Tests conducted in 10 countries have brought consistent results: an excellent return on investment for growers of red table grapes.
For years there's been a clear, unmet need to improve color on key varieties in all key table grape producing countries. Standard methods for coloring have not provided sufficient color, and growers face potential residue issues with ethephon in several of these countries.
This is where ProTone Plant Growth Regulator, from Valent BioSciences Corporation, comes in. This PGR has been trialed extensively in table grape growing regions around the world since 2003. It's been tested under relevant cultural practices — including different trellising and training systems, canopy management irrigation systems, and application methods — under specific and varied climatic conditions.
Chile features five regions of table grape production, some of which feature dry or even desert conditions. Red varieties, which account for more than 30,000 hectares (75,000 acres), are grown mainly under an overhead trellising system. Applied via electrostatic spray equipment, ProTone significantly increased the number of boxes of grapes harvested from Crimson, Flame Seedless, and Red Globe varieties.
In the Aconcagua Valley of Chile, growing seedless table grapes can be especially challenging. But use of ProTone on Crimson Seedless significantly increased the number of harvestable bunches, boosting one grower's yields from 16% harvestable under standard programs to an astonishing 88% harvestable. In the company's most recent testing in Chile, total yields produced with ProTone reached 4,000 boxes harvested per hectare, compared with 2,250 boxes under conventional treatments.
The United States has just over 51,000 acres of red table grapes, primarily located in California's northern and southern San Joaquin Valley and the Coachella Valley.
In Kingsburg, CA, trials, use of ProTone significantly increased the number of boxes of Crimson Seedless that one grower was able to pick early in the season. In addition, the grower was able to harvest nearly 300 more boxes per acre than he had with his standard coloring program, netting an additional $4,500 per acre.
With more than 18,000 hectares (45,000 acres) of table grapes, South Africa has three distinct growing regions focused mainly on an export market with strict quality standards. High temperatures and summer rainfall make grape coloring a challenge, but results have shown that the use of ProTone offers increased harvests of Crimson and Flame Seedless, and Red Globe varieties.
The use of ProTone in the Northern Cape region significantly increased the percentage of harvestable bunches of Flame Seedless that one trial grower was able to pick early in the season. Various ProTone combinations for that location resulted in approximately 70% harvestable bunches (accumulated) at the second harvest, compared to the grower's 36% harvestable bunches using ethephon only. The result? Premium prices on the early market and significant increase in income per hectare.
Trials in three additional countries have supported the registration and launches of ProTone in 2010.
Australia has more than 30,000 acres of table grapes with product going primarily to export in Asia, though the country has its own strong local market. Its trellising systems are similar to those in California, and due in part to high labor costs bunches are not exposed and spray coverage is a challenge. Four production regions — that have used ethephon on a limited basis — target early or late season market windows.