cross-pollinators

[snewman]

Can anyone explain the biology behind the need for different varieties of a fruit tree species for proper pollination? It seems odd to me that in order to get, say, a macintosh apple tree to produce macintosh apples, you have to also plant some other variety, like gala, etc.

 

[patandchickens]

My understanding is as follows:

All apples are relatively self-incompatible, meaning their ovules cannot reliably be fertilized by their own pollen. Ovules not fertilized do not develop properly, so you get either no fruit at all setting from that flower, or a small very misshapen fruit that ripens poorly or just falls off still green. (Some varieties are less-self-infertile than others, but AFAIK all do *better* with crosspollination.)

(edited to add: self-incompatibility is not uncommon in the plant kingdom. One can imagine it to be an accidental byproduct of How Genes Work, or one can imagine it to have some selective advantages in promoting genetic diversity. Anyhow there are lots of plants that don't self. Although of course there are also lots of plants that do.)

So all varieties need (to some extent or another) genetically-different pollen in order to produce good set of good fruit.

Not all varieties can pollinate all other varieties, however, for two main reasons: a) different varieties flower at different times, and obviously something that flowers the first week of May is not going to do a bit of good for something else that flowers the third week of May. And b) triploids, including many of the newer and larger-fruited cultivars, tend to be pollen-sterile i.e. they just don't produce viable pollen and thus are 'shooting blanks'.

There may be more to it than that, I dunno, but I think that's the main picture.

Hope that helps some,

Pat

 

[snewman]

That helps a lot, thank you!

 

[mamarosa]

So basics are 2 varieties that bear fruit at the same time.
so a liberty and a mc intosh which are different and bear fruit the same time of year????

thanks if this is right
mamarosa

 

[patandchickens]

So basics are 2 varieties that bear fruit at the same time.
so a liberty and a mc intosh which are different and bear fruit the same time of year????

thanks if this is right
mamarosa

It's not when they bear fruit, it's when they flower, which is not necessarily the same thing. Also I don't think most of the triploids (Mutsu, etc) make good pollinators no matter *when* they flower.

So, you want something that flowers at the same time, and is not triploid. There should be lots of possibilities.

Good luck,

Pat

 

[barefootgardener]

Apple trees can also be pollinated by crab apple tree's (As long as it is not sterile) and also by neighboring apple trees in the area.