Virginia Grape Disease Updates

Many people in northern VA are about to see blooms in a few weeks, and I am sure the rest of the regions are about to see bloom very soon.  Bloom is a start of the critical time for cluster infections by downy mildew, powdery mildew, and black rot. Bloom time is also the critical period to prevent Botrytis, ripe rot, and bitter rot, because pathogens of these diseases can infect flower parts and develop symptoms later. What I recommend often is the use of protectant 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 experienced rain every weekend (and looks like another rainy weekend coming up), we need to be on top of downy mildew and black rot manageme...

It's approximately 10% bud break on our 10 years old Chardonnay and about 25% on 5 years old Chardonnay. Hopefully, we won't get frosted!!

Bud break for our younger (2-3 years old) Chardonnay happened around 4/20/2018, and for older Chardonnay, it was the last weekend, (4/27/2018). Looks like we are about 1-2 weeks behind of a "typical" spring. But as with a typical spring, rain comes when grapes break buds! Looks like we will see some precipitations this weekend.  Please make sure to have a good protection against Phomopsis as we discussed in the previous post.   Let's hope that our season will be as good as 2017.

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. Inspir...

It looks like the 2017 season for us has officially begun. Our 8 years old Chardonnay at Virginia Tech's Winchester AREC was about 10% bud break as of yesterday. Despite a warm winter, a colder spring might have kept things slow (I am not complaining!) Once again, the important disease at this point is Phomopsis cane and leaf spot. Please refer to my previous post about Phomopsis management. Also for our Chardonnay plot, we have a chronic issue with climbing cutworms. Since we know the location of our vineyard where we always see some damages, we typically apply an insecticide to the panels of vines that is facing a wooded area. Without spraying the whole vineyard, it seems to provide adequate control. Good luck with the 2017 season. I will post key disease management tips as the season moves along.

Our 6 years old  Chardonnay had 100% bud break today (4/22/2015)!  Looks our our season has officially started. There has been a few email inquiries came to my inbox about climbing cutworm.  We have applied Intrepid to "hot spot" which is a few panels facing wooded area for us.   Please refer to Doug's posting and UC IPM for more information.

A line of rain went through Winchester area resulted in 10 h of wetness with an average of 69F.  It was downy and low Botrytis risk event.  Please refer to the comments on previous posts on late season disease management. FYI: Our Chardonnay berries are hitting 20-21 Brix and pH is getting near 3.0.  We will see what the forecasted thunderstorms towards the end of this week will do for it...

Many people in northern VA are about to see blooms (our Chardonnay vines are trace bloom as of June 2 nd , the one on the picture is one of the few with many open flowers), and I am sure rest of regions are going through bloom by now.   Therefore, many of us are in the critical time for cluster infections by downy mildew, powdery mildew, and black rot.   Bloom time is also critical period to prevent Botrytis, ripe rot and Bitter rot, because pathogens of these diseases can infect flower parts and come back later. We do have materials with kick-back activities against downy (Ridomil products, Phosphonates, etc.) and black rot (myclobutanil, etc.), but infection on flowers and young fruits can happen very fast.   Unless we have a very dry season, this is the time where you have to be proactive.   Thus, what I recommend often is use of protectant materials to protect tissues for 4-6 weeks for V. vinifera varieties, and 3-4 weeks for V. labrusca varieties, w...

Our 5-yr old Chardonnay is about 50% bud break stage as of today. At this time of the year, the number-one concern is Phomopsis cane and leaf spot. They produce spores on old infected cordons and trunks during the spring, and they can infect tissues even if temperature during a rain event is in 40s. Only option we have against this disease is a protective application of fungicide, such as mancozeb, captan, and Ziram. A QoI fungicide such as Abound and Pristine are also effective; however, I would recommend keeping them for the later part of the season.  Since they can be active under cold rain event, my recommendation is to protect even when shoots are about 1-3 inches long. The decision to spray for Phomopsis also depends on the history of the vineyard. The vineyard with previous history of Phomopsis tends to carry the same issue year after year.  You are probably wondering about the risk of Phomopsis from this week's rain.  At our vine...

Our 5-yr old Chardonnay is still in the mitten stage, only a few broke buds.  At least we do not see the risk of frost in the 10-day forecast... Once they broke buds, the first disease to be considered is Phomopsis.  It is because a) Phomopsis produce spores from previously infected canes, cordons, and trunks, b) the spores are active even in 40's, and c) young leaves and clusters are susceptible to infection.  The best approach is use of Mancozeb, captan, or Zirum as a protective application.  QoI fungicides such as Abound and Pristine works too, but you want to keep them for later in the season.

--> I just visited another vineyard down in the south where Norton vines were in full bloom, and when I came back, our Chardonnay vines were in trace-bloom.  As we discussed at this year’s VVA meeting, bloom is a very critical time for disease management.   Downy mildew, powdery mildew, and black rot tend to show up around this time of the season, and berries will be susceptible to these diseases until 4-6 weeks after bloom.    In addition, Botrytis, ripe rot, and bitter rot can cause infection on flowers.   Management of Botrytis, ripe rot, and bitter rot at bloom time can be important because these fungi can infect flower, and come back later when berries are maturing.   As you know, development of a disease depends on so many factors such as availability of inoculum (~ disease history), past and future weather conditions, variety, canopy management, etc., thus, I will not go in to details.  However, based on the past few weeks of ...

Both Chardonnay and Merlot are near 100% bud break as of today.  At this point, one disease to be considered is Phomopsis cane and leaf spot.  If you have a history of Phomopsis in your vineyard(s), mancozeb, or captan, or ziram will be a good choice for protection of young tissues. I have not seen much of Phomopsis in our young vineyards, so, I will skip this spray, and start my program around 5-10-inch shoot growth, targeting downy, powdery, and black rot prevention.

The two hot days we had pushed things quickly.  Our Chardonnay buds are swelling and some are even broke.  Our Merlot is bit behind, but not by much.  Cab sauvignon seems to be still tight.  Looks like the season will start very soon!  Since we saw a bit of damages, I applied climbing cutworm treatment to the area of vineyard where we historically have issues.

Our Merlot and Chardonnay hit veraison over the weekend.  We placed bird netting and thinking about to spray for Botrytis, and here we received a strong storm followed with a long wetness period.  I will update once this wetness period finishes.

Winchester area received rain from a thunderstorm last night around 7:30PM.  An estimated leaf wetness period is 14.5 hours with an average temperature of 63F.  It was a risk event for Phomopsis, black rot, downy mildew, and Botrytis. Our Chardonnay is in full bloom and Merlot is about 60-70% bloom now.  Hopefully this weather won't affect fruit set.

We are about 60-70% bloom on our Chardonnay.  Merlot is still in trace bloom stage. Winchester area received a series of rains from around 3:00 AM this morning, and relative humidity stayed above 90% until around 3:00 PM.  Thus, we had 12 hours of an estimated leaf wetness period with an average temperature of 63F.  It accounted for black rot, Phomopsis, downy mildew, and Botrytis infection event (note: Botrytis typically takes more time (>15-17 hours of wetness) to infect than the model says).  The forecast is calling for more rain tomorrow and Wednesday.  We will see how it goes.

Here comes 2012 version of " Workbook for developing an effective fungicide program for Wine grapes in VA " (<- click to download a pdf file).  If you receive Tony's Viticulture Notes, you already have it. I have been publishing it as a "guideline" in the past, but this year, I decided to format it more like a workbook that helps you plan for the season.  I hope you will find it as a good companion to the PMG ( Pest Management Guide from VCE ). I was hoping to get it ready before the season starts, but I missed it by 2 weeks.  Hopefully recent cooler weather holds off disease pathogens! As noted in the workbook, it is still a work in progress.  If you have any suggestions or comments, please let me know. I mentioned about uneven development in the last post, but as of this morning, our 4-yr old Chardonnay and Merlot are 100% bud break with some of them are 2-3 inches (4 leaves exposed) stage.  We are also looking for another potential frost even...

Our 4-yr old Chardonnay was about 10% bud break yesterday (the 21st) morning.  Our 4-yr old Merlot was <5% bud break. Older vines are still holding off. Well, the season has been officially started whether I am ready or not! Also, I updated the season template based on comments from users.  If you have any comments or suggestions, please let me know.

Two weeks of 80's and 70's surely moved things forward.  When I checked our Chardonnay buds last week, it was swelling, but was still tight, but now it looks like they are ready to go at any moment. (Note: these are 4-yr old young vines.  Also, sorry for out of focus pictures.  I forgot to take my camera with me yesterday.) Hopefully, it will go well with a longer than usual growing season, and we end up having early harvest this year!! The first disease to be concerned is, as usual, Phomopsis.  The best management strategy against Phomopsis is use of a protective fungicide such as mancozeb or captan, since we do not have any material with curative activity. Also, since we had a warm dry early summer before Irene, many of us saw quite a bit of powdery mildew.  Chances are, we have a plenty of inoculum.  Although we do not typically see powdery mildew until later in the season, with this warm winter, I am not sure what will happen.  I know it is ...

I noticed that some of Chardonnay and Merlot started blooming on Friday.  I ended up spraying on Saturday for pre-bloom treatment.  Once again, from bloom to 4-5 weeks after bloom is critical periods for black rot, downy mildew and powdery mildew cluster infection.  Please stay on top of your program during this period.  Once you successfully protect your vines through this period, you can relax a bit. I saw a little bit of downy mildew development in our vineyards, but nothing major.  I am wondering how recent hot and dry weather conditions affect their population.   We will see... Speaking of hot weather, I've noticed that there is air quality alert issued to Fredrick county.  I don't know what would be the effect to grape diseases, but it does affect us.  Make sure to hydrate yourself and keep eye on your body conditions.