TITLE:

Roundup Ready vs. Stacked Gene Varieties Under LEPA Irrigation, AGCARES, Lamesa, TX, 2000.

AUTHORS:

Randy Boman, Mark Kelley, Alan Helm, Tommy Doederlein, and John Farris; Extension Agronomist-Cotton, Extension Assistant-Cotton, Extension Assistant - Cotton, EA-IPM, and CEA-Agriculture.

MATERIALS AND METHODS:

            Varieties:                               Paymaster 2326RR, Paymaster 2326BG/RR, Paymaster 2200 RR, Paymaster 2280 BG/RR, Deltapine 458 BRR, and Deltapine 5415 RR

            Seeding rate:                         15 lb seed/acre - 40" spacing (John Deere Max Emerge vacuum planter)

            Plot size:                                8 rows by variable length (570-915ft long, 0.35 to 0.56 acres/plot)

            Planting date:                       May 10

            Irrigation and rainfall:

                        Irrigation

                                    April:             2.00"

                                    May:               1.50"

                                    June:               0.50"

                                    July:               3.15"

                                    August:         4.05"

                                    September:    2.00"

                        Rainfall

                                    April:             0.30"

                                    May:               0.70"

                                    June:               4.70"

                                    July:               0.80"

                                    August:         0.00"

                                    September:    0.00"

                        Total moisture:         19.70"

            Insect management:            2.5 oz/acre Tracer for beet armyworms on August 2

            Nitrogen management:       Preplant - 30 lb N/acre as 32-0-0

                                                            May 12 - 30 lb N/acre as 32-0-0 

                                                            June 27 - 30 lb N/acre as 32-0-0

                                                            July 21 - 30 lb N/acre as 32-0-0

                                    Total N:         120 lb N/acre fertigated 32-0-0

            Harvested:                            October 22 (John Deere 7445 with field cleaner)

RESULTS AND DISCUSSION:

            Roundup Ready cotton cultivars are widely used across the Texas High Plains. However, producers also have the option of utilizing added protection from bollworms and other lepidopterous pests through the advent of stacked gene varieties (Roundup Ready plus Bollgard). The purpose of this study was to determine if the added cost for worm protection with boll guard is economically beneficial to producers. Varieties which had only the Roundup Ready gene (Paymaster 2326RR, Paymaster 2200RR and Delta and Pine Land (D&PL) 5415RR) were compared head to head with their stacked gene (Roundup Ready with Bollgard) counterparts (Paymaster 2326BG/RR, Paymaster 2280 BG/RR, and D&PL 458BRR) from the same recurrent parent lines. Plots were planted on May 10 with a John Deere Max Emerge II at 15 lb seed/acre. Plot size was 8 - 40" rows by approximately 800 ft row length. Plots were center pivot LEPA irrigated and 30 lb N/acre preplant (as 32-0-0) was injected through the system. An additional 90 lb N/acre (32-0-0) was fertigated at 30 lb N/acre increments throughout the growing season. No over-the-top or post-directed Roundup Ultra applications were made to the project due to lack of significant weed populations. Plots were harvested using a John Deere 7445 with a field cleaner. Harvested material was dumped into a weigh wagon with integral digital scales to determine individual plot weights. Grab samples were taken to determine gin turnouts and the resulting lint samples were submitted to the International Textile Center at Texas Tech University for HVI analysis.

            Data from this project indicated that no significant differences in bur cotton, lint turnout, seed turnout, lint yield or seed yield were observed (Table 1). Rainfall was encountered at the site in September and October which resulted in lint weathering and some small preharvest losses for D&PL open boll varieties. Significant differences were obtained for lint to seed ratio (lb of lint/lb of seed). This indicated that lb of seed required to generate one bale of lint was lower for the two D&PL picker type varieties. Results for HVI lint quality parameters indicated that small but significant differences for +b (yellowness) parameter (Table 2) were observed. The D&PL varieties had a significantly lower +b (less yellowness) value than the Paymaster varieties with the exception of PM 2280BG/RR. However, this difference was low enough that it did not result in better HVI color grades for the picker types. Color grade was 42 for all varieties. No differences among varieties were observed for any economic parameter reported (Table 3). However, trends existed for Roundup Ready varieties to have a higher net value ($/acre) than their stacked gene counterparts. This is for the most part due to the added cost for the Bollgard technology fees. Relatively low lepidopterous pressure was encountered, but beet armyworms did reach threshold levels by August 2. A single application of 2.5 oz/acre of Tracer was applied across all varieties on that date. Additional multi-site and multi-year applied research is needed to evaluate the added value of Bollgard technology from the stacked gene varieties.

Table 1. Bur cotton yield, lint turnout, seed turnout, seed/bale, and lint and seed yields for the Roundup Ready vs Stacked Gene project, Lamesa, TX.

¹ CV, coefficient of variation.

² OSL - observed significance level or probability of a greater ‘F’ value.

³ LSD 0.05 - least significant difference at the 5% level (NS=Nonsignificant).

Table 2. HVI fiber quality measurements for the Roundup Ready vs Stacked Gene project, Lamesa, TX.

¹ CV, coefficient of variation.

² OSL - observed significance level or Probability of a greater ‘F’ value.

³ LSD 0.05 - least significant difference at the 5% level (NS=Non-significant).

Table 3. Loan value, lint value, seed value, seed cost, gin cost, and net value for the Roundup Ready vs Stacked Gene project, Lamesa, TX.

¹ CV, coefficient of variation.

² OSL - observed significance level or probability of a greater ‘F’ value.

³ LSD 0.05 - least significant difference at the 5% level (NS=Nonsignificant).

⁴ Costs assumed included $1.55 for ginning and $100/ton for cottonseed.

⁴ Seed and tech fees are based on seed suggested retail prices and Monsanto technology fees at 15 lb/acre seeding rate for respective variety.