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Copyright 2005, Board of Trustees, University
Institute of Food and Agricultural Sciences
Florida MDR 98 Peanut1
D. W. Gorbet and F. M. Shokes2
Florida MDR 98 is a new runner, market-type
peanut cultivar (Arachis hypogaea hypogaea L.)
released by the University of Florida Agricultural
Experiment Station. MDR stands for disease
resistance. This cultivar has good resistance to late
leafspot, stem rot/white mold, rust and tomato spotted
wilt virus (TSWV), which is essentially the same
disease resistance package as Southern Runner, only
better. MDR 98 has excellent yield potential, grade,
and oil chemistry and should allow growers to lower
fungicide inputs and reduce the risk of loss to disease,
without compromising yield or quality (5).
Florida MDR 98 originates from a cross made in
1984 between Southern Runner (SR) and an F plant,
which was from a cross of Andru 93 and UF81206.
UF81206 has better late leafspot, white mold, and rust
resistance than SR, with some resistance to the peanut
root knot nematode, but the latter is hard to shell and
grades poorly. The cross incorporates some of the
earliness and seedling vigor of Andru 93, in addition
to disease resistance. A pedigree selection program
was followed in the F-F generation under unsprayed
conditions (no leafspot control), and yield testing
began in the F generation. Florida MDR 98 was
initially tested as 84x28-5-4-2-b3-B or UF91108.
UF91108 was first yield tested in 1990 in unsprayed
conditions at Marianna and was entered in sprayed
tests in Marianna and Gainesville, Florida, in 1991.
UF91108 was tested in the Uniform Peanut
Performance Test (UPPT) in all major peanut
producing states in 1993-95. UF91108 was tested in
sprayed and unsprayed tests at multiple locations in
Florida before its release in 1998 as Florida MDR 98
Florida MDR 98 has shown moderate to good
resistance to late leafspot, white mold, and TSWV,
with greater pod yields, larger seed size, and better
grades than SR. MDR 98 has mid-oleic (65+%) fatty
acid oil chemistry, as compared to about 50% oleic for
Florunner (FR) and 80% for SunOleic 97R. Florida
MDR 98 has about the same maturity and growth habit
as SR, but its center stem is usually more prominent
with larger leaflets. The plant foliage color is very
similar to slightly darker green than for SR (5).
1. This document is S-401, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences,
University of Florida. First published April 2000. Please visit the EDIS Web site at http://edis.ifas.ufl.edu
2. D. W. Gorbet, professor, Department of Agronomy, North Florida Research and Education Center-Marianna, IFAS, University of Florida and F. M. Shokes,
former professor, Department of Plant Pathology, North Florida Research and Education Center-Marianna, IFAS, University of Florida, presently Center
Director, Tidewater Agricultural Research and Extension Center, Suffolk, Virginia. The use of trade names in this publication is solely for the purpose of
providing specific information. It is not a guarantee or warranty of the products named and does not signify that they are approved to the exclusion of others
of suitable composition.
The Institute of Food and Agricultural Sciences is an equal opportunitylaffirmative action employer authorized to provide research, educational
information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.
For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension
Service/Institute of Food and Agricultural Sciences/University of Florida/Christine Taylor Waddill, Dean.
Florida MDR 98 Peanut 2
Figure 1 shows a field of Foundation seed
production being inverted in 1998. Plants show
typical runner growth habit with runner market-type
Yield and Quality
The average pod yields, grades, and disease
ratings for Florida MDR 98 in unsprayed field tests
(1990-96) at Marianna, compared to SR and FR, are
shown in Table 1. MDR 98 gave better yield, grade,
and disease resistance than SR, with a 16% yield
advantage. Yields and disease ratings of FR indicate
the high disease pressure in these tests (5).
Data from sprayed tests at Marianna and
Gainesville are shown in Table 2 (1991-96). Florida
MDR 98 showed a yield and grade advantage over FR,
especially at Marianna. Ratings for TSWV were
much lower for MDR 98 than for FR, indicating its
level of resistance to this disease (5). Data from
UPPT results in the southeast (Alabama, Florida, and
Georgia) for 1993-95 indicate a 27% yield advantage
of Florida MDR 98 (UF91108) over FR (1,2).
Results from Marianna field studies that were
inoculated with S. rolfsii (white mold) are shown in
Table 3. MDR 98 had a 44% pod yield advantage over
SR and a 224% advantage over FR, indicating that
MDR 98 has better resistance to S. rolfsii than SR.
Figure 2 shows a plot of MDR 98 compared to FR in
the 1996 test, which shows the much greater disease
present in FR (5).
Florida MDR 98 is a protected variety (USDA
Plant Variety Protection Certificate) and registered to
be sold only as a class of certified seed. Seed
inquiries should be made to Florida Foundation Seed
Producers, Inc., P.O. Box 309, Greenwood, FL
The authors wish to express their appreciation to
Florida peanut producers, the Florida Peanut Advisory
Council and Florida Foundation Seed Producers, Inc.
for financial support for this research. We also want
to thank Dr. Harold Pattee (USDA-NCS), Mr. Walt
Mozingo (VPI-Suffolk), Dr. Albert Culbreath and Dr.
Jim Todd (UG-Tifton), UPPT cooperators (Dr. Bill
Branch, Tifton, Ga. and Dr. Jim Bostick, Headland,
AL), Dr. Ben Whitty and Dr. Sean O'Keefe
(UF-Gainesville), Dr. P.C. Andersen and Ms. Kristen
Hill (UF-Quincy NFREC), M&M Mars (Mr. Charles
Ivy, Dr. Doug Manning, and Dr. L.J. Romanczyk),
and Planters-LifeSavers (Dr. Doug Smyth). Special
thanks go to Wayne Branch, Mike Bordelon, Charlie
Riddle, Charles Bryant, Todd Mathews, Harry Wood,
George Person, Mary Chambliss, Frank Harris and
numerous other temporary helpers that provided
dedicated technical support.
1. Branch, W.D., J.P. Bostick, D.W. Gorbet, T.G.
Isleib, J.S. Kirby, H.A. Peacock, C.E. Simpson,
and O.D. Smith. 1995. Uniform Peanut
Florida MDR 98 Peanut 3
Performance Tests 1994. UGA/CPES Res.
Progress Rpt. No. 5-95, 21 pp.
2. Branch, W.D., J.P. Bostick, D.W. Gorbet, T.G.
Isleib, J.S. Kirby, R.W. Mozingo, H.A. Peacock,
C.E. Simpson, and O.D. Smith. 1996. Uniform
Peanut Performance Tests 1995. UGA/CPES
Res. Progress Rpt. No. 4-96, 24 pp.
3. Culbreath, A.K., J.W. Todd, D.W. Gorbet, F.M.
Shokes, and H.R. Pappu. 1997. Field response of
new peanut cultivar UF91108 to tomato spotted
wilt virus. Pit. Dis. 81:1410-1415.
4. Gorbet, Dan, Leonard Dunavin, Ben Whitty,
Harry Wood, and Fred Shokes. 1999. Florida
peanut variety trials 1993-98. UF/IFAS,
Marianna NFREC Res. Rpt. 99-1. 7 pp.
5. Gorbet, D.W., F.M. Shokes, A.K. Culbreath,
J.W. Todd, and E.B. Whitty. 1998. Florida MDR
98 A new multiple disease resistant peanut
cultivar. UF/IFAS. MariannaNFREC Res. Rpt.
98-3. 6 pp.
Florida MDR 98 Peanut 4
Table 1. Pod yield, grading, and disease data for Florida MDR 98 (from nineteen tests at Marianna, FL) that were not
sprayed for leafspot control, 1990-96.
Yield 100 seed Leaf spot disease
Variety (Ibs/A) %TSMK1 %ELK2 wt. (g) (1-10)3
Fla. MDR 98 3311 81.3 32.9 66.1 4.4
Southern Runner 2847 79.1 9.2 54.4 4.6
Florunner 769 78.6 8.2 55.4 9.5
1TSMK = total sound mature kernels (ride 16/64 inch screen).
2ELK = extra large kernels (ride 21.5/64 inch screen).
3Disease rating 1-10, 1= no disease, 10 = all plants dead from leafspot.
Florida MDR 98 Peanut 5
Table 2. Pod yield, grading, and disease date for Florida MDR 98 from Marianna and Gainesville sprayed (leafspot)
Yield 100 seed TSWV (1-10)
Variety (Ibs/A) %TSMK %ELK wt. (g) Disease1
Marianna (6 tests)
Fla. MDR 98 5282 80.6 35.3 70.0 2.5
Florunner 3968 80.2 14.7 60.2 5.7
Gainesville (3 tests)
Fla. MDR 98 3294 77.7 40.7 ----
Florunner 3167 74.8 20.6 ----
1 TSWV = tomato spotted wilt virus, 1=no disease, 10 = 100% of plot severely infected.
Florida MDR 98 Peanut 6
Table 3. Pod yields and disease ratings for Florida MDR 98 in studies inoculated with S.rolfsii, causing white
mold/stem rot at Marianna (1995-96).
Yield (Ibs/A) Disease (1-10)1
Variety 1995 1996 Avg. 1995 1996 Avg.
Fla. MDR 98 4106 3963 4035 2.8 3.3 3.1
Southern Runner 3107 2512 2810 2.7 4.3 3.5
Florunner 1725 766 1246 6.0 8.7 7.4
1 Disease rating 1-10, 1 = no disease, 10 = 100% infection and plants dying.
Florida MDR 98 Peanut 7
Table 4. Peanut cultivar test results at Marianna, 1997-98.
Cultivar Pod yield (Ibs/A) %TSMK TSWV (1-10)1
Fla. MDR 98 3656 79.2 2.7
Georgia Green 3048 78.5 4.4
Southern Runner 2783 77.2 3.4
Andru 93 2942 77.4 5.8
Florunner 1954 79.4 6.3
1 Disease rating 1-10, 1 = no disease, 10 = 100% of plot severely infected.