The scenario is this: I have an organic grower that grows primarily cider fruit; old true cider apples that already have a tendency towards biennial bearing. This year several varieties set up way heavier than they should have and so return bloom could be/will be a real problem next year. Typically, a grower will thin the excess apples within 45 days of fruit set to ensure a good return bloom. These trees were thinned with Regalia and oil [which has shown good responsiveness] at bloom and petal fall. It worked with some varieties, but not so much with others. The grower didn’t have time to do much handthinning. Typically, a conventional grower could apply a synthetic growth hormone (auxin or ethylene] to trigger the fruit bud formation process. Even late in the season, like now, some effectiveness using synthetic ethylene has been shown to trigger fruit bud formation when for all intents and purposes the “sweet spot” timing was gone a long time ago.
This made me wonder about using a nutritional spray or a product with some plant growth hormones, amino acids, etc (seaweed, kelp) at this time of year and/or between greentip and ½” green next year to transform some of the undifferentiated buds to flower buds. Gibberllic acid produced by seeds is what seems to really impact flower bud formation – a GA suppressor could in fact suppress the impact of too many apples and increase flower bud formation. My theory is that shifting the hormone balance with in the tree – artificially or otherwise – would positively influence return bloom. Ditto for proper nutrition...
thoughts.?
Mike Biltonen, Know Your RootsZone 5b in New York