D.D. Minner, F. Valverdi, D. Li and N. Christians - Iowa State University
D. Roe - Gardner Memorial Golf Course, President IGCSA
J. Newton - Veenker Memorial Golf Course
The Iowa winter of 2002/2003 was dry and open with little snow cover and no naturally occurring surface ice. These conditions favored turf injury caused by desiccation. On 3 January snow was transported from a local ski resort to provide a minimum of 4 inches of packed snow for treatments designated "snow cover". Ice treatments cover treatments were started on 5 January by applying 0.5 inches of water in the evening and allowing it to freeze. By 8 January all snow and ice had melted from the plots and the melted water ran onto some of the other treatments as indicated at the Veenker Golf Course research site. By 10 January freezing conditions returned and snow and ice were again started for the designated treatments. There after a combination of natural snow and man-made snow was placed on the required treatments to maintain the minimum of 4 inches of packed snow cover. Snow remained on the "continuous snow cover" treatments for 66 days after 10 January. Treatments designated for "ice cover" also began on 10 January and by 23 January all "ice cover" plots had 4 inches of ice cover. Ice cover lasted for 66 continuous days following 10 January. Treatments #6 and 8 were designated as snow and ice removed halfway through the winter. Snow and ice were removed on 18 Feb giving these treatments 39 days of continuous snow or ice cover.
Creeping bentgrass Study - Veenker Memorial Golf Course
Treatments 7 and 10 were abandoned at this test site because water ran onto some of the plots during a melting period on 7 and 8 January. The 6-inch metal boarders around each plot that extended two inches below and four inches above the soil surface failed to retain the melting water. A deeper plastic boarder will be used next year to contain any melting snow and ice. Treatment 1 designated as "dry" also received 0.5 inches of melted water uniformly across all plots. These plots were kept in the study with the understanding that they received a one-time watering during the week of January 8
Core samples taken every week through out the study and recovered in the green house did not indicate any visible turf injury. Turf quality, winter injury, and clipping yield are still being analyzed for the winter samples.
Prior to spring green-up all winter treatments produced brown turf, however the color of turf browning varied from dark brown/black to light tan and even bleached white. This difference in winter turf browning also resulted in significantly different rates of spring green-up and turf recovery in the field (Table 2, picture 2). On 26 March the dry #1, continuous ice #3, and ice removed #6 treatments had significantly more turf browning than the treatments containing wet#2, snow #4 and 8, and Evergreen cover #9. In this year of desiccation it was apparent that snow and artificial covers improved turf recovery during spring green-up. Since the weekly sampling data showed no apparent differences in winter injury it could not be determined exactly when during the winter that injury occurred, if it occurred at all. It should be noted that ice treatments in this study caused reduced turf quality during spring green-up as opposed to complete turf loss that has been experienced in some winters. Had ice naturally occurred during the 2002-03 winter our results indicate that there would have been no real reason to remove the ice on the bentgrass study because all "ice cover" plots eventually recovered in the spring.
Data from the impermeable cover #5 was difficult to interpret since sampling through the cover resulted in holes in the cover that eventually allowed water to leak onto the plots below the cover. This treatment will not be sampled next year so that all winter moisture will be eliminated from the impermeable cover treatments. The water impermeable cover treatment was intended to produce a drier soil condition under a cover of ice.
Poa annua/creeping bentgrass Study ISU-Research Station
The study area consisted of a 50% stand of Poa annua and 50% creeping bentgrass that was planted in September 2002 using core aerifier plugs. When winter treatments were applied the area had approximately 75% turf cover and the grass was mowed at 0.5 inches. Because of the turf mixture winter sampling sometimes produced bentrass plugs and sometimes produced Poa annua plugs. We are currently reestablishing the area with 100 % Poa annua from aerifier plugs.
The natural winter injury that occurred through out Iowa indicated that both creeping bentgrass and Poa annua were killed on putting greens. Severe loss of bentgrass did not occur on the Veenker Golf Course research green. The mixed Poa/bent green at the ISU Research Farm had only mild injury to the bentgrass and severe injury to the Poa annua. On 25 March the ice covered treatments #3, 6, and 7 showed much more browning compared to the snow covered treatments #4 and 8 (Table 2, picture 3). We are waiting for seedhead formation to take a final rating on how much of each species survived, however it appears that the ice treatments killed all of the Poa annua and that the snow cover treatments #4 and 8, and the evergreen cover#9 kept the Poa annua alive.
Table 1. Winter treatments
| Simulated winter conditions | Winter | Spring | Proposed Description | |
|---|---|---|---|---|
| 1 | Dry/Open | Dry | Dry | No cover, no ice, no snow - turf subject to desiccation |
| 2 | Wet | Wet | Wet | Turf hydrated no surface ice |
| 3 | Ice continuous | Ice | Ice | Extended ice cover for 90 days |
| 4 | Snow continuous | Snow | Snow | Extended snow cover 90 days |
| 5 | Impermeable cover | Adequate moisture | Adequate moisture | White impermeable cover designed to prevent plant hydration and ice encasement. 4 inches of ice over cover. |
| 6 | Ice removal | Ice | Ice remove | Ice removed after 60 days of ice formation |
| 7 | Ice melt/freeze | Ice | Melt/freeze | Ice removed after 60 days of winter, melt/freeze cycle applied in the spring |
| 8 | Snow removal | Snow | Melt/freeze | Snow removed after 60 days of winter |
| 9 | Turfcover/Dry | Dry | Dry | Evergreen turf cover - ice/snow removed |
| 10 | Turfcover/Snow | Snow | Snow | Evergreen turf cover - ice/snow present |
| Winter - January, February | Snow - 4 inches of snow cover |
| Spring - March | Ice - 4 inches of ice cover |
Table 2. 2003 turf quality in field plots during spring green-up on a scale of 1-10, 10= completely green, 6=lowest acceptable quality, 1=bleached completely white.
| Creeping bentgrass - Veenker Golf Course | Poa annua/bentgrass - ISU Research Station | ||||||
|---|---|---|---|---|---|---|---|
| Winter Treatments | Mar 19 | Mar 26 | Apr 30 | Mar 25 | Apr 2 | Apr 30 | |
| 1 | Dry | 2.0 | 2.7 | 5.0 | 3.0 | 3.3 | 6.0 |
| 2 | Wet | 2.3 | 4.0 | 6.0 | 3.0 | 4.0 | 6.3 |
| 3 | Ice continuous | 2.7 | 2.7 | 4.7 | 1.0 | 2.3 | 5.7 |
| 4 | Snow continuous | 3.7 | 5.0 | 6.7 | 5.0 | 5.0 | 6.7 |
| 5 | Impermeable cover | 3.3 | 3.3 | 6.7 | 4.0 | 3.7 | 5.3 |
| 6 | Ice removal | 2.3 | 3.0 | 4.7 | 1.0 | 2.3 | 5.7 |
| 7 | Ice melt/freeze | -- | -- | -- | 1.0 | 2.7 | 6.3 |
| 8 | Snow removal | 3.0 | 4.3 | 6.0 | 5.0 | 4.7 | 6.3 |
| 9 | Turfcover/Dry | 2.7 | 4.0 | 6.7 | 4.7 | 4.0 | 6.3 |
| 10 | Turfcover/Snow | -- | -- | -- | -- | -- | -- |
| LSD.05 | 0.81 | 0.76 | 0.70 | 0.31 | 0.84 | NS | |
Picture 1. Veenker Golf Course winter trial 23 January 03. Trt#8 snow removal, trt#6 ice removal, trt#4 continuous snow, trt#9 turf cover, trt#5 impermeable cover with ice cover.
Picture 2. Veenker Golf Course creeping bentgrass research green showing the effect of winter snow cover and ice cover during spring green-up on 1 April 03.
Picture 3. Poa annua/creeping bentgrass study at the ISU Research Station on 26 March 03. Plots with bleached white appearance received "ice cover" treatments.
Picture 4. Frozen plug sampled from treatment #3 "continuous ice cover" on 23 Jan 03.
Picture 5. Impact hammer drill used to sample greens during the winter to determine when the grass actually dies. Plugs of grass are recovered in the greenhouse.
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ISU Turfgrass:2003 Turfgrass Report | College of Agriculture |
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