April’s Chill: Bentgrass Growth Stops, 1st Stress Diseases, and Greenhouse Research
Patience. A typical spring so far? It’s gotten cold again and it feels more like March than April. Most notably creeping bentgrass growth is on pause and, as a consequence, the greens have gotten less green. When putting, it’s a more colorful look again as greens are now patchy shades of greens, bronzes, reds and if Poa annua is a component, you may see that light up as well — a bright fluorescent yellow. Simply said, this is plant physiology in action. Turfgrass exhibits chlorophyll pigment reduction plus a carefully choreographed mix of cellular changes (membrane properties are altered and cell water content is reduced) for cold temperature acclimation.
Image 1. In the landscape, tulips are in bloom. Cog Hill Golf & Country Club, Lemont, IL. Settle Apr 19, 2023
Nature is the best teacher of patience. For example, this latest April cool-down coincided with scheduled cultivation events of greens, fairways and tees. Superintendents (and golfers) will have to wait a little longer for surfaces to fill in and expectations of 7 days are now ~14 days. Aerification channels, of which roots preferentially enjoy, are on the mend. But spring continues. The landscape is increasingly in bloom and lilacs, Syringa sp., are the latest addition. Undoubtedly, the biggest change is as you look up. Gradual at first. Native deciduous trees leafing-out en masse. Patience.
Anthracnose of Creeping Bentgrass, Colletotrichum cereale
Stress Disease No. 1. Off-color turfgrass can be an indication of stress OR it can be an indication of disease. In a week, superintendents and staff have doubled down in their scouting of turfgrass health. A few odd things were found. And in summary, what we are finding are diseases that are atypical for this time of year. For example, anthracnose is most commonly associated with Poa annua caused by midday wilt during a hot summer.
Take home message. Creeping bentgrass is currently experiencing environmental stress. Anthracnose is a result.
Leaf Spot, various fungi that produce conidia/spores
Stress Disease no. 2. Leaf spots can mean normal plant defense mechanisms aren’t up to speed. Leaf spots are often associated with senescing leaf blades at seasons’ end or situations where a semi-dwarf state exists (e.g., ultra dwarf bermudagrass greens in the winter months). In season, leaf spots are associated with plant stress by any number of factors.
Weather can be stressful. Chicago’s shoulder seasons — happening right now — can be a difficult environment for even cool-season turfgrass. That’s a fact. Why the most experienced superintendents will tell you they hold off on pushing growth (nitrogen fertility) until all risk of frost is over. And for Chicago that is about April 21. Though, last freeze in the spring for Chicago can vary quite a bit. Click here for more information.
- Chicago’s EARLIEST last spring freeze = March 19, 1925
- Chicago’s LATEST last spring freeze = May 25, 1992
Weed of the Week — White Clover, Trifolium repens
White clover is a weed, or is it? I say that because the CDGA is part of the NCERA-221. It is a regional group of turfgrass scientists from a multi-state region. In the past they collaborated on a project called LIST (Low Input Sustainable Turf). That project looked at combining legumes or clovers as a way to create a system in which nitrogen fertility inputs could be reduced or not used at all. Click here for more information.
Divot Mix Seed Germination Study by Shehbaz Singh, MS
Rationale. A greenhouse study to evaluate and confirm earlier findings of chewings fescue growth in different rootzone mixes. Results of a CDGA divot study indicated chewings fescue seed in a divot mix resulted in speedy recovery. Compared to creeping bentgrass, chewings fescue is very different because it has a bunch type growth habit. As such is much less competitive when accidentally introduced into other areas such as a Kentucky bluegrass rough. Instead, chewings fescue does not persist.
Objective. Observe growth of chewings fescue in different kinds of rootzone materials that can be used as a divot mix in golf course tees or fairways.
Material and Methods. A greenhouse experiment lasting four weeks was conducted at North Shore Country Club in Glenview, IL. The study used 2 inch diameter cone-tainers. Six different treatments (rootzones) were used in this experiment in a randomized complete block design with 6 replicates.
1. Round Sand
2. Round Sand + Biochar (10%)
3. 8–1–1 Mix (80% sand, 10% soil and 10% compost)
4. Compost (Yard Waste)
5. Angular Sand 1
6. Angular Sand 2
Materials and Methods Cont. Fifty seeds of chewings fescue were counted and placed in each cone-tainer. Watering occurred immediately after seeding on March 31, 2023. Thereafter, overhead watering occurred weekly to ensure growth. Cone-tainers were kept in metal-tray so that tube ends were submerged in water to ensure optimum germination. Twice per week, data was collected for seed germination (plant number) and shoot growth (plant height). At study end, data was collected for root parameters (root length) and plant biomass (dry plant weight).
Greatest Plant Number. In both study 1 and 2, compost and round sand showed more seed germination in comparison to other rootzone mixes. The average seed germination for all rootzones at end of study 2 (43 seed germinated out of 50) was greater than study 1 (36 seed germinated out of 50). Air temperature in the greenhouse during study 2 was relatively higher than during study 1 which probably favored seed germination.
Lowest Plant Number. Round sand with biochar had lower germination in both studies for unknown reasons. Angular sand 1 and angular sand 2 also had lower or intermediate germination in both studies. It shows that the angularity of sand can negatively affect the germination of chewings fescue seed. Hence, use angular sand is not recommended for a divot mix.
Greatest Plant Height. In both study 1 and 2, compost had greater average plant height than all other rootzone mixes. The higher nutrients/fertility of compost supported more growth of chewings fescue. Average plant height at the end for all rootzone mixes in study 2 (6.7 cm) was greater than study 1 (5.35 cm).
Intermediate and Lower Plant Height. Angular sand 1, angular sand 2, and round sand + biochar ranged between intermediate to lower for plant height. Interestingly, the round sand in study 2 was on lower end for plant height, but germination numbers were high. However, to use round sand as divot mix, plant height does not matter as much as germination does.
Inconsistent Results. The 8–1–1 mix was inconsistent during the greenhouse studies. It ranked in the high group for plant height and germination number during study 2. However, it ranked intermediate for the same parameters in study 1.
Root Length. Average root length for all rootzone mixes in study 2 (10.9 cm) was greater than in study 1 (6.7 cm).
Compost Consistently Best. Compost had deeper roots in both studies. In comparison, the 8–1–1 Mix and round sand matched compost with deeper roots in study 2 but were intermediate in study 1.
Shorter Roots. Angular sand 1, angular sand 2 and round sand + biochar had shortened roots in both studies. Hence, the angular sands should not be used in a divot mixes. It is unknown what caused round sand + biochar have reduced root growth.
Final Photo
