Thinning with pollen tube growth model and Regalia+Oil

  • February 1, 2024 at 12:17 am #1841
    Chris McGuire

    Thinning fruits in our apple orchard has always been a challenge, and for the past two summers we trialed thinning with bloom sprays of Regalia and oil timed according to the pollen tube growth model on NEWA. For us, this technique did not work as well. Regalia+oil does not seem to thin to any significant extent, possibly because of a change the manufacturer made to the Regalia formulation some years ago, and we found it pretty challenging from a practical, time/logistics, standpoint to implement the pollen tube growth model in an orchard with many varieties. If you’re interested in learning more about this, check out our farm’s webpage for a link to a written report and video describing the project.

    I am happy to answer questions or discuss if anyone is interested.

    Chris McGuire
    Southwest WI

    February 1, 2024 at 1:56 pm #1842
    Brittany Kordick

    Thank you so much for putting together this outstanding presentation and letting us know about it! We use several of the NEWA pest/disease models to help guide the management of our orchard, but I admit, I always assumed that trying to comprehend, follow, and apply the pollen tube growth model would be a bridge too far for us to implement in our particular setup. Thus, I’ve generally glossed over any presentations and studies having to do with the model and only mildly wondered what I might be missing. When I saw that your video presentation regarding your on-farm research was about 30 minutes long I nearly skipped it, as well, but I’m so glad I didn’t. You do a wonderful job of breaking down the flower to fruit process (very helpful diagrams, by the way), introducing growers to the PTGM model and evaluating your own thinning trials. Watching your video saved me an immense amount of time, just in terms of the time I’d have otherwise spent sifting through info to understand how the model works, let alone the time and expense of actually playing with Regalia and oil for thinning in our own orchard. Unfortunately, of course, it all served to confirm my instinct that trying to utilize the PTGM is not for us in our orchard!

    I also skimmed your more in-depth research report and particularly appreciate the insights you included at the end about the thinning difficulties presented by 1 year old wood.

    Thank you also for the other valuable data from on-farm research you’ve made available on your website! Your dried apple “trials” are of particular interest to us as many of the original varieties we planted in our orchard were specifically for their usage dried.

    Well done and thanks again for sharing!

    February 2, 2024 at 12:23 am #1843
    Chris McGuire

    Thank you for the kind words! I am glad it was helpful.

    March 31, 2024 at 3:10 am #1893
    Josh Willis

    Chris, thanks for sharing your experiences. Have you tried NEWA’s carbohydrate model for Apple Thinning? And it sounds like you skipped potassium bicarb as a spray for these models because it did not work well for you previously?

    I am going to post somewhere else on HON about this model, for those interested.

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