MSU Extension

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.    

Various new(er) fungicides are available for use on fruit crops in Michigan. Some of these you may already know and others you may be less familiar with. The fungicides are listed in alphabetical order with relevant information on the crops they are labeled for and guidelines/restrictions. As with all fungicides, read the label carefully before use. Labels and material data safety sheets (MSDS) can be found on the following website: www.cdms.net. Descriptions of all fruit fungicides and efficacy ratings of recommended fungicides can be found in E-154 (Michigan Fruit Management Guide).

AgriStar Sonoma (myclobutanil) is a generic version of Rally, which used to be called Nova. It is labeled for broad-spectrum disease control in grapes, apples, and stone fruit. Note that AgriStar Sonoma is not labeled for other berry crops, whereas Rally is. The REI is 24 hours and the PHI is 1 day for stone fruit is and 14 days for apples and grapes. The efficacy of this product has not been specifically evaluated in Michigan.

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 as 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. Forum may be applied through irrigation systems with restrictions (see the label). Forum is not for use in greenhouse and transplant production. The REI is 12 hours and the PHI is 28 days. Forum has not been evaluated for disease control in Michigan.

Iprodione (iprodione) has the same active ingredient as Rovral. It is a contact fungicide with locally systemic properties. It is labeled on grapes, cherries, peaches, nectarines, plums, apricots, blueberries, strawberries, raspberries, blackberries, gooseberries, and currants. Note that Iprodione is labeled for blueberries but Rovral is not. Thorough coverage is essential for effective control. Alternating Iprodione with fungicides with a different mode of action may delay the buildup of resistant pathogen strains. Do not exceed a 4-spray maximum for wine grapes and berries-, a 2-spray maximum for stone fruit, and a 1-spray maximum for table grapes and strawberries. Do not apply after first fruiting flower in strawberries or after petal fall in stone fruit. Iprodione may be applied through irrigation systems with restrictions (see the label). The spray suspension should be applied within 24 hours of preparation and the pH of the spray solution should be buffered to 5.0-7.0 if necessary to prevent potential active ingredient degradation. The efficacy of this product has not been specifically evaluated in Michigan.

Legion (fosetyl-Al) has the same active ingredient as Aliette. It is available as an 80 WDG formulation. This product is labeled for control of Phytophthora collar and root rot and fire blight in apples and pears (bearing and non-bearing) and apple blister spot in bearing trees; Phytophthora collar and root rot in stone fruit (non-bearing); Phytopthora and anthracnose (and suppression of Phomopsis and Alternaria fruit rot) in blueberries; Phytophthora root rot in raspberries, blackberries, and cranberries; downy mildew in grapes; and red stele and leather rot in strawberry. Do not tank mix Legion 80 WDG with copper compounds or apply to foliage that bears copper residues from previous sprays as this could result in phytotoxicity to crops. Stickers, spreaders and wetting agents are not recommended with this product. Legion is acidic in nature and must not be tankmixed with acid-type compatibility spray adjuvants, such as Buffit Spray Aide, Triton AG-44M, or with adjuvants that aid foliar penetration, such as Herbex or Induce. The REI is 12 hours. The PHI is 12 hours for blueberries and strawberries, 14 days for apples and pears (365 days in non-bearing pome and stone fruit trees), 15 days in grapes, 30 days in cranberries, and 60 days in raspberries and blackberries. This product has not been specifically evaluated in Michigan.

MetaStar (metalaxyl) has the same active ingredient as Ridomil. MetaStar is for soil application only and is not to be used for foliar applications, except in solutions used to dip plants. MetaStar is labeled for control of Phytopthora diseases in apples, stone fruit, blueberries, cranberries, raspberries, strawberries. This label is for field use only and is not intended for use on transplant trays, greenhouses, lath houses, float houses, hydroponic production, or in bedding plant structures. MetaStar may be applied through irrigation systems with restrictions (for instructions see the label). Applications are usually made in the spring and the fall. The REI is 48 hours and the PHI is 45 days for raspberries and cranberries. In strawberries, an application at fruit set is allowed for control of leather rot. No PHI is indicated for the other crops if application instructions are followed.

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 has not been tested for disease control in Michigan vineyards.

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 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 percent 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.

Rampart (mono- and dipotassium salts of phosphorous acid; equivalent to 3.9 lb phosphorous acid per gallon) is a systemic phosphite fungicide labeled for apples, cherries, peaches, nectarines, plums, apricots, blueberries, strawberries, raspberries, blackberries, cranberries, gooseberries, and currants. The target diseases listed are root rots (Phytophthora, Pythium, Fusarium, Rhizoctonia), downy and powdery mildew, anthracnose, and bacterial diseases. Application is foliar, aerially, as a root dip or through the irrigation system (with restrictions). In fruit trees, the product may also be applied via trunk injection. Do not apply at less than 3-day intervals. Do not apply to plants that are dormant, or heat or moisture stressed. To avoid copper phytotoxicity, do not apply to plants that have been treated with copper-based compounds at less than 20-day intervals. Allow foliage to dry completely after application. Do not apply when conditions favor wet tissue for prolonged periods greater than four hours. The REI is four hours and the PHI is 0 days. This product has not been evaluated for disease control in Michigan.

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 disease warning systems forecast disease infection periods or 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.

Regalia (extract of Reynoutria sachalinensis = giant knotweed) is a plant extract-based biofungicide that can be used in organic production. The proposed mode of action is by increasing the plant’s natural defenses. This induced resistance is not systemic but is there is some translaminar protection. 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 various diseases of apples, pears, cherries, peaches, nectarines, plums, apricots, grapes, blueberries, raspberries, blackberries, gooseberries, and other berry crops. Regalia has a 0-day PHI and a 4-hour REI. In a blueberry trial in Michigan, Regalia provided good control of mummy berry and moderate control of anthracnose. In grapes, Regalia showed good control of powdery mildew, and moderate control of downy mildew and Botrytis bunch rot. More trials are needed to assess this product in Michigan fruit crops.

TebuStar (tebuconazole) has the same active ingredient as Elite. Tebustar is labeled for cherries, peaches, nectarines, and grapes. The PHI is 0 days for stone fruit and 14 days for grapes. The efficacy of this product has not been specifically evaluated in Michigan.

Topaz (mono- and dipotassium salts of phosphorous acid; 3.9 lb phosphorous acid per gallon) is a systemic phosphite fungicide labeled for apples, cherries, peaches, nectarines, plums, apricots, blueberries, strawberries, raspberries, blackberries, cranberries, gooseberries, and currants. The target diseases listed are root rots (Phytophthora, Pythium, Fusarium, Rhizoctonia), downy and powdery mildew and fire blight. Application is foliar, aerially, as a root dip or through the irrigation system (with restrictions). Do not apply at less than 3-day intervals. Do not apply to plants that are dormant, or heat or moisture stressed. To avoid copper phytotoxicity, do not apply to plants that have been treated with copper-based compounds at less than 20-day intervals. Allow foliage to dry completely after application. Do not apply when conditions favor wet tissue for prolonged periods greater than four hours. The REI is four hours and the PHI is 0 days. This product has not been evaluated for disease control in Michigan.