Influence of Nitrogen Rate and Timing, Fungicide Application Method, and Simulated Rainfall after Fungicide Application on Brown Patch Severity in Tall Fescue

Abstract

Tall fescue lawns can be fertilized during the summer months at modest N rates without affecting brown patch severity.• When an appropriate fungicide such as Heritage was used for brown patch management, the method of fungicide delivery did not affect brown patch suppression.• Simulated rainfall up to 0.5 inches within 15 min of fungicide application did not compromise fungicide efficacy. AbstractIn North Carolina, tall fescue (Festuca arundinacea Schreb.) is widely grown throughout the Mountain and Piedmont regions. North Carolina is in the transition zone, which is subject to hot, humid summers that predispose tall fescue to brown patch (Rhizoctonia solani Kühn). Field trials were conducted over a 2-year period (2015)(2016) to evaluate the effects of nitrogen rate and timing, application method of a fungicide, and rainfall following fungicide application on brown patch severity on lawn height tall fescue. Seven rates of urea providing 0 to 6 lb N 1000 ft -2 year -1 were initiated each year in March with repeat applications monthly at 1 lb N 1000 ft -2 . In a separate study, various timings of urea were conducted throughout the year for a total of 3 lb N 1000 ft -2 yr -1 . In 2015, no significant differences in disease severity or turfgrass quality were observed among the seven N rates. Only the application of 6 lb N 1000 ft -2 yr -1 resulted in significantly higher brown patch compared with the non-treated control in 2016. No significant differences in disease severity or turfgrass quality were observed in the timing study in both years. Azoxystrobin was applied with a ride-on spreader/sprayer (11 gal water-carrier acre -1 ), a commercial applicator gun (130 gal water-carrier acre -1 ), and a research spray boom (88 gal water-carrier acre -1 ). No differences were detected among application methods. A rainfall event of 0.5 inches was simulated with overhead irrigation 30 min after application of fungicides. No differences were detected among the fungicide treatments, and all provided excellent control of brown patch.

Brown patch severity as affected by cool‐season turfgrass species, cultivar, and nitrogen rate

“…Higher rates of annual N were found to increase brown patch severity compared to unfertilized TTTF or lower rates of N (Burpee, 1995;Cutulle et al, 2014;Watkins & Wit, 1993). However, other studies reported that annual N rates (<294 kg N ha −1 ) throughout the growing season did not affect brown patch severity in Coronado TTTF (Butler et al, 2019;Teuton et al, 2007). Currently, best management practices for N fertility with regard to management of brown patch among all cool-season species are to avoid an abundance of quick-release N sources and prevent insufficient N to avoid enhancing disease severity (Tredway et al, 2023).…”

“…Future studies focused on quantification of potential reductions in fungicide requirements to manage brown patch could further demonstrate sustainable approaches for turfgrass disease management. Previous research evaluating the relationship between N fertilization and brown patch severity has only compared responses within an individual species (Bloom & Couch, 1960;Burpee, 1995;Butler et al, 2019;Fidanza & Dernoeden, 1996a;Watkins & Wit, 1993). Traditional management recommendations have been to limit or avoid N applications during the spring and summer to avoid enhancing brown patch severity across all cool-season turfgrass species (Couch, 1995;Tredway et al, 2023;Watschke et al, 2013).…”

“…Nitrogen fertilization can also influence plant physical barriers (e.g., cuticle permeability and lignin content), biochemical defenses (e.g., production of phytoalexins, antimicrobial proteins, defense‐related enzymes), and defense responses (e.g., systemic acquired resistance), which can alter plant susceptibility to select pathogens (Camargo et al., 2014; Huang et al., 2017; Ngadze et al., 2012; Sela et al., 2013; Sun et al., 2020; Wang et al., 2014). The relationship between brown patch severity and N fertility practices, however, remains complex (Burpee & Martin, 1992; Butler et al., 2019; Fidanza & Dernoeden, 1997).…”

Nutritive value of fall‐stockpiled tall fescue pastures on southeastern U.S. farms

“…It was rapidly adopted and has become prolific even in areas not intentionally sown because of seed dispersal by birds, machinery, etc. It has a clumping growth structure from production of short rhizomes and abundant tillers over time, although with dense seed placement forms a thick sod as well (Butler, Galle, & Kerns, 2019), and many varieties have been developed specifically for recreational turf (Karcher, Richardson, Hignight, & Rush, 2008). One of the key characteristics of this forage is its association with a mutualistic fungal endophyte, Epichloe coenophiala , which renders the plant moderately toxic to herbivores with production of ergot alkaloids during peak growth periods in spring and fall (Stuedemann & Hoveland, 1988).…”