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Evaluate the plant growth regulator Apogee[TM](Prohexadione calcium, BASF Corporation) for
vegetative growth suppression, in a randomized and replicated field study. Determine the effect of
multiple standard applications of Apogee[TM]on vegetative growth control of a highly vigorous, mature
apple cultivar under Northeast region growing conditions.
Maintaining the balance between vegetative and reproductive growth in apple trees is essential for
optimizing an orchard production system. This balance is extremely difficult to attain, since the balance
is influenced by many factors, including conditions the grower can control as well as those the
orchardist cannot regulate. Maintaining this balance is essential for influencing all factors that effect
optimum fruit quality in the current season, increased spray deposition within the canopy of the tree,
increased air movement within the orchard and return bloom the following year. The growing
conditions of the Northeast region favor the development of vegetative growth that adversely affects
fruit production. This growth results in an increase in management costs (i.e. pruning and harvest) and
a reduction in yields and fruit quality.
With the loss of Alar in the late 1980's, the grower's ability to reduce vegetative growth using
Plant Growth Regulators (PGR) became extremely hindered. Presently, the only compounds that
chemically alter vigor are Ethephon and NAA. Both compounds provide limited activity against
vegetative growth control.
Apogee[TM]is a unique PGR compound currently in the latter stages of the Environmental Protection
Agency's (EPA) product registration process. Apogee[TM]has the ability to greatly alter orchard
management techniques with regards to the vegetative vs. reproductive processes. Apogee[TM]has a
unique mode of action that inhibits the biosynthesis of gibberellin. Gibberellins are natural plant
hormones that regulate cell elongation. This cell elongation is the direct component of vegetative shoot
growth. Therefore, prohibiting the biosynthesis of gibberellins directly reduces vigorous vegetative
shoot growth.
The direct vegetative growth controlling properties Apogee[TM]provides may correlate to many beneficial
side effects. Research of these aspects is still preliminary, but the results are proving favorable.
Apogee[TM]applications may provide added benefit with regards to; reduction of dormant and summer
pruning, improved fruit color, a reduction in the incidence of fireblight (shoot blight), reduction of
many diseases, insects and horticultural problems as well as increased spur health and a reduction in
June Drop.
________________________
1North Jersey Tree Fruit Technician, Rutgers University, Snyder Research and Extension Farm, 140 Locust
Grove Rd. Pittstown, NJ08867
2
3
County Agricultural Agent, Rutgers Cooperative Extension of Hunterdon County, 4 Gauntt Place Flemington,
NJ08822
Plant and Soil Science Technician, Rutgers University, Snyder Research and Extension Farm, 140 Locust
Grove Rd. Pittstown, NJ08867
1999 North Jersey Tree Fruit Annual Report
39