Details of grape production cited at field day, tour

By LYNN MONTGOMERY | East Texas Edition

Besides diseases and insects, tour-goers were also given a variety of vineyard information. Above, Scott Thompson, owner of St. Jane Vineyard, detailed the importance of maintaining the vineyard grounds and between the rows. -- Staff photos by Montgomery

June 23, 2005 - If you have grape growing on your mind, you should also be thinking about things like sour rot, downy mildew, and even the Grape Berry Moth.

People from across the region learned about these diseases and insect, plus more, during the June 13 East Texas Grape Field Day at Scott and Paula Thompson's St. Jane Vineyard, Palestine.

The informal field day was led by Dr. Ed Hellman, a viticulture specialist with the Texas Cooperative Extension. (Viticulture is defined as the growing of grapes.) Several county Extension offices in the region hosted the educational event.

Hellman began the presentation by talking about the difficulties of growing grapes. He said, "It is extremely difficult to grow grapes in this part of Texas because of the humidity."

Diseases that can wipe out the crop favor high humidity. These fungal diseases include Black Rot, Downy Mildew, Powdery Mildew and Anthracnose. Growers in this part of Texas will have problems with the four diseases all year, he said.

Hellman added there are some fungicides on the market to help control the grape diseases but "you can't use one product all season."

He also stated growers should "develop a strategy" for spraying their crop, including looking at fungicide labels and the cost of those fungicides.

Other diseases that someone who wants to grow grapes should know is bunch rot and sour rot.

Bunch rot is a fruit-rotting disease of ripening grapes and involves one or more fungal or bacterial species. It is caused by "some type of injury to the berry."

Sour rot is a form of bunch rot but involves the bacterium Acetobacter and has a vinegar smell of acetic acid. According to literature at the field day, as berries ripen and sugar content exceeds 8 percent, injured fruit become increasingly suspectible to bunch rot pathogens.

The viticulturist said, "Muscadines are less susceptible to these diseases and if you want to grow organically, muscadines are the better way to go."

Another problem in the vineyard is the Grape Berry Moth, which is "becoming a major insect pest of grapes in Texas and can cause serious economic loss to commercial vineyards."

These moths feed only on grapes and produce multiple generations per year, with the first generation of the year applying the most direct damage to the grape. The reasoning is this generation is the earliest to hatch and feeds on the tender flower clusters and newly-formed berries. The second and subsequent generations increase the chance of bunch rot.

Vineyards, Hellman pointed out, can monitor the insects by using pheromone traps, which will monitor the timing of the first adult berry moth emergence. The traps should be installed when shoot growth reaches about 12 inches on the most advanced variety.

The recommended insecticide for the grape berry moth is Sevin 50% WP, Sevin 80% WP, Sevin 4F, Imidan 70% WP, or Danitol 2.4 EC.

Once the insects and diseases were discussed, the field day group toured the 3.5-acre vineyard, including the nursery. The vineyard is home to Blanc du Bois, Lenoir, Cynthiana and SV 12-327 varieties of grapes.

According to the Texas Department of Agriculture, Texas is the country's fifth-leading wine state and has over 40 wineries. Today, Texas wine grape growers operate 210 vineyards on approximately 3,200 acres, of which most are in the Texas Hill Country and the Texas High Plains.

For more information about St. Jane Vineyard go online to www.stjanevineyard.com. For those who would like more information about growing grapes go online to http://winegrapes.tamu.edu.