1998 Iowa Turfgrass Research Report
Effects of Primo and Beacon on Poa annua Populations in Creeping Bentgrass Maintained at Green Height
Barbara R. Bingaman, Nick E. Christians, and Michael B. Faust
The objective of this control study was to evaluate CGA #136872 (Beacon) and the growth regulator, Trinexapac-ethyl (Primo) as Poa annua controls in green height creeping bentgrass.
This study was conducted on a practice green at Veenker Memorial Golf Course in Ames, IA. The turf in this area consisted of creeping bentgrass with an infestation of Poa annua that ranged from 33 to 65% through the season.
The study was a randomized complete block design with three replications. Individual plot size was 5 x 5 ft. There were five treatments including an untreated control, CGA #136872 (Beacon), and Primo. CGA #136872 (Beacon) was applied in single applications at 10 and 20 g product/A and at 10 g product/A in split applications. A methylated seed oil surfactant, SCOIL MSO, was added to CGA #136872 (Beacon) at 0.25% V/V for all applications. Primo 1EC was applied at 0.3 fl oz/1000 ft2 monthly from June through September.
Initial applications of all materials were made on June 5. The sequential application of CGA #136872 (Beacon) was made on June 26. Additional Primo 1EC applications were made on July 10, August 13, and September 4. The materials were mixed with 283 ml of water (3 gal/1000 ft2) and were applied at 30 psi with a CO2 backpack sprayer equipped with TeeJet™ #8006 flat fan nozzles. All applications were made between 6:30 and 7:00 a.m. Following applications, the plot was watered with the normal watering schedule in the late afternoon.
Phytotoxicity data were taken on June 10, June 19, June 26, and July 2. Phytotoxicity was assessed using a 9 to 1 scale: 9 = no damage, 6 = moderate tip burn (browning) and 4 = severe tip burn (Table 1). Visual turf quality data were taken weekly beginning June 10 and ending September 16 (Table 2). Visual turf quality was assessed with a 9 to 1 scale: 9 = best, 6 = lowest acceptable, and 1 = worst turf quality. Poa annua control was represented by estimating the percentage of area per plot covered by Poa annua. Percentage cover data were taken on June 19, June 26, July 15, July 21, and August 21 (Table 3). The presence of Poa annua seedheads also was recorded on July 2, July 15, July 21, and August 21 (Table 4). Seedhead numbers were estimated using many = a large number of uniformly distributed seedheads, moderate = a moderate number with a uniform distribution, few = a small number with a sporadic distribution, and none = no seedheads within the plot. Additional percentage cover data will be taken spring 1998 beginning at greenup. Winter damage also will be assessed in early spring.
There was severe phytotoxicity on bentgrass treated with CGA #136872 (Beacon) on June 10 through July 2 (Table 1). This material caused significant levels of phytotoxicity when compared with Primo 1EC-treated and untreated bentgrass. In addition, this phytotoxicity translated into significant brown areas in bentgrass treated with CGA #136872 (Beacon) on June 19, June 26, and July 2 when compared with Primo 1EC-treated and untreated bentgrass. There was no phytotoxicity detected after July 2.
There were no significant visual quality differences from July 21 through September 11 (Table 2). Primo 1EC-treated bentgrass had a darker green color than the CGA #136872 (Beacon)-treated and the untreated bentgrass from August 7 through September 11 but the difference was not significant.
Bentgrass treated with CGA #136872 (Beacon) showed reductions in percentage Poa annua cover for July 15 and July 21 but the percentages were not different from the Primo-treated and the untreated bentgrass (Table 3). On August 21, there were significantly lower Poa annua populations in bentgrass treated with CGA #136872 (Beacon) at 10 g and 20 g product/A and with Primo 1EC when compared with the other treated and untreated bentgrass.
Seedhead formation on Poa annua was suppressed by treatment with CGA #136872 (Beacon) and Primo 1EC. There were fewer seedheads in treated bentgrass than in untreated on July 2, July 15, July 21, and August 21.
Table 1. Phytotoxicity1 and percent brown area2 in plots of creeping bentgrass in the 1997 Poa annua control study.
|
|
|
|
|
|
|
|
||||
|
|
|
(initial) |
(sequential) |
|
|
|
|
|
|
|
|
|
Untreated control |
|
|
|
|
|
|
0 |
0 |
0 |
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
17 |
8 |
0 |
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
32 |
20 |
0 |
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
10 |
7 |
28 |
|
|
Primo 1EC |
|
|
|
|
|
|
0 |
0 |
0 |
|
|
LSD0.05 |
|
|
|
|
|
|
13 |
9 |
6 |
1Phytotoxicity was assessed with a 9 to 1 scale: 9 = no damage, 6 = moderate tip burn (browning) and 4 = severe tip burn.
2Percent brown area per plot represents the total area with dying Poa annua and bentgrass with tip burn.
Initial applications were made on June 5 and sequentials on June 26, 1997. Primo was applied June 5, July 10, August 13, and September 4.
Table 2. Visual quality1 in plots of creeping bentgrass in the 1997 Poa annua control study.
|
|
|
(initial) |
(sequential) |
|
|
|
|
|
|
|
|
|
|
Untreated control |
|
|
|
|
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
|
|
|
|
Primo 1EC |
|
|
|
|
|
|
|
|
|
|
|
|
LSD0.05 |
|
|
|
|
|
|
|
|
|
|
1Visual quality was assessed with a 9 to 1 scale: 9 = best, 6 = lowest acceptable, and 1 = worst quality.
Initial applications were made on June 5 and sequentials on June 26, 1997. Primo was applied June 5, July 10, August 13, and September 4.
NS = means are not significantly different at the 0.05 level.
Table 3. Percentage Poa annua cover1 in plots of creeping bentgrass in the 1997 Poa annua control study.
|
|
|
(initial) |
(sequential) |
|
|
|
|
|
|
|
|
|
|
|||
|
|
Untreated control |
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
Primo 1EC2 |
|
|
|
|
|
|
|
|
LSD0.05 |
|
|
|
|
|
|
1Percent Poa annua cover represents the area per plot covered by Poa annua.
Initial applications were made on June 5 and sequentials on June 26, 1997. Primo was applied June 5, July 10, August 13, and September 4.
NS = means are not significantly different at the 0.05 level.
Table 4. Presence of Poa annua seedheads1 in plots of creeping bentgrass in the 1997 Poa annua control study.
|
|
|
|
|
|
|||
|
|
|
(initial) |
(sequential) |
|
|
|
|
|
|
Untreated control |
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
136872 + SCOIL MSO |
|
|
|
|
|
|
|
|
Primo 1EC |
|
|
|
|
|
|
1The presence of Poa annua seedheads was estimated as: many = a large number uniformly distributed, moderate = a moderate number with a uniform distribution, few = small number with a sporadic distribution, and none = no seedheads within the plot.
Initial applications were made on June 5 and sequentials on June 26, 1997. Primo was applied June 5, July 10, August 13, and September 4.
NS = means are not significantly
different at the 0.05 level.
 |
ISU Horticulture:Publications:1998 Turfgrass Report | College of Agriculture |