Agriculture Reference
In-Depth Information
Originally called the Sultanina Bianca, it was popularized in this country by William
Thompson, a California nurseryman in the late nineteenth century. By far the most widely
planted table grape in the United States (this one variety accounts for more than 25 per-
cent of the total acreage), the Thompson Seedless is also the dominant raisin grape and is
used (though almost never credited) in making inexpensive wines.
The fact that it has become something of a poster child for flavorless grapes is due
much more to poor handling than to poor genetics. Properly grown and matured to full
ripeness, the Thompson Seedless has startlingly good flavor. Perhaps it does not have
quite as much character as the Concord or Muscat, but it does have a pleasingly flowery
quality. The problem is that you can rarely find a fully mature Thompson Seedless in
the market. When ripe, the variety has a tendency to "shatter" - that is, the grapes fall
off the bunch. This is inconvenient for the grower, the retailer and the consumer. And so
Thompsons are usually picked when they are still green. At this point they can be sweet,
but they are never much more. Still, if you ever happen across a bunch of Thompsons that
are amber-gold in color, snatch them up and see what you've been missing.
The modern absence of high-flavored grapes is not due to a lack of effort by plant
breeders. Every couple of years, it seems, another great green hope is unveiled - a grape
with distinctive flavor that will meet all the commercial requirements of growers and re-
tailers. Almost inevitably, this new hope is found wanting in some way. One of the most
recent attempts is a grape called Princess, introduced in 1999. This is a large green grape
that, when decently ripened, has a haunting Muscat flavor. Like an Internet IPO, it was
jumped on early by farmers, whose ardor then abruptly cooled. It turns out that just as
those first vines were coming into full bearing, problems emerged. The grape is extremely
unreliable in terms of production - depending on the early weather, farmers could have a
great year or a lousy one. And so they've moved on to the next hopeful variety.
In a big-money industry like grape growing, any possible advantage must be exploited.
This goes for even the most popular grapes. The Thompson Seedless, for example, is
coddled like some kind of exotic bonsai tree. Not only are the vines trained to grow along
specially designed trellises, but they are also meticulously pruned to manage the right
number of leaves, the right number of shoots and the right number of grape clusters. And
that's just the start.
Left to its own devices, Thompson Seedless vines produce grapes that are quite small,
particularly when picked early. To get around that, farmers have come up with some in-
novative techniques to increase grape size. The first is called "girdling," and it involves
cutting a ring in the bark all the way around the base of the vine just as the grapes begin
