I'm wondering if a plum tree and apple tree can cross pollinate? Specifically looking at alderman plum and honeycrisp apple varieties.
Houston County Minnesota
Thank you for writing.
The simple answer is that a plum cannot cross pollinate an apple. But the answer is a bit more complicated.
Honey crisp needs another apple that flowers at about the same time to cross pollinate with as bees, wasps, butterflies and other insects carry pollen from one tree to another. https://homeguides.sfgate.com/list-cross-pollination-trees-honeycrisp-apple-trees-50455.html
Even if you select an apple tree that flowers at the same time as a plum and bees go back and forth between them, they will not fertilize eachother. They are different kinds of living beings. You will need a cross pollinator for an alderman plum. https://extension.umn.edu/fruit/growing-stone-fruits-home-garden
Houston County is growing zone 4b 5a so you have a lot of flexibility on plants. I hope this helps.