Apogee is the newest plant growth regulator from BASF. It’s registered on apples to reduce pruning costs by reducing new shot growth, but John Helm, technical service representative for BASF in California, told Central California apple growers recently that the compound that inhibits biosynthesis of gibberellin, resulting in a reduction of cell elongation and less vegetative shoot growth, may have management uses not yet known.

Helm told the Central California Apple Symposium in Stockton, Calif., recently that Apogee could become a production tool for apple producers like Pix is for California cotton growers. Pix evolved from something growers use to control plant height to a product that set more bolls and therefore increased yields.

Apogee has been registered for only a year in California, and its use is not widespread, admitted Helm. It has been used for two to three years on apples elsewhere.

Cotton growers learned the advantages of Pix by adapting it to their management system and Helm encouraged apple producers to do the same thing: "to figure out how it will work in your system. Try it and leave an untreated check" to see how it can effects total orchard management.

In California, Helm said trials are showing that the plant growth regulator is most effective when applied early, at the one- to three-inch new shoot growth stage, in split applications. High vigor trees respond best to split six-ounce applications (about 12 days apart) and low vigor trees in three- to four-ounce split applications.

Helm said Apogee has proven to reduce pruning time by 25 to 45 percent and will reduce hard winter pruning.

It does not control existing fire blight because it is not a bactericide. However, by reducing shoot growth it reduces the amount of young shoot growth, the tissue most susceptible to infection.

Helm said Apogee can accomplish desirable fruit thinning at the same time it improves light penetration. This reduces shading of spurs and improves the red coloring in some varieties. Because it reduces tree wood, it also improves spray coverage.

It also can be applied post-harvest to an early variety like Gala. This will reduce regrowth and retain fruiting branches that would normally be removed by summer pruning.

Helm said the product costs about $40 per acre to apply at the half-pound rate.