Yes that is absolutely true.
Have you looked at Lavi1? I am sure you have seen this since you know all things pear related.
Lavi 1—A new Pyrus betulifolia rootstock for ‘Coscia’ pear (Pyrus communis) in the hot climate of Israel [2013]
The vegetative and reproductive performance of ‘Coscia’ pear (Pyrus communis L.) grown on eight rootstocks [OHF 217, OHF 333 and OHF 97 (USA breeding of P. communis); NY 095, NY 221, NY 36 and Lavi 1 (Israeli selections of Pyrus betulifolia) and a seedling (Davis A×B) of P. betulifolia] were compared over a 7-year period. The trial was conducted at the Experimental Orchard Farm Station in northern Israel on well-drained, pH 7.5 soil. Trees were planted in December 2005 at 4.0m×2.0m spacing and trained with a central axis. The most vigorous trees were on the local and clonal P. betulifolia rootstock Lavi 1, followed by the three OHF and NY rootstocks; the P. betulifolia seedling produced the weakest tree. Tree size was positively correlated to yield and fruit size. Thus, the highest cumulative yield and cumulative yield of large fruit (>55mm) per tree were harvested from trees on Lavi 1, followed by the two OHF rootstocks (217, 97) and NY 221. The lowest cumulative total and large-fruit yields were obtained on the P. betulifolia seedling rootstock. These results could be due to the excellent water status, e.g., the high midday stem water potential (SWP) values of ‘Coscia’ trees on Lavi 1 rootstocks in comparison with the other rootstocks. The positively high correlation between tree size (trunk cross-sectional area) and water status (SWP) and the similar correlation between SWP and cumulative total yield or yield of large fruit support this hypothesis.
This was a euro pear trial but their newer p betulifolia did the best and p betulifolia seedling did the worst (a rigorous 7 yr trial)
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https://ir.library.oregonstate.edu/downloads/bk128b73v
Richard Bell rootstock review paper
Basically says OHxF97 produces a nearly standard size tree vs p communis seedling or p betulifolia but with better precocity “more precocious”
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Actually had not heard of it at all but thanks for letting me know about it. Somehow whatever i know i always find there is alot i dont know.
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