the virus name. Koch’s postulates have not been completed with most of the viruses that cause disease in grapevines. The postulates state that a pathogen must be isolated in pure form from a diseased plant, later the pathogen (virus in this case) is introduced to a healthy plant, and the newly infected plant must show the same symptoms as the original infected one. Clearly Koch’s postulates are important because they could prove the cause and effect of a pathogen causing disease.

As I will describe below, researchers can tweak the definition of Koch’s postulates to prove that a virus causes a specific disease and drop the word “associated” from the virus name. Within the Closteroviridae family, species of GLRaV are classified in three genera, Ampelovirus, Closterovirus, i Velarivirus. Grapevine leafroll associated virus -1, GLRaV-3, and GLRaV-4 belong to the Ampelovirus genus. Grapevine leafroll associated virus -2 is a Closterovirus and GLRaV-7 is a member of the Velarivirus genus. Some researchers claim that GLRaV-7 should not be considered a leafroll virus because it only produces mild symptoms in grapevines. Further, recent research has shown that GLRaV-7 was isolated from a mixed leafroll infected vine and symptoms were due to the other leafroll virus present at the time. When found alone GLRaV-7 does not appear to show typical leafroll symptoms.

Grapevine red blotch virus (GRBV) is the second virus species discovered in grapevines that carries DNA instead of RNA as its genetic material. Both its molecular and structural characterization has placed GRBV in a new genus, named Grablovirus, within the Geminiviridae family. As stated above, it has been difficult to demonstrate Koch’s postulates, with grapevine-infecting viruses. There are many reasons for this. Firstly, there are no alternative hosts that are susceptible to most grapevine infecting viruses (some exceptions exists).

Secondly and most important, grapevine viruses cannot be mechanically transmitted onto grapevines. These viruses need to be introduced to a vine via grafting (graft-transmission) and/or need a biological vector for successful transmission. Dr. Marc Fuchs team at Cornell University was able to demonstrate that GRBV genetic material is responsible for red blotch foliar symptoms in red fruited grapevine varieties. The work was done using sophisticated recombinant DNA molecular techniques to introduce the virus genetic material into tissue cultured grapevine plants. Time will tell, after the plants grow, if the infected vines also display the detrimental effect of the virus in organoleptic qualities of the fruit (i.e., reduction of sugar).

Viral Symptoms are Remarkably Similar

Vines infected with leafroll viruses produce smaller grape clusters that ripen unevenly with lower sugar content. Foliar symptoms include downward rolling, reddening or yellowing of leaves depending on the grapevine variety. Other foliar colors associated with leafroll virus infection include pink, purple, and orange speckles. The leaf veins may remain green or take many other colors (yellow, purple, or red). Grapevine red blotch virus infection may display different red leaf discoloration which usually appear spotty or blotchy.

However, these symptoms are indistinguishable from leafroll, especially when rolling of leaves are absent in GLRaV- infected vines. In some cases, GRBV infected vines may display red veins, but red veins have also been observed in non-infected vines, and many red-blotch infected vines do not display red veins.

In my opinion, red vein symptoms cannot be used as a diagnostic tool. In white-fruited varieties red blotch disease displays yellow blotchy discoloration in leaves. While the symptoms of leafroll and red blotch can be confused, these diseases are caused by different types of viruses that can often be found in mixed infections, complicating the visual diagnosis. Although, the change in colors of the leaves in the fall is a tale-tell of virus infection, the most important negative effect of both GLRaV and GRBV infection is the reduction of sugar in fruit resulting in reduced Brix values and delayed fruit maturity.

Some GLRaVs and their strains are more aggressive than others. Researchers have described the Alfie (Australia and New Zealand), BD (Italy), and Red Globe (U.S.A) strains of GLRaV-2. These strains are molecularly similar and have been associated with graft incompatibility, vine decline and death. Some researchers report that GLRaV-1 and -3 induce more severe symptoms than GLRaV-4.

However, symptoms vary depending on the grape variety, rootstock, and climatic conditions. At the moment, two different clades of GRBV have been reported but no differences in their biology or effect on symptoms in the vineyards have been observed so far. Just as seen with leafroll, the symptom expression of GRBV infected vines is affected by climatic conditions and the author has noted differences in the effect on sugar reduction in sunnier and warmer areas (i.e., California coastal areas with more fog and lower sunshine yield fruit with lower sugar concentration than the same grape varieties grown inland with more sun exposure).

Transmission and Spread of the Viruses

Ampeloviruses (GLRaV-1, -3 and -4) are transmitted by sap-sucking insects (mealybugs and soft scale insects) in a non-specific manner. This means, different mealybug and soft scale insect species can transmit any leafroll virus. Research has shown that the citrus (Planococcus citri), grape (Pseudococcus maritimus), long-tailed (Pseudococcus longispinus), obscure (Pseudococcus viburni) and vine (Planococcus ficus) mealybugs as well as the soft scale insects Pulvinaria vitis i Ceroplastes rusci are able to transmit GLRaVs. Mealybugs and soft scale insects feed on the vine’s sap by inserting their sucking mouthparts into the plant’s vascular system (phloem). The honeydew excreted during the feeding process attracts ants that nurse and aid mealybugs to be transported to different positions of the vine or a different vine in the row.

Mealybugs may be difficult to observe as they can hide beneath the bark. In these cases, ant activity and the growth of a black fungus (sooty mold) are good indicators of the presence of mealybug vectors in the vineyard. No insects able to transmit GLRaV-2 or GLRaV -7 have been reported to date and their propagation (just like all other GLRaVs) is performed by humans who produce and distribute cuttings from infected vines.

Work by researchers at Cornell University and the University of California reported that the three cornered alfalfa hopper (Spissistilus festinus) can transmit the GRBV in greenhouse and laboratory conditions. Although, the three cornered alfalfa hopper has been found in vineyard blocks where red blotch disease has spread, transmission experiments in the field have not been completed to date. It is interesting that grapevine is not the preferred host for Spissistilus festinus that prefers to feed on legumes, grasses, and shrubs. While research continues to determine if other vectors are capable of transmitting GRBV it is clear that the rapid expansion of this virus in vineyards was due to propagation and grafting of cuttings from infected vines. This also explains the arrival of GRBV to many countries in Asia, Europe, and South America where GRBV had not been previously reported. In summary, both, GLRaVs and GRBV are graft transmissible and predominantly propagated by producing cuttings of infected rootstock and scion material.

Diagnosis and Status of Foundation Plant Material

The distribution and concentration (titer) of leafroll and red blotch viruses is different in infected plant material. While leafroll detection appears to be seasonal (best detected late in the growing season), detection of red blotch virus can be performed any time of the year. Further, work performed in my lab showed that red blotch virus can be detected in high titers in any part of the vine. The work showed that red blotch virus can be detected in any tissue tested, new or mature leaves, petioles, green or lignified canes, as well as cordons and trunks. In contrast, leafroll viruses are generally found in low concentrations and are best detected in mature leaves, canes, cordon, and trunk. If a vine has been infected through cuttings, the older the plant material is, the easier it is to detect GLRaVs.

Keeping both leafroll and red blotch viruses out of the productive vineyards relies on clean planting stock programs. Sadly, a few years ago the University of California at Davis Foundation Plant Services (FPS) scientists announced the finding of a few vines infected with GRBV in the Russell Ranch foundation block. The block was planted with vines produced with a tissue culture technique that is capable of eliminating potential harmful viruses. The block was tested using the “Protocol 2010” that includes a list of viruses that are harmful to grapevines. Initially, four vines were found to be infected with GRBV in 2017, in 2018 the number increased to 24 vines,in 2019 the positive results were over 300 vines, while this year results showed that 788 are infected with GRBV. Until last year, the block was the source of California Registration and Certification Program (CDFA R&C) material to nurseries registered in the program. Because of the GRBV positive status FPS suspended the sale of vines from the Russell Ranch block. To learn more about GRBV epidemiology, the GRBV-infected Russell Ranch block will be used as a research block to study the transmission and spread of the virus.

The block was tested using the “Protocol 2010” that includes a list of viruses that are harmful to grapevines. Initially, four vines were found to be infected with GRBV in 2017, in 2018 the number increased to 24 vines, and in 2019 the positive results increased to over 300 vines infected with GRBV. Until last year, the block was the source of California Registration and Certification Program (CDFA R&C) material to nurseries registered in the program. Because of the GRBV positive status FPS suspended the sale of vines from the Russell Ranch block. To learn more about GRBV epidemiology, the GRBV-infected Russell Ranch block will be used as a research block to study the transmission and spread of the virus.

Conclusions

This author is involved in applied research with the goal to determine the ideal process to protect clean planting grapevine stock and newly planted vineyards from infection of viruses and fungal pathogens. Presently, information on what is the distance needed at the foundation and nursery blocks to avoid infection from diseased blocks is lacking. The results of the research will develop the best strategy to isolate and monitor clean planting stock.

Until we have this information my recommendation is that nurseries and growers determine the health status of grapevine stock prior to planting to avoid the propagation and/or introduction diseased vines to the vineyard. Yet, it is very important to isolate and monitor newly planted vineyards to avoid the introduction of disease via insect vectors. It is important to remember that lack of symptoms does not always correlate with a healthy diagnostic result (rootstock varieties as well as non-grafted vines are usually asymptomatic), so it is best to test a statistical sample of the nursery propagated material to be sure of its health status.


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