Plant growth regulator (PGR) products are important tools in modern temperate fruit production systems.
PGRs provide cost-effective management solutions for some of the tree and crop management issues faced by producers.
We have grouped some of the most important PGRs for pome and stone fruit production according to their uses in:
managing vegetative growth
managing harvest and fruit quality
bud dormancy and manipulation of flowering.
Vegetative growth management
Vegetative growth management products (Table 1) can be used in conjunction with other management tools such as pruning, root pruning, thinning and fertiliser and water management to encourage the desired shoot growth within the tree canopies.
Harvest and fruit quality management
Harvest and fruit quality management products (Table 2) can be used to delay or advance maturity and improve postharvest fruit quality attributes such as colour, firmness and storage potential.
Within this group, the active constituent 1-methylcyclopropene (1-MCP) with its ability to block the fruit ripening hormone ethylene, has had a significant positive effect on the quality of the fruit being delivered to consumers.
Bud dormancy & flowering
Marginal or insufficient winter chilling can result in a delayed, protracted and uneven bloom.
Bud dormancy products (Table 3) can help break dormancy and/or compress flowering to encourage more even bloom, pollination and fruit-set.
The effective pollination period for cherry flowers is known to be very short and sometimes weather conditions or pollinating insect activity at flowering are insufficient to achieve the desired fruit-set.
Table 3 also includes a product based on the active constituent aviglycine (AVG) for prolonging cherry flower life to help maximise the effective pollination period.
Use of PGR products
Tree and crop manipulation using PGRs is not an exact science and there are many factors in an orchard system that can influence the effects of their use.
PGRs also feature prominently when managing crop load in deciduous fruits.
Always read and understand all label recommendations thoroughly and seek additional advice before using PGRs in your orchard.
Download the Orchard plant protection guide
See this article in Tree Fruit August 2023
