Virginia Grape Disease Updates

If you are interested in starting a new vineyard, or just have started, please join our beginner's workshop. Introduction to mid-Atlantic wine grape production  Virginia Tech’s AHS Jr. AREC Winchester, VA (Frederick County) Team-taught program designed for those either exploring grape production or recently engaged in wine grape production. On-site registration will occur from 8:00 to 8:30 am. Program 8:30 am: Introduction and market opportunities: Tony Wolf, Virginia Tech 9:00 am: Vineyard business planning considerations and Vineyard Calculator – predicted cash flows : Tremain Hatch, Virginia Tech 10:15 am: Lender’s perspective on vineyard enterprises : Marilyn Adams, Farm Credit of the Virginias 10:45 am: Vineyard site evaluation and environmental challenges : Mark Sutphin, VCE 11:30 am: Mapping soil variation and geomorphology to improve vineyard design an

I had a meeting and did not able to post it in timely manner, but there was a wet event on Monday-Tuesday this week.  It was 14+ hours of wetness and average was around 60F.  It was a risk event for downy mildew, and very low risk for Botrytis. Other than a slight chance of rain tomorrow, it looks like we will have a nice cool week!  For the late season spray recommendations, please refer to previous posts. http://grapepathology.blogspot.com/2014/08/note-on-sour-rot.html http://grapepathology.blogspot.com/2014/08/last-stretch-spray-consideration.html

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...

As the harvest approaches (plus recent rain events in some part of VA), I am receiving several emails on sour rot.  It is often confused, but not all late season rots are sour rot.  Sour rot is basically a disease caused by bacteria that form acetic acid, such as Acetobactor and Gluconobactor .  It is often associated with wounds (birds, insects, hail, too much rain, early season powdery mildew, certain very fair-skin varieties, etc), high Brix level (13-15 or higher), warm temperature range (high 60F to mid 70F). Since these bacteria cannot penetrate berry skin tissues by themselves, what we typically recommend is wound management (e.g., bird netting, grape berry moth management, etc.), and many people mention that it works.  However, with a potential role of Spotted Wing Drosophila (or lesser extent, African fig fly), which may able to penetrate skin, there is a possibility that we may see more sour rot in the future.  Luckily, Dr. Wayne Wilcox's group at Cornell University

Due to the rain event over the weekend, many people are concerned about protection for next week or two before the harvest.  At this point, the tools are rather limited due to PHI as well as wine making consideration. For downy mildew (especially for foliage, your berries are protected at this point), you can use Phosphonate (= phosphorous acid) product or captan.  (Both have 0-day PHI) For late season rots, especially Botrytis, you can use captan, Elevate (both have 0-day PHI), Switch (7-day PHI), Rovral (7-day PHI), Scala (7-day PHI), Vanguard (7-day PHI), or maybe Endura, Pristine or Luna products (these three have 14-day PHI). For ripe rot and bitter rot, a QoI (Abound, Pristine, Sovran, Flint, etc = 14-day PHI) and captan seem to be the key product.  Our lab is investigating the efficacy of a phosphonate too. As usual, please consider the situation at your vineyard as well as weather forecast.  If you do not see any issues at your place, picking in 7-day, and don't see

I was away for several weeks for a series of meetings, and of course things happen when you are not around... 7/28: 9 hours of wetness, around 66F (low Botrytis and downy risk event) 8/6:   12 hours of wetness, around 64F (low Botrytis and downy risk event) 8/7: 13 hours of wetness, around 57F (probably not much of risk event) 8/11: 19 hours of wetness, around 60F  (low Botrytis and downy risk event) 8/13: 13 hours of wetness, around 60F  (low Botrytis and downy risk event) 8/20: 14 hours of wetness, around 65F  (medium Botrytis and downy risk event) 8/23: 6 hours of wetness, around 65F (low Botrytis and downy risk event) 8/24: 10 hours of wetness, around 62F  (low Botrytis and downy risk event) I will have a few more updates coming up...

As we expected, Winchester area had a wet weekend.  We had to major rain events, which resulted in 11 hours and 10 hours of wetness, both are in upper 60F to lower 70F range.  These are downy mildew and Botrytis risk events.  Once again, humid nights we are experience can be a precursor event for downy mildew risk events because these nights favors spore production of downy mildew pathogen.

Winchester area received a shower yesterday, resulted in 5+ hours of wetness in lower 70F.  It was an infection risk event for downy mildew, and very low infection risk event for Botrytis.  In addition, we observed dews in the last two nights, indicating high humidity, which can trigger downy mildew to produce spores.  As usual, late season downy tends to appear on younger leaves on the top of the canopy.  Please keep eyes on them!  There is a chance of rain on Sunday and Monday.

Winchester area had a wet weekend.  We ended up having 9+ and 16+ hours of wet events, and both of them are in upper 60F.  Needless to say, these were disease risk events for downy mildew and Botrytis.  These were events for black rot too, but the clusters should be resistant to infection at this point.  Looks like we are expecting some rain during this week too.  Please keep your eyes on downy mildew.

After 13+ hours of wetness on the 13th-14th rain event, we had another wetness event starting from last night.  It resulted in 11 hours of wetness with an average temperature near 70F.  It was infection event for downy mildew, black rot, Phomopsis and Botrytis.  With the back to back rain event and high humidity during the night, I would keep eyes on downy mildew development.  It tends to show up on younger leaves (at the top of the canopy) first.  Also, many of varieties are about to be berry-touch/bunch closure stage, which is one of timings for Botrytis application.

Winchester area received a shower yesterday (11th, very early in the morning) which resulted in ~7 hours of wetness with an average temperature of high 60F.  It was risk event for downy mildew (with a good chance of spore production because it was a night time event) and Phomopsis, and a borderline case for Black rot.  (once again, please note that your berries should have become more resistant to downy, powdery, and black rot infection at this point).  Since we had a back-to-back rain event, please keep eye on next potential rain for downy mildew, especially you are due to a next application.  There are chances of rain on Monday and Tuesday.

A thunderstorm went through Winchester area yesterday evening, resulted in 12+ hours of wetness (on going) with an average temperature of near 70F.  This most likely to be resulted in risk event for downy mildew, black rot and Botrytis. However, please note that the risk of black rot (especially on clusters) should be low because vines are about to be done (or already done) with their critical period for cluster infection.  (Plus, if you have not seen much black rot until this point, the risk is low too.)  The same goes with downy mildew cluster infection, but downy mildew can still infect leaves, especially the young ones. People in the south and some early varieties in the north is approaching bunch closure.  This is one of application timing for Botrytis so that we can get the material to the inside of the clusters.

Finally, we are having relatively dry weeks!  Most of us are about to finish critical time where clusters are susceptible to infection by downy mildew, powdery mildew, and black rot.   This critical time varies by varieties, but in general 4 to 6 weeks and 3-4 weeks from bloom for V. vinifera and V. labrusca species, respectively.   After this critical period, you should be able to relax a bit because these pathogens no longer able to cause disease on berries. So, what’s next?   As usual, disease dynamics really depends on environmental conditions, varieties grown, and cultural practice you employ, but in general, this is the moment when you will be thinking about late season diseases such as Botrytis, ripe rot, bitter rot, and sour rot.   The spray timing for Botrytis is at bloom, bunch closure, and veraison.   The pathogen seems to be active throughout the season, and the reason we recommend application of a Botrytis specific material at bunch closure

We have not received precipitation since the 21st, but every night since then has been humid.  Dews that formed 3-4 AM stayed until 9-10 AM in some days.  Once again, these conditions favors downy mildew spore development.  If your vines are covered with a previous application, you do not need to worry about it, but if not (say, the last application was more than 10 days ago, or you had more than 1.5-2 inches of rain since the last application), then you may want to consider a protective application before next thunderstorm hits, which may happen in the next few days.  We are almost through with the critical period, though!

Winchester area was rained out pretty much whole day yesterday, resulted in two wetness events, one with ~16 h of wetness with low 60F, and another one with ~7 hours of wetness with high 50F.  These resulted in infection risk event for black rot, downy mildew, Botrytis and Phomopsis.  Once again, please try to be on top of the situation while we are in the critical period for cluster infection.

A thundershower hit Winchester area around 6PM last night, resulted in 16 hours of wetness with lower 60F in average temperature.  It was disease risk event for black rot, downy mildew, Phomopsis, and Botrytis. As with last few rains, it resulted in a warm and humid night that helps downy mildew to produce spores.  Many of us are still in critical period for cluster infection, and this is the time of the year to be on top of the game.  Please refer to previous few posts about spray ideas.

Boy, what a week! Winchester area received about 17 hours of wetness with average temperature of 20 C (68F) on the 11th, 14 hours of wetness with average temperature of 22 C (72F) on the 12th, and right now on-going wetness with 17hour + with an average temperature of low 20C (68F). These events are warm and long enough for downy mildew, Botrytis, Black rot and Phomopsis.  On top of that because of evening rain events, night time conditions have been favoring downy mildew development.  Our main concern is downy and black rot since our clusters are currently in critical period.  These berries are susceptible to the infection by these pathogens. It looks like the weekend weather is promising, and a 10-day forecast is calling for a chance of rain again on Tuesday... what can we do? For our vines, the last application was made 10 days ago, and we received a total of 1.47 inches of rain at the site.  Last application was mancozeb + sulfur + Phosphite (Prophyt, Phostorl, etc.) + Rally

The rain event started on the night of the 8th resulted in about 14 hours of wetness with about 65F in average temperature.  This was infection risk event for downy mildew, Botrytis, Black rot, and Phomopsis.  Also, in the last two nights, the evening thunder storms brought up night time relative humidity, thus, we should keep watching out for downy mildew development.

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, which should transla

A quick update: A series of rain event since 5/29 around Winchester area produced two Phomopsis infection events and one black rot infection events.  Two consecutive humid nights probably promoted downy mildew spore production too.  Things are still wet, thus I will update the length of wetness once things dry out.

We had a short shower event last evening; however, it was short and relative humidity did not stay high for a long time.  Thus, it was not a major disease infection event, except, probably downy mildew, since it only take about 90 min under optimal condition. Speaking of downy mildew, we have seen the beginnings of downy mildew in our experimental vineyard. Although our last application of mancozeb was only 10 days ago, rain events and humid nights probably promoted their development. At the beginning, you will see yellow circular discoloration on upper surface of the leaf.  Please note that sometimes insect can cause similar symptoms. However, if you flip over, you will see tiny white growth (please click the picture to access to a higher resolution file).  This won't happen with an insect damage. Please scout your vineyard, and if you see similar symptoms, it is probably a good idea to incorporate some of fungicides with kick-back activity.  In fact, we applied a phosp

There were a few isolated light showers passed around Winchester area early this morning, resulted in 6 hours of wetness with low 60's average temperature.  This was a low infection risk event for Phomopsis, but since the rain was very light one (< 0.001 inch), I would say the risk was probably negligible.

Another thunderstorm went through Winchester area last night.  Although the first few hours were warm, the temperature dropped to low 50's during the night.  The total wetness was 15 hours and average temperature was around 55F.  It was light infection event for Phomopsis.

A thunderstorm went though Winchester area yesterday afternoon, and since then the cloud cover kept RH very high.  So far we observed 17+ hours of wetness, and the average temperature has been in low 60's.  This event accounted for Phomopsis and black rot infection events.

Looks like we will rains throughout the week.  Our chardonnay vines are about 1-2 inches shoot length, and we have been spraying mancozeb and sulfur this morning to provide protection against Phomopsis (+powdery mildew, sulfur at this time of the season is more like an insurance) Rains in last week were all short ones for us, and did not result in disease event, but it looks like some people in the south saw longer rain events than we did. Please check with your local weather service.  Website such as weather underground (linked on the right hand side of this blog) let you see historical weather data at near by stations.

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 vineyard, we r

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.

Some of northern VA growers contacted us about splitting of the trunks and cordons which became apparent in the last few weeks.  Although the cold injury model showed that temperature we experienced were below the threshold temperature (i.e., the buds should be safe in many cases), the cold winter then a few days of warmth followed by another cold temperature probably caused some of vines to show more or less like "Southwest injury" on trunks and cordons.  If you have these suffering vines, you would probably think about re-training damaged cordon or trunk.  If you decided to do, please keep in your mind that the big wound can invite various vascular/trunk pathogens such as Esca and Botryosphaeria.  These disease may not damage the vines in a short time, but it can shorten the life of the vine.  As I noted in my trunk disease management page , there are few options to provide protections on these wounds. The bottom line is that you should pick a day without rain in the

The cold temperature during this winter probably resulted in many trunk splitting or scarring on less winter hardy vines.  I am planning to conduct a quick study on the effect of protective paint on the development of crown gall.  If you have vines with split or scars, especially on the young vines (1-2 years on the ground), please let me know.  It will be one-time application, so, it won't take much of your time.

I have a feeling many of you are working on pruning right now to take an advantage of the warm weather.  Please find a handout for the pruning time disease management against many of trunk diseases by clicking this link.

It looks like the winter is finally over.  I hope everybody is ready for the new season. We will start off our season with a vineyard meeting at Cardinal Point Winery at Afton.  The meeting is from 11AM until 3PM or so (note: please bring your lunch).  One of the major focus of the day will be frost protection.  We will also cover seasonal updates as well. Also, I have changed a few things on this blog.  Other than little more modern look to it, the major additions are project pages.  Our lab has several active projects going on right now, and we are finding more about our pathogens that will lead to the development of better management tools.  These page should explain more about our activities.  I will add more pages, but for a starter, I have added trunk disease project page.  As a part of our activities, I have also updated our recommendations for trunk disease management, so,  please take a look. 

Rescheduled Vineyard IPM Meeting Meets this Friday Date:           Friday, March 21, 2014 Time:          10:00 a.m. to 4:00 p.m. Location:   The Nelson Center, 8445 Thomas Nelson Highway, Lovingston, VA Contact:     Michael Lachance, Nelson County Extension Unit;  (434) 263-4035 The central Virginia vineyard IPM meeting, originally scheduled earlier this month will be meeting this Friday, March 21 st in Lovingston, Virginia,  located roughly 30 miles south of Charlottesville & 35 miles north of Lynchburg on Highway #29. Dr. Mizuho Nita and Tremain Hatch will conduct this informative, pre-season briefing on how to manage the challenges of the 2014 growing season.  In addition, Dr. Jeff Derr will contribute recommendations for vineyard weed control.  This will be an excellent opportunity to review our past challenges to quality grape production and discuss who improvements can be made regarding plant protection. You have the option of bringing a bag lunch

If you are pruning, and wondering whether you can protect pruning wounds from infections by trunk diseases, t here is a supplemental label of Rally for control of various trunk diseases (Botryosphaeria, ESCA, and Eutypa).  Also we have a special use label of Topsin-M for VA.   You can apply them with a sprayer or as a paint.  It would be a very good idea to use them, especially when you are making a big cut.  The timing of application would be soon after pruning and before a rain. Also, double pruning (early winter rough cut followed by the final cut in early spring) showed to reduce 95% of trunk disease in a CA study.

Here are handouts from 2014 IPM meetings.  IPM Practices in Vineyards (Doug Pfeiffer) Review of grape diseases symptoms and biology (Mizuho Nita) Viticulture Updates (Tremain Hatch) YAN: Its importance and modification in the winery and vineyard (Molly Kelly) Looking forward to meet you at the meetings!!

We will have two IPM workshops this week. At Ingleside vineyard (http://www.inglesidevineyards.com/) on this Thursday (the 6th).  They are located in the northern neck area At Beliveau Estate (http://www.beliveauestate.com/) on this Friday (the 7th).  They are close to Roanoke. If you can make it to these meetings, that would be great. Also, we rescheduled the Nelson county meeting.  It will be held on March 21st.  I think the location will be the same, Nelson county extension office. If you have not done, please check our new Pest Management guides for 2014 season.  The links are under "Resources" at the right hand side of this blog.  I will come up with a 2014 version of my workbook soon.

Due to the inclement weather, we decided to postpone our IPM meeting at Nelson county.  I will post a new date once we come up with one. Stay warm and be safe!

Here are handouts from the MD grower association meeting, which was held last week.  It was a great opportunity for me to meet our fellow growers in Maryland!! Review of IPM Lifecycles of grape diseases Fungicide updates Nita lab projects The links will take you to a Google drive.  You may need to download the files to your computer by clicking a printer icon because images look blurry on the Google drive window. Speaking of meetings, our winter IPM meetings will start soon.  The first one will be at Philip Carter Winery .  We will start from 10AM.  Please bring your won lunch!

Here is a copy of grape disease updates presentation I have given at the VVA meeting.  (It will open Google Drive, if you find the images to be blurry, please download the file to you computer by clicking "print" icon.  You do not need to sign in to download.)  There are quite a bit of information to cover, so, hopefully this and handout you have in the package would be good companions.  Once again, we will have four IPM workshops throughout the state in the months of February and March.   Please join us.

I hope you are enjoying the VVA meeting. Here is my handout from the VVA meeting , just in case if you would like to have a color copy.  I will upload my other presentation later, probably tomorrow night.  If you are looking for spray guides and workbook, you can find them under "Resources" on the left hand side of this blog. I will hang around until Saturday.  If you have any questions, please do not hesitate to talk to me.

There is a supplemental label for the use of Luna Tranquility with wine grape (you can click this link to download.  It will open Google Doc, but you can download via clicking print icon on Google Drive) .  Luna Tranquility is a sister fungicide to Luna Experience.  It has a fluopyram (FRAC group 7 = SDHI, medium risk) mixed with a pyrimethanil (FRAC group 9, the same as Scala).  As a product, it has an efficacy against powdery mildew and Botrytis . ž Application rate is 16-24 fl oz/A, and the maximum usage allowed is 54.7 fl oz/A per season; however, as usual, we recommend not to use it more than twice a season for management of fungicide resistance.  PHI is 7 days, which is shorter than that of Luna Experience (14-days).  It has a 12-h REI, but it does not have the 5-day cane work restriction as Luna Experience has.   We have tested in Winchester in 2013 season, and both Luna Experience (FRAC groups 7 + 3) and Tranquility provided excellent control against Botrytis.   My only co

Happy New Year everyone!  I hope we will have a nice season!  Hopefully your vineyard did not get too cold this week.  Temperature reading at our research station was about 0F... For those of you attended an IPM meeting at West Chester, PA, here are copies of my presentations.  These links will open Google Drive page.  The files were too big to upload to the server I am using. Pictures look blurry in Google Drive, but if you download the file (by clicking on the printer icon), you can open a pdf file with better pictures. Downy, Phomopsis, and Botrytis Fungicide Updates Also, please mark your calender for upcoming VA IPM workshops!  (Click the table to enlarge.)