[Market-farming] Intentionally crossing tomatoes

Marlin Burkholder glenecofarm at planetcomm.net
Thu Feb 10 23:13:13 EST 2005


For the past number of years I have had unintended cross pollination of some
of my tomato varieties, most frequently occuring with pototo leafed
varieties like "Brandywine" and some of the cherry tomatoes.  I always
thought that it only appeared that way because the effects of these
crossings are more easily observed when one starts seeing potato leafed off
types among his non potato leafed transplants or when something besides
cherry tomatos start appearing on the cherry tomato plants.  Then I learned
last year that crosses do indeed occur more more frequently among potato
leaf and cherry varieties because they are more primative and have
differences in stamen or pistol lengths (I don't remember which) with those
of more modern varieties which renders them more susceptable to crossing.

Well anyway, now I am thinking of trying to intentionally cross two
varieties that I like a lot, but both have highly contrasting positive and
negative characteristics I would like to combine in hopes of ending up with
a new variety that would minimize the weaknesses of both of them and combine
the best of both of the parent varieties.  These are the two varieties:

* Blosser-- a large pink beefsteak slicing type.  Strengths are it's
relatively good yield of smooth well shaped fruits with a moderate sized
stem core compared to other heirloom varieties and a superb low acid flavor.
Weaknesses are it's susceptability to mosaic virus diseases and cracking,
the bane of many hierlooms.

* Eva's Purple Ball-- a smaller tennis ball sized pink salad tomato.
Strengths are it's superior resistence to cracking, disease resistence, and
a small stem core.  The main weakness is the lack of size.  My customers are
looking more for the larger slicing types.

I would like to breed the cracking resistence and smaller stem core of the
EPB into the larger beefsteak style slicing tomato represented by the
Blosser.

What would be the better "no brainer" method for accomplishing this cross?
I recall reading somewhere that the guy who bred the "Morgage Lifter"
variety in the 1930's did so by surrounding a pollen receiver plant with up
to a half dozen pollinator plants and saving seed from the best fruits off
the pollen receiver.  My question would be "which variety should be the
pollinator and which should be the pollen receiver?"  Should I consider
doing some in both directions?  Maybe I should consider using "Brandywine"
instead of  "Blosser" for my larger sized variety in this cross.  Both
Brandywine and Blosser yield a similar sized fruit but I like the shape of
the Blosser a little better.  However, Blosser has the standard tomato leaf
shape as opposed to the potato leaf shape of Brandywine.  Based on previous
experience, I wonder if Brandywine would cross easier with EPB than would
Blosser and if it would be easier to identify the crossed plants among my
seed starts the following spring.  The potato leaf makes a good marker.   If
possible I would like to avoid having to hand pollinate.  How many years
would I need to repeat this process in order to get a new true breeding
variety.  How would this differ from a hybred?  I hope some of you with
plant breeding experience can weigh in on this one.

Marlin Burkholder
Virginia






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