It is not too late for “dormant” sprays against Phomopsis in grapes

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.

Lime sulfur (calcium polysulfide) has traditionally been used as a dormant spray in crops such as apples and raspberries to eradicate pathogens and insects that overwinter in or on the wood. The disadvantage of lime sulfur is that it is odorous, corrosive and relatively expensive. In grapes, we have done several years of trials with more affordable alternatives, such as sulfur and copper, applied late in the dormant season (at budswell) for control of Phomopsis viticola, the fungus that causes Phomopsis cane and leaf spot and overwinters in canes. These trials showed that a single late-dormant application without any additional fungicides applied during the season could reduce Phomopsis rachis and fruit infection at harvest by 40 to 70%. We also saw reductions in black rot, powdery mildew, anthracnose, and downy mildew. Interestingly, downy mildew was only reduced by dormant sprays of copper, whereas sulfur was more effective against powdery mildew.

In 2005, we tested whether applying “dormant” sprays at 1- to 2-inch shoot growth was still effective at controlling Phomopsis in ‘ Niagara’ grapes, which it was (Table 1). However, Sulfur 6L appeared to perform a little better at that timing than Cuprofix, especially when considering percent berry infection, although rachis infection is the most important measure of this disease as it is more closely correlated with yield loss. We have to keep in mind, however, that the 2005 season was rather unusual, so these treatments have to be repeated to confirm the results, but at least they are encouraging.

Trial in ‘Niagara’ grapes in Lawton, MI, 2005


Treatment, rate/A

Application timing

Phomopsis rachis infection

Phomopsis berry infection


Severity (%)

Control [%]***

Severity (%)

Control [%]









Sulfur 6L 10 pt








Sulfur 6L 10 pt

1-2” Shoot growth







Cuprofix Disperss 3 lb








Cuprofix Disperss 3 lb

1-2” Shoot growth







Dithane Rainshield 3 lb

1”, 6-10”, 10-16” shoot







Abound 2.08 SC 12 fl oz

Bloom, 2 nd+3 rd postbloom







Ziram 76 DF 3 lb

1st postbloom







*Budswell spray: April 14, 2005; 1-2 inch shoot spray: April 25, 2005 **Values in the same column that share a letter are not significantly different from each other at the 95% confidence level.
***Percent control relative to the untreated.

We did not see any phytotoxicity as a result of these treatments in ‘ Niagara’ grapes, even when applied at 1 to 2 inches of shoot growth. Phytotoxicity can only occur when there is green tissue present. As there is a concern about sulfur sensitivity of ‘ Concord’ grapes, we are not recommending sulfur sprays after bud break in ‘ Concord’ at this time. However, we did not see any phytotoxicity in ‘ Concord’ grapes in Fennville, Michigan, from Sulfur 6L applied at budswell. Also, sulfur phytotoxicity is more likely at temperatures above 85 to 90ºF, which are unusual at this time of the year. In summary, copper and sulfur appear safe to both cultivars when applied before bud break, but after bud break, it is probably best to avoid using sulfur on Concord grapes until further studies show otherwise. Another choice for Concords is Dithane, which when applied at this stage, also serves to eradicate pathogens from woody tissues. Remember that it is important to ensure good coverage of the canes by focusing nozzles of spray equipment on the trellis.

Dormant sprays should not be used as a stand-alone disease control measure. A mancozeb spray around mid-May when Phomopsis is expected to be most active may be beneficial. Mancozeb applied at immediate pre-bloom aids in control of Phomopsis as well as black rot and downy mildew. A strobilurin fungicide, such as Abound, applied at bloom or 1st post-bloom is recommended to provide additional protection of the clusters against Phomopsis as well as black rot, powdery mildew, and downy mildew.

One added tidbit of information: the company that makes Cuprofix Disperss (Cerexagri, Inc.) is in the process of changing the product formulation. This means that both the old and new formulation of Cuprofix may be hard to find. The new formulation is called Cuprofix Ultra 40 Disperss and is twice as concentrated and twice the price, so adjust the application rate accordingly (follow label). Cuprofix has worked well for us in the past and disperses well in the tank without clogging nozzles. However, if it is hard to find, there are other copper products available (Kocide, Champ, etc.) that are also expected to have activity.

Dr. Schilder’s work is funded in part by MSU’s AgBioResearch.

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