Ralsstonia – Und derstanding g and Recognizing a Serrious Bacterrial Pathogeen Tamii Van Gaal, GGSPro G Techn nical Specialiist- Email: gg [email protected] m, 800-888-00054 x 89129, 1.5.2015 with rate revision 1.6.2015 Ralsttonia solanaccearum is a so oil borne bacterium that cau uses the vasccular disease kknown as baccterial wilt or southern wiltt. This pathogen is important duee to its ability to infect crop ps important tto both horticculture and aggriculture. In tthe greennhouse, the diisease is mostt often spread d via contamin nated plant m material, media, water and ssap transmitteed through mechhanical meanss. Chemical control c is not possible; p infeected plants shhould be remooved from production. Cleean up proceedures are loccated at the en nd of this bullletin. The U United States government lists R. solana acearum racee 3 biovar 2 aas both a quarrantine pathoogen and a “SSelect Agent” undeer the Agricultture Bioterrorrism Protectiion Act of 200 02. Due to thiss special stattus, disposal oof plants infeccted by R. solannacearum racce 3 biovar 2 is tightly regu ulated. Geneeral biology Ralsttonia solanaccearum is a grram negative, soil-borne, ro od-shaped baacterium. The speciies is sub-diviided into fivee different races and biovarrs. Race 1 bioovar 1 occurs naturrally in the so outheastern Un nited States. All A other racees are found gglobally, but are nnot considered d to be establiished in to thee US. All racees and biovarss are serious crop pathogens. As a species, Ralsstonia infects over 200 hosst species, a very large rangge for a hogen. Race 1 biovar 1 infe fects the greatest number off hosts, speciific plant path incluuding many ho orticultural crrops. Races 2, 4 and 5 infect a handful oof agriccultural crops,, including ginger and banaana. Race 3 biovar b 2 is an important pathoogen of solanaceous vegetaables, includiing tomato, po otato and egggplant, along with horticultural crops, includ ding geranium m. Ralstonia iss known to innfect weeds, primarily those off the solanaceous family (n nightshades). Certain aquattic weeds are recoggnized as sources of Ralsto onia infection n in surface water. w Infectio n in some weedds can be laten nt, i.e. withou ut symptom ex xpression. Slo ow infection and mortalityy rates in weeds are low, making g them an ideaal host for susstaining the paathogen. ural crops suscceptible to Ra alstonia infecction are Tablee 1. Some of the horticultu listedd below. Ralstonia infects over 200 hosts, so many more m crops thaan those listedd are susceptib ble. Agerratum Browallia Chrysanthemu C um Coleuss Cyclamen Dahllia Egg gplant Fuchsia F Geraniium Gerbera Gingger Hyd drangea Impatiens Lantan na Lilies Mariigold Nassturtium Nicotiana N Pepperr Perilla Salviia Tom mato Verbena V Vinca (flowering) Zinnia © 2015 Griffin Greenhouse Supplies Geranium infected with R Ralstonia. Tomato inffected with Raalstonia. Photo creddit: Clemson U University Ralsttonia can infeect plants thro ough stomata (natural open nings on the leeaves), stem iinjury or via tthe root systeem. Primary infecction in weedss and agricultural crops is via v the roots. Once in the pplant, Ralstonnia then infeccts the vasculaar tissue, speciifically the xy ylem, and spreeads through the plant. Mo ost strains of R Ralstonia preefer warm tem mperatures (800-90˚F) and high soil moisturee, though racee 3 biovar 2 iss more toleran nt of cooler teemperatures. R Ralstonia cann both survivee and spread in soils, potting media m and wateer. In thee greenhouse, the disease is i easily spreaad through cu uttings and othher activities which cause plant woundiing and sap spreaad, such as pru uning. Thereffore, all cuttin ng tools mustt be disinfecteed at regular iintervals. Thee disease can aalso be harboored in plant debris, old po otting media and a water. In field conditioons, Ralstoniaa is known too spread via pllant roots, injured or healthy, and is found d in irrigation n and surface water. w In the ggreenhouse, oone can expecct spread withhin baskets and ccombination pots p via the ro oots, across sttanding waterr (pot to pot), within recircculating waterr systems andd even in drips from m overhead basskets. Ralston nia doesn’t prroduce sporess, so splashingg water won’tt spread the ddisease per se,, but splasshing water caan spread infeected media, plant p tissue, sap s or bacteriaal ooze. Ralsttonia can be sspread by sapp on clothing. It is nnot transmitteed through thee air. uting and dettecting infecttion Scou Althoough Ralstonia infections are rare in No orth American n greenhouse s, when they do occur a co ommon point of entry is incoming plantt material. If yyou are notiffied of such a problem by your y supplier,, dump all imp pacted materiial from speciified shipmen nts, symptomaatic or not. Fo or remaining crops c or otherr possible infecctions, scoutin ng is importan nt to prevent disease d spread d. Leaf wiltinng is most oftenn the first sym mptom noticed d. Wilt from Ralstonia R may y look differeent from wiltinng caused by drought or ro oot disease. While W droughtt and root diseease generrally cause a full plant wiltt, wilt caused d by Ralstonia a often is one--sided. It is comm mon for a leaff to wilt on on ne side of the midrib, for part p of a leafleet to wilt, for one branch to wilt or for on ne half of the plant p to wilt. Inspection off the vascuular tissue (xy ylem) serving g or below thee wilted area will w reveal di scoloration. Geranium innfected with Raalstonia. Ralsttonia infection in geranium m can be conffused with Xanthomonas. U Unlike Xanthhomonas, Ralstonia infecttion does not produce p leaf spots. Also, R Ralstonia may impact the ro oots, whereas Xanthomonas infection do oes not impacct root tissuee. Stunting may m be evidentt with Ralston nia. Due to possible co onfusion with h other diseasees, GGSPro recommends r tthat suspect fo disease preesence. Sensittive test stripss for in-housee testing for plantts are tested for Ralsttonia are avaiilable from Agdia (800-622 2-4342, www w.agdia.com). Tests Geranium innfected with Xaanthomonas. should be perform med using affeected tissue an nd care must be taken to foollow the recom mmended testting protocol precisely. Im mproper bufferr temperaturee (too cold) or ann improper am mount of tissu ue (too much) are known to o result in falsse positives. H However, when the protocol is follow wed, the test strips are quite reliable. It is important to t understandd that the test strips do not identify Ralsstonia to the race//biovar level. Further, speccialized testing g is required to identify racce and biovarr. wing infection n Sanittation follow Ralsttonia is know wn to be relativ vely persisten nt in debris an nd soil, survivving for moree than a year iin a resting staate, up to 2-3 yearss when in asso ociation with plant debris. The pathogen n also survivees quite well in water. For these reasonss, thorough sanitation efforts should s be made following an infection and a disposal oof infected pllant material. pose of all inffected plant material, m weed ds and debris off-site. Infeccted plant maaterial should be double It is ccritical to disp baggged at the end of the day an nd workers sh hould not returrn to the norm mal productioon area that daay. All clothinng should be washhed using stan ndard laundry y detergent. Do not reuse po otting media and do not reeplant into a bbasket or com mbination pot that ccontained an infected plantt. © 2015 Griffin Greenhouse Supplies Hard Surface Sanitation 1. Remove all debris, including plant tissue and any media, from benching and floors. Discard offsite. 2. Chemically clean hard surfaces with a detergent cleaner such as Strip-It. Include all surfaces located within 10 feet of infected plant material or exposed to any downstream water draining from infected plant material, including areas under hanging baskets. 3. Rinse well with clear water. 4. Apply a disinfectant, such as Kleengrow, SaniDate 5.0 or ZeroTol 2.0. Allow the surface to stay wet for at least 10 minutes without rinsing. Recirculating Water System Sanitation Treat all recirculating systems, including ebb & flow, troughs and flood floors. 1. Eliminate biofilm and bioslime build-up, which may harbor pathogens, by using biocides such as ozone or chlorine dioxide or a detergent cleaner such as Strip-It. 2. Rinse well with clear water. 3. Apply a disinfectant, such as Kleengrow, SaniDate 5.0 or ZeroTol 2.0. Pot Sanitation GGSPro recommends that pots associated with Ralstonia infection are not reused. If this is not possible, please follow the following procedure. 1. Physically remove and discard all debris and media. 2. Soak in a solution of Strip-It. 3. Rinse well with clear water. 4. Soak for 10 minutes in a disinfectant solution, such as Kleengrow, SaniDate 5.0 or ZeroTol 2.0. Allow pots to air dry slowly without rinsing. Table 2. Sanitation Products, Use and Rates Product Use Rate Strip-Ita (no plant contact) Cleaning hard surfaces Cleaning irrigation systems Cleaning pots 5 oz/gal Direct inject at 1:50 or treat at 2.5 oz/gal 2.5 oz/gal (refresh when dirty) Kleengrowa Disinfecting hard surfaces Disinfecting irrigation systems Disinfecting pots Disinfecting tools 0.5 oz/gal 50 oz/100 gal (no plants present) 0.5 oz/gal (10 min soak, monitor with QAC test strips) 0.5 oz/gal (5 min soak, monitor with QAC test strips) SaniDate 5.0b Disinfecting hard surfaces Disinfecting irrigation systems Disinfecting pots Disinfecting tools 0.5 oz/gal 50 oz/100 gal*, soak for 12 hours; repeat 0.5 oz/gal (10 min soak, monitor with PAA test strips) 0.5 oz/gal (10 min soak, monitor with PAA test strips) ZeroTol 2.0b Disinfecting hard surfaces Disinfecting irrigation systems Disinfecting pots Disinfecting tools 2.5 oz/gal Direct inject at 1:50 or treat at 2.5 oz/gal 2.5 oz/gal (10 min soak, monitor with PAA test strips) 2.5 oz/gal (10 min soak, monitor with PAA test strips) a Rates courtesy of Pace-49 Inc., bRates courtesy of Biosafe Systems (*revised 1.6.15 by BioSafe) Resources Alvarez, B., E.G. Biosca and M.M. Lopez. 2010. On the life of Ralstonia solanacearum, a destructive bacterial plant pathogen. Current Research, Technology and Education Topics in Applied Microbiology and Microbial Biotechnology, Vol. 1. ISBN (13):978-84-614-6194-3. Formatex Research Center. USDA. Action Plan for Ralstonia solanacearum race 3, biovar 2 found in nursery facilities. 2003. CAPS Pest Data Sheet: Ralstonia solanacearum Race 3 Biovar 2. Cooperative Agricultural Pest Survey. https://caps.ceris.purdue.edu/dmm/1610 © 2015 Griffin Greenhouse Supplies
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