Wetting Agent Treatments Research Articles

Identification of wetting agents for water conservation on deficit‐irrigated hybrid bermudagrass fairways

AbstractWetting agents have been reported to alleviate localized dry spot and save water while maintaining turf quality at an acceptable level. However, limited research has been conducted on comparing the effects of different wetting agent products. A study was conducted from May to October in 2018 and 2019 in Riverside, CA to evaluate 10 wetting agent treatments on performance of ‘Tifway II’ hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] under deficit irrigation at three reference evapotranspiration (ETo) levels: 45, 55, and 65% ETo. Ten wetting agent treatments were selected based on manufacturer recommendations. Plots were evaluated for visual turf quality, percent green cover (PGC), dark green color index, normalized difference vegetation index (NDVI), soil volumetric water content, soil moisture variability, and proline content in dry‐leaf samples. Wetting agent treatments improved turf quality and PGC, and decreased soil moisture variability. Moreover, up to 16% increase in soil moisture levels was observed on treated vs. untreated control. No differences were observed for NDVI, proline content in leaves, or fall color retention. Overall, soil moisture variability declined in 2019, and turf quality improved in both years when any wetting agent treatment was applied, and only minor differences were observed among wetting agent treatments evaluated in this study. Other physiological indicators and soil rootzone characteristics are needed to gauge the effects of wetting agents under deficit‐irrigated turfgrass.

Effect of late‐fall wetting agent application on winter survival of ultradwarf bermudagrass putting greens

AbstractPlant tissue desiccation and low‐temperature exposure are two common causes of winter injury to ultradwarf bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis Burtt Davy] putting greens. Unlike low‐temperature exposure, winter damage caused by tissue desiccation can occur regardless of temperature and may be worsened by soil hydrophobicity. Wetting agents are commonly applied to actively growing ultradwarf bermudagrass putting greens to remedy the negative effects of soil hydrophobicity. Less is known about the effect of wetting agent applications to dormant ultradwarf bermudagrass putting greens. This research aimed to quantify the effects of a late‐fall wetting agent application on winter injury and the soil volumetric water content of a sand‐based ultradwarf bermudagrass putting green. Single applications of three wetting agents at two rates were made in early December of 2015, 2016, and 2017 to a ‘TifEagle’ ultradwarf bermudagrass putting green and were compared with an untreated control. Spring green‐up and soil volumetric water content were monitored from March to May of each season. Water drop penetration time tests were conducted twice each season to quantify reductions in hydrophobicity compared with the untreated control. On multiple dates, wetting agent treatments had significantly more green turfgrass coverage than the untreated control. In general, wetting agents reduced water drop penetration times in the top 2 cm of the soil profile. This research suggests that late‐fall or winter applications of a wetting agent can reduce injury and enhance spring recovery of sand‐based ultradwarf bermudagrass putting greens.

Influence of Management Practices on Distribution of Fungicides in Golf Course Turf

Core Ideas Most fungicide residues remained within the verdure/thatch layer. Irrigation and wetting agent had little effect on fungicide distribution. Distribution patterns for four modern fungicides were similar. Fungicides are often applied to control root diseases that affect golf course turf. Post‐application irrigation and wetting agents are suggested to improve fungicide performance by facilitating downward movement into the root zone. How irrigation and wetting agent treatments influence fungicide distribution in the turf profile remains unclear based on existing literature. The research objective was to investigate the influence of a wetting agent and post‐application irrigation on the distribution of modern fungicides in a sand‐based creeping bentgrass (Agrostis stolonifera L.) putting green. Fungicides used in two distinct experimental runs in field plots included azoxystrobin, fluxapyroxad, propiconazole, and pyraclostrobin. Fungicide + irrigation, fungicide + wetting agent, and fungicide + irrigation + wetting agent treatment effects were compared with a fungicide‐only treatment. Turf was sampled at –1, 0, 3, 7, 10, 14, 21, and 28 d after fungicide application. Core samples were collected and separated into three components—verdure/thatch, and soil at two depths, 2 to 5 and 5 to 8 cm. Fungicide was extracted from each turf component and analyzed thereafter using liquid chromatography–triple quadrupole mass spectroscopy. Results showed that the majority of fungicide was captured by verdure/thatch, and that fungicide concentration in verdure/thatch was 1 to 2 orders of magnitude higher compared with other turf components. Further, in almost every case, there was no measurable effect of irrigation, wetting agent, or the combination on fungicide distribution in the turf profile. Research results can help improve understanding of fungicide distribution in turf and provide scientific context for recommendations regarding root disease control in golf course turf.

Influence of Irrigation and Wetting Agent on Fungicide Residues in Creeping Bentgrass.

Fungicides (azoxystrobin, propiconazole, pyraclostrobin, and thiophanate-methyl) were applied to field plots of creeping bentgrass established on a sand-based root zone substrate and maintained at a cutting height of 0.34 cm. The wetting agent, a modified alkylated polyol, was applied 24 h prior to fungicide application. Irrigation (0.51 cm) was applied to plots immediately after the fungicide spray. Turf was sampled nine times over 42 days to examine fungicide residues in three components of the turf profile: verdure/thatch, roots, and soil. Residues were extracted from samples and then quantified using a liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) procedure. The experiment was run twice. Wetting agent had little or no effect on fungicide distribution in any of the turf components. Postapplication irrigation had little effect on residues observed in the verdure/thatch component. Significant irrigation treatment effects were observed in root and soil components, but results varied among fungicides and sampling dates. Where significant effects were observed for the irrigation plus wetting agent treatment, results generally mirrored outcomes for irrigation treatment.

Hydration Efficiency of Traditional and Alternative Greenhouse Substrate Components

Wettability is a major factor in determining whether a material can be effectively and efficiently used as a component in greenhouse substrates. Poor wettability can lead to poor plant growth and development as well as water use inefficiency. This research was designed to test the wettability and hydration efficiency of both traditional and alternative components of substrates under different initial moisture contents (MCs) and wetting agent levels. Peatmoss, perlite, coconut coir, pine bark, and two differently manufactured pine tree substrate components (pine wood chips and shredded pine wood) were tested at 50% and 25% initial MC (by weight). The objective of this research was to determine the effects of initial MC and wetting agent rates on the wettability and hydration efficiency of these substrate components. Each component received four wetting agent treatments: high (348 mL·m−3), medium (232 mL·m−3), low (116 mL·m−3), and none (0 mL·m−3). Hydration efficiency was influenced by initial MC, wetting agent rate, and inherent hydrophobic properties of the materials. Wetting agents did increase the hydration efficiencies of the substrate components, although not always enough to overcome all cases of hydrophobicity.

Comparison of Postfire Soil Water Repellency Amelioration Strategies on Bluebunch Wheatgrass and Cheatgrass Survival

Soil water repellency can limit postfire reseeding efforts and thus increase the susceptibility of a site to weed invasion. We evaluated the effectiveness of wetting agents and simulated anchor chaining for improving seedling growth and survival in water-repellent soil, for the native perennial bluebunch wheatgrass (Pseudoroegneria spicata) and invasive annual cheatgrass (Bromus tectorum). Research was performed in a glasshouse, on 20-cm-diameter soil cores that were excavated from underneath burned Utah juniper (Juniperus osteosperma) trees. The experiment was arranged as a randomized split-plot design, with the two grass species sown separately under four soil treatments: 1) no treatment (control), 2) simulated anchor chaining (hereafter referred to as “till”), 3) wetting agent, and 4) till plus wetting agent. Soil water content was highest in the wetting agent treatment, lower for till, and lowest in the control. Overall, the response of bluebunch wheatgrass and cheatgrass was similar among treatments. At the conclusion of the study, wetting agent cores had twice as many seedlings as the control, while the till and control were similar. Despite a lower number of seedlings, tilling in general resulted in the same level of biomass as the wetting agent treatment. Overall, biomass in the till and wetting agent treatments was at least twofold higher than the control. No benefit was found in applying both till and wetting agent treatments together in comparison to just applying wetting agent. Because of a lack of correlation between glasshouse and field settings the results of this study need to be interpreted with caution. Our data may indicate that if cheatgrass is not already present on the site, anchor chaining or treating the soil with wetting agent can increase establishment of seeded species.

Ameliorating water repellency under turfgrass of contrasting soil organic matter content: Effect of wetting agent formulation and application frequency

Abstract Water conservation strategies are being developed in regions of the world expected to experience decreases in water resources due to changing climates. Strategies advocated for improving water-use efficiency may increase the incidence of soil water repellency in sandy-textured soils. We evaluated the effect of soil wetting agent formulation, and application frequency, on water repellency in sandy soil with two contrasting organic matter (OM) contents under kikuyugrass [Pennisetum clandestinum (Holst. Ex Chiov)], and irrigated at 60% replacement of net evaporation in a climate subject to hot, dry summers. The randomized plot design included two turfgrass ages [established from 20 week (7.7% OM) or 20 year old (30% OM) turfgrass in 2005, the latter included a 50 mm ‘mat’ layer], two soil wetting agent formulations (granular or liquid); two application frequencies (one or two applications per irrigation season); and plots of both turfgrass ages that did not receive any wetting agent (nil control). Both wetting agent formulations contained the same active ingredient (propylene oxide–ethylene oxide block polymer), and all wetting agent treatments received the same rate (69 L active ingredient ha−1). Water repellency in the surface soil (0–5 mm), measured using the molarity of ethanol droplet test (MED), ranged from 1.09 M to 4.32 M during the irrigation season, and was more severe in the soil with high OM (average MED, 3.3 M) than low OM content (average MED, 2.7 M). Applying one application of either granular or liquid soil wetting agent at the commencement of the irrigation season decreased the severity of soil water repellency by up to 30% in the high OM soil and by up to 60% in the low OM soil during the summer, and without the need for a second application. The decline in soil water repellency in response to soil wetting agent application was not matched by an increase in soil VWC in summer, and turfgrass quality was considered acceptable throughout the study. The soil wetting agents were less effective at treating water repellent sand containing a significant amount of OM than sand with low OM content.

Wetting agent and cultural practices increase infiltration and reduce runoff losses of irrigation water

Wetting agents are mainly used to manage water repellency in soils but they do provide other benefits like increase in water retention and reduction in physiological moisture stress in plants. Experiments were conducted at the California State Polytechnic University, Pomona on a loamy sand soil situated on an 8% slope with an established turfgrass maintained under golf course fairway management conditions. The effect of cultural practices like core aerification followed by sand topdressing and application of a wetting agent in reducing runoff of irrigation water was evaluated. Runoff events after the cultural practices and the wetting agent treatment (Dispatch applied at 877 ml/ha) was repeated four times over a time period when the matric potential ranged from 15-40 kPa. An empirical formula based on Horton's equation was used to predict maximum runtime of sprinklers to prevent runoff from turf on slopes. Total irrigation runoff was calculated based on overspray, surface runoff and percolation or seepage over a specified period of time. When Dispatch was added to the irrigation water vertical movement of water was more pronounced than the control (water alone). The least runoff occurred when the soil had the highest matric potential. Dispatch treatments resulted in 43% and 55% higher total wetting surface area at 30 minutes and 60 minutes respectively compared to the water alone treatment. Cultural practices like core aerification, topdressing with sand and using a wetting agent reduced the volume of surface runoff by increasing the infiltration rate and the time period when visible surface runoff was first observed since the start of the irrigation event.

Effects of Flutolanil Fungicide and Primer Wetting Agent on Water-repellent Soil

Localized dry spot (LDS) caused by water repellent soil is a common problem on golf course putting greens having a predominately sand root zone. Fairy ring often causes LDS by developing hydrophobic soil. Although the fungicide flutolanil is labeled for the control of fairy ring, golf course superintendents often apply flutolanil to all LDS caused by hydrophobic soil and other conditions. The objective of this study was to determine the effect of flutolanil on an existing hydrophobic soil. The study was conducted on a creeping bentgrass [Agrostis palustris (synonym A. stolonifera)] experimental golf green in which the top 4 inches (10.2 cm) of the root zone was a moderately hydrophobic sand. Six treatments were used: uncored, cored, flutolanil (two applications.), flutolanil + Primer wetting agent (two applications.), Primer (two applications.) and Primer (three applications.). Plots receiving the fungicide and wetting agent treatments were cored before application. Each treatment containing the wetting agent significantly reduced soil water repellency. Flutolanil without wetting agent had no effect on soil hydrophobicity.

Wetting Characteristics of Different Peat and Peat: Bark-based Potting Media: Influence of Wetting Agents in Improving Wetting and Rewetting Performance

Eight different peat-based or peat: bark-based potting media were evaluated for their wetting performance when treated with the media wetting agent AquaGro 2000 (2–5 oz/yd3). Upon initial irrigation, no differences in wetting uniformity were observed in seven of the eight test media regardless of their media wetting agent treatments. In four media, water retention was reduced by media wetting agent treatment, however, uniform distribution of water was achieved. AquaGro 2000 improved uniformity of initial wetting in one medium in which the initial moisture content was 6.5%. Uniformity of wetting and water retention improved with increasing wetting agent rate. All media were allowed to air dry and then were re-irrigated. Wetting agent-treated media rewet uniformly, while rewetting varied greatly in untreated media (7.5%–82.5%). Less than 50% of the mass of untreated media wet subsequent to drying. Those portions of the untreated media that did wet retained up to three times more water per unit volume compared to AquaGro 2000-treated media. AquaGro 2000 enhanced uniformity of rewetting, reduced water logging, and improved drainage at all rates (2–5 oz/yd3) tested. Media composition (peat vs. peat: bark did not affect wetting agent efficacy.

Stability and Effectiveness of Wetting Agents in Stored Growing Media

Three soilless media of different composition (peat: vermiculite, bark: peat: vermiculite, peat: vermiculite: polystyrene) received one of three wetting agent treatments (AquaGro 160 at 60 ml or 120 ml·m–3; or AquaGro L at 120 ml·m–3) and were subsequently analyzed for wettability after storage for up to 4 months. The respective untreated media served as the controls. All media were stored in closed bags at 24 ± 4C. Water retention was greater in wetting agent-treated media than in controls. Both wetting agents facilitated uniform distribution of water in the media. Control media became more difficult to wet over time, whereas wetting agent treatments maintained uniform wettability of media throughout the storage period. Wetting agent chemistry, treatment rate, and media composition influenced wetting characteristics during media storage. All three wetting agent treatments improved wetting of the peat: vermiculite over the 4-month test period. In bark media, AquaGro 160 applied at 120 ml·m–3 enhanced wetting throughout the study. Media containing polystyrene were difficult to wet. AquaGro 160 applied at 120 ml·m–3 improved wetting for up to 2 months.

829 PB 311 WETTING AGENT EFFECTS ON TURF SOIL-WATER REPELLENCY

Soil-water repellency is often a problem for turfgrass grown on sand soils. Wetting agents used to alleviate repellency often provide mixed results. We evaluated AquagroL and an experimental material (ACA 864) at 0, 7, 14, and 21ml/m2 applied monthly to tifgreen bermuda grown on a soil-water repellent Margate fine sand over 6 months. Alleviation of repellency was based upon water drop penetration time (WDPT). Wetting agents did not effect turf quality, cover, or discoloration. Wetting agents did not reduce repellency 1 month after initial application. At 2 months, ACA 864 at 21ml/m2 significantly reduced WDPT. With repeat applications, lower rates of ACA 864 provided reductions in WDPT similar to the highest rate of ACA 864, suggesting an additive effect over time. There was a decline in WDPT for all wetting agent treatments, except the control, over time. Repellency decreased with soil depth, and repeat wetting agent application reduced WDPT at lesser depth.

EFFECT OF LEACHATE FRACTION AND WETTING AGENT ON THE SOIL NO3-N PROFILE UNDERLYING A GREENHOUSE CROP

Chrysanthemums, cultivars Red Grenadine and Buckaroo, were produced in 15 cm pots in the greenhouse and fertilized with a 210 mg/l N solution at a volume of either 550 ml or 1000 ml. The nutrient solution applied to half the pots contained a wetting agent (AquaGro L), the remaining pots received no wetting agent. Soil core samples were removed, at 15 cm increments to a depth of 90 cm, from the soil profile underlying each treatment group. Leachate samples were collected and the volume and NO3-N content determined. Final and mid-term plant dry weight were determined, and the tissues (leaves and flowers) were analyzed for NO3-N and total nitrogen content. The leachate fraction (LF) from pots receiving a wetting agent (WA) was greater (p<0.05) than from pots receiving no WA (29.1% vs 26.4% respectively). However, WA did not greatly affect the amount of NO3-N in container effluent or the total NO3-N deposited on the soil underlying the crop; these were most influenced by LF. NO3-N content in the upper 15cm soil zone under pots irrigated to a high LF was higher than under the low LF pots after two weeks and by week 10 (end of the study) significant differences were measured in the 30-45 cm soil zone. At final harvest, significant differences in plant dry weight, potting medium NO3-N, and plant total N content were observed in response to both LF and WA treatments.

Pre-forcing Treatments Influence Bud Break and Shoot Elongation in Forced Woody Species

Abstract Experiments were conducted to evaluate the feasibility of pre-forcing treatments for the release of bud dormancy of dormant stems of lilac, privet and Vanhoutte spirea. The new softwood growth of these dormant stems was used either as explants for in vitro culture or as cuttings for rooting studies of woody plant species in the off-season. A pre-forcing 15% bleach solution (0.78% NaOCl) soak hastened bud break, enhanced percentage of bud break, and promoted shoot elongation. Pre-forcing wetting agent treatments produced similar results to those of the bleach soak with variation among wetting agents and plant species. Smaller treatment differences were observed in the forcing characteristics when stems were collected later in the winter, probably because the cold requirement of the buds had been completely or partially met. This technique will provide explants for in vitro culture and softwood cuttings for propagation of woody plants over an extended period.

Leachability of a Wetting Agent Treatment for Water-Resistant Soils

Burned chaparral watersheds in southern California have been found to possess a “nonwettable” soil property. This resistance to wetting is believed to be instrumental in producing high surface runoff and erosion rates during storm periods. A laboratory leaching study was conducted to estimate the teachability of a remedial wetting agent treatment in this problem soil. Results from the study showed that the wetting agent treatment persisted after 40 cm of water have passed through the soil samples.

Seed Germination and Establishment as Affected by Non‐Wettable Soils and Wetting Agents

To study the effects of soil wettability and wetting agents on seed germination and establishment, three substrates (naturally occurring non—wettable soil, and a wettable quartz sand) were placed in small plastic containers and received applications of wetting agent in liquid, wetting agent on perlite, and no treatment as a control. The containers were seeded to wimmera ryegrass and were placed both on a 30° slope and on the level in a controlled temperature chamber (70°F). Seed placed on a non—wettable soil which received no wetting agent treatment failed to germinate in those containers placed on the slope. Good germination occurred on soil which was treated with a wetting agent and on wettable sand. The same are primarily due to water relations; water ran off the sloping non—wettable soils. Wetting agent treatment on the wettable sand reduced both germination and establishment of the tested plants.

Physical Soil Amendments, Soil Compaction, Irrigation, and Wetting Agents in Turfgrass Management I. Effects on Compactability, Water Infiltration Rates, Evapotranspiration, and Number of Irrigations1

AbstractUnamended soil and soil amended with peat, lignified redwood, and calcined clay were used to grow common bermudagrass in a greenhouse experiment. Two compaction treatments, 2 wetting agent treatments, and 2 irrigation programs were superimposed on each of the soil materials for a total of 32 treatments. Water infiltration rates were in the general order of unamended soil < peat < lignified redwood = calcined clay amended soil. Compaction decreased the infiltration rate of unamended and peat amended soil, but had no effect on the other two soil mixes. Wetting agent increased the infiltration rate into unamended soil. Soil compactability was in the order unamended soil > peat > lignified redwood > calcined clay amended soils. Soil compactability was greater under set schedule irrigation as compared to tensiometer guided irrigation. Wetting agent reduced the compactability of peat. Evaportranspiration and number of irrigations were greater under set irrigation as compared to tensiometer guided irrigation. Other results of this experiment will be presented in subsequent papers.