Manipulation of Source Plant Material for Improved Virus Elimination

The 1998-1999 research plan has been accomplished on schedule. Grapevine shoot tips were excised from Cabernet Sauvignon clone 5 mother plants with the same virus status grown in the field and in the greenhouse in each month from May to October to compare virus elimination success. Some preliminary information is now available as detailed in this report. Observations were made on rooting, contamination, and incidence of red, vitrified tissue. Generally, tips excised from greenhouse source plants in June had optimal growth and rooting. In the next few months, disease testing of the 1998 explants will allow us to determine the relative importance of source and time of year on successful virus elimination by tissue culture.