I bought a Kindle edition of Dr. Carol Deppe’s new book THE TAO OF VEGETABLE GARDENING: CULTIVATING TOMATOES, GREENS, PEAS, BEANS, SQUASH, JOY, and SERENITY.
Right off the bat I took note of her challenge. Quoted by Carol …
”I include a comprehensive list of all known late blight resistant tomato varieties. I also issue a call to arms to all lovers of heirloom tomato flavor to save these wonderful flavors by breeding new late blight resistant heirloom –style varieties of our own—that is, to create the heirloom tomatoes of tomorrow.”
Well well well. I am doing just that. I am including late blight Ph2 and Ph3 resistance genes into not only my own creations but into classic heirlooms like Brandywine and Pineapple. I have hundreds of lines awaiting segregation proof for LB resistance. Bravo Dr. Deppe!
Last Edit: Jan 21, 2015 0:19:52 GMT -8 by Tom Wagner
I've read the chapter on late blight. I hope this will give idea to more folks to hybrid heirlooms and disease resistant cultivars.
I think this is a good place to ask, how do you know that some of your cultivars (e.g. Skykomish) are homozygous for ph-2 ans ph3 ? Is it by comparing disease resistance with know cultivars with both homozygous genes ?
Post by Tom Wagner on Jan 25, 2015 14:38:36 GMT -8
I guess some history on my interest in Late Blight resistance is in order. When I live in other states, late blight resistance was harder to ascertain as it wasn't a sure thing to happen on clockwork...it was a lot more sporadic. However, when I got to Washington, the state, it was a sure thing. The potato experience was eye opening for me but that is for another topic. Tomatoes in 2004 in my first year in Washington were largely wiped out just as they started to ripen. At the time I had only ph-2 lines among my late blight resistance. As everything died except those, I immediately went to work evaluating hybrids between the various ph-2 lines that were homozygous and then ph-3 and in combinations.
Bottom line: Hybrids with heterozygous ph-2 and ph-3 still are not resistant enough for long term blight infestation. That means Iron Lady and Mountain Magic are not enough...it sure is a help but totally homozygous lines like Skykomish and Magic Lineup are best. The Magic Lineup is getting better and better at resisting late season cool weather and blight at the same time.
True breeding homozygous traits are necessary for OP heirlooms and even for hybrid heirlooms.
I am going to grow out a few lines from crosses Randy Gardner made including one of a ph2 + ph3 red crossed to Brandywine Sudduth. I have F2 seed so should see some serious segregation this year. This is obviously not enough to cover the other required disease tolerances including tomato spotted wilt. I would like to get something out of the Ohio Dave Francis lines that would help. He broke linkage between SW5 and I3 to combine both resistances. It would be nice to have that moving into an open pollinated variety.
Iron lady F1 is homozygous for Ph2 and Ph3, thats why Carol Deppe propose to use it for breeding new desease resistant hybrids. Too bad she didnt include your OP cultivars to the list, they would have been much more demand for them
According to Dr. Mutschler-Chu, "The project that led up to Iron Lady was one that I was aiming at three fungal diseases that defoliate plants in the temperate climate — late blight, early blight, and Septoria leaf spot. The logic was that in order to eliminate the need for fungicide of any sort, be it organic or the ones conventional [farmers] use, the key was to control all three diseases genetically; that if you lacked control over any one of these, you would not eliminate the need for spraying. So they had to cover all three."
Of her collaboration with North Carolina State tomato breeder Randy Gardner (now retired), she explained, "So the Iron Lady is actually a cross between lines from the two institutions. One of the parents is one that I developed with control of all three diseases. ... And the other parent is a North Carolina line that has late blight– and early blight–control."
Iron Lady is homozygous for early and late blight, but heterozygous for septoria. IMO, the septoria tolerance is weak. It goes down in my garden just as fast as most other tomatoes. I'm not sure if this is because my garden is being hit with a different strain of septoria or if something else is going on. Regardless, LA2175 S. Habrochaites is just about immune to all three diseases in my garden. I have some F2 seed to grow out this year from a cross of LA2175 with Piennolo Del Vesuvio.