By William Terry Kelley
University of Georgia
Many old tomato varieties are still in circulation. But in recent years, many gardeners have adopted hybrid varieties that have better disease resistance and better yields.
Even more recently, tomato growers have been faced with the ever-increasing presence of tomato spotted wilt virus. Transmitted by thrips, this virus is not only the plague of commercial growers but is actually even worse for home gardeners.
Only in the past couple of years have varieties been introduced that have resistance to TSWV. Since then, many gardeners have opted to go with a resistant variety to be able to grow tomatoes successfully.
TSWV resistanceOver the past few years, there have been two varieties with resistance to TSWV: "BHN 444" and "BHN 555." These have become more available to gardeners in the past year or two.
This season, for the first time, three new varieties with TSWV resistance were released: "Amelia," also known as HMX 0800, from Harris Moran Seed Company; "BHN 640," an improved BHN 444 from BHN Genetics; and "503," from Seminis Seed Company.
These varieties are generally only available in large seed quantities. So gardeners will find it easier to buy plants than seed.
However, in 2002, TSWV was detected to some degree in resistant varieties. The resistance in these varieties is from a single dominant gene. In layman's terms, this means that the resistance can more easily be broken by the virus than if it were a multi-gene resistance trait.
Fragile resistanceThe resistance in all of these varieties is the same. Therefore, when resistance is broken in one it will likely be broken in all of them.
What does this mean? Primarily it means the resistant tomatoes available right now will probably only buy growers a little time before TSWV overcomes this resistance.
In the meantime, we can hope that other types of resistance can be found.
Other than TSWV-resistant types, there still are an abundance of tomato varieties available.
Two companies that specialize in tomatoes include Tomato Growers Supply Company (www.tomatogrowers.com) and Totally Tomatoes (www.totallytomato.com). In all likelihood, if it's a variety that has been grown to any extent in gardens over the past 100 years, you'll find it in one of these catalogs.
Heirlooms, novelties, hybridsThis is not to say you can't get many of the same varieties from other companies. And some have excellent proprietary varieties only they can sell. However, those specializing in tomatoes have a long list of heirloom and novelty varieties, as well as many hybrids.
For instance, have you ever heard of a white tomato? "White Beauty" is only one of several white varieties available. "Cherokee Purple" has dusky, rose-purple fruit. "Green Zebra" is amber green with dark green stripes when mature. "Hillbilly" is a huge, bicolored tomato that has yellow-orange skin with red streaking.
There are many beefsteak varieties, oxhearts, brandywines, paste and grape tomatoes, too, and many imported from other parts of the world.
'Mortgage Lifter'Remember "Abraham Lincoln" (the tomato, not the president)? It was introduced in Illinois in the 1920s. "Mortgage Lifter" is a variety Uncle Joe used to grow. Legend has it that the first farmer that grew it sold enough tomatoes to pay off his mortgage.
There's a difference between garden varieties and shipping tomatoes. The ones for commercial growers have been bred for shipping (including all TSWV-resistant varieties). They will stay firm longer than garden varieties. But tomatoes will almost always taste better when picked vine-ripe.
Whether you're looking for an old favorite, something with disease resistance or just a novelty, though, there is a tomato out there for you.
(Terry Kelley is a former University of Georgia Cooperative Extension horticulturist with the UGA College of Agricultural and Environmental Sciences.)