Georgia Green, the new runner-type peanut cultivar from the University of Georgia, has sparked a lot of interest among peanut growers. Georgia Green combines less vegetative growth and similar maturity (compared to other popular runner-type cultivars), and excellent yield potential, with resistance to tomato spotted wilt virus. In 1996 and 1997, Georgia Green performed very well in terms of yield, grades and suppression of spotted wilt epidemics. In fact, the performance of Georgia Green with regard to spotted wilt suppression was even better when this cultivar was grown in the larger plantings in growers' fields than previously observed in small plot tests. This is encouraging, not only in terms of the use of Georgia Green, but also in light of new breeding lines that have potential for release as cultivars and the impact that may be expected from planting sizable acreage to TSWV-resistant cultivars. Virugard is a new large-seeded runner type peanut cultivar from Agratech. We have less information on this cultivar than on Georgia Green, but in field tests at the Coastal Plain Experiment Station in 1997, incidence of spotted wilt and yield in Virugard was very similar to those in Georgia Green. Virugard had incidence of spotted wilt that was approximately half that of Georgia Runner. In our tests, Virugard took less time to mature than did either Georgia Green or Georgia Runner. FL MDR 98 (Previously UF 91108) from the University of Florida, is a new large seeded runner-type cultivar with multiple disease resistance. In addition, it has a higher level of oleic acid in its oil composition than most cultivars. Although the level is not high enough to class MDR 98 as "High Oleic", it is considered a "Mid-Oleic" peanut. Any new release requires some education on the part of researchers, extension personnel, consultants and growers to deal with characteristics that are unique for that particular cultivar. The following are some of the most frequently asked questions and some anticipated questions about Georgia Green, Virugard, and MDR 98, particularly as related to use of these cultivars for disease management.

Question: Southern Runner, Georgia Green, Virugard, and FL MDR are described as being resistant to tomato spotted wilt virus. Does this mean if you plant these cultivars you won't have any spotted wilt?
Answer:No. Not one of these cultivars is immune to TSWV. All four have a good moderate level of resistance to tomato spotted wilt virus, but in extremely heavy disease pressure situations, even these cultivars can be damaged by spotted wilt. Combining the use of Southern Runner, Georgia Green, Virugard, or MDR 98 with practices such as avoiding early or late planting dates, establishing good plant stands, and the use of phorate insecticide is strongly encouraged. (See the TSWV Risk Assessment Index.) Subsequently, use of reduced seeding rates to "stretch" the available seed of these cultivars or use of lower quality small (high count) seed may result in sparse stands that will be an invitation to trouble with spotted wilt, even with this cultivar. The larger seed size with Virugard also may complicate stand establishment in some situations. More attention should be paid to number of seed planted per foot than pounds per acre.

Question:: How resistant are these cultivars?
Answer: Southern Runner, Georgia Green, Virugard and MDR 98 appear to be similar in their reaction to TSWV. Typically, incidence of spotted wilt in any of the four has been about half that in Florunner or Georgia Runner. In addition, plants of these cultivars that are infected, generally tend to be less severely affected than Florunner or Georgia Runner.

Question: Is the lower incidence of spotted wilt in these cultivars due to resistance to thrips?
Answer: No. The preponderance of our data indicates that Southern Runner, Georgia Green, Virugard, and MDR 98 are just as attractive to thrips, and just as good a host for thrips reproduction as any of the other cultivars evaluated.

Question: These cultivars have resistance to spotted wilt. Are they resistant to fungal diseases as well?

Answer: Georgia Green and Virugard do not have significant levels of resistance to either early or late leaf spot, white mold or Rhizoctonia limb rot. Therefore, fungicide requirements for both foliar disease control and soilborne disease control will be the same as those of other popular runner cultivars such as Florunner, Georgia Runner or GK-7. Use of Georgia Green has resulted in better yield response to full-season fungicide applications for soilborne disease control than other available cultivars. Therefore, use of this cultivar may increase the return on investment for fungicides in some fields, depending on overall disease pressure. Response or Virugard to varying fungicide input is being determined. As with other available cultivars, it is essential to initiate fungicide applications BEFORE epidemics of these fungal diseases begin. Southern Runner and FL MDR 98 have moderate levels of resistance to late leaf spot, and white mold. Southern Runner is susceptible to Rhizoctonia limb rot. The susceptibility of MDR 98 to this disease is not well characterized. Both of these cultivars do require fungicides for disease control, but may require less fungicide for leaf spot control and white mold control than other available cultivars.

Summary: These cultivars offer a good level of resistance to spotted wilt. However, none of these cultivars is a "magic bullet" that will solve all of our production problems. For best results from any of these cultivars, growers are encouraged to follow sound cultural and management practices. The new cultivars, Georgia Green, Virugard, and MDR 98 should be very valuable additions to our peanut production system, particularly in those areas that have been hardest hit by tomato spotted wilt virus.

For more information on any of these or related topics, feel free to contact Albert Culbreath by phone (912) 386-3370, fax (912) 386-7285 or email (spotwilt@tifton.cpes.peachnet.edu).