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Plant Growth Regulators and Thinning

Chapter authors - Teryl Roper, Brent Black

 

Plant growth regulators (PGRs) can be used with some precision for controlling bloom, thinning fruit, regulating growth, and adjusting harvest season of orchard crops.  PGRs are absorbed by plant cells, primarily through the leaves and fruit, where they interact with the biochemical “machinery” of the plant.  They work by mimicking naturally occurring plant hormones, or by blocking the production or activity of natural plant hormones.

This publication provides information on which plant growth regulators to use for a specific effect and gives instructions on how, when, where, and in what quantities to apply them.  Because plant response can vary greatly due to a range of factors, it is important to keep detailed records of use and plant response to help you fine-tune applications for your orchard.

Additional Information

Naturally Occurring Plant Hormones

Factors Affecting Plant Response