Postemergence herbicide options for mature goosegrass [Eleusine indica (L.) Gaertn.] control in bermudagrass (Cynodon spp. Rich.) turf are lacking. Greenhouse and field trials were conducted to determine the lowest rate at which topramezone, with or without triclopyr, controls goosegrass while maintaining acceptable bermudagrass quality. Greenhouse dose–response studies determined herbicide rates for field trials. In field trials, topramezone at 6.13 to 12.3 g a.i. ha−1 applied twice at a 3‐wk interval eliminated 8‐ to 18‐tiller goosegrass at three of four locations. The same topramezone treatments did not reduce smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.] cover more than 53% when applied alone and not more than 84% when applied with triclopyr at 140 g acid equivalent ha−1. The number of days over a threshold of 30% injury or stunting (DOT30) within the 28‐d period following each of two herbicide treatments was calculated for 31 bermudagrass varieties. Bermudagrass injury DOT30 following the first treatment ranged from 11.1 to 17.8 d, depending on variety. The addition of triclopyr increased injury DOT30 but reduced the severity of discoloration by eliminating white tissue discoloration. All varieties were severely injured but completely or near completely recovered by 28 d after each treatment. Generally, topramezone at 6.13 or 12.3 g a.i. ha−1 applied twice controls goosegrass in bermudagrass. Addition of triclopyr improves smooth crabgrass control and decreases severity of bermudagrass injury but increases suprathreshold‐injury duration.

Core Ideas Tembotrione controlled weeds selectively in bluegrass, fescue, and zoysiagrass turf. Topramezone controlled key weeds better than mesotrione and tembotrione. Topramezone was among the safest herbicides on four of the six turfgrasses tested. Results will aid herbicidal‐risk assessment near potentially sensitive turfgrass species. The study supports considerations for herbicide label expansion or registration in turf. Mesotrione (2‐[4‐(methylsulfonyl)‐2‐nitrobenzoyl]‐1,3‐cyclohexanedione), tembotrione (2‐[2‐chloro‐4‐(methylsulfonyl)‐3‐[(2,2,2‐trifluoroethoxy)methyl]benzoyl]‐1,3‐cyclohexanedione), and topramezone ([3‐(4,5‐dihydro‐3‐isoxazolyl)‐2‐methyl‐4‐(methylsulfonyl)phenyl](5‐hydroxy‐1‐methyl‐1H‐pyrazol‐4‐yl)methanone) are new herbicides that control many troublesome weeds, but little is known about the response of several turfgrass species to these herbicides. A multiyear study was conducted to determine the response of six turfgrass species and four weeds to these three herbicides. Study results generally agreed with previous reports of turfgrass and weed response to mesotrione, and suggest that tembotrione could be safely used, depending on rate, to control weeds such as smooth crabgrass [Digitaria ischemum (Schreb.) Schreb. ex Muhl.], broadleaf plantain (Plantago major L.), and white clover (Trifolium repens L.) selectively in tall fescue [Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.], Kentucky bluegrass (Poa pratensis L.), and zoysiagrass (Zoysia japonica Steud.) turf. Topramezone at 36.8 g a.i. ha−1 controlled smooth crabgrass and white clover better than mesotrione or tembotrione, and smooth crabgrass control by topramezone had similar results as in other studies. Predicted maximum turfgrass injury based on the Gaussian function applied over time generally showed that maximum injury caused by topramezone was less than tembotrione and mesotrione on creeping bentgrass (Agrostis stolonifera L.) and perennial ryegrass (Lolium perenne L.), less than tembotrione and equivalent to mesotrione on tall fescue and perennial ryegrass, equivalent to tembotrione and more than mesotrione on bermudagrass [Cynodon dactylon (L.) Pers.], and more than tembotrione and mesotrione on zoysiagrass. The area under the progress curve per day of visual injury and normalized difference vegetation index were consistent with trends in predicted maximum injury.

Annual bluegrass (ABG) (Poa annua L.) is a prolific seed producer in the spring on golf courses that in turn decreases aesthetic quality and trueness of ball roll on coolseason putting greens. Proxy (ethephon) applied twice in the spring after green-up is the current industry standard after the loss of Embark (mefluidide) from the turf and ornamental market. However, plant growth regulators including Proxy have been used for years to help suppress ABG seedheads with inconsistent success. The primary objective of this study was to determine if ABG seedhead suppression is improved by adding a late fall application of Proxy to the two traditional spring applications of plant growth regulators at nine locations with diverse environments. A second objective was to determine the importance of including Primo Maxx (trinexapac-ethyl) in fall and spring applications. Adding a late fall application of Proxy prior to the two spring applications (F+S+S) improved control of ABG seedheads over the traditional two spring applications (S+S), but the magnitude of improvement varied among locations. Abbreviations: ABG, annual bluegrass; AUSCPC, area under seedhead cover progress curve; CBG, creeping bentgrass; DAISA, days after initial spring application; F+S+S, Proxy + Primo Maxx applied once in fall plus twice in spring; GDD, growing degree day; S+S, Proxy + Primo Maxx applied twice in spring. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Only four herbicides are registered for smooth crabgrass or goosegrass control on creeping bentgrass golf putting greens. None of the four herbicides control weedy grasses for the entire season or control weeds postemergence when applied once at labeled rates. Three of these have product labels that prohibit repeated use or application during stressful summer conditions. We hypothesized frequently applying herbicides at low doses could provide season-long control of summer grasses while minimizing turf injury. Seven field experiments were conducted on creeping bentgrass putting greens to evaluate various herbicides applied monthly, biweekly, or weekly for postemergence and residual control of goosegrass and smooth crabgrass as well as creeping bentgrass putting green tolerance. Metamifop applied twice monthly at 200 g ai ha−1, topramezone applied eight times weekly at 1.5 g ae ha−1, and siduron applied weekly at 5.6 kg ai ha−1 or four times biweekly at 11 kg ha−1 did not injure creeping bentgrass greater than 10% and maintained creeping bentgrass quality and cover equivalent to nontreated turf. Weekly or biweekly programs of fenoxaprop or quinclorac caused unacceptable injury and quality decline. Metamifop applied monthly and either fenoxaprop program controlled both smooth crabgrass and goosegrass 97 to 99% throughout the growing season. Programs containing either quinclorac or siduron controlled smooth crabgrass 99 to 100% but did not control goosegrass greater than 39%. All topramezone programs controlled smooth crabgrass 69 to 77% and goosegrass 93 to 98%. In additional studies, siduron applied five times biweekly did not injure creeping bentgrass putting greens and controlled smooth crabgrass greater than 90% at seasonal, cumulative rates between 17 and 65 kg ai ha−1. This method of frequent, low-dose herbicide treatment to control smooth crabgrass and goosegrass on golf putting greens is novel and could be legally implemented currently with siduron.

Immediate, post-treatment irrigation has been proposed as a method to reduce hybrid bermudagrass [Cynodon dactylon (L.) Pers. x Cynodon transvaalensis Burtt Davy] phytotoxicity from topramezone. Immediate irrigation is impractical since it would take a turfgrass sprayer 10 to 15 minutes to cover an average golf course fairway or athletic field. There is also insufficient evidence regarding how post-treatment irrigation, immediate or otherwise, influences mature goosegrass [Eleusine indica (L.) Gaertn.] control from topramezone or low-dose topramezone plus metribuzin programs. We sought to investigate bermudagrass and E. indica response to immediate, 15-minute, and 30-minute post-treatment irrigation compared to no irrigation following topramezone at 12.3 g ae ha−1, the lowest labeled rate, or topramezone at 6.1 g ha−1 plus metribuzin at 210 g ai ha−1. We also evaluated placement of each herbicide and their combination on soil, foliage, and soil plus foliage to help elucidate the mechanisms involved in differential responses between species and herbicide mixtures. Responses were largely dependent on trial due to bermudagrass injury from high-dose topramezone being nearly eliminated by immediate irrigation in one trial and only slightly affected in another. When post-treatment irrigation was postponed for 15 or 30 minutes, topramezone alone injured bermudagrass unacceptably in both trials. Bermudagrass was injured less by low-dose topramezone plus metribuzin than by high-dose topramezone. All post-treatment irrigation timings reduced E. indica control compared to no post-treatment irrigation. The herbicide placement study suggested that topramezone control of E. indica is highly dependent on foliar uptake and phytotoxicity of both bermudagrass and E. indica is greater from topramezone than metribuzin. Thus, post-treatment irrigation likely reduces topramezone rate load with a concomitant effect on plant phytotoxicity of both species. Metribuzin reduced 21-d cumulative clipping wt and tiller production of plants, and this may be a mechanism by which it reduces foliar white discoloration from topramezone.

Goosegrass [Eleusine indica (L.) Gaertn.] remains problematic for bermudagrass [Cynodon dactylon (L.) Pers.] turf managers due to the ineffective, selective control of mature plants with available POST herbicides and lack of sufficient residual activity from those herbicides to control seedling plants. Topramezone controls mature E. indica, but past efforts to suppress potential injury to bermudagrass turf have been inconsistent. We hypothesized that metribuzin at 210 g ai ha−1 in admixture with topramezone would improve bermudagrass tolerance while conserving mature E. indica control. In preliminary field studies, metribuzin mixed with topramezone at 1.2 or 2.5 g ae ha−1 applied twice at a 3-wk interval reduced bermudagrass injury and white discoloration compared to topramezone applied alone, but metribuzin did not safen bermudagrass to mesotrione. Topramezone at 3.7 g ha−1 plus 210 g ha−1 metribuzin applied twice at a 3-wk interval offered improved bermudagrass tolerance while it still controlled mature E. indica during fifteen field and two greenhouse studies in Virginia. This program offered a 10-fold decrease in suprathreshold duration of white-discoloration compared to topramezone alone at 6.1 g ha−1. Bermudagrass absorbed three times less radioactivity than E. indica at timings up to 48 h after treatment with 14C-topramezone. Bermudagrass also metabolized twice as much topramezone compared to E. indica at 48 h after treatment. Metribuzin reduced 14C absorption by approximately 25% in both species. These studies confirm the performance of a novel, low-dose topramezone plus metribuzin program for mature E. indica control in bermudagrass turf, and suggest that selectivity between bermudagrass and E. indica to topramezone is due to differential absorption and metabolism. The fact that metribuzin reduces topramezone absorption in both species suggests that it may help reduce bermudagrass phytotoxic response to topramezone, but its role in altering selectivity between bermudagrass and E. indica may be due to other factors.

I n t e g r a t e d Tu r f g r a s s M a n a g e m e n t : We e d B i o l o g y a n d C o n t r o l

A 77-year-old male with a history of cataract extraction and intraocular lens placement 5.5 years prior, was referred for idiopathic corneal edema of the right eye. Six months prior to initial consult with a Cornea specialist, the patient presented with acute onset cystoid macular edema (CME) and later developed anterior chamber (AC) cell. The cornea became diffusely edematous and decompensated on topical steroids and hypertonic drops. During the Descemet's membrane endothelial keratoplasty (DMEK) procedure, a sequestered retained lens fragment (RLF) migrated out of the posterior chamber and was aspirated. The remainder of the surgery and post-operative period was unremarkable. This case is the first reported in which a significantly delayed onset of inflammatory reaction from a sequestered RLF led to full corneal decompensation requiring keratoplasty. This case highlights the importance of RLF suspicion in delayed presentation, even when RLFs are not visible via slit-lamp or on gonioscopic view.