This article provides some recent updates on fungicides currently registered for fungal disease control in cranberry. Specific usage instructions such as rates, timing, and precautions can be found on the fungicide labels, the 2022 Cranberry Pesticide Chart from the Cranberry Institute, and the 2022 Wisconsin Cranberry Pest Management Guide. Please make sure you have the most up-to-date versions of these documents and get rid of older versions. If you notice an inconsistency between the product label and the UW spray guide or Cranberry Institute chart, always follow the instructions on the label. Check with your handler about rule changes and restrictions. REMEMBER, the label is the law, read and follow the directions on the label.

What is FRAC?
The Fungicide Resistance Action Committee or FRAC works to prolong the effectiveness of fungicides prone to resistance issues and minimize crop losses in the event of resistance. A FRAC group is a number and/or letter combination used to distinguish different fungicides based on their mode of action.

Mancozeb (FRAC M3) – In cranberry, mancozeb offers broad-spectrum control against fruit rot pathogens, however mancozeb can result in reduced fruit color if applied during bloom and/or fruit set stages, critical application timing for fruit rot control. As of January 4, 2021, mancozeb is no longer approved as an active substance at the European Union (EU) level. Mancozeb will soon be undergoing a registration review by the US EPA. A public comment period has not yet been defined. As more updates become available, I will share them here in the Cranberry Crop Management Journal.

Chlorothalonil (FRAC M5) is currently undergoing registration review by the EPA. In Wisconsin, this chemistry is not widely used due to the large proportion of harvested fruits that are destined for export markets where residues are not tolerated. However, fruits for domestic consumption may still utilize chlorothalonil for fruit rot control in accordance with handler rules and the fungicide label. For decades, chlorothalonil has been an important tool for fungicide resistance management due to its multi-site activity. This chemistry is a critical tool for fruit rot control in the northeast where disease pressure is significantly higher. In Wisconsin, chlorothalonil remains the only broad-spectrum fungicide used to treat upright dieback. Currently, there are no new updates on the registration review process, but I anticipate learning more by late 2022.

Tank Mixes vs. Pre-mixes

As many navigate fruit rot management this season and the increased costs of pesticides, there may be interest in using the most affordable products available. Fortunately, in Wisconsin, we’ve seen excellent fruit rot control with our registered single-site and premixed chemistries in FRAC groups 3 and 11. The tank mix of Indar + Abound has been the grower standard for many years but with the addition of pre-mixture chemistries to the cranberry fruit rot management toolbox, I want to highlight some important differences between these current fungicide offerings as growers prepare themselves for their first in-bloom spray application.

Tank mixing = two or more chemical pesticides mixed in a spray tank prior to spraying.

Pre-mixture = product that contains two or more active ingredients.

• Indar + Abound is a common and highly effective tank mix for fruit rot control in Wisconsin. Indar is a member of the FRAC 3 group of fungicides and contains the active ingredient fenbuconazole. Abound is a member of the FRAC 11 group of fungicides and contains the active ingredient azoxystrobin. This tank mix combination is often considered a grower standard in Wisconsin and has performed consistently in Wisconsin fungicide trials in low and high disease pressure years.
• Quadris Top is a pre-mixed fungicide also shown to be very effective against fruit rot and cottonball. This premixture includes active ingredients azoxystrobin (FRAC 11) and difenoconazole (FRAC 3). This fungicide is growing in popularity due to the convenience of the active ingredients being combined in the product.
  • NOTE: While Indar + Abound and Quadris Top include active ingredients in the same FRAC groups, they are not identical products. Specifically, Quadris Top is not Indar and Abound mixed together. While Indar + Abound and Quadris Top both contain the same FRAC 11 fungicide, azoxystrobin, the rate of azoxystrobin is different in Abound than in Quadris Top. Furthermore, Indar contains the active ingredient fenbuconazole, while the FRAC 3 component of Quadris Top contains difenoconazole. Fenbuconazole and difenoconazole are different chemistries but have the same mode of action.
• Quilt Xcel is also a pre-mixed fungicide, and while it is registered for both cottonball and fruit rot control, it should only be used for cottonball control as it recommends applications at early bloom rather than later as is generally needed for good fruit rot control. Similar to the fungicides listed above the active ingredients in Quilt Xcel include fungicide chemistries in FRAC groups 3 and 11. The FRAC 11 chemistry is azoxystrobin and the FRAC 3 chemistry is propiconazole (different than the active ingredient in Indar and the FRAC 3 chemistry in Quadris Top).

There are benefits to tank mixing fungicides, and there are benefits to premixes. The choice is yours, and there is no wrong answer as it depends on your operation. I offer some general considerations below.

	Tank Mixes	Pre-mixtures
PROS	May reduce costs depending on price of individual ingredients Fungicide resistance management by mixing different active ingredients Customize mix of chemicals to fit your needs Can adjust rates of each chemistry in tank mix	May reduce costs depending on price of pre-mixed product Fungicide resistance management as product contains different active ingredients Less handling than mixing individual active ingredients Less inventory required (i.e., only one container)
CONS	May increase costs depending on price of individual ingredients More handling compared to pre-mixed chemistries Requires understanding of chemicals and their interactions Requires more inventory	May increase costs depending on price of pre-mixed product Recommended application timing may not be optimal for all ingredients One of the chemistries may have a reduced rate Cannot adjust rates of each chemistry

***The mention of a product is not an endorsement. The label is the law. Check handler guidelines for additional rules and regulations.

This article was posted in Cranberry, Disease and tagged Cranberries, disease, FRAC, fungicide, Fungicide Resistance Action Committee, Leslie Holland, Wisconsin Fungicide Update.