Friday, September 30, 2016

Rain rain...

It has been pretty wet week so far. At Winchester, we observed about 11 hours of wetness on the 26th with an average temperature of 64F, 50+ hours (and counting) from the 28th to today with an average temperature of 61F. It is certainly long and warm enough for Botrytis infection.

Whether we require a fungicide application for Botrytis or not at this point depends on several potential factors. The first one, of course, is whether you had a previous application or not. If you had a previous application to cover these rain events, you probably do not need to be concerned much.

The second one is a time to harvest. If you still have several weeks to go, you may want to consider an application, but if you will harvest within a few days, I am not sure an application of fungicide will help you much since we do not have any curative materials for Botrytis. Whatever we spray at this point will be good against future infections, but not the infection happened already.

The third is cultivar. Chances are, many fruits out there at this point would be that of red cultivars, which is relatively less susceptible to Botrytis infection than whites, especially the one with a loose cluster architecture. I can see some white cultivars such as Petit Manseng can still be out there, but Petit Manseng is also less susceptible to Botrytis than many other whites.

The fourth is the environment. The rain this week was pretty severe, but the last major rain event at Winchester was 18 August. We had wetness event here and there, but these were relatively short events (many are less than 5 hours in leaf wetness), thus, I have a feeling that this dry weather did not favor spore production of Botrytis. Thus, even the environment was favoring this week, spores might not be available to cause infection. Since it has been pretty dry, the application you have made a while ago may still not be washed away too.

The other late season disease you may want to consider is sour rot. With this rain, berry skin may be damaged and that may invite sour rot pathogens to come in. Our understanding is that sour rot is caused by several different types of pathogens, thus, often time, a broad spectrum fungicide is recommended. I do not think any of fungicide works to stop the on-going infection, but you may want to stop the spread of sour rot. Something like copper or captan may be a good choice, especially if you have a few weeks to harvest. Both Switch and Fracture list Botrytis and sour rot (for suppression, not control) as a target disease. Also, polyoxin-D materials such as Ph-D or Oso list not only Botrytis, but also Alternalia, which is also known to cause late season general rot, as target pathogens.

Lastly, here is re-posting of a list of fungicide with relatively low PHI for your reference.

Wednesday, September 7, 2016

On these unusually slow ripening issues

Maybe I should keep posting that rains are coming... Each time I do, it looks like rains disappear. ;)

If you have not subscribed to the email list of Dr. Tony Wolf, who is our viticulturist, please do. It always have a wealth of information. In his latest newsletter, he explores potential reasons why some of cultivars are stalling on ripening process this year. Our Chardonnay is still stuck at 19 Brix or so too!

The below is a link to his newsletter, but it typically take several days for the newest one to appear. Thus, the best way is to subscribe to his email list (the instruction for subscription is listed on the page too).

http://www.arec.vaes.vt.edu/alson-h-smith/grapes/viticulture/extension/VN_options_index.html

Friday, September 2, 2016

List of low PHI materials for Botrytis, powdery mildew, and downy mildew

Well, I was hoping that the rest of the season would be nice and sunny, but I was little naive. Looks like some portion of VA may be affected by tropical storm Hermine. Plus, probably due to the hot several weeks with no cooling time during the night in August, some cultivars have been very slow to ripen. I was bit surprised to see our Chardonnay is still around 17 Brix this week.

Thus, I complied a list of fungicides with relatively low PHI (7 days or less). I cannot cover every single fungicides out there, but I tried to cover common ones. Please click here to download the table from Google drive.

NOAA's precipitation prediction for Harmine as of 2 Sept. 2016

Tuesday, August 16, 2016

Last stretch!!

I heard that some of early cultivars are ready to be picked on 7-10 days.  Looks like no tropical storms to worry, yet... (crossing my fingers!)

There have been frequent thunderstorms went through our area, and some of them (like the one we had last night) resulted in a significantly long wetness event (8 hours). These wetness events, especially the one happens overnight, are preferred by downy mildew pathogen since they produce spores in dark, moist conditions.

Please check my previous post on late season downy mildew. As usual, protection is the best approach.  If you have seen some downy mildew on foliage, it would be best if you can mix a protective material (e.g., copper, captan) with a phosphonate (Prophyt, Phostrol, etc). If there is heavy downy mildew already happening, please do not use Ridomil (metaxel) products because they are known to be overcame by the downy mildew pathogen.

Some of reds are probably going through veraison, which would be a good timing for your Botrytis application. Make sure to rotate mode of action since Botrytis is known to develop fungicide resistance. Please refer to my previous post for details on Botrytis management.  Also note that as with Botrytis, a key for sour rot management is the protection of fruits from any wounding events (birds, insect, human activities, etc). These pathogens tend to take advantage of existing wounds.


Friday, July 29, 2016

Another extensive rain event recorded

As many other parts of VA, we have been experiencing thunderstorms running through our area in the past week for so. Yesterday, we had about 9 hours of wetness with an average temperature of low 70's, then followed by a very humid night with an average temperature of mid-60's. These conditions are conducive for downy mildew development. Please check the previous posting for more information on downy mildew management.

Also, as veraison approaches near (or happening for some cultivars), please check 12 July posting on late season disease management.

Tuesday, July 19, 2016

A quick reminer on downy mildew

At Winchester, we had 8 hours of wetness observed on last Thursday, then there are several short rains/thunderstorms. Moreover, the night time relative humidity has been fairly high (> 95%) in the past few days. These conditions favors downy mildew development because downy mildew pathogen prefer to produce spores under dark humid conditions.

At this point, you do not need to worry about downy mildew infection on clusters; however, they can still infect leaves. Often time, you will see infection on the top of the canopy around this time of the year because younger leaves are more susceptible than older ones. Once infection gets severe, it can defoliate infected leaves.

As usual, it is much better and easier to have a preventative program than try to play a catch up game. There are many good protective materials for downy mildew, such as Revus products, Zampro, Forum (Please note that these three share the same mode of action), and Ranman. In our small trial, we found that fixed copper worked pretty well against downy mildew when we compared with captan. Captan worked too, but a fixed copper product lasted longer than captan. Some wine makers do not like to see captan or copper used late in the season, so, this time of the season maybe the best timing to use copper and captan for downy mildew. You can also use a phosphorous acid product as well. For some cultivars, you may still use zirum which has a 21-day PHI. Please mix and match to rotate among mode of action groups.

Tuesday, July 12, 2016

Seasonal disease management considerations toward the end of the season.


Most of us are about to finish critical time when 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, cultivars 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 timings for Botrytis is at bloom, bunch closure, and veraison.  The pathogen seems to be active throughout the season. The main reason we recommend application of a Botrytis specific material at bunch closure is that this most likely to be the last opportunity for you to deliver the material into the clusters, especially if you grow tight cluster cultivars, such as Chardonnay. 

Also, please keep in your mind that Botrytis is very well known for its capacity to overcome fungicides.  Thus, a rotation of mode of action groups is very important aspect for Botrytis management.  Mode of action for a particular fungicide can be found as a FRAC code, which you should be able to locate on the label.  Here’s a short list of materials for Botrytis and their FRAC code in parenthesis: Elevate (17), Scala (9), Vangard (9), Switch (9+12), Inspire Super (9+3), Luna Experience (7+3), Aprovia (7), Meteor/Rovral (2), Endura* (7), Pristine* (7+11). 

The material with an asterisk has a high concern on resistance development. Please note that the group 7 is considered a high risk, but I did not put an asterisk on Luna and Aprovia. I am not indicating that they are not high risk materials; I just simply do not have enough data. However, since they belong to the same mode of action group, I would be very careful on the usage.

When you are in doubt, please rotate the FRAC code because two different fungicides with two different chemical names may have the same FRAC code as you see on the list above. Also, tank-mixing with other material, such as captan, which has weak to fair activity against Botrytis, will help lowering the risk of fungicide resistance development.  If you think one of fungicides you are using is not providing sufficient control, please contact Dr. Baudoin or me.

Another management tip for Botrytis is about wounding on berries.  Although Botrytis is capable of causing disease by penetrating grape’s fruit skin tissues, it prefers going after wounds.  Also, at bloom infection by Botrytis tends to develop into disease when grape fruit skin is damaged, but when the skin is intact, the risk of disease development will be much lower.  Thus, management of the source of wounds such as insects (esp. grape berry moth), or birds, or powdery mildew at early in the season, can results in the management of Botrytis.  Moreover, sour rot pathogens also really like going after wounds; so, the same wound management would be the key for the sour rot management as well. 

Both ripe rot and bitter rot are considered as a warm season diseases, and in fact, people in the south tend to suffer more from these diseases; however, we can find ripe rot in Northern VA year after year.  In addition, I have heard from growers from PA and MD that they are having issues with ripe rot as well.   


Unfortunately, ripe rot in particular, has been misdiagnosed more than other rots.  It shows up as if the berries are sunburned, thus you will see a round dark brown lesions on the top portion of an infected berry.  The difference would be the tiny dots you will see within the lesion, which are fruiting bodies of the pathogen.  As the time progresses, the lesion expand into the whole berry, and infected fruits become shriveled raisin-like fruits (please see the picture above).  With a severe infection, you may see the majority of berries on a cluster shriveled down.  Unlike sunburn, it does change the taste of the fruit and wine.  Unfortunately, the change is in the negative direction, and a study showed that a consumer panel could detect only 3% contamination in the mast.

Both ripe rot and bitter rot seem to be able to infect berries from time of flowering to the harvest.  Thus, protection is important, especially if you have experienced issues with these diseases in the past.  Mancozeb, ziram captan, and QoI (Strobirulin) fungicides are currently recommended.  Please rotate among these mode of actions because some of isolates causing ripe rot are not sensitive to some of those materials. Our recent research effort showed that fixed copper materials have a good efficacy as well, thus, it maybe a good idea to tank mix these materials with a fixed copper. (Note: due to the 66-day PHI of mancozeb, you may not have enough days remained to spray mancozeb at this time of the season.)

Tuesday, July 5, 2016

An update on yesterday's post

Just an update on yesterday's post: At Winchester, AREC, a total leaf wetness hours was 29 hours, with an average temperature of 67F. Thus, this rain event was warm and long enough for both downy mildew and black rot. Also, it was long enough for Botrytis as well.

For the details of downy and black rot kick back activity fungicides, please refer to yesterday's post.

Monday, July 4, 2016

An extensive wetness event recorded (and still going)

A cool and wet Fourth of July weekend resulted in a very long leaf wetness hours. So far, more than 12 hours of wetness has been recorded at Winchester AREC, and at this rate, it will go on over the night (= potentially it will be a longer than 24 hours of wetness event).

As noted in my previous post, the April frost event(s) probably resulted in a prolonged bloom period. Because of that, I have a feeling that some portions of clusters of many of cultivars are still under a critical period for downy mildew, powdery mildew, and black rot for at least one more week.

If your vines were protected with materials such as mancozeb (for downy, and black rot), Revus, Forum, Zampro, Presidio, or Ranman (for downy), Luna Experience, Rally, or other DMI (for black rot) or Abound, Pristine, or other QoI (for black rot), you should not worry too much about it. However, if your vines were not well protected, (e.g., last application was more than 12 days ago, or you have missed some of protective materials in the previous application), then you may need to use a fungicide with a kick-back activity to stop the potential infection which maybe going on right now. For downy mildew, you may use a phosphite (Prophyt, Phostrol, etc), or a Ridomil product. For black rot, you may use a DMI (Rally, tebuconazole), or a QoI (Abound, Pristine, etc). (Note: a DMI works better than a QoI in terms of kick-back activity).

Also, while I am talking about "kick-back" activity, please note that the kick-back or curative activity means that you may stop the on-going infection process 3-5 days after the initiation of infection, and while it is not showing symptoms. It does not work on existing downy or black rot symptoms. In fact, none of fungicides we use truly eradicates existing symptoms. Thus, often time, it is the best to have a good protective program, rather than trying to spray after the fact. Especially during the critical period for cluster infection, which is from bloom to 4-5 weeks after bloom.

Tuesday, June 28, 2016

Another reminder on seasonal diseases


Photo: we have started to see powdery mildew on clusters. I hope you are not!

Looks like series of thunderstorms are hitting various part of the state this week. Just a reminder that due to April frost events, some of us experienced extended bloom. This not only means potential lag in harvest time for these late clusters, but also, an extended critical period for seasonal diseases. Grape clusters are susceptible to black rot, downy mildew, and powdery mildew from bloom to 4-5 weeks after bloom (3-4 weeks for American grapes). Thus, this is the time I want you to be on top of the game (i.e., nice coverage, 7-10 days interval, good selection of fungicides to be applied).

Many growers told me that if they are clean around the Fourth of July weekend, you don't expect outbreak of black rot, downy mildew, and powdery mildew. I generally agree with their assessments since in many years, bloom happens late May or early June. However, this year, bloom started the first week of June, but I saw delayed bloom until the middle of June, thus, I will keep my schedule relatively tight until early to mid-July (i.e., rather than the Fourth of July weekend, I would aim for the next weekend). Since we are having several rain events in the past few days, I would watch the forecast carefully, and prepare for good protection against, downy (e.g., Revus (Top), Zampro, Ranman, mancozeb, Phosphite, etc), black rot (DMI (Rally, Revus Top, Luna Experience, etc), mancozeb, QoI (Pristine, Abound, etc)), and powdery mildew (Vivando, Luna Experience, Quintec, Tanos, sulfur, etc). Please note that some of mixed materials may have efficacy on multiple diseases.

Also, we will have a vineyard meeting at Arterra Wines in Delaplane, VA from 11:00 AM tomorrow. I hope to see you there!


Tuesday, June 21, 2016

Handout from last week's meeting + we are still in the critical period!

Here's my handout from last week's meeting at Stone Tower Winery. Thanks for those who attended the meeting!

It looks like we may have rains here and there this week. Since we have not had significant rains in the past week or so, the risks of downy maybe low, but most of us are still in the middle of critical period for cluster protection. Please refer to my at bloom post for more details on disease management tips for this time of the year. Once we pass this period, we can relax a bit, in terms of fungal disease management.

Monday, June 6, 2016

What to do when you receive a lots of rain after fungicide application?

At Winchester area, we ended up having a pretty good weekend. There were several periods with rain, but it was not as extensive as the forecast. We received about an inch total over 2-3 days. However, it looks like the central VA received more rain than we did.

I would like to share a question I received from a grower today.

"With all of the rain events we have had lately and bloom being an important stage for fungicide application Should we spray after a significant rain event before the recommended 7-14 day interval? Specifically, I applied fungicide June 3rd and received quick but heavy rainfall on the 4th and 5th. Riding through the vines it looks as though there is still chemical residue on leaves and clusters. Can I base a decision off of this observation?"


It really depends on what you have sprayed, what we are expecting in the next few days, how the vines are maintained (shoot thinning, etc), cultivars, etc, so, I cannot give you a quick answer.

Typically, after drying, these fungicides stick pretty well with leaves and application rates are often time much higher that what you need to control diseases. Thus, even after considerable amount of rain and removal of spray residues, you can still achieve a good disease control. Please see this excellent article from MSU (http://msue.anr.msu.edu/news/fungicide_properties_and_weather_conditions) for more information.

However, since this is the critical time, I would be on a safer side. I don't think you have to spray today or tomorrow, but I may recommend to spray at 7-day interval, rather than extending it to a longer period. Depends on how the weather goes and target disease to be, but if you have a concern on downy mildew or black rot, this may be the time you want to use something with a kick-back activity (a phosphite or Ridomil product for DM, DMI for black rot). Powdery mildew fungus prefers dry weather, but if you have been struggling with PM in the past, and you are expecting a dry weather after this rain event, you may want to consider adding a PM specific material such as Quintec, Vivando, Torino, etc.

Also, as I noted in a previous post, some of you may have a rather long period of bloom due to damages caused by the April frost events. (For example, some of our Chardonnay vines are in full bloom today yet others are still lagging behind, which are probably on shoots from secondary buds) Depending on the situation, you may have to consider two applications for at bloom disease management especially to target Botrytis (e.g., Rovral, Elevate, Switch, Luna Experience, etc), ripe rot (QoI, mancozeb, zirum, captan, copper, etc), and bitter rot (same as ripe rot). It will get tricky, but please make sure to rotate FRAC codes!

Finally, I am not an entomologist, but this is also the time I start to see the incoming of grape berry moth in our vineyards. Please keep eye on them so that they won't cause damages on later in the season.

Friday, June 3, 2016

Another rain events in the forecast...


Our Chardonnay vines are getting close to full bloom, and of course, we are expecting more rain over the weekend. Just an another reminder that from bloom to 4-5 weeks after bloom is the critical period for downy mildew, black rot, and powdery mildew infection on clusters, and at bloom application is very important one for Botrytis management.  Please see recent post about the at bloom fungicide application consideration as well as recent updates on fungicides. This would be the timing where you will thrown in some good materials into your tank mix! It is much easier to protect the vines than try to play a catch up game after disease outbreak,

Friday, May 27, 2016

Quick reminder about black rot

I noticed that some of our 'Cheloir' vines are in trace bloom and also it has quite a bit of black rot. As I suspected, the cold rains we received were long enough for pathogens beyond Phomopsis to be able to infect vines. If you have not seen black rot lesions on leaves and shoots, the pictures below are good examples. If you click on them, it should open a larger picture. Please note the small dots on these lesions. These are fruiting bodies that contains spores.

Once again, most of us will be seeing bloom in the near future, and it will be a start of critical period for so many diseases. Please be on top of your game (shoot thinning, canopy management, and of course, fungicide applications). Mancozeb, as well as both DIM and QoI fungicides are very effective against black rot pathogen. Looks like we are expecting some rains again next week!

Black rot on leaves
 Black rot on shoots and rachis


Friday, May 20, 2016

Seasonal updates and notes

1) What to do this and next week
It looks like we have a window today for application, and after the rains over the weekend, next week looks good too. Right now, I am not too concerned about powdery mildew because it has been too cold and wet for this disease; however, next week will be nice and dry (I hope!) Thus, if you are concerned about powdery, you may need to add powdery mildew specific material (Quintec, Vivando, Torino, Luna Experience, etc) for your next application. Of course, something like Luna would be good for black rot, so, you may want to hold off until at bloom application (which may happen soon for people in the south)

Also, make sure to cover for downy mildew too. Although temperature has been low, with all the rain we received, I have a feeling downy mildew pathogen can cause infection. I would use a phosphonate material (Prophyt, Phostrol, etc) at this time of the year so that I can keep the use of a big gun (Ridomil product) for at bloom application, if needed.

As usual, please rotate mode of action (= FRAC code), and keep the use of newer materials (i.e., anything other than mancozeb, captan, zirum, copper and sulfur) to less than three times a season. Limiting the use to twice is even better! A phosphonate can be used more than 3-4 times per season, but don't over use it either. Tank mixing a newer material with a broad spectrum material will help too. This is for management of fungicide resistance, which is the reason why I cannot recommend QoI for downy mildew any longer.

2) At bloom application
Due to the spring frost events,  some of cultivar may ended up having a mix of shoots from the primary and secondary buds, thus, chances are they will bloom at different timing. Please make sure to cover for both blooms. At bloom protection is very important for so many diseases!


3) Phomopsis (note the yellow specks on the picture above)
Yes, we have seen it. The weather is too conducive for Phomopsis development this year. It would be very difficult for anyone to stop it. A good news is that unless it infects rachis or damage the shoot to the point it cannot grow, most of the time, damages from Phomopsis is not as critical than other fungal diseases, such as powdery mildew. However, it is one of more difficult to manage disease, once it gets out of hand, and it can also cause fruit rot. Please make a note (literary) of where (or which vines) you found Phomopsis this year.  Chances are, you will find them again on the same spot in the future because Phomopsis resides in old infected cane and cordon tissues. If it limited to a certain part of your vineyards, you may want to consider doing a spot treatment next year. Mancozeb, Zirum, captan, and phosphonate are effective materials, and QoI and SDHI materials are also effective too. Since none of them have kick-back activity against Phomopsis, nothing much we can do about the infection already happened; however, make sure to keep these materials in your tank mix so that you won't suffer from Phomopsis fruit rot.

4) Luna Experience
As I mentioned back in February, Luna Tranqulity is no longer available for grape. Also, Luna Experience received a new supplemental label for a slightly higher rate of application (click here to download for your record keeping). Please keep in your mind that Luna Experience (and Pristine) has a 5-day REI for cane work (12 hours for all the other activities).

5) Notes from NJ Twilight meetings
Thanks for those of you who attended NJ Twilight meetings last week. Here are notes from the meeting. 1) Fungicide updates and 2) Virus research updates.

That's it for today! Hopefully, we can enjoy better weather soon!


Sunday, May 15, 2016

Bloom time disease management considerations


Due to many rain events and relatively cold weather, it looks like we are somewhat back in truck in terms of the growth stages. When shoots are about 10-12 inches long (i.e., right now), downy mildew, powdery mildew, and black rot tend to show up. Then, at bloom time, flowers and young berries will be susceptible to these diseases, and young berries are susceptible until 4-6 weeks after bloom.  In addition, Botrytis, ripe rot, and bitter rot can cause infection on flowers.  Yes, it is a lots of diseases to think about. What you need to think about is which disease(s) have been the major issues at your vineyards. The disease history of your vineyards tends to repeat itself.

Downy and black rot management depend on weather condition.  I have seen cases where downy or black rot developed prior to bloom under wet conditions, and this year would be such a case, if you could not keep up with the protection. If you have concerns on downy or black rot, think about the use of a DMI or QoI material for black rot, and Phosphite (= Phosphorous acid) or Metalaxyl (Ridomil) product for downy mildew.  Revus, Zampro, and Ranman, can provide a very good protection against downy mildew. Based on the past few weeks of rain events and a trend of warm humid nights we observed, it would be a nice idea to think about downy mildew, since these humid nights can promote spore production of the downy mildew pathogen.   

As for powdery mildew, I prefer to start powdery mildew management (i.e., the use of a DMI or other newer materials such as Quintec, Vivando, Luna, etc.) at pre-bloom application in our plots due to heavy powdery mildew pressure at our plots. It seems to reduce the cases of cluster infection for us.  However, please note that in my vineyards, our trials tend not spray as often as many of you.

Development of Botrytis depends on what type of varieties you grow, as well as your canopy management strategies.  White-fruited varieties with tight cluster architecture tend to be more prone to Botrytis.  I.e., a red-fruited variety with loose clusters probably does not have many issues with Botrytis, especially if the canopy is well maintained.  Bloom time is important for Botrytis management because this fungus can infect flower and flower debris, and come back later when berries are maturing.

Warm weather conditions help development of ripe rot and bitter rot.  Both of them cause infection from bloom to harvest; however, you do not see actual rots until near harvest.  It is very similar to Botrytis in this regard.  Additional issue here is that both diseases can change the flavor of wine.  If you have seen ripe rot or bitter rot, it would be a nice idea to protect flowers with mancozeb, captan, Ziram, or a QoI.

For Botrytis, ripe rot, and bitter rot, please keep in your mind that early season powdery mildew management can become important to prevent these diseases.  These pathogens are very good at infecting through wounds (plus, the flower infection of Botrytis requires wounds to become rot); thus, scars, which will turn into opening of the skin, caused by powdery mildew infection on young berries can be the ideal targets for them.

Lastly, please keep in your mind about fungicide resistance issues.  You can locate FRAC code on the fungicide label (or you can take a look at our Pest Management Guide).  Even if two products are different in names or came from different companies, if they have the same FRAC code, they are basically the same in terms of fungicide resistance management.  Please rotate the FRAC code.  For newer materials such as DMI (or SI) or QoI or SDHI, my recommendation is not to repeat the application more than two times, and limit the use of it to no more than three times a season. Less number of application is better for fungicide resistance management.

Friday, April 29, 2016

More on Phomopsis and other disease concerns

Well, it looks like we will see more rains coming in next week or so. Sounds like a typical start of the season for VA vineyards, doesn't it?

Since most of vines have 2-10 inches of shoots, our main focus will still be Phomopsis, especially if your vineyard(s) experienced Phomopsis in the past.  At Winchester, we are experiencing 27+ hours of wetness with the average temperature of 48F or so. This will be a low Phomopsis risk event, and counting.

Plus, especially if you had a serious downy mildew issue in the past season, it may not be a bad idea to think about downy mildew because the next series of rains for this weekend and early next week may happen when air temperatures will be in 60's and 70's.  As for Phomopsis, a protective spray of mancozeb, captan, etc. is pretty much the only mean of management, but we do have some options for downy after the rain event.

So, if you did not spray before this series of rains, but you are lucky enough to have a window for a spray before the big rain on Sunday, you may want to go ahead with it. I would go with mancozeb (if your aim is Phomopsis alone) or add a phosphite (Prophyt, Phostrol, etc.) to the mix, if you have a reason to believe downy could be an issue at your location. Also, trial reports from Michigan State showed that a phosphite would work against Phomopsis too. (I am not sure that it can have a kick-back activity, though)

If you won't have a chance before Sunday, or you have applied before this week's rains, then I would add a phosphite to the next mix of your fungicide application. As I mentioned above, I am not sure it can have a kick-back activity against Phomopsis, but at least it will provide a good kick-back activity against downy mildew. It looks like the next opening will be on or after Tuesday.

FYI: For our plots, we sprayed mancozeb earlier this week before the rain for older Chardonnay plot where we started to see Phomopsis in the last two years, but did not spray "organic" plot where we have not seen Phomopsis. The timing for next application will be either late next week or early in the week after, depending on the weather conditions.

Friday, April 22, 2016

Disease management after frost events...

Several growers contacted me recently to discuss about disease management after recent frost events. Here are my take on it.

1) If you have some damages on your shoots/buds.
As usual, you work with the growth of the vine, but not with the calendar dates. If you have lost a lots of growth from the primary buds, you may have to start over your spray program.  If you have mixed growth from the primary and secondary buds, you may need to adjust your spray program based on what may come from the secondary buds, especially around bloom. Flowers from the secondary buds may lag behind, thus, you may need protect flowers for a longer period of time.

2) If you have extensive damages on your shoots/buds to the point that you may not able to expect crops.
Based on what I heard, we are not seen this scenario this year. However, if you happened to have the major issue from the frost events, well, first of all, I am sorry.  Second, you still need to have some level of disease management in order to keep canopy clean so that your vines will crop next year. Vines probably need a decent canopy management to have good penetration of lights to encourage flower cluster formation for next season as well.

If you are not expecting crop this year, you can treat these vines as you may do for younger non-baring vines. You can use a mix of mancozeb and sulfur, or a fixed copper by itself (especially if your vineyards do not have a bad history of powdery mildew) and spray every 10-14 days.

Once again, the main target at this time of the year will be Phomopsis cane and leaf spot. Looks like we are expecting several days with some chance of rain over next 10 days or so.

Here's an update from our vineyard. As I noted earlier, our younger Chardonnay vineyard was hit very hard.  It was not as bad in some vines, but I am still expecting close to 70-80% damages on some vines. For some, like the one from the picture below, we may need to be retrain from lower shoots since majority of buds look very bad. We will see how the secondary buds will do.


Buds on older Chardonnay vines were tighter than the ones on younger ones when we experienced several days with mid-20's. Damages based on visual assessment were about 5-20%, depending on the vine. Some vines may have a looser canopy later, but nothing seems too serious.


[Please note that long internodes above the buds are for our experiment (we are looking for trunk diseases), you should not have these on your vines. ;)]

Our other cultivars, Cab sauv and Cab franc were most likely tight enough at the time of frost events.  I did not see any damage on them.

Friday, April 8, 2016

Spring cold injury and insect damages...

As with many other places in the VA, we were suffering from frost damages.  We experienced several near freezing events this year, and most notably, a few hours of 25F on Thursday morning. Our younger Chardonnay planting (4th leaf) had a bud break around 4/1, and being suffered more from it.  I estimated about 80-90% of emerged shoots are now gone. Our older Chardonnay (8th leaf) is about a week behind, and my visual estimate as of yesterday was about 25% loss.  Some buds/shoots look like they are surviving, but I am not sure how it will go after tomorrow morning...

There is a very nice blog post about spring frost from Dr. Michela Centinari at PSU.  If you are interested in, please follow this link.

The other items I noticed in our vineyards is damage from climbing cut worm.
For us, it always starts from the Eastern side of our vineyard which is facing a small patch of wood.  If it is a warm weather, I would spray for it, but I think I will wait until the temperature gets warmer near the end of next week. Here's an information page on climbing cutworms from Doug.

Monday, April 4, 2016

Early spring disease consideration: Phomopsis cane and leaf spot


Our 7-yr old Chardonnay vines are in bud swell stage, and others are tagging along.  It looks like we will see bud break in a week or two.

One of diseases you need to consider this time of the year is Phomopsis cane and leaf spot.  It causes minor leaf spots, but more importantly, it can cause necrotic lesion on shoots and rachis.  It also causes berry infection; however, it is not common with wine grapes because of our spray programs.  Materials for black rot and downy mildew are often effective against Phomopsis, thus, the coverage for these diseases are also working as management of Phomopsis, especially later in the spring/summer.

Phomopsis takes a while to establish in the vineyard; however, once it is established, it is difficult to get rid of this disease.  Some varieties, such as Viognier and Seyval blanc, are more susceptible to Phomopsis than others.  Phomopsis tends to become noticeable as a vineyard gets older because of it life cycle. The fungus survives in canes and trunks that were infected in previous years. (= Please remove old trunks and cordons when you retrain the vine!)  During the spring, it will produce spores that are splashed by rain onto new tissues.  It produces spores only during the springtime. Thus, luckily, unlike other diseases we face, there are only one major infection period throughout the season.  Phomopsis spores can cause infection under relatively cooler environment (upper 40s).  Thus, springtime rain events are ideal for Phomopsis to produce spores and cause infection. Therefore, it is important to protect young tissues when they come out from the older canes and trunks.  

If rain events are coming into the picture after bud break, mancozeb (Penncozeb, Dithane, etc.), Ziram, and captan are an effective protective material against Phomopsis.  (QoI, such as Pristine, works too, but you don't want to use them this early in the season.)  Protection is the only mean of chemical management because no materials are effective after the infection.

Friday, February 26, 2016

Handouts from recent IPM workshops

Thanks again for those of you who were able to attend IPM workshops.  I hope you enjoyed the meetings, and if you have any suggestions or comments, please do not hesitate to contact me.

Here are copy of fungicide updates and interactive fungicide planning presentations.

2016 Fungicide updates
(Please note: I just learned that Luna Tranquility won't be available for grape...  Too bad since it would be a good material for Botrytis management.  We still have Luna Experience, but there will be a label language change for grape.  I will post it once I learn more about it.)

Interactive fungicide planning.

Also, I think many of you have already participated, but there is a survey for evaluation of my Extension activities.  If you could spend 3-4 min of your time to answer it, I would greatly appreciate. (This is the same as the one Tremain sent out and I distributed at the VVA and other meetings.)


This is a questionnaire to help evaluate impact of the grape pathology extension program of Dr. Mizuho Nita at the AHS Jr. Agricultural Research and Extension Center. We would like to gauge the public value of this work and to help identify areas that to strengthen. We greatly appreciate your time and input here in determining if and how these research and educational programs have benefited your business. The survey is anonymous. 


Monday, February 15, 2016

Two IPM workshops and two webinars

There are several extension activities in the next few weeks that you maybe interested in.

1) IPM workshop at Early Mountain Vineyards
This will be a full day IPM workshop to cover viticulture, entomology, weed science, plant pathology, and legal and safety updates. This will count towards VA private pesticide applicator license hours (full credit for category 90).

Date: Feb. 16th 2016.
 
Agenda
9:30 Introduction and overview of workshop 
9:45 Viticulture updates – Tony Wolf
10:15 Worker Protection Standards- Roberto Quintero
11:00 Entomology updates - Doug Pfeiffer
11:45 Weed science updates - Jeff Derr
12:30 Lunch (please bring a lunch)
13:15 Laws and regulations - Roberto Quintero
14:15 Pathology Updates- Mizuho Nita
15:00 Interactive Scheduling – in teams
16:00 Meeting Adjourns
 
2) Interactive Integrated Grape Disease Management workshop at Dobson, NC
This will be a half-day IPM workshop that focus on grape disease management and legal and safety updates. This will also count towards your private pesticide applicator license hours.
Title: Interactive Integrated Grape Disease Management Workshop 

Date and time: February 18 from 1-5 pm Location: NC Cooperative Extension, Surry Center, 210 North Main Street, Dobson, NC 27017. 

Mizuho Nita, Assistant Professor and Grape Pathology Extension Specialist, AHS AREC, Virginia Tech Joanna Radford, NC cooperative Extension agent 
 
In this workshop, audiences will participate on a development of a full season grape disease management plan. This will be hands-on workshop with a lot of interactions. Items to be discussed are: integrated pest/disease management, fungicide resistance (FRAC code, rotation, etc.), and biology and management strategies for key diseases at each grape growth stages, from dormant to after harvest. At the end of the workshop, we will develop a mock-up plan(s) for a season, and critique as a group. This will count toward four hours of NC pesticide credits – categories N,O,D,X.  Also, full credit for VA category 90.

Agenda
1:00 PM - 1:10 PM Introduction
1:10 PM- 1:40 PM  Safety and legal updates (Joanna Radford)
1:40-3:20 PM Grape pathology, fungicide updates (Mizuho Nita)
3:30-4:45 PM Interactive fungal disease management planning (Mizuho Nita)
5:00 PM Discussion and adjourn
 

3) Webinar on clean plants for the eastern wine and grape industry
How the National Clean Plant Network, new testing protocols and a revitalized NY certification program will reduce the risk of nursery-transmitted viral pathogens.

Time: Thursdays at Noon (Eastern Time). March 10, 17, 24, and 31.

Since 2008, National Clean Plant Network Centers have joined together to efficiently produce, maintain, and distribute healthy grapevine budwood to the industry.  These materials are starting to make their way to nurseries, and ultimately, to end-users.  This four-part webinar series will cover the process of producing and distributing virus-tested plant material, graft-transmissible diseases and their impact, New York State’s new testing and certification program, and New York nurseries’ investment in new motherblocks and propagation procedures.

March 10: The Pipeline:  From tissue culture to your vineyard.
Joshua Puckett, FPS, UC Davis and Tim Martinson, Cornell University
March 17: Viral diseases transmitted through nursery stock in the East: Grapevine Leafroll Disease, Tomato Ringspot, and Grapevine Red Blotch
Marc Fuchs, Cornell University; Annemiek Schilder, Michigan State University; and Mizuho Nita, Virginia Tech
March 24: Crown gall biology and management; Value of virus-tested plant material.
Tom Burr, Cornell University and Shadi Atallah, University of New Hampshire
March 31: New York’s revitalized grapevine certification program, and New York nurseries’ plans for the future
Marc Fuchs, Cornell University; Margaret Kelly, NYS Department of Ag and Markets; Dennis Rak, Double A Vineyards; Eric Amberg, Grafted Grape Nursery; Fred Merwarth, Hermann Weimer Nursery

Preregistration is required.  Register online at:  http://tinyurl.com/NCPNgrapes
For more information and list of speakers:
 
 4) Webinar on grapevine red blotch disease
 
Grapevine Red Blotch Disease: What You Need to Know


Friday, February 26, 2016
 
Summary:

Grapevine red blotch disease and the virus associated with it has been confirmed in many major grape production regions of the United States and Canada. Since the identification of the virus in 2011, several teams of researchers from across North America have been intensely characterizing the disease and effects on grapevines, as well as characterizing the virus, its spread, and potential management. Considerable progress has been made, but much remains unknown. Speakers representing many of these labs will be presenting their work and what it means for the grape industry. For more information, please contact Frank Zalom at fgzalom@ucdavis.edu . (or visit their registration page)

Agenda (note that times are Pacific)

10:00 
Welcome and Introduction
Frank Zalom, UC Davis
10:05 
History of red blotch, symptoms and significance
Mysore Sudarshana, USDA-ARS, Davis, CA
10:20 
Etiology of red blotch
Marc Fuchs, Cornell University, Geneva, NY
10:35 
Detection and genetic diversity of the virus
Keith Perry, Cornell University, Ithaca, NY
10:50 
Effect of red blotch on grapevine performance
Rhonda Smith, UC Cooperative Extension
11:05 
Red blotch situation in Oregon
Vaughn Walton, Oregon State University and Bob Martin, USDA-ARS, Corvallis, OR
11:20 
Red blotch and the virus in Canada
Sudarsana Poojari, Agri-Canada, Canada
11:35 
Red blotch and the virus in Europe
Jean-Sebastian Reynard, Agroscope, Switzerland
11:50 
Virus Spread, disease gradient, and insects
Brian Bahder, UC Davis
12:05 
FPS and NCPN, Protecting the supply chain of grapevines from red blotch
Deborah Golino, FPS, UC Davis
12:20 
Question and Answer
Speakers (moderated by Frank)

For more information on the speakers, click here

If you need more information about the webinar, please contact Frank Zalom at fgzalom@ucdavis.edu .

 

Wednesday, February 3, 2016

Handouts from 2016 VVA meeting

Here are handouts from my presentations from the VVA meeting.

1) Slides from "Interactive Grape Disease Management Workshop"
2) Results from the "planning session". Please note that this is the results of answers from randomly selected people, and I am providing this as a note from the workshop.  Although it looks "OK", this is not what we recommend.
3) Slides from "Biology and Management of Grapevine Crown Gall"

It was very nice to see you all at the meeting.  As usual, I really enjoy talking to all of you!

If you have missed the VVA, there will be two meetings that we will host:
1) IPM workshop at Early Mountain Vineyards on 16 Feb from 9:30 AM
2) Interactive grape disease management workshop at Surry county Extension Center (210 North Main St., Dobson, NC 27017) on 18 Feb from 1:00 PM.

I will post details of these meeting in a few days.

Sunday, January 10, 2016

Happy New Year and Upcoming Meeting Announcements for 2016 Winter!


Upcoming meetings:

A. Virginia Cooperative Extension and Virginia Tech will offer pruning workshops in Central/Southern Virginia (Amherst) and Northern Virginia (Winchester) this January.

Beginning grape growers and experienced grape growers are invited to either workshop.

The content will include a review of these topics:

·      grapevine dormant pruning
·      grapevine cold hardiness
·      disease management at pruning
·      pruning as a component of canopy management

We will then go out to the vineyard for guided practice pruning grapevines before the meeting adjourns.

 Please bring pruning shears and prepare to be outside; rain or shine.

 Pruning Workshop Schedule for 2016:
Date / Time:    12 January 2016   / 1:00 – 3:30 pm

Lazy Days Winery
1351 N Amherst Hwy, Amherst, VA 2452

Date / Time:     13 January 2016 / 1:00 – 3:30 pm

AHS Jr. AREC
595 Laurel Grove Road,
Winchester, VA 22602
            
Contact: There is no registration or fee for either workshop. Please contact Tremain Hatch with any questions (540) 869-2560 x11. 

If you are a person with a disability and desire any assistive devices, services or other accommodations to participate in this activity, please contact Tremain Hatch, AHS Jr. AREC at (540) 869-2560 ext. 11 during business hours of 8 a.m. and 4 p.m. to discuss accommodations 5 days prior to the event.

*TDD number is (800) 828-1120

 B. Virginia Vineyards Association’s Winter Technical Meeting

The VVA’s winter technical meeting is just around the corner, 28-30 January 2016. Meeting location again is the Omni Hotel in Charlottesville. The technical program includes research updates, some contemporary recommendations on vine fertility management; an afternoon session on adapting varieties to Virginia’s challenging climate; and much more. As an “on” year for (Virginia) private pesticide recertification, the program includes sessions that will be meet recertification credit needs. The full program and registration information are available on the Virginia Vineyards Association’s website.  Hope to see you there!

C.  Save the Date - Grape IPM workshop

16 February 2016

Virginia Cooperative Extension Specialists will review pest management considerations for a full day IPM workshop.  The morning of review will be followed by interactive pest management scheduling for the 2016 growing season.

 We will have only one IPM meeting this year, centrally located at Early Mountain Vineyards near Madison VA. 

The meeting will begin at 9:30 am.

What: 2016 Vineyard IPM Workshop

When: 16 February 2016, beginning at 9:30am

Where: Early Mountain Vineyards

This workshop will take place indoors- bring a notepad, writing utensils, bagged lunch and a copy of your spray program from last year.

 There is no fee for the workshop; however, please confirm your participation by sending a message to Tremain Hatch Thatch@vt.edu by 12 February 2016. This will help with printed handouts etc.

 Please address questions to Tremain Hatch thatch@vt.edu

 If you are a person with a disability and desire any assistive devices, services or other accommodations to participate in this activity, please contact Tremain Hatch, AHS Jr. AREC at (540) 869-2560 ext. 11 during business hours of 8 a.m. and 4 p.m. to discuss accommodations 5 days prior to the event.

*TDD number is (800) 828-1120