Euler tour An Euler tour of a strongly connected, directed graph G D .V; E/ is a cycle that traverses each edge of G exactly once, although it may visit a vertex more than once. a. Show that G has an Euler tour if and only if in-degree./ D out-degree./ for each vertex 2 V . b. Describe an O.E/-time algorithm to find an Euler tour of G if one exists. (Hint: Merge edge-disjoint cycles.)

Rabbit 23March2016-PlantPathology-Dr.Lawrence-AuburnUniversity Tobaccomosaicvirus • finaltest(knowit’savirus) • mottlingofleaves • NEVERwillfindasign;nosignbecausevirusparticlessotiny • severesymptoms • moresevereonyoungertissue • nocureforit • seeddiscolorationblackhilumspreads • control:sanitation,avoidhostfor2years,biocontrol,milk(denaturestheproteins), resistantvars • diseasecycle:phloemmovementissystemic,staysinleavesforyears,easilyspread, Wheatmosaicvirus(Furoviruses) • protozoavectors • wheatmosaic,peanutclump • patches,mottlingandrings,rootshaveexcessivebranching,reducedyield,canlook undermicroscopeforit, • overwinterinvectors,transmittedbyzoospores,limitedtoroots,somemoveinthe xylemNOTthephloem • control:sanitation,virusfreeseed Filamentousviruses:PotatoVirusX(mechanical) • Potexciruses:singleflexuousrod,celltocellmovementofprotein • attackorchids,affectmanycrops,losses,stunting,discoloration,NOvectors, transmittedbycontact,transmittedinlegumesaretransmittedbyseed • control:virusfreepropagativematerial Potyviruses:PotaoVirusY(aphids) • largestgenusofplantviruses • beancommonmosaicvirus,lotsofdifferenthosts,singlerod • symptoms:mosaics • transmittedbyaphids • nonpersistent(afternoon) • overwintersinperennialhostsorseed,longeritispresentthegreaterthelosses • control:resistantvarieties,virusfreeseed,insecticideskillaphids!,KILLFASTAND EARLY Cucumbermosaicvirus • worldwide,infectsmorevarietyofanyothervirus,mosaic,stuntingleafandfruit malformations • vegetablesaffectedcommoningardens • isometricparticlesshapedpackedintightly Rabbit • overwinterandaphidstransmitvirusesNONPERSISTANT • mechanicallytransmittedbyhandlinginfield • control:virusfreetransplants,resistantvarieties,removalofwildhosts • crossprotection:avirulentstrainofavirus Tomatospottedwiltvirus(Tospoviruses) • widespread,ornamentalsinfected,widehostrange500species,isometricparticle • sphericalparticles • hasmembrane • symptoms:vary,chloroticandnecroticrings,fruitsmalformed,stuntedgrowth • NOSIGN • affectstobacco,too:severe:raggedappearance • transmittedbythrips • larvaegetthevirus,KEEPthevirusevenpastpupation,adulttransmititafterfeeding for30mins • control:virusfreetransplants,thripscontrol,transgenicplants • avoidplantingwhenthripsareactiveinseason note:NOcottonvirusesinNorthAmericasofar KnowSigns: Fungal,bacterial,virus,nematodedamage(haven'tcoverednematodesyet) FridayMarch252016:moregeneralinformationandvideoonviruses NOCLASS