Skip to main content

Post bloom disease management considerations


As of today, it is about 10% bloom at our Chardonnay plots. Since bud break was about 2 weeks ahead of a typical year, things are moving along as we would expect. Of course, bloom in VA almost always has to happen in rain...

As for bloom time disease management consideration, please refer to the previous post.

From this point on, 4 to 5 weeks will be a critical period for management of downy mildew, powdery mildew, and black rot. Please make sure to keep your vines covered. Once again, providing a protection is much better and easier than playing a catch-up, especially if it comes to grape disease management in VA.

You can use protective materials such as mancozeb, copper, and sulfur as your backbone, and add more specific (and often locally systemic) materials. Some of these materials have efficacy against multiple diseases (either by itself or through the combination of two materials). Examples are

  • DMI, aka SI (FRAC = 3), e.g., Rally, tebuconazole, Mettle, etc. Inspire super is a mixture of difenoconazole (FRAC 3) and cyprodinil (FRAC 9). 
  • QoI (aka strobilurins, Abound, Flint, etc., FRAC = 11), 
  • SDHI (Luna Experience (FRAC 7 + 3), Aprovia and Kenja (FRAC = 7), Pristine (FRAC 7 + 11), etc.) 


Other disease-specific materials include:

  • for Downy mildew: Revus and Forum (FRAC = 40), [note: Revus Top is a mixture of Revus and difenoconazole (FRAC = 3)], Zampro (FRAC 40 + 45), Ranman (FRAC = 21), Phosphites (aka Phos acid, Prophyt, Phostrol, etc., FRAC = 33), etc.
  • for Powdery mildew: Quintec (FRAC = 13), Vivando (FRAC = U8), Torino (FRAC = U6), etc.


Why am I listing all FRAC codes? Because it is very important for you to rotate these FRAC codes to avoid fungicide resistance development. Please do your best to limit the use of a FRAC code (with exceptions of FRAC codes start with M) to 2 times per season. 

Some people prefer to use captan as one of backbone materials. One thing you need to remember is that captan does not have much efficacy against black rot. Thus, if you use captan, you should mix with either FRAC 3 or 11 material for black rot management. Also, please remember that you cannot use captan with an oil because the combination will cause toxicity to grapevines.

Please refer to our pest management guides, which you can find on the right-hand side of this blog under "resources" for more information.


Comments

  1. Mizuho, I ask myself this question every year. Reading the Pristine label, it states a 120 hr (5 day) REI for all cane-tying, cane-turning, or cane-girdling. Otherwise it is 12 hrs. Aside from differences in definition, when is a shoot a cane? Are we talking late season when the shoots have fully lignified? Using Pristine now, does this prevent me from returning to do shoot positioning, leaf pulling, and other canopy work for 120 hrs? Thanks!

    ReplyDelete
  2. Hi There,
    Technically speaking shoots become canes when they are lignified. Thus, if you are very particular about the rule, all the activities listed on the label may not be applicable. However, there is reason(s) for the long REI, and thus, I feel that it is probably safer to follow the 5-day REI for other vineyard activities. (Unless the REI was set with a wrong reason, which can happen too!)

    ReplyDelete

Post a Comment

Please leave your comment here. In order to avoid spam messages, l moderate comments, thus it may take a few hours for your comment to be posted on the page.

Popular posts from this blog

Season's Greetings!

I hope you and your family have a good holiday season and a Happy (and safe) New Year! Thanks again for your support of our programs. Here are some recent media highlights. 😉 The link will open a new window. AHS AREC promotional video  that highlights some of our activities. The link did not work... It asks you to log in to VT. I will request the IT people to change the setting, but in a meantime, here's the same video. We also appeared in  the Library of Congress project “Winery Workers of Virginia”. One more announcement: I will be moving this blog to a new location ( ext.grapepathology.org ) early next year. I had to make a change due to the email subscription service, which has been terminated.  You do not need to change your bookmark or your email subscription. The URL will be forwarded to a new site and your email subscription has been moved to a new site already. 

Up-coming meetings and Sentinel Vineyard Report #2

  I think many readers of this blog subscribe to Tony’s viticulture note, but just in case, here is some information that you may be interested in. The second Sentinel Vineyards Report is out now.  The report is attached at the end of this post.  Make sure to subscribe to Dr. Beth Chang’s Blog here:  https://sites.google.com/vt.edu/vtenology/home Two upcoming meetings: New Grower Workshop 4 November 2021 at Winchester VA Team taught sessions for new grape growers and those considering developing a wine grape vineyard in the Mid-Atlantic.  Registration is required ( and the deadline is this Friday! ). Please click the link below.   https://register.ext.vt.edu/search/publicCourseSearchDetails.do?method=load&courseId=1600122 Virginia Wineries Association Annual Meeting November 15 & 16, 2021 Hybrid event: in-person (Richmond, VA) and remote virtual options The technical session theme on Day 2 is “Wine Stabilization – ...

Recent downy mildew risk events

 It seems that several rain events have happened over the course of the past two weeks or so. Here is a summary of recent downy mildew risk events, based on the NEWA stations and DMCast. Bristol, VA Fifteen days with potential DM infection event(s) since Sept 1. The latest event happened last Sunday. Floyd, VA Eleven days with potential DM infection event(s) since Sept 1. The last event happened last Friday. Charles City, VA Twelve days with potential DM infection event(s) since Sept 1. The latest event happened yesterday. Central VA Since there was a wide variation among stations, I am listing several around Central VA. Tyro, VA Nine days with potential DM infection event(s) since Sept 1. The latest event happened yesterday. Red Hill and Crozet, VA Only one day with potential DM infection event(s) since Sept 1. Olympic Lake Thirteen days with potential DM infection event(s) since Sept 1. The latest event happened last Sunday. Washington, VA Eight days with potential DM infection e...