Why do you feel that Brandywine benefits from grafting? It certainly isn't a common practice.

The primary benefit from grafting any variety, the reason the process exists - lots of discussions here about it - is increased tolerance of the terminal soil borne diseases, especially the viral ones. And then only if certain rootstock is used. If those diseases don't exist in your soil then any benefits gained are far outweighed by the high cost of rootstock, the extra work and time involved, and the high percentage of graft failure.

The secondary benefits some 'claim' for grafting - increased size of fruit, increased production, etc. are primarily marketing claims; possibly to justify the increase costs of grafted plants. Those claims are highly debated and have mixed research results.

Your best source of info about any soil disease issues in your area is your local county ag extension office.

Opalka is a wispy plant by nature in its shape and leaf formation. Even in peak condition it appears weak by comparison to other varieties. That's its genetics so grafting isn't going to change that.

San Marzano Redorta is quite vigorous all on its own. But both, since they are heirloom/are open pollinated, have far less disease resistance than most hybrids. Grafting could overcome that only IF the disease in question is soil borne but not if it is one of the common air borne diseases.

Dave

Ok. Thanks. I really don't know what I have in my soil.

Only one variety is failing, and it's Fresh Salsa Hybrid from Burpee (which is not worth growing again even without disease problems), the plants turned yellow, then brown on all but the tips, and the description doesn't have any resistance codes in it.

Everytning else I'm growing is at least Verticillium and Fusariam 1 resistant.

I don't know if it's soil-borne or not.

I will say that fusarium is common in MD per the local literature, and the Fresh Salsa plants look like the pictures of it. I'll have to check a stem:

I haven't grown opalka, but I have grown something very similar to the Redorta (the fruit looks identical although the place and time I got is very different, and it is very droopy), and these types are not lacking in vigor. In general droopy leaved tomatoes have high vigor (ability to do well over a long season, setting well even at high cluster number). In varieties lacking vigor, grafting on a vegetative stock will improve yield over a long (think commercial greenhouse) season.

In your case I would say soil diseases are more important. If you have them, this could be important.