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Feature
New Fungicide Products
By Amanda Scherer, Assistant Professor and Extension Plant Pathologist and Dave Han, Associate Professor and Extension Specialist, Turfgrass Management Auburn University and Alabama Cooperative Extension System
Turfgrass diseases can be a serious and costly problem in grasses used in golf courses, sports fields, and landscapes. Fungicide applications are a key component of the integrated pest management strategy for turfgrass disease prevention on golf courses and landscape management. Turfgrass management professionals have a wide range of fungicides to select from including contact vs. systemic fungicides, protectants vs. curatives, and single active ingredient products vs. combination products.
Contact fungicides are protectants that provide a chemical barrier on turf leaf blades and stems to inhibit fungal growth. Contact fungicides require multiple applications on a regular schedule and adequate coverage to prevent disease. Classic examples include broad spectrum, multisite fungicides such as chlorothalonil (i.e., Syngenta’s Daconil Action®, Sipcam’s Echo 720®, etc.) and fluazinam (i.e., Syngenta’s Secure®). Contact fungicides tend to be cheaper, but since they do not enter a plant, they will be mowed off as a leaf grows. Also, new leaves that emerge after a spray will not be protected. Finally, contact fungicides cannot protect roots, so they are only useful against foliar diseases.
In contrast, systemic fungicides penetrate plant tissue and are then moved within the plant. Since they are absorbed, they can protect roots if they are watered in well and absorbed by the roots. This is important: very few fungicides can move down from the leaves to the root system. So, to combat a root disease, fungicides must be watered in to ensure they get past the thatch and into the soil, where roots can pick them up.
Although systemic fungicides have specific modes of action, they have both curative and protective properties that provide extended residual activity. Thus, systemic fungicides do not need to be applied as often as contact fungicides. Some examples include azoxystrobin (i.e., Syngenta’s Heritage®), mefentrifluconazole (i.e., BASF’s Maxtima®), and pydiflumetofen (i.e., Posterity®). Regardless, it is important to realize that not all fungicides are equally effective on all diseases. Labels should be referenced carefully to properly select the correct fungicide for a given disease.
A majority of the turfgrass fungicides available today are sitespecific fungicides that belong to one of the following groups of fungicides: demethylation inhibitors (DMIs; FRAC group 3), Qo Inhibitor (QoIs; FRAC group 11), and succinate dehydrogenase inhibitors (SDHIs; FRAC group 7). These fungicides carry medium to high risk for fungicide resistance development, which includes several of the systemic turf fungicides. More specifically, resistance has been confirmed for the following diseases and FRAC groups in the United States: anthracnose to QoI fungicides and thiophanate-methyl, dollar spot to thiophanate-methyl and DMI fungicides, gray leaf spot to QoI fungicides, and Pythium blight to phenylamide fungicides.
To reduce the risk of fungicide resistance in turfgrass pathogens, applicators should not rely on fungicides alone for disease control. If possible, modifying the environment to increase air flow over the turf, reduce soil compaction and improve drainage will help make conditions less conducive to fungal growth. Making sure that the turfgrass has enough sunlight and the proper fertilization to be healthy will improve its ability to outgrow diseases. Consider switching to less susceptible turfgrass varieties in areas with a history of disease. Finally, limit the number of applications of at-risk fungicides, and alternate or tank mix with different FRAC groups.
Combination fungicide products, products that contain more than one active ingredient, can also help to mitigate fungicide resistance, and broaden the spectrum of activity of the fungicide. Although they were rare a little over a decade ago, there are now more than two dozen combination fungicides currently labeled for turf disease management. Some examples include Headway® (azoxystrobin + propiconazole; Syngenta), Posterity® Forte (azoxystrobin + propiconazole + pydiflumetofen; Syngenta), Lexicon® Intrinsic® (fluxapyroxad + pyraclostrobin; BASF), Armada® or Tartan® (triadimefon + trifloxystrobin; Bayer).
In terms of new fungicides, there have been a few products released over the last few years including the following fungicides:
Densicor® (Bayer Environmental Science US Inc.) is a new DMI fungicide that contains prothioconazole (FRAC group 3). It is labeled for use on greens, fairways, and tees in cool and warm season turf. It can protect turf against anthracnose, brown patch, dollar spot, fairy ring, large patch, spring dead spot, and take-all. See label for complete application instructions and use restrictions.
Densicor® (Bayer Environmental Science US Inc.) is a new DMI fungicide that contains prothioconazole (FRAC group 3). It is labeled for use on greens, fairways, and tees in cool and warm season turf. It can protect turf against anthracnose, brown patch, dollar spot, fairy ring, large patch, spring dead spot, and take-all. See label for complete application instructions and use restrictions.
Dexter™ SC (UPL NA Inc.) is a new QoI fungicide that contains a familiar active ingredient, azoxystrobin (FRAC group 11). It is labeled for use on residential, greens, fairways, and tees in cool and warm season turf. It can protect turf against anthracnose, brown patch, gray leaf spot, large patch, meltingout, Pythium blight, spring dead spot, and take-all. See label for complete application instructions and use restrictions.
Maxtima® (BASF Professional and Specialty Solutions) is a new DMI fungicide that contains mefentrifluconazole (FRAC group 3). It can be sprayed at any temperature and any turf variety established in cemeteries, commercial and industrial sites, sod farms, and golf course greens, fairways, roughs, and tees. It is not currently labeled for use on residential lawns or athletic turf. Maxtima® is labeled for use to help manage anthracnose, brown patch, dollar spot, fairy ring, spring dead spot, and take-all. See label for complete application instructions and use restrictions.
Tourney EZ® (Valent U.S.A. LLC Professional Products) liquid formulation is the next generation of Tourney Fungicide. It is a DMI fungicide that contains metconazole (FRAC group 3). It can be sprayed on cool and warm season turfgrasses on golf courses, lawns and landscape areas around residential, institutional, public, commercial and industrial buildings, recreational areas, athletic fields, and sod farms. Tourney EZ® can help manage anthracnose, brown patch, dollar spot, fairy ring, gray leaf spot, large patch, rust, and take-all. See label for complete application instructions and use restrictions.
Union® Fungicide SC (PBI-Gordon Professional) is a new combination product that includes azoxystrobin (FRAC group 11) + cyazofamid (FRAC group 21). This product provides protection against several diseases by combining both active ingredients including anthracnose, brown patch, fairy ring, gray leaf spot, melting out, pythium blight, and rust. It is labeled for use on all turfgrass species established in residential areas, recreational areas, commercial and industrial buildings, athletic fields, golf courses and sod farms. See label for complete application instructions and use restrictions.
