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T o p a z’ S w eet Pota to
D.R. Paterson1 and D.R. Earhart2
Texas A&M University Agricultural Research and Extension Center,
Overton, TX 75684
was susceptible to soil rot (Pox) caused by
Streptomyces ipomoea (Person & W. J. Mar
tin) Waks. & Henrici. This cultivar was early,
uniform in emergence, and had good plant
production in sprouting trials. ‘Topaz’ is
similar in dry matter and yield to ‘Jewel’.
Av a ilab il ity
T.E. Boswell1
Texas A&M University, Plant Disease Research Station,
Yoakum, TX 77995
Addition al index words. Ipomoea batatas, vegetable breeding, disease resistance, insect
resistance, root knot nematode, fusarium wilt
Foundation planting stock in limited quan
tities will be available commercially for the
1987 crop season. Requests for roots should
be made to the Foundation Seed Service,
Texas A&M Univ., College Station, TX
77843.
The ‘Topaz’ (Fig. 1) sweet potato [Ipom
oea batatas (L.) Lam.], developed by the
Texas A gricultural Experiment Station,
combines high yield good sprout production,
and excellent baking and canning quality.
Or igin
‘Topaz’, previously tested as 8W2641,
originated as an open-pollinated seedling of
W-26 polycrossed at the U.S. Vegetable
Laboratory, ARS/USDA, Charleston, SC
29407 in 1973 with other parental types de
veloped for multiple disease and soil insect
resistances. W-26 was from the fifth gener
ation of mass-selection population I. Seed
lings from which ‘Topaz’ was selected were
evaluated by us.
De sc ription
The vines of the ‘Topaz’ are trailing with
medium intemodes. Stems and leaves are
green. The leaves are medium in size and
generally heart-shaped. The roots have good
girth and are slightly tapered at each end.
They have a medium orange flesh color and
a smooth, bronze, skin color. ‘Topaz’ was
third in U.S. No. 1, fourth in marketable,
and fifth in canning grade yield of roots among
eight entries tested by the National Sweet
Potato Collaborators Group at 16 locations
in 1982 (Table 1). In 1983, of 6 entries in
the replicated trials at 19 locations, ‘Topaz’
was first in U.S. No. 1 and marketable grades
and third in canning grade of roots (Table
1). ‘Topaz’ rated better than the check cul-
tivars in baking but not in canning quality.
‘Topaz’ was found to be resistant to both
fusarium wilt (stem rot), caused by the soil-
borne fungus Fusarium oxysporum f. sp. ba
tatas (Wr.) Synd. & Hans., and to southern
root knot (Meloidogyne incogn ita). ‘Topaz’
was susceptible to the wireworm-Diabro-
tica-Systena (WDS) complex. Intermediate
resistance to the sweet potato flea beetle
(SPFB) was noted in this cultivar. ‘Topaz’
Received for publication 4 May 1987. Texas Ag
ricultural Experiment Station Scientific Journal
Series no. 21195. The cost of publishing this pa
per was defrayed in part by the payment of page
charges. U nder postal regul ations, this paper
therefore must be hereby marked advertisement
solely to indicate this fact.
Pro fes sor
2Research Associate
Table 1. A 2-year comparison of yields and quality of ‘Topaz’, ‘Jewel’, and ‘Centennial’ sweet potato
cultivars from 1982 and 1983 National Sweet Potato Collaborators regional trials in 16 states.
Yield ( t-ha -1)2
Year and
cultivar U.S. no. 1 Canning
Total
marketable
Canning
scorey
Baking
scorey
1982
Topaz 19.1 ax 7.2 a 29.4 a 74.1 75.9
Jewel 14.2 a 7.8 a 24.8 a 76.3 75.5
Centennial 17.9 b 6.6 a 27.3 a 77.3 73.1
1983
Topaz 17.0 a 7.2 a 26.8 a 74.1 75.9
Jewel 15.6 a 6 . 1 a 24.2 a 76.3 75.5
Centennial 14.6 a 7.8 a 23.1 a 77.3 73.1
z States include Alabama, Arkansas, California, Georgia, Kansas, Louisiana, Maryland, Missouri, New
Mexico, New York, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia;
t-ha-1 x 0.446 = U.S. tons per acre.
y Rated in a scale of 0-1 00 for each o f 10 characters—the higher the score, the better the quality.
Average of seven baking and canning trials in 1982 and six baking and canning trials in 1983.
x Mean separation in columns within years by Duncan’s multiple range test, 5% level.
Fig. 1. Roots of ‘Topaz’ sweet potatoes.
