In search of.... Better disease resistance
 

My tomato plants have been wiped out by septoria, gray mold, early blight, and sometimes late blight every time I've grown tomatoes for the last 35 years. So what did I do? I searched for better disease resistance by growing countless hybrids, tons of open pollinated disease resistant tomatoes, and eventually delving into germplasm from TGRC. In 2011, I grew a range of TGRC lines with the intent of finding something that could combat the intense disease pressure in my garden. I found 3 plants with better than normal leaf disease tolerance. LA2175 and LA2869 are both S. Habrochaites which means a LOT of work required to move the disease resistance into a domestic tomato background. I'm still working with these, but it is definitely a long term project. LA0417 (S. Pimpinellifolium) was unusual in that one single plant out of about a dozen showed significantly better resistance.


I saved seed from that single plant (pollen) and crossed it to Piennolo (female stigma). This was a relatively easy cross as Piennolo is potato leaf while LA0417 is regular leaf. The next year I grew out the regular leaf offspring and started selecting. I'm up to 4 generations now and have some decent results. There are 4 hybrid plants in my garden. All are potato leaf, all are resistant to foliage disease, all are the size of large cherries in the 1 inch diameter range. 3 of the 4 plants have slight nipples inherited from Piennolo. All 4 plants carry the genes for long shelf life. One of the plants shows susceptibility to early tissue necrosis in the fruit, probably a result of insect damage. One plant has not yet matured fruit though it should within the next week. All of the fruit taste good to very good though they are admittedly not as good as the best heirlooms such as Brandywine or Cherokee Purple.



Now the $64,000 question. If I make seed available from the best plant(s), would you be interested in growing a good flavored large cherry size tomato that has outstanding disease resistance to southern heat and humidity?

Although I live in the north. My plants suffer from Early Blight, Septoria (and sometimes grey mold) every year. Our temperatures are also rising. We've had temps in the 80's and 90's during June and July!

I would be very interested in growing a good-flavoured large cherry-sized tomato with outstanding disease resistance to heat and humidity.

Many people say that PL plants have better disease resistance, yet I find that the PL plants (especially the dwarfs) seem more subject to disease than the RL varieties in my garden.

Linda

[B][SIZE=4][FONT=Garamond]I'm sure a lot of people here would be very interested, myself included.[/FONT][/SIZE][/B]

[B][SIZE=4][FONT=Garamond]And though I don't live in the south like you, I have been experiencing much more frequent (and long-lasting) heatwaves that really have a serious negative affect on the plants.[/FONT][/SIZE][/B]
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[B][SIZE=4][FONT=Garamond]P.S. - I hope the seeds aren't $64,000!
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Cherries are taking forever to get ripe this year.
Even the neighbors were complaining.
I am just starting to get a few now, from bought plants.

I grew an experimental hybrid from Seminis this year which came very close to being the perfect tomato. It doesn't have a name, but is identified by Seminis as SV7846TH[B]. [/B]It is indicated to have resistance to almost every letter in the alphabet. While I had a good variety of diseases in my garden this year, SV7846TH never developed a single yellow leaf. It did have a tendency to develop BER on some early fruits in heavy, extended rain. Later fruits never had a blemish. I would like to grow it again, but I don't know where to obtain the seeds. Seeds N Such sent out a free gift with early orders last year, but their web page seems to be down.


It is indeterminate and highly productive of perfectly round, large tomatoes. It is productive from mid spring to late summer. It is probably a great commercial tomato because it remains firm and green for an extended period, which means it should ship well and ripen in storage well and have an excellent taste.

Here is the resistance package for SV7846TH.

ToMV:0-2 = Tomato Mosaic Virus 0, 1, and 2
Fol:0,1 = Fusarium 1, 2
Ff:A-E = Leaf Mold A through E
Va:0 = Verticilium A
Vd:0 = Verticillium D
Intermediate TYLCV = tomato Yellow Leaf Curl Virus
Intermediate Ma = Meloidogyne Arenaria Nematodes
Intermediate Mi = Meloidogyne Incognita Nematodes
Intermediate Mj = Meloidogyne Javanica Nematodes

It is missing:
Tomato Spotted Wilt
Fusarium 2
Septoria
Early Blight
late Blight

[URL]https://www.worldseed.org/wp-content/uploads/2019/12/Path_codes_September_2019-_vegetables.pdf[/URL]


It has rin which is ripening inhibitor. This is a seriously bad gene in terms of tomato texture making fruit rock hard for shipping.

My tomatoes stayed green and hard on the vine for an extended period. When they started turning pink, they quickly ripened to bright red. They seemed to have no white core and retained a firm texture when ripe. I left a couple of ripe tomatoes on the kitchen counter beside other varieties which quickly softened when ripe. SV7846TH stayed firm while other varieties softened. The BER on early fruits is the only thing I can complain about.



I thought the SV7846TH would have made perfect fried green tomatoes because of their firmness when green and perfectly round shape. I didn't try it, but they made great BLT's

rin is penetrant meaning that it is always expressed whether heterozygous or homozygous. SV7846TH has a single copy which is why the fruit turns red but stays firm and has long shelf life. It is fairly easy to separate out from otherwise useful genetics by stabilizing for plants that don't have firm fruit.

Don take some cuttings and overwinter them if you don't have any more seed.


FP good luck with the progress.

[QUOTE=Fusion_power;758347]My tomato plants have been wiped out by septoria, gray mold, early blight, and sometimes late blight every time I've grown tomatoes for the last 35 years. So what did I do? I searched for better disease resistance by growing countless hybrids, tons of open pollinated disease resistant tomatoes, and eventually delving into germplasm from TGRC. In 2011, I grew a range of TGRC lines with the intent of finding something that could combat the intense disease pressure in my garden. I found 3 plants with better than normal leaf disease tolerance. LA2175 and LA2869 are both S. Habrochaites which means a LOT of work required to move the disease resistance into a domestic tomato background. I'm still working with these, but it is definitely a long term project. LA0417 (S. Pimpinellifolium) was unusual in that one single plant out of about a dozen showed significantly better resistance.


I saved seed from that single plant (pollen) and crossed it to Piennolo (female stigma). This was a relatively easy cross as Piennolo is potato leaf while LA0417 is regular leaf. The next year I grew out the regular leaf offspring and started selecting. I'm up to 4 generations now and have some decent results. There are 4 hybrid plants in my garden. All are potato leaf, all are resistant to foliage disease, all are the size of large cherries in the 1 inch diameter range. 3 of the 4 plants have slight nipples inherited from Piennolo. All 4 plants carry the genes for long shelf life. One of the plants shows susceptibility to early tissue necrosis in the fruit, probably a result of insect damage. One plant has not yet matured fruit though it should within the next week. All of the fruit taste good to very good though they are admittedly not as good as the best heirlooms such as Brandywine or Cherokee Purple.



Now the $64,000 question. If I make seed available from the best plant(s), would you be interested in growing a good flavored large cherry size tomato that has outstanding disease resistance to southern heat and humidity?[/QUOTE]

I am certainly no scientist or plant biologist with any suggestions for foliage disease resistance. I'm surprised you didn't mention TSWV and spider mites which are almost always two of the top killers down here for me. I have had a fairly bad year with EB, TSWV and spider mites this season along with a fusarium resurgence that is discussed in another thread. I try to prevent EB as long as possible with Daconil and then switch to mostly copper sprays as the season moves on. I usually get one copper spray done each week and it has greatly reduced all the speck and spot disease problems I used to have but it doesn't seem very effective with EB so when it isn't too rainy I put on some Daconil in between copper sprays. If we are having frequent rains I will use the diluted bleach spray between rains every two or three days which really slows all the diseases especially gray mold if it is used early enough.

I think this far south we are just doomed to endless repeats of disease and pest eruptions on a yearly basis. Once in a blue moon we get a season with lower than normal humidity and get a break from some of the diseases but it is usually accompanied by very dry conditions meaning lots of watering and smaller fruit and less fruit overall. I see the rare plants each year that seem to be very tolerant of most foliage diseases and try to save seed from those as well but I haven't noticed or kept up with whether it makes much difference. Good luck with your work with disease tolerance. You will need it.

Bill

TSWV has several known effective genes with Sw-5 and Sw-7 the most effective. I have not yet attempted to stack these genes into this line. Amelia is an example with Sw-5. All I have selected for in this line is septoria resistance though it has a bit of other resistance to foliage disease. I noticed a small amount of gray mold on one of the plants 2 days ago so that may be a weakness.

[QUOTE=JRinPA;758550]Don take some cuttings and overwinter them if you don't have any more seed.


FP good luck with the progress.[/QUOTE]


Thanks Jr, I may do it. I think I got five seed and germinated three. I paid attention to where I planted one and it has performed very well. I think I planted the other two in a bed which has a history of not being kind to tomato plants but very kind to pepper plants. I believe my watering pattern is designed more for the peppers than tomatoes. I noticed this morning one tomato plant in that bed has started growing well after hardly doing anything until now. I was intending to pull the plant and dispose of it. It now has at least one tomato on it which is growing large and it is blooming in the high heat. I found one of the two "lost" plants. Now two of the three are in good health while other varieties around them are dying from the heat. I'm still wondering where the third plant is but I expect it to reveal itself by it's action.

Fusion Power, in the years I have been growing tomatoes, disease resistance has been the single most important factor to getting a reasonable crop for the effort.
To answer your question, although in the north, I too would grow your disease resistant large cherry if you make the seeds available. As you know I have limited space so I cannot do a large growout for selection purposes, but I would certainly start multiple plants and select early for the ones that get the space.
Will also happily share with you seed of the lines that have become my favorites for their disease resistance, your choice determinate or indeterminate.


I have a brand new problem this year that came from the jute I used to support my plants. Everywhere it touched the stem, this disease developed. Some of them looks like it will soon eat right through the stem, and those plants have few fruit so seems to have affected them already. Only two plants that were tied with the jute have shown resistance to the disease, whatever it is. These are not my known 'favorite' lines which consistently showed disease resistance to F6, it is a new one to come forward. They are a four parent cross at F2: a Stupice X Black Cherry F2 selection crossed with PI120256 X Eva Purple Ball F1, that is the PI120256 I got from you (thanks!), Turkish origin, costuloto type ribbed fruit and cold tolerance. I selected for earliness only in allocating space this year. The two resistant plants have cluster structure like Stupice ie branched in two. Both have lots of ribs on the small fruit so the multi-locule genetics is in play. One has produced more regular shaped fruit, the other has many more ribs and has a few more lopsided ie uneven pollinated fruit during our humid weather.

IDK what the disease is from the jute. If it is bacterial I guess I cannot get seeds from these plants and will have to go back a generation and start over - that would be too bad, to miss the opportunity to select for resistance, on the risk of getting diseased seeds.



Anyway the quest for disease resistant OP plants continues north and south. Glad to hear that you got some promising results.

Bower,


I don't know if the "disease" can be passed internally or externally with the seed. If it is carried on the seed and is indeed a pathogen, the bleach cleansing method I believe Carolyn used to use should kill it. If internal, there probably is nothing you can do.


I have experienced damage to branches in the past from different tieing methods which resulted in a type of necroses which looked like a disease but wasn't.

It's only anecdotal, but year in and year out Neves Azorean Red seems to show almost no signs of disease in my garden until later in the season, when age and stress presumably weaken the plant. Not sure if you or anyone else have had a similar experience. I've often wondered if this variety were tested as they do for hybrids, what the resistance level to the major tomato diseases would be for NAR.