James A. Murphy’s research while affiliated with The State Of New Jersey and other places

Bentgrass (Agrostis spp.) cultivars vary in resistance to dollar spot caused by Clarireedia jacksonii. Using a damage threshold to schedule fungicide applications has potential for reducing fungicide inputs. Two field trials managed as fairway turf in North Brunswick, NJ, from 2018 to 2021 assessed the effectiveness of damage threshold fungicide schedules to control dollar spot on bentgrass cultivars varying in disease resistance. Two factorially arranged randomized complete block designs (3 × 6 and 3 × 9, non‐inoculated and inoculated, respectively) were used. A fungicide scheduling factor included a calendar schedule and two damage threshold schedules that applied fungicides either within 24 h or the next application day (NAD) once a 105 mm² m⁻² of symptomatic area was observed. The cultivar factor included six (Trial 1) and nine (Trial 2) bentgrass entries ranging from low to high dollar spot resistance. Damage threshold schedules on the resistant cultivar Declaration reduced fungicide inputs up to 78% compared to the calendar schedule. Reduced fungicide inputs for each cultivar were achieved by delaying disease onset in the non‐inoculated trial and extending the application interval in both trials. The 24‐h threshold schedule controlled dollar spot equivalent to the calendar schedule on more resistant cultivars. There was a lower risk of severe disease outbreaks when threshold applications were applied on the NAD schedule compared to the calendar schedule on the resistant cultivars. Thus, using a low damage threshold to apply fungicides on resistant bentgrass can effectively control dollar spot with fewer fungicide inputs.

Routine application of topdressing sand is widely practiced to manage putting green surfaces. Topdressing with finer sand and/or at minimal rates can enhance incorporation, greatly reducing the concerns of interference. A 7‐year field study investigated the effects of topdressing and cultivation practices on turf quality and surface characteristics of creeping bentgrass (Agrostis stolonifera L.) grown on a sand‐based rootzone. A 3 × 2 × 2 factorial design evaluated sand size (medium‐coarse, medium‐fine, and fine‐medium), rate of topdressing during mid‐season (0.24 or 0.49 kg m⁻² every 10–14 days), and cultivation (hollow tine cultivation [HTC] plus backfilled with medium‐coarse sand or noncultivated). Sand size and topdressing rate significantly affected turf quality, surface volumetric water content (VWC), and surface hardness, with their effects dependent on cultivation. Without HTC, VWC increased as the topdressing sand size became finer. However, when HTC was applied, VWC was not increased by topdressing with medium‐fine sand during any year. The practice of HTC also offset the effect of fine‐medium sand increasing VWC during the first 4 years, but not Years 5 through 7. Therefore, caution is needed when considering fine‐medium sand for topdressing putting greens. Additionally, after 5 years of treatment, the lower topdressing rate led to a wetter surface compared to the higher rate in the absence of cultivation, but not when HTC was applied. The major drawback of HTC was disruption of the turf surface, which resulted in better turf quality on noncultivated plots throughout the trial.

Sand topdressing is the practice of applying a thin layer of sand to the surface of a turf. The history of sand topdressing dates back over a century on the Old Course at St. Andrews, Scotland. Sand topdressing is critical for improving root zone physical properties, supporting healthy root systems, and alleviating compaction stresses at the soil surface of highly trafficked turfs. A primary benefit of using non-amended sand for topdressing is to avoid adding additional organic matter when the management objective is to prevent excessive organic matter (thatch) accumulation. However, there is a long-running debate about whether topdressing alone is sufficient for organic matter control. The documentation of organic matter accumulation is limited. Multiple years are often needed for sufficient organic matter to accumulate and enable the detection of differences among topdressing treatments. In a three-year case study on an annual bluegrass (Poa annua) putting green turf, our data suggest that topdressing sand decreases organic matter content on a mass basis by diluting thatch and forming a mat layer. The growth of healthy turfgrass can contribute greatly to organic matter accumulation at the surface of the soil profile. Thus, a successful topdressing program needs consistent applications to match the growth pattern of turfgrass for the local climate. A more comprehensive understanding of organic matter build-up and its subsequent role in soil and plant health is needed. Cultural management solely based on thresholds of organic matter content in turfgrass systems does not acknowledge that other evaluations such as layering, root health, water infiltration, and surface firmness need to be carefully considered before implementing cultivation management practices to reduce organic matter.

The effect of potassium on dollar spot of annual bluegrass (ABG; Poa annua L. forma reptans (Hausskn.) T. Koyama) and creeping bentgrass (CBG; Agrostis stolonifera L.) is poorly understood. Two field trials were conducted in 2020 and 2021 to determine the effect of K fertilization on dollar spot of ABG and CBG turf grown on a sand mat layer overlying a sandy loam (fine‐loamy, mixed, semiactive, and mesic Typic Hapludults) and mowed at 2.8 mm. A 4 × 2 factorial, randomized complete block design evaluated K (potassium sulfate) applied at 0, 3.4, 6.9, and 13.8 kg ha⁻¹ every 2 weeks and N (urea) applied at 4.9 kg ha⁻¹ every 7 or 28 days over 20 weeks. Infection centers were counted over a 2‐week period each year after inoculation with Clarireedia jacksonii in mid‐September and used to calculate the disease severity. Increasing K fertilization rate consistently increased dollar spot severity on ABG and CBG. Higher N rate either slightly increased or did not affect disease severity on ABG, and either decreased or had no effect on CBG. This is the first study to document the impact of K fertilization on dollar spot severity of ABG turf. Regression analysis indicated that increases in both leaf tissue and mat layer K were associated with greater dollar spot severity on both species. Future research should determine whether the increased dollar spot response to K fertilization occurs at higher antecedent mat layer and leaf tissue K. Additionally, a broader range of N rates may clarify the dollar spot response.

Annual bluegrass (Poa annua L.) is sensitive to high‐temperature stress, and approaches that can improve plant growth during summer months are important for golf courses managing P. annua putting greens. The objective of this 2‐year field trial was to determine plant health benefits for selected fungicides and the combination with a plant growth regulator (PGR), trinexapac‐ethyl (TE) on P. annua growth under putting green conditions during summer months. The following treatments were foliar sprayed at 14‐day intervals from June to September in 2020 and 2021: (1) untreated control with water, (2) Daconil Action, (3) Appear II, (4) Daconil Action and Appear II, and (5) Daconil Action, Appear II, and Primo Maxx (TE). Applying individual and combination treatments resulted in significant improvements on P. annua summer performance, as manifested by increased visual turf quality and other vegetation indices evaluated using multispectral radiometer (normalized difference vegetation index, leaf area index, and stress index or digital camera [percent canopy cover and dark green color index]) in both years. The combined treatment programs, Daconil Action and Appear II or Daconil Action, Appear II, and Primo Maxx were more effective than the untreated control and each individual treatment. The results suggest that there existed synergistic effects of multiple fungicides and PGR, which could be particularly useful in promoting plant health of P. annua under heat stress conditions.

Dollar spot is an important disease of both cool- and warm-season turfgrasses caused by six fungal species in the genus Clarireedia, yet the ecology and epidemiology of these pathogens remains poorly understood. The goal of this study was to determine the distribution of Clarireedia in asymptomatic and symptomatic creeping bentgrass (Agrostis stolonifera) in the field using a previously developed qPCR assay. To determine the horizontal distribution of the pathogen, the abundance of Clarireedia spp. was measured in leaf and crown tissue from 90, 1-cm diameter cores spaced 10-cm apart in May 2019 and 2020 (asymptomatic tissue) and August 2019 and July 2020 (symptomatic tissue). Thirty-seven to 69% of cores sampled from asymptomatic turfgrass and 77 to 95% of cores taken from symptomatic turfgrass yielded positive detections for Clarireedia. Spatial analysis indicated that Clarireedia was randomly distributed in the field in both asymptomatic and symptomatic turfgrass. To assess the vertical distribution of the pathogen, the abundance of Clarireedia was measured in the foliar, crown, and thatch layers of 39, 1-cm dia. x 2.5-cm deep cores of creeping bentgrass maintained at fairway height (9.5 mm) during 2019 and 2020. Clarireedia was most abundant in foliar tissue, followed by crown tissue, and thatch (lowest abundance) throughout the two-year study. Both studies provide evidence that Clarireedia is widely distributed in turfgrass swards prior to symptom development and that it can persist within turfgrass as an endophyte. These findings will improve our understanding of Clarireedia epidemiology and may lead to more sustainable dollar spot management.

Turfgrasses are susceptible to a wide variety of ectotrophic root-infecting (ERI) fungi that cause root rot (Tredway et al., 2023). Among the root rot diseases, fairway patch, caused by Phialocephala bamuru P.T.W. Wong & C. Dong sp. nov., was recently identified and characterized in Australia infecting bermudagrass (Cynodon dactylon) and kikuyu (Pennisetum clandestinum) grass (Wong et al., 2015). Symptoms begin as small, 5-10 cm diameter patches of yellowed turf that may coalesce into larger areas of diseased grass. A characteristic sign of fairway patch is roots colonized by dark brown to black, ectotrophic mycelium. In June 2020, many tan colored, irregular-shaped patches ranging from 10-30 cm in diameter developed on a hard fescue (Festuca brevipila) cultivar ‘Beacon’ turfgrass field in North Brunswick, New Jersey, USA. The centers of these patches later died and became sunken or filled in partially by recovering hard fescue. The patches grew into tan irregular-shaped rings with diameters up to 3 m by Aug 2023. Symptoms were indicative of a root disease. Five ‘Beacon’ hard fescue soil cores at the interface of the symptomatic and non-symptomatic area were sampled in Aug 2023. Root and crown samples were observed under a dissecting microscope and dark ectotrophic hyphae were observed on both. Roots with visible ectotrophic mycelium were removed, rinsed in sterile water three times, cut into 5 mm pieces, and plated onto 10% potato dextrose agar amended with streptomycin and gentamicin at 100 mg/L (PDA+). The plates were incubated at 25°C in the dark for 5 days. The most abundant colonies being characteristic long, septate hyphae that were hyaline at the edge and dark brown to black in the center and resembled the fungus described in Wong et al., 2015. These colonies were subcultured onto PDA+ medium and selected for molecular identification. Other less abundant colonies could be identified using morphology after subcultured and had no record being pathogenic to turfgrass. To confirm the isolate’s identity, its internal transcribed spacer (ITS) region was amplified in PCR using the ITS1F/ITS4 primers (Bellemain et al., 2010). The amplicon was then sequenced with both ITS1 and ITS4 primers by Sanger sequencing. Sequences were assembled (GenBank #PP000819). The consensus sequence was then BLASTn analyzed with default settings, and the result showed 99.64% sequence identity with P. bamuru (GenBank #MG195534.1). Koch’s postulate was conducted in an environmentally controlled growth chamber. Six healthy ‘Beacon’ hard fescue plugs were sampled from the field. Three of the six plugs (treatment) were each inoculated with P. bamuru by placing 20 g of P. bamuru colonized millets beneath and around the plug before filling the pots with sand. The other three plugs (control) received the same treatment except the P. bamuru colonized millets were autoclaved. The pots were incubated in the growth chamber with a 16 h light period and 25/20°C day/night temperatures. Symptoms resembling those observed in the field appeared on the treatment pots after 21 days of incubation while the control pots remained healthy. The roots from the treatment pots were examined under the dissecting microscope to confirm the colonization of P. bamuru on the roots, and P. bamuru was reisolated and confirmed using the aforementioned morphological traits and molecular assays (GenBank #PP000820). This is the first report of a turfgrass root rot disease caused by P. bamuru in the United States. Further epidemiological, disease ecological, and pathogen biological studies are required to clarify the importance of this disease in the United States and establish proper disease containment or control measures.

Creeping bentgrass (CB; Agrostis stolonifera L.) grows well in low phosphorus (P) soils in monoculture, however, the soil P concentration range that provides CB an advantage over annual bluegrass (AB; Poa annua L.) in mixed swards is unknown. The objective of this research was to determine how P and soil pH influence species composition when AB and CB are established from tillers in polyculture. Replicate greenhouse experiments evaluated five P rates (0, 3, 6, 9, and 12 kg ha⁻¹ P via triple superphosphate) and two soil pH levels (5.6 and 7.1). The highest P rate in the high pH soil resulted in the most AB cover (61%). Phosphate applied at 3 kg ha⁻¹ P in the low pH soil provided the greatest CB cover (72%), which was fivefold greater than AB cover. All P‐receiving treatments in the low pH soil had similar green cover, but a species advantage for CB was only observed in the 3 kg ha⁻¹ P treatment. Turfgrass quality was greatest when ≥6 kg ha⁻¹ P was applied to low pH soil but was only slightly reduced at 3 kg ha⁻¹ P. Regardless of pH, withholding P resulted in the lowest AB cover (<4%); however, these treatments resulted in poor turfgrass quality and low green cover (<30%). Aboveground shoot biomass increased linearly with P rate and was greater at the lower pH. In moderately acidic sand, AB was less competitive than CB when Mehlich‐3 P ranged from 4 to 6 mg kg⁻¹.

Magnaporthiopsis meyeri-festucae is a recently identified root-infecting pathogen of fine fescue (Festuca spp.) turfgrasses. Although it is phylogenetically similar to other root-infecting turfgrass pathogens such as M. poae, management of M. meyeri-festucae is distinct and highlights the need for fast and accurate identification. The objective of this study was to develop a rapid detection method for M. meyeri-festucae using recombinase polymerase amplification (RPA) to assist turfgrass managers in identifying the disease in the field and to facilitate further epidemiological research on the pathogen. Three isolates of M. meyeri-festucae and eight isolates from four related Magnaporthiopsis species were used to test the specificity of the RPA assay targeting M. meyeri-festucae. Rapid visualization of the RPA assay results using a mixture of purified amplicon and SYBR-safe fluorescence emitting asymmetrical cyanine dye showed that the assay was effective at detecting M. meyeri-festucae on turfgrass roots with no observed incidence of false positives or false negatives. The assay also differentiated between M. meyeri-festucae and other Magnaporthiopsis species, though overall sensitivity was lower compared to a PCR-based method. The RPA assay successfully detected M. meyeri-festucae following inoculation onto and grinding of turfgrass roots, indicating possible utility as a rapid field diagnostic tool for turfgrass managers. The fast and accurate RPA M. meyeri-festucae detection method presented here will be used for additional field and laboratory applications that will help improve the management of this emerging pathogen.

The annual bluegrass weevil (ABW) is typically regarded as a pest of fine turfgrass, but recent research has found withholding insecticides for ABW control can reduce annual bluegrass cover. The objective of this research was to evaluate threshold-based insecticide and paclobutrazol programs for annual bluegrass control. The effect of three insecticide programs (preventive, threshold, and no insecticide) and four rates of paclobutrazol (0, 70, 105, or 210 g ha ⁻¹ applied monthly) were evaluated. Replicate experiments were conducted from April to November in both 2018 and 2019 on a mixed creeping bentgrass and annual bluegrass fairway in North Brunswick, NJ. By the conclusion of both experiments, all paclobutrazol programs reduced annual bluegrass cover compared to the nontreated. In threshold and no insecticide programs, reduction in annual bluegrass cover was enhanced by paclobutrazol at 105 g ha ⁻¹ in both years, and at 70 g ha ⁻¹ in the 2019 experiment. Paclobutrazol at 210 g ha ⁻¹ reduced annual bluegrass cover to < 20% regardless of insecticide program. In 2019, threshold-based ABW control without paclobutrazol provided similar annual bluegrass control as monthly applications of paclobutrazol at 70 and 105 g ha ⁻¹ with the preventive insecticide program. Turfgrass quality reductions from threshold-based insecticide programs persisted for a shorter duration than the no insecticide program, regardless of paclobutrazol treatment. Threshold-based ABW insecticide programs that allow ABW feeding damage to occur can reduce annual bluegrass cover. These reductions were further enhanced by paclobutrazol applications. The combination of threshold-insecticide programs with moderate rates of paclobutrazol (70 to 105 g ha ⁻¹ ) provided reductions in annual bluegrass cover similar to the highest rate of paclobutrazol (210 g ha ⁻¹ ) without ABW damage. Turfgrass managers integrating the threshold insecticide approach and monthly paclobutrazol applications can achieve greater annual bluegrass control than either strategy alone if temporary reductions in turf quality can be tolerated.