• A total of 28 breeding lines and reference cultivars were evaluated at the Caddo Research Station for agronomic characteristics and soilborne diseases (Sclerotinia blight and pod rot).
• The six-entry runner trial included Lariat, FloRun ‘107’, Southwest Runner, ACI 509, IPG517and one USDA-ARS breeding line. The 14-entry Spanish/Valencia trial tested four Spanish and one small-seeded runner breeding line from USDA-ARS, six Valencia breeding lines from New Mexico State University, and cultivars IPG 1288, OLé, and TAMVal OL14. The Virginia trial evaluated eight entries: Jupiter, Comrade, Bailey II, Emery and four breeding lines from USDA-ARS.
• The 28-entry disease trial was planted on June 21 and dug 136 days after planting (Nov. 3), accumulating 2,823 growing degree days (GDD) in Fahrenheit. The season was marked by above-average temperatures for August and September (both 3 degrees above the 15-year mean). Compared to the 15-year average for rainfall, June and July experienced more, while August and September had less. Moderate to moderately high levels of Sclerotinia blight were observed in the runner and Virginia genotypes, but little pod rot was observed in this trial. The field also had high levels of parasitic nematodes.
• Moderately low levels of pod rot were prestent in the Virginia pod rot nursery.  Jupiter and the susceptible genotype PI 378012 gad 21% and 28% pod rot, respectively.

 

A major goal of the ARS peanut research program in Stillwater is to develop and release high-oleic peanut cultivars for the Southwest with improved yield, disease resistance and seed characteristics. In 2023, we evaluated commercial and advanced breeding lines of runner, Spanish/Valencia and Virginia peanuts in small plots at Oklahoma State University’s Caddo Research Station in Fort Cobb. The objectives of these field studies were:

1. To compare advanced breeding lines to commercially available cultivars for resistance to Sclerotinia blight and agronomic characteristics, such as yield, seed, and pod qualities.
2. To evaluate a selection of Virginia entries for pod rot resistance in a field where soilborne levels of the pathogens causing peanut pod rot were promoted by planting susceptible genotypes the previous year.

 

Methods for Evaluating Advanced Breeding Lines and Cultivars

A total of 28 breeding lines and reference cultivars (6 runner, 14 Spanish/Valencia and 8 Virginia market types) were evaluated. Runner and Virginia peanut market types were each grown and evaluated separately, but Spanish and Valencia entries were combined in the same field and analyzed together. All advanced breeding lines were high oleic. Each entry was planted at a density of 5 seeds/ft in plots consisting of two 15-foot-long rows with 36-inch-wide beds. A randomized complete block design was used by dividing the field into four sections (blocks) to account for potential disease gradients and environmental variables. All plots were planted approximately one month later than normal (June 21) to ensure green foliage was available for late-season development of Sclerotinia blight. All plots were inverted on Nov. 3, 136 days after planting, and threshed on Nov. 6, 2023.

 

Additional water was applied to all plots 14 times (total 9.95”) between June 30 and Oct. 4, using a center pivot system. Each row in the two-row plots was inoculated with 0.5 grams of Sclerotinia minor sclerotia on Sept. 12. Fields were managed for weeds, foliar diseases and southern blight (caused by Agroathelia rolfsii) following Extension recommendations but were not managed for Sclerotinia blight, pod rot or nematodes. Entries were evaluated for Sclerotinia on Oct. 13. Disease incidence was measured by counting the number of 6-inch sections within each plot that had symptoms of Sclerotinia blight. On Aug. 21 and Oct. 10, approximately 20 soil cores were collected near the taproots from the four plots planted with Jupiter for nematode counts. All plots were examined for pod rot on the same day the plants were inverted.

 

Peanut grades were determined following USDA-Agricultural Marketing Service guidelines, using two 200-gram samples from each plot. Two 500-gram samples per plot were used to determine pod sizes in the Virginia entries. Yield was adjusted by factoring in the area lost by plots in the path of the center pivot wheels. Data were analyzed using one-way ANOVA in PROC GLIMMIX of SAS (ver. 9.4)

 

The Type I error rate for pairwise comparisons of breeding lines and cultivars was controlled at ɑ = 0.05 using the ADJUST=TUKEY option. Crop value for each market type was calculated using the following 2023 contract prices per ton: $650, runner; $950, Valencia; $700, Spanish; and $725, Virginia.

 

The pod rot nursery was planted on June 21 to reduce the number of volunteers, and plots were dug and rated for pod rot on Oct. 17.

 

Summary of 2023 Field Conditions

A total of 2,823 growing degree days in Fahrenheit accumulated for the 2023 disease trial. The season was characterized by above-average temperatures for August and September (+3F from 15-year mean), above-average rainfall for June and July, and below-average rainfall for August and September (Table 1). Cooler evening temperatures in October favored the development of Sclerotinia blight. Little southern blight and pod rot were observed. The nematology lab at Oklahoma State University found 331 ring and 20 root-knot nematodes per 100 cc (=3.4 oz.) of soil in the Aug. 21 samples. By Oct. 10, there was an average of 910 ring and 1,050 root-knot nematodes per 100 cc of soil (Kelli Black and Nathan Walker, pers. communication) – numbers considered to be very high levels of infestation for both nematodes.

 

Performance of the Siz Runner Market-type Entries

• Runner entries with the highest yield (≥4,584 lbs. per acre) and crop values (≥$1,049 per acre) were South-west Runner, ARSOK R109-1 and Lariat (Table 2). Average seed grade varied among entries from 61% to 72%.
• Moderately high levels of Sclerotinia blight were observed in mid-October, and the most resistant entries included Southwest Runner (<1%), Lariat (9%) and ARSOK R109-1 (12%).
• Three-year averages were calculated for four entries (Table 3), but plots from 2021 and 2022 were in the field 30 and 12 days longer, respectively, than in 2023. Lariat, Southwest Runner and ARSOK R109-1 had similar yields. Seed grade for Lariat was higher than FloRun ‘107’ and Southwest Runner but not significantly different than R109-1. Southwest Runner had more resistance to Sclerotinia blight than FloRun ‘107’ and R109-1 but was similar to Lariat in resistance.

 

Performance of the 14 Spanish/Valencia Market-type Entries

• OLé and ARS small-seeded runner breeding line ARSOK R58B had the highest numerical yields (4,811 and 4,244 pounds per acre, respectively; Table 4). Yields among Valencia market-type entries were statistically similar.
• Crop value was highest for all Valencia market type entries except NM310 due to the higher contract price for Valencia. Within the Valencia entries, NM16-17 had the highest numerical yield (4,039 lbs/A), and IPG 1288 had the best grade at 72%.
• OLé had the highest yield of the entire Spanish/Valencia trial at 4,811 lbs/A. The small-seeded runner, AR-SOK R58B, was among the highest yielding (4,244 lbs/A) and had the best grade at 74%.
• Minimal Sclerotinia blight (<2%) was observed except in IPG 1288 which had 38% disease.
• OLé had the highest numerical yield among the seven entries evaluated for the past three years (Table 5). Few differences in seed grade were observed, and the entries had little Sclerotinia blight.

 

Performance of the Nine Virginia Market-type Entries

• Among the Virginia entries, ARSOK V99 had the highest crop value ($1,120/A; Table 6) and the highest numerical yield (4,537 lbs/A).
• Average seed grade was relatively low, ranging from 65% to 68% but did not differ significantly among entries. ARSOK entries V98, V99 and V103-1 had the lowest levels of Sclerotinia blight (<11%), while Emery was the most diseased (39%).
• Entries differed significantly in number of pods per ounce (Table 6) and pod size distribution (Figure 1). ARSOK V103-3 (81%) and Comrade (75%) had the largest percentage of super jumbo pods by weight.
• Over the past three years, ARSOK V99 had the highest numerical yield (4,400 lbs/A) and the least amount of Sclerotinia blight (6%; Table 7). Seed grade was highest in Comrade and ARSOK V99 (69 and 68%, respectively)

 

Pod Rot Nursery

In 2023, moderately low levels of pod rot were observed in the pod rot nursery (Table 8). The susceptible control PI 378012 and Jupiter had above 20% pod rot. Comrade had intermediate levels of disease (11%), and all other entries had 5% or less pod rot.

 

Acknowledgements

We thank Angie Harting, Lyndsey Aguirre, Kyren Bunyard, Amna Dar and Macy Koch at USDA-ARS, and Robert Weidenmaier, Harley Houston and Brennan Leighton at the Caddo Research Station for invaluable technical support. Kelli Black and Nathan Walker provided nematode counts. Seeds for several commercial lines were originally provided by Birdsong, Hampton Farms and the International Peanut Group. New Mexico State University breeder Naveen Puppala provided additional Valencia breeding lines. This research is supported by USDA-ARS Current Research Information System (CRIS) Project No. 3072-21220-009-00D, the Oklahoma Peanut Commission, the National Peanut Board and OSU Ag Research. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. The USDA is an equal opportunity provider and employer.

 

Tables

• Table 1
• Table 2
• Table 3
• Table 4
• Table 5
• Table 6
• Table 7
• Table 8