Turfgrass Scouting Report: October 20, 2019

The king of cool, Dean Martin

Things are definitely starting to cool down here in the Chicagoland area. There has been a number of frost advisories in the area over the last few weeks and some reports of light frosts on golf courses in the area. I think until we get a hard frost the leaves on the trees will be hanging around for a while. On the disease front things are quiet with very little activity. On the weeds front annual grassy weeds i.e. crabgrass and goosegrass are already starting to checkout. Just like the leaves on the trees, once we get a hard frost the grassy weeds will for sure checkout for this year.

Weather

We’ve seen some big changes in the air and soil temperatures. In the last two weeks here at the Sunshine Course the maximum temperatures have been fluctuating between ~55–90°F, while the minimum temperatures have been fluctuating between ~35–75°F. Soil temperatures have decreased to ~55°F during the past two weeks.

In the first half of October we’ve had 4 rain days here at the Sunshine Course, with amounts ranging from~0.1–0.6 inches.

Out west they’ve been having “potentially historic” October storms bringing approximately 2 feet of snow. I for one, am glad we’re not at that stage (getting snow) here yet!!

We have had several frost advisories in the area over the last few weeks, winter is coming!!

Looking ahead we only have 2 wet days forecast with a 90% chance of thunderstorms on October 21. It looks like to the windy city will live up to it’s name on October 22 (I know, it’s about the politics not the weather). Temperatures are starting to get down there towards the end of the month with the high’s forecast to be in the 40’s. It looks like it’s going to be good irrigation blow out weather.

The colors of the foliage on the trees are starting to change and there has been some leaves fall, but not many. The two pictures above were taken on the same day at the time, it has always fascinated me how differently trees react to the change of the seasons.

The renovation work at the Sunshine Course continues, we have now core aerified all tee’s and fairway’s. Again we would like to thank Mr. Troy Tietjens and JW Turf for providing the required machinery for the required maintenance practices.

Below are few recently published scientific articles related to turfgrass science. I always like to stay up to date on recent advancements, I hope you enjoy.

Title: Jing, Z., Virk, S., Porter, W., Kenworthy, K., Sullivan, D. and Schwartz, B., 2019. Applications of unmanned aerial vehicle based imagery in turfgrass field trials. Frontiers in Plant Science, 10, p.279.

Abstract: “Recent advances in remote sensing technology, especially in the area of Unmanned Aerial Vehicles (UAV) and Unmanned Aerial Systems (UASs) provide opportunities for turfgrass breeders to collect more comprehensive data during early stages of selection as well as in advanced trials. The goal of this study was to assess the use of UAV-based aerial imagery on replicated turfgrass field trials. Both visual (RGB) images and multispectral images were acquired with a small UAV platform on field trials of bermudagrass (Cynodon spp.) and zoysiagrass (Zoysia spp.) with plot sizes of 1.8 by 1.8 m and 0.9 by 0.9 m, respectively. Color indices and vegetation indices were calculated from the data extracted from UAV-based RGB images and multispectral images, respectively. Ground truth measurements including visual turfgrass quality, percent green cover, and normalized difference vegetation index (NDVI) were taken immediately following each UAV flight. Results from the study showed that ground-based NDVI can be predicted using UAV-based NDVI (R2 = 0.90, RMSE = 0.03). Ground percent green cover can be predicted using both UAV-based NDVI (R2 = 0.86, RMSE = 8.29) and visible atmospherically resistant index (VARI, R2 = 0.87, RMSE = 7.77), warranting the use of the more affordable RGB camera to estimate ground percent green cover. Out of the top ten entries identified using ground measurements, 92% (12 out of 13 in bermudagrass) and 80% (9 out of 11 in zoysiagrass) overlapped with those using UAV-based imagery. These results suggest that UAV-based high-resolution imagery is a reliable and powerful tool for assessing turfgrass performance during variety trials.”

Title: Doherty, E.M., Meagher, R.L. and Dale, A.G., 2019. Turfgrass Cultivar Diversity Provides Associational Resistance in the Absence of Pest Resistant Cultivars. Environmental entomology, 48(3), pp.623–632.

Abstract: “ Turfgrasses are ubiquitous in urban landscapes and can provide numerous ecosystem services. However, most warm season turfgrasses are produced, planted, and maintained as cultivar monocultures, which may predispose them to herbivore attack and reduce the services lawns provide. Though rarely done, host plant resistance can be used as a strategy to reduce herbivory and preserve beneficial services. Increasing turfgrass cultivar diversity may provide similar or greater benefits through associational resistance, whereas conserving desirable maintenance and aesthetic traits. However, no studies have examined this in warm season turfgrasses. To address this, we evaluated host plant resistance to fall armyworm (Spodoptera frugiperda [J.E. Smith] [Lepidoptera: Noctuidae]) in commercially available cultivars of St. Augustinegrass (Stenotaphrum secundatum [(Walt.) Kuntz] [Lepidoptera: Noctuidae]) and then investigated if the resistance or susceptibility of St. secundatum cultivars carried over in mixed cultivar plantings. Through a no-choice experiment and a limited-choice experiment, we detected no host plant resistance in monocultures of St. secundatum cultivars. However, we did find that as cultivar diversity increased, female Sp. frugiperda larval weight and herbivory decreased. Additionally, choice tests indicated that larvae prefer less diverse stands of St. secundatum cultivars. Interestingly, our results suggest that in the absence of host plant resistance, warm season turfgrass cultivar diversity may reduce herbivore pest fitness and damage. These results demonstrate that warm season turfgrass cultivar diversity may be a viable integrated pest management tool that warrants further investigation.”

Title: Rahayu, R., Mo, Y.G. and Soo, C.J., 2019. Amendments on Salinity and Water Retention of Sand Base Rootzone and Turfgrass Yield. SAINS TANAH-Journal of Soil Science and Agroclimatology, 16(1), pp.103–111.

Abstract: “This research was column pot experiment with turfgrass was Kentucky bluegrass (Poa pratensis) plant irrigated saline irrigation and the column soaked in saline water. Rootzone profile consisted of 20 cm using saline lake dredged up sand. The sand amendments of the root zone were soil, zeolite, bottom ash, and peat. The mixtures of topsoil were; 90% sand + 10% peat moss, 80% sand + 10% soil + 10 % bottom ash, 80% sand + 20% soil, 90% sand + 5% peat + 5% zeolite, and 80% sand + 20% bottom ash. Interruption layer with coarse sand with diameters over 2 mm of 20 cm and 10 cm loamy soil as the bottom layer of the column. The result showed that Kentucky bluegrass could grow in sand based growing media amended by peat, sandy loam soils, bottom ash and zeolite being irrigated by 2 dS m-1 saline water. Sand-based growing media amended by peat resulted in the highest clipping weigh but showed the highest salt accumulations. Sand amended by bottom ash and applied gypsum decreased clipping weigh, decreased SAR and increased calcium (Ca) when compared to the soil + peat (SP). Sand amended by zeolite and gypsum decreased clipping weight, decreased sodium adsorption ratio (SAR) and higher Ca. Higher soil moisture retention of growing media promoted the growth of Kentucky bluegrass in spring, and lower moisture content promoted the growth in summer and fall season.”

Title: Moore, D.B., Guillard, K., Geng, X., Morris, T.F. and Brinton, W.F., 2019. Predicting Cool-Season Turfgrass Response with Solvita Soil Tests, Part 1: Labile Amino-Nitrogen Concentrations. Crop Science.

Abstract: “ Current turfgrass fertilizer recommendations do not account for potential mineralizable N in the soil. The Solvita Soil Labile Amino-Nitrogen (SLAN) test measures a labile fraction of soil N. This study was conducted across 9 yr (2008–2016) in Connecticut to determine if responses from predominately Kentucky bluegrass (Poa pratensis L.) and tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] lawns are correlated to SLAN–N concentrations, and to determine the probability of turfgrass responses equaling or exceeding the response from benchmark urea rates in relation to SLAN–N concentrations. Randomized complete block design field experiments were set out with 23 rates of an organic fertilizer (0–2000 kg N ha−1 yr−1) and four different rates of urea (50, 100, 150, and 200 kg N ha−1 yr−1). Yearly spring soil samples were analyzed for SLAN–N concentrations, and turfgrass growth and quality responses were collected during the growing seasons. Turfgrass responded positively and linearly (P < 0.001) to SLAN–N concentrations, but correlations were relatively weak to moderate. When spring soil SLAN–N concentrations were ≥158, 165, 198, and 217 mg kg−1, there was a ≥90% probability that overall combined responses across species and measured variables would be equal to or greater than responses obtained from 50, 100, 150, and 200 kg urea N ha−1 yr−1, respectively. The SLAN test has promise as an objective soil test to categorize the N fertilization response potential of turfgrass soils, and this would be helpful in guiding N fertilization.”

Anyone in the southern part of the state interested in Dr. Lee Miller’s most recent disease report can find it here.

Please don’t hesitate to call or email and I will ensure you get a rapid response.

Thanks,

Subscribe to scouting reports: http://cdgaturf.org/

Twitter: CDGATurfgrassProgram

Bobby Kerr, Ph.D. Director of Turfgrass Programs. Chicago District Golf Association, 11855 Archer Ave, Lemont, IL 60439. C: (312)-519–7940. W: (630)-685–2307.

Ron Townsend, MS. Manager of Turfgrass Research. Chicago District Golf Association, 11855 Archer Ave, Lemont, IL 60439. W: (630) 685–2310.

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CDGATurfgrassProgram

Dedicated researchers and turf pathologists working for golf course superintendents in the Chicago area.