Treatment Plan

*Please Note: Black Rot symptoms can easily be confused with Anthracnose symptoms. Review of both factsheets is encouraged to confirm your diagnosis.

Cultural practices used to reduce black rot inoculum include removing mummies from the vineyard and/or burying them around bud break by cultivating soil under the vines. Control is improved using canopy management practices that promote air circulation, speed drying of leaves and fruit, and improve spray penetration.

Mancozeb is the active ingredient in Dithane F-45 Rainshield (liquid formulation) and Manzate Pro-Stick Fungicide (dispersible granules). Mancozeb products are the backbone for black rot control in vineyards. They provide protectant control of black rot as well as anthracnose, downy mildew, Phomopsis, and angular leaf scorch, and are at low risk of developing resistance. The maximum allowance for all products containing mancozeb ranges from 18-19.2 lb of active ingredient per acre per season. At the maximum use rate, Dithane or Manzate Pro-Stick can be used up to six times per season, but not within 66 days of harvest. Mancozeb sprays for black rot should not be delayed beyond the immediate pre-bloom spray as the immediate pre-bloom through post-bloom periods are critical for control of black rot. Under severe pressure, such as serious black rot was present in the vineyard the previous year, and warm, wet conditions are anticipated prior to the next spray, applications should be started as early as 3-5” shoot growth. Mancozeb applications for other diseases such as Phomopsis and anthracnose might be warranted as early as 1” shoot growth. Once applications commence they should be continued on a 7-10 day schedule prior to bloom, and 10-14 days after bloom. Use the shorter spray intervals following periods of high rainfall. As a general rule of thumb, one half of a mancozeb product will be washed off following one inch of rain. For applications at 3-5” shoot growth, apply 1.6 to 3.2 qt Dithane or 2-4 lb Manzate Pro-Stick. For applications at 10-12” shoot growth through the immediate pre-bloom spray, apply 2.4 to 3.2 qt Dithane or 3-4 lb Manzate Pro-Stick. For post-bloom application, apply 3.2 qt Dithane or 4 lb Manzate Pro-Stick.

Ziram 76DF Fungicide provides protectant control of black rot and Phomopsis, and suppression of downy mildew with low risk of disease resistance development. Ziram is similar to mancozeb products for control of black rot and Phomopsis, but less effective than mancozeb for control of downy mildew. Ziram can be used from 6” shoot growth until 21 days to harvest with a maximum 24 lb per acre per season; hence, Ziram is most useful where applications for control of black rot are needed within the 66 day PHI requirement for mancozeb products, or after the maximum seasonal use rate of mancozeb has been reached. Apply 3-4 lb Ziram for applications prior to bloom, and 4 lb Ziram for post-bloom applications. 21 day PHI, 48 hr REI.

Rally 40WSP, Mettle 125ME Fungicide, the difenoconazole portion of Revus Top, and the tebuconazole products TebuStar 45WSP (water soluble packets), Amtide Tebuconazole 45WDG Fungicide (water dispersible granules) and Orius 20 AQ (liquid formulation) are fungicides with similar chemistry (DMI or sterol inhibitor fungicides, Resistance Group Number 3) that provide control of black rot and powdery mildew, and in some cases are labeled for control of anthracnose. All the sterol inhibitor (SI) fungicides provide limited (several days) protective activity against black rot and are also effective when applied after the start of an infection period (typically 3-7 days). Protective activity of sprays for black rot control can be extended by tank-mixing with mancozeb. Powdery mildew resistance to the SI fungicides is widespread where the products have been previously used, so it is recommended that the combined use of all SI fungicide products is limited to a maximum of three times per season. For control of black rot, applications of the SI fungicides can begin as early as 3-5” shoot growth. Mancozeb products and Ziram also provide excellent protective control of black rot and are better choices for black rot control at the 3-5” stage if powdery mildew control is not needed. For applications prior to the immediate pre-bloom spray, apply 3-4 oz Rally or 3-5 fl oz Mettle or 7 fl oz Revus Top or 3-4 oz TebuStar or 8.6 fl oz Orius 20 AQ. For immediate pre-bloom or later applications, apply 4-5 oz Rally or 5 fl oz Mettle or 7 fl oz Revus Top or 4 oz TebuStar or 8.6 fl oz Orius. Do not use Revus Top on Concord, Concord Seedless, and Thomcord (causes injury) and use caution when applying on V. labrusca, V. labrusca hybrids, and other non-vinifera hybrids where sensitivity is not known – the use of Revus Top by itself or in tank mixtures with materials that may increase uptake (adjuvants, foliar fertilizers) may result in leaf burning or other phytotoxic effects. 14 day PHI for all SI products listed; 12 hr REI for all SI products listed, except 24 hr REI for Rally 40WSP.

Abound Flowable Fungicide and the pyraclostrobin component of Pristine Fungicide are fungicides with similar chemistry (strobIlurin fungicides, Resistance Group Number 11) that provide control of black rot, powdery mildew, downy mildew and Phomopsis. Pristine also controls Botrytis, while Abound provides suppression only. Pristine is also registered for control of anthracnose. Black rot control with Abound and Pristine is primarily protective with only limited post-infection activity. Although labeled for use starting at the 3-5” shoot growth stage, Abound and Pristine should be saved for the immediate pre-bloom or later sprays. Powdery mildew and downy mildew resistance to the strobIlurin fungicides has occurred in many vineyards following several years of repeated use. It is highly recommended that the combined use of all strobIlurin fungicides including Abound and Pristine be limited to no more than 2 applications per season and rotated or alternated with unrelated fungicides. For black rot control, apply 10-15.5 fl oz Abound or 8-12.5 oz Pristine. Higher rates may be needed for control of other diseases. Do not use Pristine on Concord or Noiret as it causes injury. Use with caution on Steuben, Rougeon, Worden, Fredonia, Niagara and related varieties where injury has occurred irregularly. 14 day PHI, 4 hr REI for Abound Flowable Fungicide; 14 day PHI, 12 hr/5 day REI for Pristine Fungicide – see label for details.

IMPORTANT NOTE: Abound is EXTREMELY phytotoxic to certain apple varieties. Do not spray Abound where spray drift may reach apple trees. Do not use spray equipment which has been previously used to apply Abound to spray apple trees, as even trace amounts can cause unacceptable phytotoxicity to certain apple and crabapple varieties.