Walnut Creek, Calif.-based Valent U.S.A. has introduced ProGibb LV Plus plant growth regulator, a liquid formulation designed to meet California's strict air quality regulations.

The LV formulation also complies with the state's definition of a low volatile organic compound, or low VOC, product.

The LV product has twice the concentration of the active ingredient—gibberellic acid—compared with ProGibb 4%, said Lyndon Inouye, grape crop specialist. That means the LV formulation contains 2 grams actie ingredient per fluid ounce compared with 1 gram per fluid ounce for the older formulation.

But you apply it at the same rate of active ingredient per acre as you would the older formulation. In trials, the new product has produced results comparable to the older product.

It also is approved for organic production and is National Organic Products compliant.

"The liquid formulation is user friendly and easy to apply," Inouye says. "The only difference between 4% and LV is it's double the concentration.

Begining in 2015, the California Department of Pesticide Regulation will severely restrict the application of high VOC products, including the older ProGibb 4%.

Although Valent will continue to sell the older formulation after Jan. 1, 2015, Inouye says use of it will become onerous and will include several additional steps, including filing a notice of intent, or NOI, to apply with the county agricultural commissioner.

ProGibb is used mostly to help size grapes, but some citrus producers also use it for fruit set, rind quality management, fruit sizing and harvest management.