Does Surround contribute to biennial bearing

Just wondering if anyone else, in regions N. of Jersey and CA, but especially in the humid region have observed a seeming correlation between Surround and inconsistent cropping. It is touted for preventing sun scorch where that is a problem, but perhaps reducing access to the rays can be a problem where the sun is too weak to scorch apples.

I am seeing a strong association in large apple orchards (by home orchard standards) where crops are down this year, but in the ones managed with Surround, they tend to be absolutely barren. Same species similar crop load last year and similar light.

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@scottfsmith has mentioned a study or more where surround has a positive impact on photosynthesis due to reduced temps vs even when blocking out light. I have not read the study but merely bring it up to say maybe your correlation is just a correlation or a location specific effect

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I don’t doubt that when temps are high it may help photosynthesis- if only because it reduces evaporation by deflecting sunlight, allowing stomates to stay open in high heat, but apple trees “decide” whether to produce flower buds for the following year in spring, when temps tend to be ideal for maximum photo efficiency, as I understand it.

Spring temperatures made pollination difficult this year. I’ve got very few apples and pears and I don’t use Surround. A few warm days when Methley plum bloomed and the fruit load is very high requiring very heavy thinning but Santa Rosa bloomed a few days sooner and it only has a dozen fruit. I also noticed that when it was warm enough for bees, they were more interested in flowering shrubs with darker flowers then the fruit tree flowers. Peaches, nectarines and apricots did poorly or OK depending on when they flowered.
It’s complicated and frustrating.

Here pollinators were out in force, lapping up nectar from flowers whose ovaries had been destroyed by a late march night with temps dipping below 20F, so that was a problem, but I don’t think it is relevant to the association I’ve seen- the sites I’m seeing barren of both early and late flowering apples are favorable.

I really was only asking if anyone has noticed a connection- but then, most people don’t observe Surround managed trees and those without on the same season.