Breeding for Late Blight Resistant Tomatoes

[Diane Whitehead]

We have had a long discussion on late blight, potatoes and tomatoes.

Instead of adding to it, I'd like to start this new one on a project to start breeding this year.

I have some resistant varieties, and have bought more, from England and the U.S.

 These are the seeds I have already grown. I don't know which resistance they have.

Geranium Kiss
Legend
Bolivianische Obsttomate
Chernomor, Reg Lf
IPK LYC 859 El Salvador
Little Julia
Matt's Wild Cherry
Sky Reacher
Skykomish

These are the new ones I just bought.

Make My Day - by Tom Wagner
Cocktail Crush a new release by Burpee Europe presumably F1, but it doesn't say
Crimson Crush F1
Oh Happy Day
Losetto Cherry F1  bred from the Bangor University research

The packets promise just 10 seeds each, but if someone has a project that they would be useful for, I can spare a few.

I hope Carol can suggest the best way to proceed.

Dehybridize the new European ones?  Start crossing?

[Joseph Lofthouse]

Link to the other thread: http://opensourceplantbreeding.org/forum/index.php?topic=58.0

[reed]

I got some Iron Lady and a hybrid called Celebrity to add in to my mix. Celebrity doesn't have blight resistance but resistance to about all other tomato diseases and since blight is just one of many problems in my neighborhood I need the others too.  I'm just gonna try to cross them up several others of my own and see what settles out. I'm using Mr. Stripey, one of my favorite old tomatoes that apparently already has some resistance to try to come up with something that tastes the way we like but keep producing till frost like in the old days.  Diseases are bad enough here that I don't have to do much except wait till healthier longer lived plants show up.

[ImGrimmer]

Legend
Skykomish

didn`t show resistency here in northern Germany.

Mountain Magic has very good resistency.

I have my own tomato strain which shows often resistency but fails in some years between. But it has always better resistency than other varieties.

[nathanp]

This is in the other post as well

I found the list:
Homozygous for Ph2 and Ph3
Iron Lady
Lizzano
Skykomish (from Tom Wagner)
Crimson Crush

Heterozygous for Ph2 and Ph3
Mountain Magic
Mountain Merit
Defiant
Jasper (probably has both - not confirmed, unsure if heterozygous or homozygous)

Homozygous for Ph3
Plum Regal

Homozygous for Ph2
Legend (OP)

Possibles/Probables
Matt's Wild Cherry - probably Ph3
JTO-545 - probably Ph2
Sun Gold   Some resistance anecdotally, but I am not sure what it is from.

These are the ones I have grown. I am currently working on growing out several of the F1 hybrids to stabilize the lines. Skykomish is F8/F9 so that is stable already, though a little too long season for my climate.

Homozygous for Ph2 and Ph3
Iron Lady
Skykomish (from Tom Wagner)

Heterozygous for Ph2 and Ph3
Defiant
Jasper (probably has both - not confirmed, unsure if heterozygous or homozygous)

Homozygous for Ph3
Plum Regal

This webpage has a more complete list
https://articles.extension.org/pages/72678/late-blight-management-in-tomato-with-resistant-varieties

[William S.]

Something that really strikes me about that list Nathan is that you have four varieties in the Homozygous Ph2 and Ph3 list. It seems you me that crossing up those varieties should be done and since many of them are F1s should lead to many new varieties.

My other thought is to develop a lot of F2 crosses with my favorite tomato germplasm. Then when the blight hits should have some resistant material with those traits. Course wouldn't wait for that but rather send some F2 seed out to collaborators.

[William S.]

The one plant of Lizzano F2 I grew out is interesting. Would be good for winter breeding. Seems like it belongs in the very short season very small fruit and plant category. Saved some seeds.

Have an Iron Lady F1 in the seed saving pile. No sign of a ripe Skykomish yet. No crosses made.

[ImGrimmer]

I grew many F2 and F3 Mountain Magic plants. So far no late blight infection. LB season just started. Today I found 2 infected plants in other strains.

[William S.]

My one ripe Iron Lady didn't have many seeds. Then half sprouted while fermenting. So I have four Iron Lady F2 seeds drying. I may call that good. Picked some more and just put them in with the general bag to eat or give away. Still no Skykomish. Have to say, pretty excited about Lizzano comparatively for shortness of season. Saved lots of seeds. Would be a good addition to a variable population of short season stuff.

Lizzano X Big Hill would be interesting. Have to add that to my to do list...

[William S.]

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.

http://tgrc.ucdavis.edu/Data/Acc/AccDetail.aspx?AccessionNum=LA2175&contains=false

This was on tater mater proboards a quote from Darrel Jones. LA 2175 may be of interest for both this and obligate outcrossing tomatoes. If not already included.

[Dominic J]

And if taking eyes off LB for a moment, some of these also have interesting resistances to other diseases. Mountain Magic, for example: "High resistance to Fusarium wilt races 1, 2, and 3, late blight, and Verticillium wilt; and intermediate resistance to early blight."

When I first started growing tomatoes, I basically looked at the resistance codes, and picked the one with the most of them, and that brought me to Mountain Magic (along with a few others). I never had any disease problems with Mountain Magic, and it's been a staple of my garden ever since. Also the kids actually eat it.

It's unfortunately not homozygous for Ph2 and Ph3, but it's got them and still worthy of consideration for inclusion, I think.

[triffid]

I've read in Deppe's book that Geranium Kiss outlived all others in rainy blight season, but the particular genes that allow for this are unknown. Has anyone else found it resistant in their garden? I'll be trialing it on the plot this year.

[Diane Whitehead]

It hasn't had blight for me, but then, it is an early determinate so it wouldn't get it.

 We only get late blight when it rains, which happens in September.

[Garrett Schantz]

Galahad doesn't have early blight resistance but Johnny's seeds lists "exceptional" late blight resistance. "High resistance to Fusarium wilt (races 1, 2, and 3), gray leaf spot, late blight, nematodes, tomato spotted wilt virus, and Verticillium wilt." Also apparently has a decent taste according to Johnny's and some blogs. Don't really see too many tomatoes with all of these different high resistances. Figured I would mention it here.

[Diane Whitehead]

Good heavens!  If I gardened in an area with all those diseases, I would just buy tinned tomatoes.