Newer fungicide chemistries for grapes

Various trends in crop protection worldwide are changing the landscape for grape fungicides.

Choices for crop protection with grape fungicides are changing. We have seen an overall increase in new fungicide registrations over the past two years. One distinct trend is that there are more downy mildew fungicides on the market due to outbreaks of cucurbit downy mildew in the United States. Since these fungicides also work well against downy mildew in grapes, we are now seeing a range of new products for grapes, e.g., Presidio, Revus, Tanos, Forum, Reason and Ranman. Some of these have yet to be evaluated in Michigan.

The threat of soybean rust, an invasive disease of soybeans, has speeded up the review of sterol inhibitor fungicides by the EPA and led to the registration of several new SI products for grapes, including Mettle and Inspire Super. Growers may also have noticed that commonly used fungicides, like mancozeb and copper have become more expensive – one of the reasons is the increasing price of copper worldwide.

Furthermore, the number of natural fungicide products, including biological control agents and plant extracts (e.g., Regalia), has been steadily increasing. This has increased the number of disease control options for organic grapes.

Generic fungicides are now becoming more common since the patents have run out on a number of older fungicides. Examples of these are Legion, Nevado, Orius, TebuStar, AgriStar Sonoma and Tebuzol. In order to extend fungicide patents, companies have also started developing pre-mixes of different fungicide active ingredients. These pre-mixes have a broader spectrum of activity than single-ingredient products and are convenient to use. An example is Adament, which is a pre-mix of Flint and Elite. Pre-mixes are available for specific disease complexes, for instance powdery mildew and downy mildew or powdery mildew and Botrytis bunch rot. That way, these products can be tailored to specific cultivars or times of the growing season. 

Below are a number of newer grape fungicides described that you may or may not recognize. Those fungicides that have shown at least moderately good activity in field trials in Michigan are given an efficacy rating in the grape section of E-154, the Michigan Fruit Management Guide. Those that have not been tested in Michigan yet, or showed poor efficacy in trials, are simply listed here for your information. More products are in the pipeline and may become available this season. You will be updated on new grape fungicides as they get registered for use in Michigan. For fungicide labels and material safety data sheets, go to the label/MSDS section of the CDMS website.

Adament (tebuconazole and trifloxystrobin) is a mixture of a systemic (tebuconazole) and surface-systemic (trifloxystrobin) fungicide.  It is a broad-spectrum fungicide that is labeled for control of multiple diseases on grapes, cherries, peaches, and nectarines. Adament is rainfast when dry, generally within 2 hours. Adament is effective against cherry leaf spot, brown rot, and powdery mildew on cherries, and powdery mildew in grapes. It has excellent efficacy against powdery mildew (where fungicide resistance is not present) and black rot, and is moderately effective against Botrytis bunch rot. Adament is best used as a protectant. Do not apply this product on Concord grapes, as crop injury may result due to the trifloxystrobin (Flint) component. Do not make more than two consecutive applications or a total of six applications in grapes per season.

Forum (dimethomorph) is a new, systemic fungicide for control of downy mildew in grapes. Use Forum as a preventive application before infection occurs. The minimum application interval is 7 days. Performance may be improved by using Forum in a tank mix with another fungicide. The addition of a spreading/penetrating adjuvant is prohibited. Do not make more than 5 applications per year, and no more than one application before switching to a fungicide with a different mode of action. The REI is 12 hours and the PHI is 28 days. Forum will be evaluated for disease control in Michigan this summer.

Inspire Super (difenoconazole and cyprodinil) is labeled for control of powdery mildew, Botrytis bunch rot, black rot and anthracnose. It has preventative, systemic, and curative properties against. Difenoconazole belongs to the sterol inhibitor class of fungicides, whereas cyprodinil is active ingredient in Vangard. The application rate is 16-20 fl oz per acre. For all diseases, apply before the onset of disease. Apply on a 10-14 day schedule, with no more than 2 consecutive applications before alternating to a fungicide with a different mode of action. Do not apply more than 80 fl oz of Inspire Super per acre per season and no more than 0.46 lb a.i. difenoconazole and 1.4 lb a.i. cyprodinil. Avoid spray overlap as crop injury may occur. The PHI is 14 days, and the REI is 12 hours.

Mettle (tetraconazole) is a new sterol inhibitor fungicide. It is a systemic fungicide labeled for control of powdery mildew and black rot in grapes. When a post-infection application is used for black rot, it is recommended within 72 hours of an infection period. Mettle is absorbed quickly into the plant tissue and is rainfast within 2 hours of application. Do not make more than two applications of Mettle to grapes per year. The maximum amount of Mettle allowed per season is 10 fluid ounces and there must be at least 14 days between applications. Do not apply Mettle through any kind of irrigation system. The REI of Mettle is 12 hours and the PHI is 14 days. Mettle had performed similarly to Elite in Michigan trials.

Nutrol (monopotassium phosphate; 50% P2O5 and 32% K2O) is a water-soluble fertilizer (0-52-32) as well as a fungicide against powdery mildew. This product is labeled for control of powdery mildew in apples, stone fruits, and grapes. It is a salt and acts primarily as a contact fungicide. Nutrol will not cause phytotoxicity, even at high concentrations. Nutrol is a non-toxic, environmentally friendly product that is exempt from residue tolerances. It can also be used as a pH buffer to prevent alkaline hydrolysis of pesticides. A 1% solution will have a pH between 4.5 and 6.0. Nutrol is compatible with most commonly used agricultural chemicals. The PHI is 0-days. This product has not been evaluated in Michigan.

Presidio (fluopicolide) is a new systemic fungicide which is active against diseases caused by downy mildews and other oomycetes in grapes. This fungicide has a novel mode of action and has protective, curative, eradicative, and antisporulant properties. Presidio is locally systemic and translaminar and moves systemically via xylem tissue. Furthermore, Presidio is compatible with many fungicides and insecticides and is rainfast in 2 hours. The PHI for grapes is 21 days; no more than two sequential applications are allowed.  A tankmix with another fungicide with a different mode of action must be used with Presidio for resistance management. Presidio has worked well against downy mildew in trials in Michigan.

Quadris Top (azoxystrobin and difenoconazole) is labeled for control of powdery mildew, downy mildew, black rot, anthracnose, and minor foliar diseases; and suppression of Botrytis bunch rot. It is systemic and has preventative, systemic and curative properties. This fungicide has not been evaluated yet in Michigan, but the individual components have, and efficacy is expected to be excellent. It will be evaluated this growing season. Quadris Top can be applied at 10-14 fl oz per acre on a 10-14 day schedule. No more than two consecutive sprays are allowed and a total of 56 fl oz per acre per season. The PHI is 14 days and the REI is 12 hours. Due to the azoxystrobin component, Quadris Top is extremely phototoxic to certain apple varieties.

Ranman (cyazofamid) is a new fungicide for control of downy mildew in grapes. Ranman has limited systemic activity, so should be applied in a preventive mode. Make fungicide applications on a 10-14 day schedule when conditions are favorable for disease development. Do not apply more than 6 sprays of Ranman per season and no more than 3 consecutive sprays before switching to fungicides with different modes of action for the next three applications. Do not use any surfactant with Ranman. Application water volumes for ground application should at least be 100 gal per acre. Ranman may be applied through irrigation systems with restrictions (for instructions see the label).  The REI is 12 hours and the PHI is 30 days. This product has not been evaluated for disease control in Michigan.

Reason (fenamidone) is a new systemic fungicide for control of downy mildew in grapes. Reason is related to the strobilurins (Group 11), which means that cross-resistance may occur. Reason can be applied at 10-14-day intervals during periods of disease susceptibility. Do not make more than one application of Reason before switching to a fungicide with a different mode of action. Do not apply more than 8.1 fl oz of Reason per acre per growing season. The REI is 12 hours. Do not apply within 30 days of harvest. Reason has not been evaluated in Michigan yet, but has shown good control of downy mildew in other states.

Regalia (extract of Reynoutria sachalinensis = giant knotweed) is a plant extract-based biofungicide that is OMRI approved for organic production. It is labeled for broad-spectrum disease control in grapes. The proposed mode of action is by increasing the plant’s natural defenses. This induced resistance is not systemic throughout the plant but limited to the leaf it is applied to. The resistance reaction takes 1 to 2 days to develop. Light is required for best results. Regalia should therefore be used as a preventative treatment. Applications have to be repeated every 7-14 days to protect new growth. Regalia is labeled for control of in grapes. Regalia has a 0-day PHI and a 4-hour REI. In past trials in grapes with a different formulation, Regalia showed moderate to good control of powdery mildew and moderate control of downy mildew and Botrytis bunch rot. Regalia will be evaluated this year in grape trials in Michigan.

Revus (mandipropamid) is a new systemic fungicide for control of downy mildew in grapes. It has preventative and limited curative properties. A maximum of four sprays and two sequential sprays is allowed. The addition of a spreading/penetrating type adjuvant such as a non-ionic based surfactant or crop oil concentrate is recommended. The PHI is 14 days for grapes. This product has shown good efficacy against downy mildew in grape trials in Michigan. Revus is also available in a pre-mix called Revus Top with difenoconazole (a sterol inhibitor).

Revus Top (mandipropamid + difenoconazole) is labeled for control of downy mildew, powdery mildew, Phomopsis, black rot, anthracnose, and minor foliar diseases. It has preventative, systemic and curative properties. In Michigan trials, Revus Top gave excellent control of powdery mildew, downy mildew, and black rot; and moderate control of Phomopsis. For powdery mildew control, Revus Top can be applied on a 10-21 day interval. For downy mildew control, a 10-14 day interval should be used. Revus Top rapidly bonds to the wax layer on the plant and is rainfast as soon as the droplets have dried. Addition of a non-ionic surfactant, crop oil concentrate, or blend is recommended. No more than two sequential applications should be made before alternating with a fungicide with a different mode of action. Do not apply more than 28 fl oz/acre (= four applications) of Revus Top per season. The PHI is 14 days and the REI 12 hours. Due to the risk of phytotoxicity, Revus Top is not recommended for Concord, Concord Seedless, and Thomcord grapes. Precaution is advised on other Labrusca-type grapes and Labrusca hybrids, as adjuvants or other components in the tank-mix may increase phytotoxicity potential. The risk of phytotoxicity may be enhanced during rapid growth which may result in tender tissues and a thin wax layer on leaves.

Sonata (Bacillus pumilis QST 2808) is a protectant biofungicide that is OMRI listed and therefore can be used in organic production. Sonata is labeled for use against powdery mildew in grapes. Sonata has a 0-day pre-harvest interval and a 4-hour re-entry interval. Adding a terpene-based spray adjuvant, such as Nu-Film-P can improve coverage and control. If disease pressure is high, alternate or tank mix this product with other effective fungicides. Sonata has shown moderate to good efficacy (when tank-mixed with Nu-Film-P) against powdery mildew, downy mildew, and Phomopsis in grape trials in Michigan.

Sporan (rosemary oil, clove oil, thyme oil, wintergreen oil, lecithin, butyl lactate) is a broad-spectrum protectant fungicide for use in grapes. Sporan is OMRI listed so it can be used in organic production. Sporan has no re-entry interval and a 0-day pre-harvest interval. Diseases listed on the label are: powdery mildew, downy mildew, black rot, Botrytis bunch rot, and Eutypa dieback in grapes. In trials in Michigan, Sporan gave fair control of downy mildew and black rot.

Tanos (famoxadone and cymoxanil) is a new, broad-spectrum fungicide for control of downy mildew in grapes. It has curative and locally systemic properties against downy mildews. Tanos rapidly penetrates into plant tissues and is rainfast within 1 hour of application. It must be tank-mixed with a contact fungicide labeled for that crop (e.g., mancozeb, captan or copper). A maximum of 9 applications of Tanos including other group 11 (strobilurin) fungicides is allowed per season. The PHI is 30 days for grapes. Tanos will be evaluated in Michigan this growing season.

Vivando (metrafenone) is a fungicide with a new and unique mode of action and the first in its chemical class. No cross-resistance is known with other fungicides but its specific mode of action not known. It is labeled for powdery mildew control and is a good choice in vineyards with (suspected) fungicide-resistant strains. In a Michigan trial in 2010, Vivando had excellent activity against powdery mildew and also suppressed black rot and downy mildew (these diseases are not on the label, however). This fungicide prevents infections and limits fungal growth, sporulation, and spore viability. Since Vivando does not have curative activity it should be applied preventively. It can be applied at 10-15 fl oz any time after budbreak on a 14-day or 21-day schedule. With longer spray intervals, a higher dose should be used. Vivando is rainfast within 1 hour and redistributes across the plant surface, providing improved coverage. Use of a silicone-based surfactant is recommended. A maximum of two consecutive and a total of three sprays is allowed. The PHI is 14 days and the REI 12 hours.

Generic Fungicide Options

In the past few years, patents have run out on a number of proprietary fungicide products and “generic” versions are now available for some common fungicides. Generic products by law have to have the same amount of active ingredient as the original fungicides. However, they may have different inert ingredients or different formulations.

Generic products may be more economical than brand name products, but most have not have been separately evaluated in Michigan and may not be specifically recommended in the E-154 Fruit Management Guide. However, they are described in the “Fungicides and Bactericides for Fruit Crops” section. For more information on individual products, you can check out their labels and material safety data sheets on the following website: www.cdms.net. Generic products are expected to be similar in disease control efficacy to their brand name counterparts. However, there may be minor variations in efficacy, behavior or even potential phytotoxicity due to different formulations.

Read the fungicide label carefully as you would for any new product. Do not assume that the labels of generic products are exactly the same as the brand name fungicides that you are used to. Sometimes there are differences in the crops that the product is labeled for or in the label instructions or restrictions. An example of this is Iprodione, which is labeled for blueberries, whereas the brand name product Rovral is not. The table below lists generic products of common fungicides.

Brand name Product Active Ingredient Generic Products
Aliette fosetyl-Al Legion
Aliette phosphites (same breakdown product as fosetyl-Al) ProPhyt, Phostrol, Agri-Fos, Rampart, Fosphite, Fungi-Phite, Topaz
Elite tebuconazole Orius, Tebuzol, TebuStar
Rally myclobutanil AgriStar Sonoma
Rovral iprodione Iprodione, Nevado
Topsin M thiophanate methyl Thiophanate Methyl

 

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