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Evaluation of Calcium Silicate for Brown Patch and Dollar Spot Suppression on Turfgrasses

2006; Wiley; Volume: 46; Issue: 4 Linguagem: Inglês

10.2135/cropsci2005.04-0002

1435-0653

Qi Zhang, Jack D. Fry, Kathy Lowe, Ned Tisserat,

Coal and Its By-products

Nonfungicide alternatives for control of brown patch (caused by Rhizoctonia solani Kühn) and dollar spot (caused by Sclerotinia homoeocarpa F.T. Bennett) diseases are needed. Calcium silicate (CaSiO 3 ) was applied as a topdressing (2440 or 4880 kg ha −1 ) to evaluate brown patch suppression in ‘Bonsai 2000’ and ‘Tar Heel’ tall fescue ( Festuca arundinacea Schreb.) and ‘L‐93’ creeping bentgrass ( Agrostis palustris Huds.) in the field, or amended into soil at 7325 or 14650 kg ha −1 to evaluate dollar spot on ‘Penncross’ creeping bentgrass in a growth chamber. The Chase silty clay loam (fine, montmorillonitic, mesic Aquic Argiudoll) under tall fescue had a pH of 6.4, a high initial Si content (173 mg kg −1 ), and Si accumulation in leaves was minimal (one of five observations). Calcium silicate applied at 2440 kg ha −1 increased the area under disease progress curves (AUDPC) for brown patch by 26% in 2002 and 30% (both rates) in 2003. Tall fescue leaf P and K concentrations were reduced by CaSiO 3 and were negatively correlated ( r = −0.41 for P; −0.44 for K; P < 0.02) with brown patch. Calcium silicate topdressing increased Si in creeping bentgrass leaf tissue as well as the sand root zone, which initially contained <12 mg kg −1 Si. A positive correlation ( r = 0.81; P < 0.001) occurred between creeping bentgrass leaf Si concentration and brown patch severity in one of three years, which may have resulted from reduced leaf P and K after CaSiO 3 application. The silty clay loam (170 mg kg −1 Si) amended with CaSiO 3 before planting creeping bentgrass had no effect on leaf Si concentrations or dollar spot incidence. Thus, CaSiO 3 application to soil containing adequate Si should not be recommended for control of brown patch on tall fescue, nor should CaSiO 3 be recommended to control brown patch on creeping bentgrass grown on low Si soil or dollar spot on high Si soil. In fact, CaSiO 3 application may exacerbate brown patch disease incidence possibly because of nutrient imbalances, particularly in tall fescue.