Last updated 6/21/00 |
Table of Contents
Clark Throssell and Dan Weisenberger
Our objective was to determine the effectiveness of Prograss applied following several application schedules for the control of Poa annua.
Poa annua is a common weed on many golf courses and some athletic fields and home lawns. Control of Poa annua is very difficult through cultural and/or chemical methods. AgrEvo, the manufacturer of Prograss, felt that Prograss applied regularly throughout the summer offered potential for Poa annua control.
'Putter' creeping bentgrass was seeded on the 10th fairway of the Kampen Golf Course in Sep 1997. The fairway was fertilized to promote rapid fill in and growth. Since that time the fairway has been fertilized with 3.0 to 4.0 lbs nitrogen per 1000 sq. ft. per year. The fairway is mowed at 0.5 inches three times per week with clippings returned. Pesticides are applied as needed to maintain high quality fairway turf. Since the site of the 10th fairway is on top of the old North Golf Course an abundance of Poa annua seed was in the soil. Some of this Poa annua seed has germinated and invaded the 10th fairway making it a good site for Poa annua control research. The initial date of application was 3 May and additional applications were made at three week intervals. All treatments were applied using a CO2 powered hand-held spray boom in 2 gal water per 1000 sq. ft. Data collected were percent of plot area covered by Poa annua.
- None of the Prograss treatments reduced the amount of cover by Poa annua.
- Percent cover by Poa annua declined between 3 May and early Sep to the point where Poa annua could not be identified in any plot.
- By 28 Sep Poa annua was present in all plots and could be easily identified.
- The decline of cover by Poa annua in summer and recovery in fall is part of the normal life cycle of Poa annua.
- These results indicate the importance of rating Poa annua cover for an entire year to fully understand treatment effects.
Table 1. Percent cover of Poa annua following postemergence applications of Prograss. |
|||||||
| Poa annua covera | |||||||
| Rate of | Application | 3 | 28 | 24 | 7 | 19 | |
| Treatment | application | timingb | May | Sep | Nov | Dec | Apr |
| 1999 | 1999 | 1999 | 1999 | 2000 | |||
| lbs ai/A | weeks | ----------------- % --------------- |
|||||
| . | |||||||
| Check | --- | 18.8 | 10.5 | 6.3 | 5.8 | 18.8 | |
| Prograss 1.5EC | 1.5 | 0, 3, 6 | 20.0 | 4.0 | 5.5 | 3.0 | 12.5 |
| Prograss 1.5EC | 0.75 | 9, 12, 15 | |||||
| Prograss 1.5EC | 1.5 | 18, 21 | |||||
| Prograss 1.5EC | 0.75 | 0, 3, 6, 9, 12, 15, 18, 21 | 16.3 | 11.0 | 9.5 | 8.0 | 20.0 |
| Prograss 1.5EC | 0.75 | 0, 3, 6 | 22.5 | 13.0 | 6.3 | 9.5 | 18.8 |
| Prograss 1.5EC | 0.38 | 9, 12, 15 | |||||
| Prograss 1.5EC | 0.75 | 18, 21 | |||||
| . | |||||||
| LSD (0.05) | NS | NS | NS | NS | NS | ||
| a Percent of plot area covered by Poa annua. | |||||||
| b Denotes weeks when applications were made. | |||||||
Table of Contents
Send corrections, suggestions, and comments to biehlj@purdue.edu