TSWV Resistance vs Tolerence

[tlcmd]

Recently received my 2010 Twilley Catalog which describes several TSWV RESISTANT varieties on page 55. But on page 56 there are several TSWV TOLERANT varieties listed, 3 of which are indeterminant.

Dr Randy Gardner at NC State University who has developed several varieties of TSWV resistant determinant varieties writes, "I think all the resistant and so called tolerant tomato varieties all have the same gene(Sw-5) fo resistance. I see some varieties that I know are TSWV resistant with the Sw-5 gene that are listed as either resistant or intermediate resistant."

My own interpretation of resistant vs tolerant is that the resistant varieties are harder to infect with the disease, but the tolerant varieties can become infected with it and continue to grow and produce.

Comments or experience with TSWV resistant vs tolerant varieties please. I'm selecting seeds for spring 2010 now.

Thanks,
Dick

[carolyn137]

I can only comment on the words resistant and tolerant.

Quite a few years ago some commercial farmers sued the company from which they got their tomato seeds b'c the plants came down with diseases that they were supposedly resistant to.

After that the tomato industry changed to using the word tolerant intead of resistant.

Resistance means to most folks that the plant is totally resistant, as in it never get the disease. But the fact is that there's NO variety, hybrid or OP, that is totally resistant to ANY tomato disease. All the bred in gene does is to prolong the life of the plant for a few weeks at most, which is a boon for the commercial folks who usually harvest by measuring Brix concentrations and those extra weeks can allow for higher Brix concentrations.

About 95% of all tomato seed production is for commercial farmers, not for the home gardener, so what we see as F1 hybrid offerings is really just spillover from commercial seed production. Although of late a few companies have been introducing some varieties bred primarily for the home gardener.

So for the past several years I've used the word tolerance rather than resistance since no tomato variety is totally resistant to any tomato disease.

[tlcmd]

Carolyn,
Thanks for the reply. The only part of this that doesn't quite compute is that Twilley devotes page 55 of their 2010 catalog to "All varieties on this page are resistant to Tomato Spotted Wilt Virus" While on the next page (56) they describe the vaieties individually as tolerant. I could be misreading this page as all are "tolerant TMV, V, F, TSWV, YLC. (etc) Could it mean only tolerant to TMV which seems unlikely???

Thanks,
Dick

[Blueaussi]

Why don't you call Twilley's and ask. I've called them a couple of times over the years, and they were always very nice. I hope they haven't gotten too big for that sort of thing, but the worst they can do is tell you they can't help you.

[tlcmd]

thanks for the reply. I did email them before I initially wrote Dr Gardner and posted these questions here here and have been awaiting their reply. In the past they have been very responsive. I suppose the delay is due to the hlidays.

[carolyn137]

Originally Posted by tlcmd

thanks for the reply. I did email them before I initially wrote Dr Gardner and posted these questions here here and have been awaiting their reply. In the past they have been very responsive. I suppose the delay is due to the hlidays.

If Dr. Gardner says that he's seen TSWV varieties that are called resistant or tolerant and he says they both have the same Sw-5 gene then I can't see how Twilley can distinguish between those two words with different varieties.

One gene, one way of thwarting infection.

And yes, I've seen some varieties noted to have intermediate resistance, but what does that mean?

To me it's about the same as some folks saying a semi-indeterminate plant habit vs a compact indet, vs a semi-det. I mean either it is, or it isn't.

In my first post I really didn't address TSWV directly, just what I see as the possible difference, or not, between resistance and tolerance.

[tlcmd]

Carolyn,
You very well expressed my delimma in distinguishing between TSWV resistance and tolerance. Hence my questions on this forum and to Twilley. Thanks

Dick