Breeding for Late Blight Resistant Tomatoes

[Nicolas]

That is very cool, I haven't yet managed to make a cross between the cross I made with the PH5 current and the cross I made with Galahad F1.

You mean not enough time or your crosses didnt take ?

I've worked with only an handful of pimpi accession but maybe 90%-100% of my crosses cultivated x pimpi failed, whereas pimpi x cultivated or interspecies hybrid x pimpi are a lot easier to take (but pimpi as female is a pain to hand pollinate !)

[William Schlegel]

You mean not enough time or your crosses didnt take ?

I've worked with only an handful of pimpi accession but maybe 90%-100% of my crosses cultivated x pimpi failed, whereas pimpi x cultivated or interspecies hybrid x pimpi are a lot easier to take (but pimpi as female is a pain to hand pollinate !)

No mainly just havent gotten it attempted this year. I've only managed about 20 unique crosses this year and few of them very exciting. So I have a cross with galahad and 1/2 and 1/4 crosses with the ph5 currant tomato but no crosses between the two lineages yet.

[Steph S]

I had a couple of LB resistant plants in my trial this year, and did some crosses with Mountain Gem.
This is a very firm,large, uniform ripening red tomato, really easy to work with as a mother plant and took pollen for a cross more readily than it pollinated itself in my conditions here.  Besides being an easy mother plant, many of the fruit were bluntly heart shaped in the greenhouse conditions, which suggests to me that some important genes for shape stabilization are present - very useful for breeding beefs.
On the difficult side, it was very late to ripen by my usual standards, not very tolerant of local conditions and not resistant to the Alternaria blight we're getting in the hot sticky weather, although described as moderately resistant to EB, it did no better than my own lines, which is important for me to know as I continue looking for the resistance genes I need.
I had made my crosses already on spec by the time the blight conditions kicked in, so I did get seeds from crosses with Rodney and Skipper Pink, but to grow this out I would have to select very hard for earliness.
I also saved seeds from a cross with my GWR bicolor Kelly's Island Rumpus F4, which might be interesting to grow.  We aren't getting LB here at present, so no way to select for those useful resistance genes without marker selection.

Plum Regal, I didn't get a cross in since it was really late even to produce a flower.  It set some fruit outdoors.  This was so much later, I wouldn't try growing it again.  Also not resistant to our Alternaria.

A third plant with LB resistance genes was Mini Rose from the Ottawa Research Station back in the 70's.  The fruit are so tiny, it would be really a job to recover fruit size, probably no better than working with a pimp, so I didn't make any crosses there.

[ThomatoGarden]

Of 120 outdoor plants, 15 are left

2 x Mountain Magic F3 Salad size - hard, slow ripening, very very resistant
                              - hard, slow ripening, 

2 x Primabella

3 x Primabella x Sunviva F1 - strong growing, good taste

2 x Vivagrande x Sunviva F2 - a bit crack sensitive, strong growing, good taste

1 x Matt's Wild Cherry -

1 x Hot Streak F2 No 5 - very few seeds, potato leaf, well resistant, cracks heal,
                                  hardly rots, apple-shaped fruits

2 x Primabella x Bulgarian giant tomato F1 - salad tomato, good taste, sweet mild, lots of seeds

2 x Mountain Magic F3 Cocktail

These plants are only about 50% healthy (except the one MM F3 lettuce 70%) and will soon be removed!

Honey Moon F1 was similarly resistant, but rather slow growing.

Giant of Siebenburgen - 99% healthy in the greenhouse!?, although all the other plants there had
                           diverse diseases (including LB), and most already are
                            removed, still produces large tomatoes. Largest in August 1240g.
                           Sweet, healthy fruit.

Fruit quality:
       With wet weather like this year, the quality of the fruit is just as important as that
       resistance to diseases. When fruits burst and rot in the rain, it doesn't matter if the
       plant is healthy. Hot Streak had a very big problem here, while all the fruits of
       Honey Moon were healthy. All crosses with Sunviva were also not optimal in this regard.


Rough plan for outdoors 2025:

- Primabella x Bulgarian giant tomato F2        32
- MM F4 Cocktail No. 2                          8
- MM F4 Salad (very resistant)                  8
- Vivagrande x Sunviva F3 yellow large cocktail 8
- Vivagrande x Sunviva F3 red cocktail No. 1    8
- Primabella x Sunviva F2                       20
- Hot Streak F3 No. 5                           10   
- Honney Moon F2                                10
- Giant of Siebenburgen                         4

(i can send Seeds for free as usual (only Hot Streak F3 No5 is difficult cause not much seed and Nicolas allready reserved some))

[Roland]

Less than 10% left, that is a strong selection. The MM Salad seems interesting.

Sunviva is very sensitive to craking, perhaps you can see an improvement in F3.

I can't wait to see what segregation you will find in the F2 Primabella x Bulgarian giant.

[Roland]

https://plantbreeding.ncsu.edu/cultivars/tomatoes/
A lot of new varieties that have late blight resistance.

[reed]

Of 120 outdoor plants, 15 are left


1 x Hot Streak F2 No 5 - very few seeds, potato leaf, well resistant, cracks heal, hardly rots, apple-shaped fruits
                       
Fruit quality:
       With wet weather like this year, the quality of the fruit is just as important as that
       resistance to diseases. When fruits burst and rot in the rain, it doesn't matter if the
       plant is healthy. Hot Streak had a very big problem here, while all the fruits of
       Honey Moon were healthy. All crosses with Sunviva were also not optimal in this regard.

Rough plan for outdoors 2025:
- Hot Streak F3 No. 5                   

I see you are working with Hot Streak and it's even in your 2025 plan. I take that as you regard it as worthwhile. I grew the F1 this year and out of all the new ones it was pretty good. It wasn't noticeably disease tolerant, and the fruits cracked a bit but healed. I agree completely that disease resistance doesn't matter much if something else ruins the fruit. Hot Streak mad a nice harvest and the fruits themselves were not bothered by disease. Plum Regal is like that too, the plants might almost die but the mass amount of fruit ripens fine anyway, I/m ok with that.

Did I understand correctly that the F2 NO 5 was potato leaf? Out of how many total?

[ThomatoGarden]

I got the seeds from Roland they are working with Hot Streak and many others in their NL/Belgium Projekt.

Yes Hot Streak No 5 is Potato Leaf. 11 out of 30 were Potatoe leaf.

Hot Streak is a really good looking Tomatoe, a nephew said they look like apples thats why i allways say
apple like fruit :-) . Classic it would be heart shaped. Its worth to try selecting it.

Compared to other so called resistant commercial Tomatoes (Crimson ... , Bufallosun, Gourmonsun, ....)
up now only Hot Streak and Honney Moon showed some Potential.

[William Schlegel]

Hot Streak F1 on Johnny's has an impressive list of additional resistances. Maybe some of them are quite important in your climate?

[ThomatoGarden]

Yes this year was extreme, there were many different Diseases. At some Point i stopped to figure out what disease it was.

Even Mountain Magic (one was a bit more resistant) and Primabella had problems outside. I like selecting plants but this year was bad. At the End i was in fear to growing stronger diseases
than resistant Tomatoes!

[Roland]

A new late blight resistant variety:
Black Angel F1

https://www.johnnyseeds.com/vegetables/tomatoes/specialty-tomatoes/black-angel-organic-f1-tomato-seed-5162G.html?srsltid=AfmBOorK8lZ3RZSlhGKVWwNmZqIWc-yKvNEBAGcW9r5CIkfVuM0CPsvy

It hase a lot of resistance genes and:
Homozygous for the Crimson gene for extra red flesh,
Homozygous for the gf gene for green fles.

[William Schlegel]

http://blogs.evergreen.edu/fieldstudy-patrick/analyzing-late-blight-severity-and-summary-table/

Two of Frank Morton's Three OSSI tomatoes were evaluated in the above study for Late Blight. Notably his Estate scored number four out of the group evaluated. That seems pretty good for a cross that sounds like Peron Sprayless x (Stupice x Homestead).

Stupice was bred in the 1940's in Czechoslovakia, Homestead in Florida in 1952, and Peron Sprayless prior to 1954 in Argentina. I would suspect there might be some early modern traits in tomatoes of that vintage.

[ThomatoGarden]

Very interesting Trial, it matches with my experiences (Mountain Merrit, Matina) .

Any Source for Damsel F1 in Europe ?

Would like to test it.

[Nicolas]

As a seed saver, I do wish Damsel was open-pollinated. This would allow for annual growing and selecting the best individuals as they compete with the unique and dynamic pathogen/pest populations at each growing site.

I'm a little sad reading this. There is a lack of understanding in the gardening community about possibilities of manual crossing and selection of hybrids...

[Tim DH]

There is someone selling 'Damsel F-1' on Ebay.
They reckon the seed is 'Own Farm Organically Grown'
They also state it is 'Over a decade stable'

Hmmm..... Has the real Damsel F1 actually been available for a decade?

If so this might be an innocent/ignorant mis-understanding about what F and 1 means, and they might be selling a stable OP growout.......