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Table 1. Treatment details and thatch/mat organic matter percent at the end of the year, 2008–2010.Surface Area Removed (%)Thatch/Mat (%OM)# Treatment Details March Sept. Total Nov. 2008 Nov. 2009 Nov. 20101 Control (sand only) 0% 0% 0% 5.2% a 4.3% a 4.3% ab2 0.25" id core, 2 passes, Spring & Fall 5% 5% 10% 4.9% ab 3.4% c 3.8% cd3 Verticut, 3 mm blade, Spring & Fall 11.8% 11.8% 23.6% 5.0% ab 3.9% ab 4.0% bc40.25" id + verticut, 3 mm blade, Spring;0.25" id core, Fall2.5% +11.8%2.5% 16.8% 5.2% a 3.7% bc 4.5% a50.5" id core, Spring; 0.25" id core, 2passes, Fall11.8% 5% 14.8% 4.8% b 3.3% cd 3.3% de6 0.5" id core, Spring & Fall 9.8% 9.8% 19.6% 4.8% b 3.0% d 3.1% e70.5" id core, Spring; verticut, 3 mm blade+ 0.25" id core, 2 passes, Fall9.8%5% +11.8%26.6% 5.1% ab 3.3% cd 3.2% eLSD 0.05 0.38 0.42 0.49Our researchWe conducted our Virginia-specificstudy on 10-year-old Penn A4 practiceputting greens at the IndependenceGolf Club, near Richmond. Prior tostarting the study, analysis revealed athatch/mat layer (0" to 2" deep) with5.8% organic matter. Various combinationsof small tines (0.25" insidediameter (id)), big tines (0.50" id)and verticutting (3 mm blade) wereimposed in late March and early Septemberto provide a range of seasonalsurface removal from 0% to 26.6%(Table 1). Tine spacing was 1.33" X1.5", with a coring depth of 2". Verticutterblade spacing was 1", whiledepth was 0.75". Heavy sand topdressingof approximately 12 ft 3 (1,200lbs./M) was applied on both days ofcultivation, supplemented by fourlight topdressings of 0.15 ft 3 every 4to 6 weeks between cultivations, fora seasonal total of about 24.6 ft 3 .To track the recovery rates followingcultivation treatments in 2009 and2010, digital images were taken every7 to 14 days with a light box and analyzedwith SigmaScan software. Linearregression was then used to predictthe number of days required for eachtreated plot to return to 99% coveror a non-disrupted putting surface.Cultural management of thesegreens were identical to all others onthe golf course, receiving preventivepesticide applications, daily mowing at0.125" and annual fertilization of 4.4,3.3 and 4.3 lbs. N/M in 2008, 2009and 2010, respectively.Research resultsOrganic matter dilutionAt the end of 2008, only those coringtreatments that removed 14.8% to19.6% (Treatments 5 and 6, see Table1) significantly reduced %OM relativeto the topdressed control. Usingsmaller tines alone (Treatment 2),verticutting alone (Treatment 3) andcombinations of the two (Treatment4) failed to reduce %OM in 2008.At the end of 2009, all treatments,except verticutting alone, significantlydecreased %OM in the thatch/matlayer relative to the topdressed control(Table 1). Coring in spring and fallwith 0.5" id tines on a tight spacing toremove approximately 9.8% surfacearea to a depth of 2" (Treatment 5)resulted in the least OM (3.1%) overthe three years. These data imply thatverticutting to 0.75" does not removeenough depth of material for adequateorganic matter dilution, eventhough this procedure removes alarge amount of surface area (11.8%)with each pass.Between 2009 and 2010, very littlechange in %OM due to treatmentswas measured. The only changes ofnote from 2009 to 2010 were anincrease from 3.7% to 4.5% in Treatment4 (verticutting + small-tine cultivation)and a slight increase (3.4% to3.8%) in Treatment 2 (small tines, 2passes). Only where large tines wereused to remove 14.8% or greatersurface area (Treatments 5, 6 and 7)were %OM levels kept at significantlylower levels (3.1% to 3.3%) relativeto the topdressed control.Cultivation recovery rateThe fastest spring recovery (averagedover 2009 and 2010) of 29.5 days wasmeasured for Treatment 3 (verticutting).Large-diameter coring (Treatments5, 6 and 7) or small-diametercoring + verticutting on the same day(Treatment 4) required 35.5 to 40days for spring recovery (Table 2).Late summer/early fall recoverydata were very similar for cultivationtreatments that remained the sameas their spring counterpart. In particular,Treatment 3 (verticutting)recovered in only 25.5 days (Table 2),while large-diameter coring alone(Treatment 6) required six fewerdays of recovery (40 days vs. 34 days),relative to the spring. Fastest earlySeptember recovery of 8.5 days waswith Treatment 4, where only 2.5%surface removal occurred.Quality ratingsThe visual quality ratings at variousdates in 2008 and 2010 (Table 3) showthat the control plots (sand-topdressedonly) did not suffer summer decline,as might be expected without coreJournal of the Virginia Turfgrass Council | 17