Why clean plants?

1. Why clean plants?

3. Leafroll virus effects • Delayed maturity • Lower sugar content • Increased acidity • Lower color • Decreased crop level Declining wine quality.

8. Leafroll management costs 83 acre Cabernet vineyard

9. Leafroll management costs • Costs associated with preventing spread • Insecticides • Crew movement • Extensive sanitation procedures • Loss of revenue potential

10. 1994 planting – 11 years of revenue on a 30-40 year investment!!

11. Leafroll management costs • Costs associated with preventing spread • Insecticides • Crew movement • Extensive sanitation procedures • Loss of revenue potential • Fallow period?

13. Virus Spread

19. Clean vines for new plantings • Certified material

22. Clean vines for new plantings • Certified material • Next best thing…

23. Sampling – case history • Chardonnay – “clean block” • Field observations – not possible; dormant season • Bulk sampling – 4” cane samples from standardized location on each vine. • 164 random vines ~ 1% • Focus on most prevalent virus strains = 1,2,3

24. Sampling – case history • Chardonnay – “clean block” results • 20 positive results by ELISA • Not a viable block for propagation • Plan ‘B’

25. Sampling – case history • Chardonnay – plan ‘B’ • ID a good block and reviewed results of previous testing. • During the growing season -visual symptoms surveyed in August. • 3 symptomatic vines found and tested for strains 1,2,3,5 & 7. • Bulk sample for GLRaV 3.

26. Sampling – case history • Chardonnay – plan ‘B’ results • False positive. • Bulk sampling showed no positive samples. • Use this block for propagation.

27. Deep thoughts Virus management • Start with clean material! • Scout your vineyards • Keep good records • Scouting • Testing • Planting records • Make a plan • Infected vine removal (?) • Spread prevention measures • Replanting plan$