Tomato Spotted Wilt Virus: TSWV of Peanut: Management
TSWV of Peanut
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Marianna NFREC Research Report 99-2
C-99R: A New Multiple Disease Resistant Peanut Cultivar
D. W. Gorbet, F. M. Shokes, A. K. Culbreath, J. W. Todd, and E. B. Whitty
Disease resistance has become even more important for peanut production in the USA and around the world. Breeding for multiple disease resistance has been a primary objective for the peanut breeding program of the University of Florida Agricultural Experiment Station and continues to receive major effort. Current emphasis addresses breeding for resistance to late leafspot (Cercosporidium personatum), white mold/stem rot (Sclerotium rolfsii), tomato spotted wilt virus (TSWV), Cylindrocladium black rot (CBR), and several others to a lesser extent. TSWV has become the most critical due to its widespread impact in the Southeastern production area.
‘Southern Runner’ (SR) was the first cultivar released (1986) from the Florida program with documented multiple disease resistance, namely late leafspot, rust, web blotch, white mold, and TSWV. SR was used as a parent of ‘Georgia Green’, which has been widely grown in the Southeast, primarily due to its resistance to TSWV. ‘Florida MDR 98' was released in 1998 with the same “disease resistance package” as SR, but with better levels of resistance, yields, and grades. The source of TSWV and late leafspot resistance in MDR 98 is the same as with SR (PI203396).
C-99R is the third peanut cultivar released (1999) from the Florida program with documented multiple disease resistance. This is the same “disease resistance package” and maturity as SR and MDR 98.
C-99R was tested as UF94320 or F84x9B-4-2. The cross that produced C-99R was made at Marianna in 1984, with emphasis on leafspot resistance and yield. The parents were UF81206- 1 and F72x32B-13-1-3, both of which are Florida breeding lines that have not been released. UF81206-1 is a selection from UF81206 that has very good resistance to late leafspot, white mold, and TSWV. UF81206 originates from the cross PI203396 x F427B-3-1-7-4. The male parent (72x32B-13-1-3) came from the cross PI259785 x Florigiant. PI259785 has resistance to late leafspot and TSWV. All selections for C-99R (F2-F7) were made under unsprayed (leafspot) conditions at Marianna with selection emphasis on leafspot resistance and good agronomic type. Seed from two F7 plant selections were bulked for initial yield tests in 1992 (unsprayed).
Data from multiple sites and states have shown C-99R to have good yields and grades with multiple disease resistance. Results indicate resistance to late leafspot, white mold, TSWV, rust and possibly others. Table 1 gives the pod yields, grading data and disease ratings for C-99R compared to SR and Florida MDR 98 in ten unsprayed (leafspot) Marianna tests (1993-98). Even with somewhat higher disease ratings (5.9 vs. 5.1 and 4.5) than SR and MDR 98, C-99R produced slightly better pod yields (3449 lbs/A). The TSMK value for C-99R (80.4%) was between SR and MDR 98. The ELK and 100-seed weight data indicate that C-99R has seed similar in size to MDR 98.
Further data on C-99R from Florida leafspot tests are shown in Table 2. These studies were conducted comparing unsprayed and a four-spray fungicide program for leafspot control. The four-spray treatment was a Bravo-two Folicurs-Bravo program on a 21-day schedule, beginning at 55-60 days after planting. Pod yields at Marianna indicated that C-99R performed very similar to Florida MDR 98 in these studies, both being better than SR. Gainesville data indicate a clear advantage for C-99R over SR and Florida MDR 98, based on pod yields. C-99R produced pod yields exceeding 3600 lbs/A with no fungicide for leafspot control in all tests. Grading data for C-99R indicated that it has large runner seed, similar to MDR 98 with SMK values between SR and MDR 98.
TSWV resistance has become very critical for peanut cultivars grown in the southeastern production area. Table 3 gives data on studies conducted at Marianna (Florida) and Attapulgus (Georgia) during 1994-95 growing seasons. Both locations had high disease pressure from TSWV in these tests. C-99R was significantly better than all other genotypes for disease incidence at Marianna and was generally equal to or better than the other resistant entries at both locations for TSWV incidence and intensity. C-99R produced significantly higher pod yields than all other entries at Marianna and significantly better than Florunner and NC V11 at Attapulgus in 1995.
Table 4 gives further data on TSWV studies with C-99R. The studies were conducted at Marianna and Tifton (1998) and Attapulgus (1997), Georgia. Additional breeding lines were in these tests but only the C-99R data is shown, compared to the checks (Georgia Runner - susceptible, and Georgia Green - resistant). Pod yields and disease data shows that C-99R was significantly better than Georgia Green.
Further evaluations for TSWV resistance were conducted at Marianna and Gainesville with plant spacing and planting date comparisons. Table 5 gives pod yields, grades, and disease ratings for these studies comparing C-99R to SR and Florunner (1996-97). These studies were irrigated and sprayed full season for leafspot. C-99R shows a clear yield and disease resistance advantage for both plantings and all spacings in the Marianna tests. The yields were better and disease level lower at the May vs. April plantings. In the May plantings, C-99R produced over 6200 lbs/A at the 3-inch spacing and about 5000 lbs/A for the 12-inch spacing. C-99R generally produced over 2000 lbs/A more than Florunner in all comparisons at Marianna. Differences in the Gainesville tests were not as great but still favored C-99R. The Gainesville tests had very little TSWV.
Further data on Gainesville tests are given in Table 6. These data indicate further that C- 99R would be a better cultivar choice for that part of Florida, with better pod yields than MDR 98. It should be noted that C-99R has the potential to produce even more jumbo runners (i.e., ELK values) in the sandy soils of the Gainesville and north central Florida area.
Table 7 gives results from studies that were inoculated with S. rolfsii about 45-50 DAP to produce white mold/stem rot. Prior studies have shown SR and MDR 98 to have good resistance to white mold. These data indicate that C-99R is equal to MDR 98 in resistance. Further evidence of this is noted in Table 8 and comparisons made to Florunner and Georgia Green. These studies were 4-row plots with two rows inoculated with S. rolfsii and two rows uninoculated. The resistance is even more evident when comparing C-99R to the susceptible Florunner and weaker resistance of Georgia Green.
Data for C-99R from reports of the Uniform Peanut Performance Tests for southeast tests are noted in Table 9. C-99R had better pod yields than Florunner (check) in all tests but one (Jay, 1997). Grades were very similar to Florunner and seed size was much larger.
Table 10 gives data on oil quality of C-99R, expressed as percent of palmitic, oleic, and linoleic fatty acids. These are the three most prominent fatty acids in peanut oil and have the greatest effect on oil quality. These data represent analysis of 29 samples. Results from these tests indicate that C-99R has oil chemistry very much like Southern Runner. Further lab data (1995-97) indicate that C-99R has about 51.0% oil and 27% protein, which is similar to Florida MDR 98. Flavor and blanching evaluations are acceptable for C-99R.
Limited data indicate that C-99R may be less susceptible to peanut root knot nematode (M. arenarea) than SR. Further studies are needed.
C-99R should be well adapted to the Southeast production area. The TSWV and multiple disease resistance of this new cultivar should help growers stay in the peanut business. C-99R should give growers a means to cut cost by reducing fungicide inputs. The overall disease resistance of C-99R should help stabilize production.
Foundation seed of C-99R is being maintained by Florida Foundation Seed Producers, Inc. (FFSP). This variety will be protected by a PVP and required to be grown as a class of certified seed. Inquires on production or seed of this variety should be directed to FFSP.
Addresses of Authors:
D. W. Gorbet, University of Florida, North Florida Research and Education Center, Marianna, FL 32446.
F. M. Shokes, University of Florida, North Florida Research and Education Center, Quincy, FL 32351.
A. K. Culbreath, Department of Plant Pathology, University of Georgia, Coastal Plain Expt. Station, Tifton, GA 31793-0748.
J. W. Todd, Department of Entomology, University of Georgia, Coastal Plain Expt. Station, Tifton, GA 31793-0748.
E. B. Whitty, University of Florida, Agronomy Department, Gainesville, FL 32611.