John Baldwin and John Beasley, Extension Peanut Agronomists
Choosing a variety to plant seems to be getting more complicated and could be even more so in the future with varieties of peanut with variable disease resistance, maturities, unique characteristics and specific marketing options. Several new varieties have been released but have not been in official UGA variety trials for at least three years at multi-locations. The following information may be helpful when growing different peanut varieties in the Southeast.
When evaluating the choice of a variety, there are several considerations that must be kept in mind. Good yield and grade over a wide range of conditions are usually the most important. They determine the gross return for the crop. The following tables present the yield data and other characteristics of many varieties grown at three locations in Georgia. Consistency of yield are important across locations but environmental, disease, rainfall, and irrigation factors can affect how a variety responds. The ultimate test will be how it responds statewide when growers plant sufficient acreage under many environmental and managerial conditions. When you review the tables, note that average yields presented may include only one or two years of data for some varieties. When comparing averages, be sure the same years are represented.
Some of the many factors that could influence the decision as to which variety to plant are discussed below. After evaluating those factors that apply to a particular field or farm, the next step would be to study the characteristics of the available varieties and make the appropriate selection.
If irrigation is available, most of the varieties should respond favorably. However, if irrigation is not available, there could be a greater risk in growing one of the early maturing runner varieties or a Virginia variety rather than a medium or late maturing runner variety because short term droughts could be more damaging to yield and grade.
Many producers plant all or a portion of their acreage under contract for seed increase of either Registered or Certified seed. A contract seed grower would grow a specific variety, while an independent grower would need to select the variety or varieties likely to be in demand by potential buyers. Also, there are seed certification standards that require certain time intervals between peanut crops if different varieties are grown in the same field. Do not risk loss of the seed premium by failure to follow the seed certification standards. For instance, a mixture of a late maturing variety such as Southern Runner with other varieties could result in difficulty in determining maturity. This not only would result in lower yields but also produces lower germinating seed due to immaturity. The new "High O/L" varieties such as the SunOleic and others will present an even greater problem for the seed grower in that fields as well as equipment must not have mixtures of these and other varieties due to the unique oil chemistry of the high O/L peanuts.
The presence or expected presence of certain diseases or nematodes, or the capability of control or reduction through the use of pesticides or rotations, may influence variety selection. Southern Runner has moderate resistance to late leafspot and usually shows fewer loses to white mold or infection to tomato spotted wilt virus. It could be a good choice in such situations; however it is a late maturing variety under most Georgia conditions and may also be more prone to damage from peanut root knot nematode where fields are moderately to heavily infected. Georgia Green has a similar resistance to tomato spotted wilt virus. This disease has become increasingly more prevalent in Georgia since 1986. Andru 93 and Marc I may be more susceptible to leafspot damage if the fungicide spray program does not start early and stay on schedule. These two varieties respond better under longer rotations where leafspot pressure is less severe.
In some years premiums might be paid for early delivery of peanuts. If such premiums are offered, the early maturing varieties such as Andru 93, Marc I and possibly others might be selected. Preliminary findings indicate AT-108 and ViruGard tend to be earlier maturing than GK-7. If an early Virginia variety is desired, NC 9 or NC-V11 might be selected.
The normal planting period for Georgia peanuts is April 15 - May 20, with a few south Georgia counties being able to plant slightly earlier. And in all areas some plantings may be made in late May or early June following small grain harvest. Soil temperatures should be watched and monitored carefully in each field and proper planting depths followed for different soil types no matter what the variety planted. An early planting of an early maturing variety could result in harvest starting in early to mid-August in some years. Rainfall is usually more frequent in August than in September and could interfere with harvest. Also, Southern Runner seed does not germinate quickly with early planting in cool soils, while late planting could result in maturity being slowed by cool weather in late October or early November. Thrips are often damaging to early planted peanuts, while TSWV severity is more common in either very early or very late plantings. Rust and leafspot diseases will be more damaging to late peanuts than to early peanuts.
Another area where maturity is a factor is in harvesting efficiency. By planting varieties with different maturities, the harvest period can be extended, thereby increasing the utilization of harvesting and drying equipment. For example, planting an early, mid, and late maturing variety at about the same time could extend the harvest season over several weeks. This approach to better utilization of harvesting and drying equipment would probably be more desirable than having an extended planting period because weather conditions can greatly affect the planting schedule. If planted at longer intervals, the growing conditions during the season could have more effect on maturity than the varieties themselves.
Since seed are a substantial part of the cost of growing peanuts and replanting is expensive, it would be better to plant a variety that is available in satisfactory quality rather than risk stands and yield with poor quality seed, even if it would normally be the most desirable variety.
Several publications are available from your local county extension office that describe individual varieties in detail and also provide summaries of yield, grade, and characteristics of each.
This is a brief description of peanut varieties with the high oleic acid chemistry which makes these peanuts unique from other currently grown varieties. The first of these released was SunOleic 95R from the Florida breeding program. The main difference is the components of the fats or oil in this type of peanut. The percentage of oil is similar to our currently grown varieties (48-49%) however the fatty acids making up the fat in the oil is different. The main focus on these selections is to extend the shelf-life and storability of peanuts and products made from these peanuts. The high oleic peanut contains about 80% oleic fatty acids, compared to about 50% in most peanut varieties. They contain about 2-3% linoleic fatty acid. Oleic fatty acids are monounsaturated, while linoleic fatty acid is polyunsaturated. The key difference is that monounsaturated fats are significantly less susceptible to oxidation than polyunsaturated fats. Oxidation is the main cause of rancidity in peanuts. Peanuts and peanut products with the high oleic chemistry are expected to have a shelf life five to ten times longer than that of other peanuts. Florida has approved the release of SunOleic 97R and grew some 250 acres of Foundation seed in 1996. The variety is designed to replace the previously released SunOleic 95R. In Florida, tests in 1993-1995, the SunOleic 97R had a 14% yield advantage over SunOleic 95R and a 9.9% yield advantage over Florunner. Grades in 1993-1995 were equal to Florunner and superior to SunOleic 95R. Other universities and private companies are also looking at this chemistry and are in the process of developing varieties with either mid or high oleic acid composition. Flavor Runner 458 was released by Mycogen company in 1996 as another high oleic variety. More information will be available as these varieties are tested. There are going to be tremendous opportunities in the future in varietal development which should produce higher quality and more pest resistant cultivars, as well as helping to create better demand for our products. High Oleic GK-7 is to be available in limited quantities during 1998.