Mortensen Hardy Bunch Grapes
By Bob Randall, Ph.D.
Spring 1998
In our area, it is very hard to grow the well-known seedless bunch grapes (the European species vinifera) found abundantly in our supermarkets. Red Flame, Thompson seedless, and the famous wine grapes all die quickly. This is because the hot and humid south hosts a number of diseases that attack and kill them. The worst two of these are anthracnose and Pierce’s Disease (PD).
In Houston, a bunch grape variety usually dies before it fruits. Sometimes, it has one or two good years before it dies. At best, we grow bunch grapes like short-lived perennials by taking cuttings and replanting frequently.
One answer to this is to grow improved versions of native, disease resistant southern grapes: either the hybrid “Scuppernong” type muscadines or the Munson hybrid Texas grapes. There are dozens of delicious varieties (such as Fry) with very large berries ripening one by one, a few seeds, thick skins, and flavors that make market grapes seem tasteless by comparison.
But they don’t exactly replace the thin-skinned, seedless bunch grapes, in part because the muscadines ripen in August and September while the bunch grapes ripen in June and July. So for a century, Deep South researchers, vineyard owners, farmers and hobbyists have been trying to find a bunch grape that survives and is good for table or wine.
One such effort may finally have produced results. In 1986, Professor John A. Mortensen of the Central Florida Research and Education Center at Leesburg, Florida sent Leon Atlas, MD, of Houston a large number of cuttings of experimental bunch grape crosses he had created in an effort to produce a good, disease hardy, table bunch grape for Florida. Dr. Atlas shared some of these cuttings with me, Ethan Natelson, MD. and others. Atlas, Natelson, and I grew these numbered experimental varieties. Of the number ones, BD 12-49 is still growing well at all three sites 12 years later, and E 1863 is still alive at Ethan’s. They are good golden green grapes.
According to Dr. Mortensen’s records, Florida BD 12-49 is a large-berried, light green selection with resistance to PD and good fresh fruit quality, though seeded.” It is a cross of a PD resistant Fla. E9-48 (created by Dr Mortensen from crossing Leesburg varieties Norris and Blue Lake) times a PD susceptible Arkansas 1105 (created by J.N. More at the Univ. of Arkansas Clarksville from Lakemont and Dr Robert Dunstan’s Carolina Blackrose).
On its own roots, my BD 12-49 is extremely vigorous. It often sends out 10 ft. or more of growth and when I have been careless it has climbed trees. In my experience, it is highly disease resistant, gets an occasional touch of anthracnose on a few leaves, but has no dieback -ever. It is tasty and sweet, and is large sized (3/4 inch, 4 grams per berry, 7 grapes per oz.), with only two seeds.
About two years ago, when my last E 1863 died, George McAfee and I began an effort to compare the survivor BD 12-49 with other bunch grapes in the area. I asked various fruit growers what they thought. So far, the few who have seen it, tasted it or grown it have been impressed. And I haven’t found any other disease hardy bunch grape near it in quality or vigor.
But I wasn’t prepared for what happened as a result of this effort. This summer, Dr. Natelson declared that his BD 12-49 was significantly smaller in berry size, was less tasty, and had a somewhat different shape than my BD 12-49. Naturally, I suspected a labeling mishap, so in an effort to clear up the mystery, I wrote Dr Mortensen. He replied that:
1) BD 12-49 was one of his better selections for fresh fruit. It was never released, but a grower strongly recommended it for backyard planting.
2) It was never released or patented because it is susceptible to parasitic nematodes in sandy soils. Nematode resistant rootstocks make a leaf and stem anthracnose problem much worse.
3) Because the Randall BD 12-29 grape has a 4-gram, 3/4 inch berry, it is not any of the varieties Professor Mortensen sent Dr. Atlas. Mortensen suspects that it is a Houston originating tetraploid bud mutation of BD 12-49 with 76 chromosomes instead of the usual 38. It is not, therefore, the original BD 12-49.
The next step is obviously to test the grape more widely. It is already at Harris and Ft. Bend County Extensions, and at the Old Sixth Ward Teaching Garden.
It may be that, like its parent, this grape will do poorly in sandy soil. And of course, when grown more widely, it may not survive the disease tests. Nevertheless, it is very promising. Since it isn’t BD 12-49, it needs a new name. With Dr. Mortensen’s consent, I am calling it Mortensen Hardy in honor of the man who did 99% of the work to develop it. Let’s hope it really is hardy.
