Virginia Turfgrass Council / PO Box 5989 / Virginia Beach, VA 23471 ...

Cover Story continued1,000 ft 2 ) and when watered intothe canopy immediately afterapplication. Reflectance datafrom visible red and near infraredregions of the electromagneticspectrum were collected andused for calculating simple ratiovegetation index values (RVI).Figures 1 and 2 show a portionof data generated from this study.While reflectance measurementswere higher with tebuconazoleand metconazole, none of theplots were objectionable. In mostcases, higher rates actually hadhigher RVI values, indicatinggreater health (Figure 1). Alternationwith trinexapac-ethyl didnot negatively impact the performanceof DMIs, and accordingto these data, it may actuallyimprove quality of Tourneyand Trinity.SummaryThis group, as a whole, has manybenefits for turf managers. Withthe newest additions to the class,many diseases are controlled moreeffectively, with others still beingsuccessfully controlled with olderchemistry.Over my career, I have evaluatedthousands of plots that havebeen treated with the various DMIfungicides. I could easily counton two hands (possibly even one)the number of times where a normalapplication of any of theseproducts caused significant injury. Ido not recall any situations whereobjectionable injury occurred onhigher-mowed turf, such as golfroughs, lawns or athletic fields.When using common sense, followingthe label and paying closeattention to environmental stresses,there is very little concern forserious injury from one of theseproducts. This is not to say thatserious injury to turf will neveroccur, but the likelihood is slim.Even with the newer (andtypically safer) DMI fungicides, itis probably a good idea to avoidapplying high rates to closelymowed turfgrasses when daytimeair temperatures exceed 90°F.Additionally, rotation with otherfungicide classes is recommendedfor multiple reasons.Finally, disease control withthese fungicides and others willbe optimized when the turf isfunctioning properly. Culturalpractices that alleviate stress willallow the fungicides to functionproperly as they were designed. cJournal of the Virginia Turfgrass Council | 15