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Apple Thinning: Webinar

January 22 @ 10:00 am - 11:00 am

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How PGRs and PGR-like compounds can manipulate two of the most common practices: fruit thinning and flower formation. Current and new products.

In the tree fruit industry, everyone understands how economically important fruit thinning is. The benefits go beyond just fruit size increase to include high fruit quality (color, flavor), better return bloom, greater harvest and packing efficiency, more uniform fruit ripening, less fruit drop and limb or tree breakage, and more. Although there are several chemical thinning compounds available and there are thinning models that growers can use to help make chemical thinning decisions, there are few new thinners being tested, and chemical thinning is still the single most difficult management strategy. Successful chemical thinning usually requires comprehensive assessment of multiple factors that can affect thinning responses. Timing and weather are indeed important players; however, grower’s knowledge, expertise and experience are also key components in this process.

This presentation aims to provide additional information and tools for fruit thinning that may assist growers in their decision-making process. The following topics will be discussed:


  • Flower formation and return bloom – timing, strategies
  • The importance of early thinning (especially Honeycrisp and Fuji)
  • Fruit thinning general concepts.
  • Thinner modes of action.
  • Thinning products available and products on the horizon, timings, rates, and combinations.


Poliana Francescatto works for Valent BioSciences as a Global Technical Development Specialist, with responsibilities for market and technical development of PGRs in fruit crops around the world. Before joining Valent BioSciences, Poli spent four years at Cornell University as a post-doc position as an applied fruit physiologist focusing on flower biology, plant growth regulators and crop load management of pome and stone fruit.



This session will qualify for one Washington or Oregon pesticide re-certification credit with WSDA/ ODA approval. To receive credit attendees must attend the entire 50 min seminar and participate in polls within the session.

Tree Fruit Days Webinar Series

This webinar is part of the Tree Fruit Days Webinar Series co-sponsored by WSU Extension, NW Cherries, Okanogan Hort Assoc., Pear Bureau NW, NCW Fieldmen’s Assoc.

For additional educational opportunities see and the WSU Winter Institute



January 22
10:00 am - 11:00 am


WSU Extension – Tianna DuPont
(509) 293-8758


Washington State University