Fungicide Options Table

The following table was developed as a means of summarizing the information provided in OMAFRA Publication 360 - Fruit Production Recommendations 2008-2009 and highlighting the periods during the growing season when specific diseases may be problematic. Table 6-6 in publication 360 gives more information on the relative effectiveness of these fungicides. The main purpose of the table is to give some idea of the fungicide mixtures that may be used throughout the season to manage specific diseases present in your vineyard. You should read the label to determine whether a fungicide listed in the "PM (powdery mildew), DM (downy mildew), Bl Rot (black rot) or Phom (Phomopsis)" column will work on the diseases you need to control and whether it will cause injury (e.g. burning or discolouration) on a particular variety or under specific drying conditions (See Table 6-5 Publication 360 as well as fungicide label.). It is also important that you confirm that a particular fungicide is acceptable for use by your processor and follow their pre-harvest intervals for individual pesticides

How to use this table: The "Disease" column identifies which diseases may be most problematic at each vine growth stage. This will vary somewhat depending on the susceptibility of the grape variety, the weather conditions and the history of disease in the vineyard. The fungicides are divided into groups according to which diseases they control. Dikar controls both PM and the broader range of diseases including DM, Bl Rot or Phom so it covers both columns. In the fourth column, some of the products are specific for DM control. These are marked with (DM).

In cases where there are several formulated products incorporating the same active ingredient (captan/Maestro, copper products) the active ingredient is listed rather than clutter up the table with products. It is up to you to check which specific product formulations are registered for use on grape in Ontario. Always refer to the product label!!

A separate column is set aside for Bot (bunch rot) since the labeled botryticides are very specific in their mode of action. The importance of the bloom period sprays varies from one year to the next. In years with a wet bloom period, the bloom sprays can make a significant contribution in reduction of bunch rot later in the season. In years with a dry bloom period, the best effects result from botrytricide sprays applied from bunch closure through veraison.

Choose one product from each column that contains a disease that is present or that has been a problem in the past 2 years in your vineyard. If a product is in italics, it means that it is prone to the disease developing resistance and it is very important to rotate among fungicides from different lines within that particular box (not with one on the same line, such as Sovran/Flint or Vangard/Scala). For resistance management purposes, try to avoid using products from the same chemical family more than twice in a growing season. Conversely, if a product is not underlined, there is very little likelihood that resistance will develop.

A few things to note:

1. Revus is a new downy mildew-specific fungicide. It is locally systemic, meaning that it moves into leaves and fruit so is not prone to rain wash-off one hour after drying. However, it does not move from treated leaves to untreated leaves, nor does it move a lot within tissues so coverage is still critical. It has some post-infection activity but is more effectively used when applied before infection occurs.
   
2. Dow AgroSciences has indicated that Dikar will no longer be produced after this year. There are adequate supplies to meet our needs for the 2009 and 2010. Dikar will be registered for use in Canada until 2012.
   
3. While several products containing mancozeb are still registered, none of these are currently for sale; therefore, it is not included in the table.
   
4. Ridomil Gold MZ may be applied once pre-bloom and once post-bloom with a 66 day PHI.
   
5. While downy mildew is listed on the Sovran label, Sovran will not provide complete protection under high disease pressure.
   
6. Black rot was more of an issue than usual in some vineyards in 2008. The critical period for black rot control is from immediate pre-bloom through 4 weeks post-bloom. In vineyards where severe black rot developed in 2008, or if the vineyard has a history of consistent black rot development, an additional spray two weeks before bloom may be beneficial, particularly under wet conditions. Because damaging levels of black rot usually result from spread within the cluster, sprays should continue through the end of July if more than a trace level of berry rot is present and weather conditions are suitable for infection.
   
7. Flint and Sovran have some suppressive activity against bunch rot. Including one of these products in the post-bloom spray may give some protection from bloom infections.
   
8. Generally, bloom sprays of botrycides are required only on bunch rot-prone varieties, but in wet years, most varieties will be susceptible to at least some bloom infection. In the past, it was assumed that the period between fruit set and bunch closure was relatively "safe" for bunch rot infections. However, sporulation of Botrytis on hail-injured berries while they were still green in 2008 showed that latent infections that occurred at bloom may be activated when fruit is injured well before it reaches veraison.