Category Archives: GRBaV

A Chronology of Red Blotch

Posted on November 8, 2015 by gymnosperm

The single strand DNA virus shown to be the causative agent in Red Blotch disease of grapevines will almost certainly become a new genus in the family Geminiviridae. Phylogenetic evidence suggests that GRBaV diverged about 250 million years ago before the … Continue reading →

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Red Blotch Perspective Harvest 2015

Posted on October 27, 2015 by gymnosperm

The virus seemed different in the vineyard this year. Many vines we had marked as 50% red canopy last year did not meet that threshold this year and some seemed asymptomatic. We began to notice during our vineyard survey last … Continue reading →

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Further GRBaV Observations

Posted on February 15, 2015 by gymnosperm

A number of things we have noticed about red blotch did not really fit into the themes of prior posts but we feel bear mention. The first, along the lines of Dr. Golino’s finding of a similar virus in a … Continue reading →

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GRBaV, Heredity or Environment?

Posted on February 11, 2015 by gymnosperm

The burning question in the vineyard business these days is whether or not to rip out and replant Red Blotch infected vines. On the one hand, the first variant of the disease has spread at an average of maybe 4% … Continue reading →

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GRBaV, The Vector, Which Mite It Be?

Posted on December 24, 2014 by gymnosperm

At a recent UC extension course, “Current Issues in Vineyard Health”, an impressive group of researchers presented their work. Dr. Brian Bahder revealed evidence of a second variant of GRBaV, commonly called red blotch virus, that seems to have invaded a block … Continue reading →

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GRBaV, A Null Hypothesis

Posted on November 30, 2014 by gymnosperm

As one contemplates the panoramas of red vineyards and walks rows to find disturbingly few completely asymptomatic plants, it is easy to consider a null hypothesis suggested by early notions that red blotch has been around a long time masked by similar symptoms … Continue reading →

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GRBaV, An Hypothetical Model for Disease Progression

Posted on November 11, 2014 by gymnosperm

It’s not like we really have a firm understanding why some plants typically produce brilliant red foliage before dropping their leaves and others do not. It has been suggested that anthrocyanins are produced as a sun screen as chlorophyll is … Continue reading →

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