Interactive Effects of Plant Growth Regulators and Fungicides on Epidemics of Dollar Spot in Creeping Bentgrass

Plant Disease ◽  
1996 ◽  
Vol 80 (11) ◽  
pp. 1245 ◽  
Author(s):  
L. L. Burpee
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Creeping Bentgrass ◽  
Interactive Effects ◽  
Dollar Spot

Plant Growth Regulators Applied in Winter Improve Annual Bluegrass (Poa annua) Seedhead Suppression on Golf Greens

2017 ◽  
Vol 31 (5) ◽  
pp. 701-713 ◽  
Author(s):  
Shawn D. Askew
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Treatment Program ◽  
Creeping Bentgrass ◽  
Late Winter ◽  
Floral Initiation ◽  
Early Application ◽  
Golf Greens ◽  
Annual Bluegrass

Annual bluegrass seedhead suppression on golf greens by spring-applied plant growth regulators (PGR) has been erratic between years and locations. To effectively suppress annual bluegrass seedheads on greens, current information suggest ethephon must be applied before floral initiation. Rogue seedheads, however, can sometimes be found in late winter indicating that a variable proportion of annual bluegrass plants may induce floral initiation in winter. Studies were conducted in Blacksburg and Harrisonburg, VA at five separate sites between 2011 and 2012 to determine if winter applications of ethephon or mefluidide would improve annual bluegrass seedhead suppression when applied in advance of a spring, two-treatment program. A spring, two-treatment program of ethephon plus trinexapac-ethyl reduced annual bluegrass seedhead cover 22 to 55% depending on trial and less than similar mefluidide programs. Applying an early application of ethephon in January or February prior to the spring treatment program resulted in 5 to 7 times less seedhead cover at cover maxima than the spring treatment program alone. Ethephon did not injure creeping bentgrass and caused only slight and transient discoloration to annual bluegrass. Mefluidide injured both creeping bentgrass and annual bluegrass and reduced annual bluegrass population density in late spring. Programs that consisted of an early ethephon application, a spring treatment of triademifon, and two spring treatments of ethephon plus trinexapac ethyl improved seedhead suppression and turf quality but slightly increased annual bluegrass injury. Methiozolin suppressed annual bluegrass seedheads primarily through severe injury to annual bluegrass, which led to a decline in turfgrass quality and NDVI but a substantial increase in creeping bentgrass cover. Applying PGRs in winter is a novel concept and may substantially improve ethephon consistency and performance for annual bluegrass seedhead suppression on greens.

scholarly journals Creeping Bentgrass Physiological Responses to Natural Plant Growth Regulators and Iron Under Two Regimes

HortScience ◽  
2002 ◽  
Vol 37 (6) ◽  
pp. 898-902 ◽  
Author(s):  
Xunzhong Zhang ◽  
R.E. Schmidt ◽  
E.H. Ervin ◽  
S. Doak
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Foliar Application ◽  
Creeping Bentgrass ◽  
Leaf Color ◽  
Sod Activity ◽  
Natural Plant ◽  
High Fertilization

Creeping bentgrass (Agrostis palustris Huds.) is an extensively used cool-season grass for fine turf areas such as golf course putting greens, but suffers from poor summer stress tolerance. These studies were conducted to investigate the influences of natural plant growth regulators (NPGR) and Fe on creeping bentgrass photochemical activity (PA), antioxidant superoxide dismutase (SOD) activity, root growth and leaf color under two fertilization regimes. The bentgrass was maintained in well-watered field conditions or water-stressed glasshouse conditions. A mature bentgrass was treated monthly during the field season with seaweed (Ascophyllum nodosum Jol.) extract (SWE) at 50 mg·m-2 or humic acid (HA) at 150 mg·m-2 or in combination with or without FeSO4 at 520 mg·m-2 and grown under a low or a high fertilization regime. Foliar application of SWE + Fe increased PA (14% to 15%), while applications of SWE + HA or SWE + HA + Fe increased SOD activity (49% to 114%) of creeping bentgrass in Summer 1997 and Summer 1998. There was no significant fertilization × NPGR interaction for PA and SOD activity. Bentgrass PA was increased by 13% to 46% when treated with NPGR with or without Fe compared to the control measured in May. The addition of Fe with each NPGR application improved fall and winter leaf color. All NPGR and Fe treatments increased root mass (17% to 29%) in Aug. 1997 and 1998, except HA alone in 1998. Under sustained low soil moisture (-0.5 MPa) conditions, application of NPGR with or without Fe increased PA and SOD activity. The data indicate that SWE and HA enhance the physiological function of `Southshore' creeping bentgrass, resulting in improved root growth regardless of low or high fertilization regime. However, addition of Fe to these NPGR served primarily to improve late season leaf color. The results suggest that, in addition to maintaining adequate plant-available nutrients, applications of natural PGRs, such as SWE and HA, prior to and during summer abiotic stresses would be beneficial.

scholarly journals In vitro Assessment of Sclerotinia homoeocarpa Resistance to Fungicides and Plant Growth Regulators

Plant Disease ◽  
2011 ◽  
Vol 95 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Chang-Ho Ok ◽  
James T. Popko ◽  
Katie Campbell-Nelson ◽  
Geunhwa Jung
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Cross Resistance ◽  
Sclerotinia Homoeocarpa ◽  
Dollar Spot ◽  
Active Ingredients ◽  
Dmi Fungicides ◽  
Fungistatic Effect

Dollar spot (caused by Sclerotinia homoeocarpa) is the most economically important turfgrass disease in North America. This disease is primarily controlled by fungicide applications on golf courses; however, fungicide resistance has been confirmed in three of the four systemic fungicide classes commonly used to control dollar spot. The main objective of this study was to evaluate S. homoeocarpa sensitivity to multiple chemical classes and cross-resistance among active ingredients within the same class; in particular, the association between the fungistatic effect of demethylation inhibitors (DMIs) and plant growth regulators (PGRs). Fifty-eight isolates were selected arbitrarily from four locations in the United States and assayed for in vitro sensitivity to six DMI, two dicarboximide, one carboximide, and one benzimidazole fungicide as well as three type II PGRs. A series of concentrations for each active ingredient was used to determine the mean 50% effective concentration (EC50) values and correlation coefficients were calculated for all active ingredients. The EC50 values of all active ingredients from the DMI class were highly correlated (P < 0.0001) to each other as well as to the one dicarboximide (iprodione) and two PGRs (flurprimidol and paclobutrazol). Isolates resistant to thiophanatemethyl had significantly higher EC50 values than sensitive isolates for all active ingredients assayed except for boscalid. Findings showed that multiple and cross-resistance has developed in S. homoeocarpa and that the two PGRs have a fungistatic effect on this pathogen similar to that of DMI fungicides. The high correlation of in vitro sensitivities among PGRs and DMI fungicides further suggests that PGRs may contribute to the selection of DMI-resistant isolates or facilitate decreased sensitivity to DMI fungicides in the field.

Suppression of a Perennial Subspecies of Annual Bluegrass (Poa annuaspp.reptans) in a Creeping Bentgrass (Agrostis stolonifera) Green with Plant Growth Regulators

1996 ◽  
Vol 10 (4) ◽  
pp. 705-709 ◽  
Author(s):  
B. Jack Johnson ◽  
Tim R. Murphy
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Creeping Bentgrass ◽  
Agrostis Stolonifera ◽  
Annual Bluegrass ◽  
Final Treatment ◽  
Fall Application

Paclobutrazol and flurprimidol were evaluated for suppression of a perennial subspecies of annual bluegrass in a creeping bentgrass green. Three applications of paclobutrazol in the spring (Mar. 17, Apr. 17, and May 17) followed by three applications in the fall (Oct. 2, Nov. 2, and Nov. 30) suppressed the perennial subspecies ≥ 72% at 3 wk after the final treatment. However, suppression was reduced to ≤ 57% by 4 mo after the final fall application. Flurprimidol applied in three spring and three fall applications did not suppress the perennial subspecies as effectively as paclobutrazol. Suppression was ≤ 47% at 3 wk after the final flurprimidol treatment and was only ≤ 20% by mid-March. Neither chemical injured creeping bentgrass greater than 20% in the spring. However, leaf discoloration injury from the initial October application ranged from 26 to 30% for paclobutrazol in 1993 and 21 to 28% for flurprimidol in 1994. When injury occurred in October it was temporary and the creeping bentgrass recovered within 3 to 4 wk. Paclobutrazol and flurprimidol applied in November did not injure creeping bentgrass.

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