Virginia Grape Disease Updates

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. 

  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 – ...

 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...

  Please find a link below to download a new disease management guide for non-bearing grapes. As with the other VCE guides, you need to click on the “Preview” icon, which will open a new window, then click on the “Download” icon to obtain a pdf copy. https://resources.ext.vt.edu/contentdetail?contentid=3226&quantity=1&productprice=0&contentname=Fungicide%20Spray%20Guidelines%20for%20Non-bearing%20Vineyards Also, I updated a list of fungicides that you can obtain from home garden centers. I saw several new products, but unfortunately, many of them do not list grapes on their label, so, the list is identical to the old version. If you know of other products that can be used for home gardens, please let me know. Home-garden-fungicides-2021 Download

  In preparation for hurricane Ida, here is some information that you may find useful (This is a repeat of the previous post, but I received some emails asking for them.) 1)  List of short PHI fungicides for late-season diseases (will open a pdf file) 2)  Updated presentation from the last virtual field day (will open a pdf file). Recent downy mildew risks Many of us have been experiencing more rains lately than the past several months, here are a number of days with downy mildew risk events in the past two weeks based on the NEWA’s DMCast. Many of these rains have been sporadic in terms of area and time it covered, so, use these numbers as a guide. Bristol: 14 days (latest was on 8/30) Floyd: 9 days (latest was on 8/29) Charles City: 14 days (latest was on 8/30) Tyro: 7 days (latest was on 8/30) Red Hill: 5 days (latest was on 8/29) Washington: 8 days (latest was on 8/29) Winchester: 9 days(latest was on 8/29) It is probably a good idea to protect your vines against down...

Recent rains and more rains in the forecast made me think of downy mildew. Let's take a look at what the NEWA DMCast model says about downy mildew risks from the past two weeks. Westfield, NC (South of Stuart, VA) There were six DM risk events, including one that happened today.  (Note: we have a new weather station in Bristol. You can check the weather data, but the DMCast model is not working yet. I notified the NEWA about the lack of DMCast outputs.) Floyd, VA There were four days with downy mildew risk event(s) since the beginning of the month. Red Hill There were four days with downy mildew risk event(s) since the beginning of the month. Washington, VA There were nine days with downy mildew risk event(s) since the beginning of the month. Winchester, VA There were five days with downy mildew risk event(s) since the beginning of the month. It looks like there were more downy mildew risk events as we move northwards. Also, recent warm and humid nights can promote the downy mildew...

Thanks again to those of you who made it to the meeting. It was nice to have a face-to-face meeting after the whole thing we are in together. Here's my handout from today's meeting.  It will open a new window with a pdf file.

I mistakingly placed Vivando, which does not work on downy mildew, on the downy mildew table. Please strike it out or use the updated version below. 1)  List of short PHI fungicides for late-season diseases (will open a pdf file) 2)  Updated presentation from the last virtual field day (will open a pdf file).

Thank you again for participating in our meeting. Please find two materials from today's presentation. 1) List of short PHI fungicides for late-season diseases (will open a pdf file) 2) Today's presentation (will open a pdf file). Have a good rest of the season, and hope to see you next week at the VVA summer technical meeting!!

This is another reminder about downy mildew. This post is probably more applicable to those of us who are in northern VA. We received several rain events in the past two weeks. Not all of them accounted for downy mildew infection risk events; however, recent warm and humid nighttime weather probably encouraged the downy mildew pathogen to produce spores.  Here are recent downy mildew infection risks based on the NEWA's DMCast. Floyd, VA: Downy mildew risk events on 7/6, 11, and 15. (note: the temperature sensor has been fixed recently, and that's why it shows records from mid-June.) Red Hill, VA and Olympic Lake: If you are in central VA, please check your local weather station. It seems that the numbers vary quite a bit among them. Red Hill: downy mildew risk events on 7/2 and 8. Olympic Lake, downy mildew risk events on 7/2, 6, 8, 11, 12, 15, and 16. Winchester, VA: downy mildew risk events on 7/1, 5, 9, and 13. Protective materials for downy mildew are Ziram (FRAC M3, 21-day...

It looks like many of us received some rain in the past few days, and we may see another rain toward the end of this week. Here are recent downy mildew infection risks based on the NEWA's DMCast. Floyd, VA (note: the temperature sensor has been fixed recently, and that's why it shows records from mid-June.) Crozet, VA (note: the precipitation sensor has been fixed recently! We really appreciate the willingness and commitment of the personal weather station owners!) Winchester, VA Protective materials for downy mildew are Ziram (FRAC M3), Captan (FRAC M4), Fixed copper (FRAC M1), Revus or Forum (FRAC 40), or Zampro (FRAC 40 + 45), or Ranman (FRAC 21)). There are increasing cases of Revus resistant downy mildew isolates in VA. Plus, resistance to Ranman is known among downy mildew pathogens of other crops. Make sure to spray before the rain and rotate the FRAC codes! Materials with kick-back activities are Phosphorous acids (Prophyt, Phostrol, etc, FRAC P07), and Ridomil products...

Presentation slides Thank you to those of you who were able to make it to the meeting today. Here are slides from today's presentation (open PDF).  Up-coming meetings Eastern Section American Society for Enology and Viticulture annual meeting (7 – 8 July): The ASEV/ES meeting will occur on-line this summer. See https://www.asev-es.org/ for details on the meeting, which will include research presentations and a panel discussion entitled “Future Grape Cultivars for Eastern North American Growers”. Eastern Viticulture and Enology Forum (13 July): The July 13th meeting is the next of a series of 4 virtual meetings organized by viticulture and enology extension specialists at Penn State, Cornell, and Virginia Tech. In addition to regional round-ups of seasonal progress, specialists from around the eastern US address pre-submitted questions from participants. Registration instructions and additional information about the meetings can be found on the attached Word document. Virginia Viney...

It looks like we all received much-needed rains, which is good for vine growth. However, since most of our vines are still within the critical period for cluster infection by downy mildew, powdery mildew, and black rot (~ until 6 weeks after bloom for V. vinifera , ~ 4 weeks for V. labrusca ), it also means that we may have had risk events for disease infection. Since the month of May was dry, I think the overall disease risk is low for downy, black rot, and other diseases that are driven by rain (e.g., ripe rot and Botrytis), but I just want to go over recent NEWA outputs.  Disease risks from the recent rain events Westfield (Close to Bristol, VA) It seems that the southwest VA received quite a bit of rain over the past two weeks! I would think many cultivars are close to the end of the critical period, but if you are concerned, a DMI fungicide and a Ridomil or Phos-acid product are effective for black rot and downy mildew, respectively. These materials can be applied a few days a...

Just a quick note that recent rain events were risk events for downy mildew based on the NEWA DMCast model. It seems that northern VA received more and longer rain events. In addition, we may see more rain toward the end of next week. DMCast results at Crozet station (green cells indicate downy mildew infection events) DMCast results from Winchester station Since we have been experiencing a very dry season, I was not really thinking about downy mildew. However, during recent vineyard visits, I have noticed downy mildew on leaves, and sure enough, I saw some downy mildew lesions on leaves in one of my research blocks too. Early downy mildew lesions may not be very obvious. If you are due to spray soon, grow downy mildew susceptible cultivars (e.g., Chardonnay, Vidal, etc.), and/or have seen a considerable amount (or duration) of rain recently, it may be a good idea to include a Phos acid material (e.g., Prophyt, Phostrol, Agri-Fos, etc.) in the tank mix as insurance. Please note that if...

Recent cooler weather seems to have slowed down vine development, but it looks like vines in the south are about to bloom. Bloom is a start of the critical time for cluster infections by downy mildew, powdery mildew, black rot, Botrytis, and ripe rot, because pathogens of these diseases can infect flower parts and develop symptoms later. What I recommend often is the use of protective materials to protect tissues for 4-6 weeks for V. vinifera varieties, and 3-4 weeks for V. labrusca varieties, which should translate into 3-4 sprays for V. vinifera , and 2-3 sprays for V. labrusca .  If you have hybrids, they are somewhere in between, so, 4-5 weeks to be protected.  As usual, please make sure to rotate mode of action (= FRAC) groups. Since we have not seen many rain events, I think powdery mildew will be the primary target for many of us. But please check your local weather to make sure, some downy mildew susceptible cultivars may still show downy mildew, especially, if there...

Since the past winter was more or less steady and mild, in terms of temperature fluctuations, there are less likely that many of us saw the minimum temperature at 15F or lower. For example, at Winchester, we saw 14.5F on the 21st of February, and that's it for this winter. The risk of Pierce's disease will increase with a warmer winter. I.e., less than three nights with a minimum temperature of 15F or lower will decrease the risk of Pierce's disease.  Thus, especially people in the south and eastern part of the state may need to prepare for the management of sharpshooter leafhoppers, which are the vectors of Pierce's disease. Some growers in the eastern VA use insecticides for sharpshooter leafhoppers from May to June, so, I thought it is probably a good idea to sent out a reminder.  Entomology is not my area of expertise, thus, I will copy the information from our Pest Management Guide , page 8. In some vineyards in the eastern part of the state, sharpshooter leafhop...

 Thank you to those of you who were able to join us today. Here are some of the items we discussed. Slides from today's presentation (will open a pdf file in a new window) RSS feed address for this blog (I posted under "Resources" too) You can also subscribe via email using the menu showing on the upper left part of this blog. Google will drop the email subscription service in July, but I will come up with another way to send you reminders. Thus, if you wish to be included after July, please go ahead with the subscription service. Link to my grape disease management workshop presentation videos. Please note that the closed captioning is most likely not working. I created CC with the Canvas site we used in the workshop. If you wish to watch them with CC, please send me an email so that I can send an invitation to Canvas site. Unfortunately, I don't have time to work on YouTube version right now. I will focus more on YouTube version next year. I will keep it available f...

Upcoming virtual vineyard meetings The viticulture group at the AHS Jr. AREC will be hosting a series of four monthly, on-line viticulture meetings starting Thursday, 22 April 2021. The content of each meeting will vary somewhat and will involve extension specialists who will provide seasonal updates on vineyard management, pest management topics, and emerging weather, pest or disease issues. An initial topic of each of the 4 planned meetings will be a statewide grape development roundup gathered from our “sentinel vineyard” cooperators located around the state. Each meeting will last about 2+ hours, starting at noon.  At this point, the meetings will be on-line, but stay tuned for at least one on-site meeting which we plan to host at the AREC in late-July.  The meeting dates (noon start) are: 1)     April 22, 2021 12:00 PM (EDT) Register in advance for this meeting: https://virginiatech.zoom.us/meeting/register/tZ0pceigqTMrGdOSA5D6uvJUEfYaVZKLVER7 After registe...

Our eight years old chardonnay is about 50% bud break as of yesterday, and I am sure that growers in the south have seen buds and shoots already with the early season cultivars. Although the chance of precipitation seems to be low for a while, it may be a good idea to review Phomopsis management, just in case.  It looks like rain events that happened in the past few days accounted for Phomopsis disease risk events according to the NEWA .

It looks like our Chardonnay buds are swelling, which probably means that growers in the south and central Virginia either start to see bud break. Then the forecast is calling for rains next week. I guess it is a typical Virginia spring. One of the diseases you need to consider soon after bud break is Phomopsis cane and leaf spot. It causes minor leaf spots, which are more evident to our eyes, but necrotic lesions cause more critical damage on shoots and rachis. It also causes berry rot; however, it is not common with wine grapes because of our spray programs. Some cultivars, such as Viognier, Cabernet Sauvignon, and Seyval Blanc, are more susceptible to Phomopsis than the others. Phomopsis spores can cause infection requires water, and Phomopsis spores can germinate in a relatively cooler environment (the upper 40s). This pathogen tends to produce spores in spring from previously infected canes and cordons. Thus, springtime rain events are ideal for the development of Phomopsis. It is...

If you wish to attend upcoming grape disease workshops and grapeIPM.org training, please register using this form (CLICK this line) so that I can send you an invitation to the lecture materials.  Grape Disease Workshop (3/31/21):  I prepared a series of lectures to cover basic concepts and terminologies, which I often not able to explain due to the time limitation. Also, a short version of my "usual" workshop is now recorded. In my workshops, I assume you know some concepts and terms, so, if you are not familiar with some terms such as disease triangle, curative fungicide, QoI fungicide, FRAC group, fungicide resistance, biological control agent, etc, please check out the lectures.  Each lecture runs less than 20 min, with an exception of the main workshop content, which runs around 26 min. If you do not have time to watch them all, please watch the main workshop content. On March 31st at noon , we will use Zoom to communicate. The link to the Zoom se...