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Madisonville, TN

This year we grew 19 Big Zac tomato plants. They are a mix from the following seed:

F6 1.736 DT/Thurber 2011--F5 7.18 Harp 2009--F4 5.58 Timm 2008–F3 3.9 Catapano 2007–F2 4.29 Lyons 2006--F1 Big Zac Commercial

F4 1.870 DT/Thurber 2012--F3 3.9 Catapano 2007–F2 4.59 Lyons 2006-- F1 Big Zac Commercial

F5 2.164 DT/Thurber 2012--F4 5.320 Lyons 2011--F3 3.9 Catapano 2007–F2 4.59 Lyons 2006--F1 Big Zac Commercial

The plants all have the same soil, same light, same amendments, same fertilizers, same pesticides, and the same fungicides. The plants from the 1.736 DT/Thurber 2011 have all done consistently better than the other in all regards, size of plants, growth rate, fruit size, and disease resistance. Most of the other plants have developed late blight, but the 1.736 plants remain blight free.

Is it possible that the plant descended from the 7.18 Harp line have developed more blight resistance? They all have the 3.9 Catapano in common. Has anyone else observed similar traits in the 7.18 Harp line as opposed to others? Should our seed from these plants, (3.84 Hooper 2014, 3.44 Hooper 2014, and the 3.02 Hooper 2014), retain the traits if the difference is genetic?

8/21/2014 5:50:31 PM

Allentown, PA

Hi CLoudwalker,

The answer is no if one is assured that every seed grown from the 7.18 Harp and it's subsequent offspring since the Harp tomato was grown was free of cross pollination.

We of course cannot guarantee that this is the case.
It would be impossible to ensure that the thousands of seeds that went on to produce plants from the beginning ""mother"" tomato would remain free of cross pollination.

The subsequent generations of these possible crosses could very well be showing the disease resistance that was in the other tomato strain that had crossed with the Big Zac.

Big Zac itself has a decent amount of disease resistance versus other lines that we as giant growers plant. One of those that seems to have a lower than average resistance to disease is Mega Marv.

As far as your plants showing variables in resistance could come down to air born spores of blight landing on some but not all of your plants and you pulling those plants thus stopping the advancement or like I said unintended cross pollination from generation to generation thus building up various levels of disease resistance.

One more thing, Late blight would most likely attack and destroy all of your plants in rapid succession despite their disease resistance if you did not immediately pull the affected plants.

I hope this helps, I'm sure someone else will chime in with some different information for you.

8/21/2014 6:46:40 PM

Central NY

Cloudwalker?... Isn't that the kid?...what's all the F1 F2 F3 business?...I feel dumb...

8/21/2014 7:43:37 PM

Madisonville, TN

I hadn't thought about cross pollination. I have grown different varieties near each other for years so I'm sure it happens a lot.
I have not pulled the effected plants, so they will probably all have it soon. We have had 16 tomatoes, 3 pounds or larger, so I can't complain. We also have 16 smaller plants in another patch started from cuttings from the first plants. They are doing well and were planned as fall bearing plants.

Cloudwalker is the Dad, as in Cloudwalker Photography. Cheyenne is my 16 year old daughter.

8/21/2014 10:04:06 PM

Madisonville, TN

F1 is the first generation hybrid. The next is F2, and so on.
Should the commercial Big Zac seed be a F1 or a F2? Now I'm confused.

8/21/2014 10:09:23 PM

valparaiso, in

cloudwalker I am growing an F6 and an F7 from the 7.18 Harp, and I am not sure if it is blight but something is slowly taking the plants out. With all the rain that we have had this year it is on all my vegetable plants. Pepper as well as tomato. I am leaning towards the plants not having developed any type of resistance. Just my observations.

8/21/2014 10:35:31 PM

Bloomington, IN USA

Cloudwalker, are you sure you have Late Blight on your plants?

There are literally a myriad of different fungal diseases to which our plants fall prey.

With Late Blight, there can be quite rapid progression of disease & the entire plant can turn into a green mush.

And there are sites you can look at to see if it is in your area.

I may be wrong but I don't think Tennessee is generally a hotbed of Late Blight.
More likely you have 1 of the 3 races of Fusarium or Verticillium or Bacterial Speck or Spot. Alternaria, Septoria or even Southern Blight are more likely as well.

I am not an expert in tomato diseases.
I have a Petoseed book on tomato diseases & I know just enough to be dangerous!
You could post some pics of your plants & we could all take turns guessing what disease they have but it probably would be more productive to take a plant around to your local Extension office to get a more qualified diagnosis.
Just my 2 cents.

8/21/2014 11:03:45 PM

Madisonville, TN

I am not for certain that it is late blight. I did compare to photos, but I'm no expert. I will try to post some photos this weekend.
Tonight is opening day for football at our high school. I am the team photographer and my daughter is the head majorette, so the plants will have to wait till tomorrow.
Disease or not, the giant tomatoes have been a lot of fun and will definantly be in the lineup next year.

8/22/2014 8:39:28 AM

Western PA

I had late blight last year on All my tomatoes, eaters and giants. You will get brown scabs or lessions on the fruits as well as the leaves.
It does go air borne as said above.
My thought is that the Harp plants may be possibly up wind of the infected, or you may be getting better spray coverage on those plants. It does spread quick, but I slowed it down last year by spraying mancozeb twice a week. I managed to get 2 nice ones to the scale. Even though the plant showed signs of the disease, the fruits grew very well.

So, i would stay on a good spray program and carefully pull the infected plants ( not to spread spores ) and dispose.
Best of luck !

8/22/2014 10:01:05 AM