Future Directions in RRD Research Mark Windham – University of Tennessee David Byrne – Texas A&M University

What has been accomplished? Tools developed/adapted to rose Diagnostic tools – virus Molecular Immunological Diagnostic tools – mite Visual (electron microscopy) Sampling protocol for virus (still needs work) Sampling tools for mite Plant tissue Air sampling

What has been accomplished? Tools developed/adapted for rose Monitoring app on web site Phenotyping protocol Genotyping protocol GBS and map for diploid Populations for genetic studies Diploid and tetraploid Analytical tools – FlexQTL for diploid Epidemiology RRV and Mite Biology Transmission (Tzanetakis) Mite acquires virus in less than 5 days Can transmit within an hour once acquired RRV movement in plant Systemic, how quickly move not known Found in stems, leaves, roots, flowers and pollen RRD movement in the field Large field trials tracking movement Physical barrier decrease spread Mite biology

What has been accomplished? Descriptive research Virus sequence Genetic variability of the virus Identify the vector/other mites on roses Identify mite predators associated with rose Mite behavior on rose – feeding and transmission Mite distribution Within plant Geographically Field Control Rogueing and Pruning Bag and remove plants with symptoms Pruning infected branch not effective Garden Design Barriers which are not host to mite can slow spread of the disease Biological Control of the Mite Neoseiulus, Tydeus and Amblyseius predator mites Ongoing work Where on plant? Protected areas preferred Within sepals of flower buds Within stipules of vegetative buds Found among glandular hairs When move? What environmental cues trigger movement? Conditions for optimal reproduction and growth Field studies in multiple locations – both sides of RRD line Growth chamber experiments Model to predict potential severity of RRD Survival on roses Ability to reproduce/survive vary with the rose

What has been accomplished? Descriptive research Miticide efficacy Pruning and virus elimination Garden design and mite movement Symptomology over roses Sources of rose rosette resistance Genotypic map of rose Field Control Miticides Weekly applications effective Bifenthrin, fenpyroximate, spiromesifen, and spirotetramat Optimizing spray schedule (2, 4, 6 weeks) Testing abamectin and bifenazate Antivirals Under evaluation (SePRO Corp.)

Transmission efficiency Genotype and phenotype Rose Rosette Disease Rose Rosette Virus Rose Phyllocoptes mite Host reaction Host range Transmission efficiency Vector specificity Ecology and Climate Genotype and phenotype Feeding behavior

Distribution of RRD in the USA

Virus biology Mite biology Host plant resistance What do we need to do? Virus biology Mite biology Host plant resistance

Virus Biology

Virus biology? Mechanism of resistance Virus effect on mite (Tzanetakis research) Virus movement/distribution in plant Virus variation in virulence Sampling protocol for virus Symptom development Early detection – remote sensing Multispectral Raman spectrometer

Mite Biology

Mite Biology Mite rearing and development Mite monitoring Mite epidemiology Life cycle studies Environmental influences Preference/biology on resistant roses Mite distribution on plant/in field Survey of mite species in USA Mite transmission

Breeding and Resistance

Breeding and Resistance More efficient screening technique Effect of resistant rootstock on scion Mechanism of resistance Inheritance of resistance Marker development Marker validation Marker shared with private breeders

Constructing Management Strategies

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