Tuesday, December 15, 2015

It's tempting, but it's not the time to use pruning shears, yet.

Please see the message below from Dr. Sara Spayd, who is an extension viticulture specialist at NCSU.  The information is probably more applicable to people in the southern VA, but we have not really seen cold temperature in the northern VA either. While we can enjoy outdoor activities in the middle of December, this warm weather is bit concerning for grapevines.  Let's hope for a gradual temperature drop in the near future...


Please pass this on to all grape growers:

I know this beautiful weather is tempting, but please DO NOT PRUNE - even hedging. Pruning helps to stimulate vine growth. I would not be at all surprised if you see grape buds in some degree of bud swell, particularly the European bunch grape varieties. Those varieties have very little chilling requirement and it was likely met in the few cold days that we have had. 

The short predicted cooling pattern for this weekend will do little to harden the vines and buds for any potential cold weather in January or February. Apparently the prediction is for temperatures to climb up again for Dec 24-25. A precipitous drop (30-40F) in temperatures after warm weather can cause a lot of damage.


Wednesday, November 11, 2015

Presentation and other files from Beginner's workshop at AHS AREC

It was very nice to see you all at the beginner's workshop held today at AHS AREC.  Here are: 1) my presentation (Google drive will open) and 2) disease management guide for non-bearing vines.

I hope to see you guys in the future!!

Tuesday, September 29, 2015

Very late season spray options

With this week's precipitations that we (including many meteorologists) did not anticipated last week, some of you have contacted me to seek options for the late season application, especially for red-fruited cultivars that need to stay on the vine for a few more weeks.  Here's a table for late season fungicide options, with materials that has 7 or fewer PHI (it will open Google Drive's spread sheet).  The efficacy information is based on our PMG, which can be downloaded from the right hand side of the blog.  (It says 2014, but the file is updated to 2015).  Hopefully we will see the sun soon!

Good luck with the rest of the season.  It's almost done!!!

Friday, September 4, 2015

Late season downy mildew and recent rains

I have heard from several growers that they are seeing downy mildew despite the fact that they have not seen much precipitations.  It could happen because of the humidity, especially during the night.  Warm, humid, and dark condition (just like we have been having during the last few weeks) promotes downy mildew pathogen to produce spores.

In addition to these conditions, we had lines of rain storms passed in our areas in the past two days. The length of wetness due to these storms were probably long enough for downy mildew pathogen to cause infection.

So, just a reminder.  If you have seen downy mildew, and you have not applied any protective material (captan, Revus, even phosphorous acid products) in the past 10 days or so, you may want to consider a rescue application of a phosphorous acid product to reduce the risk of infection that might have happened in the past two days of rains.  (Note: If you are considering harvest in a few days, I would wait until harvest.)

If you have not seen much downy mildew, and/or you have protected your vines within the 10 days or so, the risk of downy mildew infection would be low.

Thursday, September 3, 2015

Sour rot recap

Dr. Wayne Wilcox at Cornell University wrote an article on sour rot management on "Finger Lakes Vineyard Notes". (The link will open a pdf file)  Please check it out. 

Results from his research group is showing that 1) good canopy management matters, and 2) management of insect (fruit flies) seems to have a big impact on the development of sour rot.  Since their regions do not have issues with spotted wing Drosophila (aka SWD), even regular fruit flies, which cannot damage grape skin, can still aid transmission of sour rot pathogens.  I know some of us in VA have been managing SDW in the past few years. If you have managed SWD and have seen lower level of sour rot, please let me know.

Tuesday, August 25, 2015

Pre-harvest disease management considerations

Now the season is wrapping up, and one of questions I get often is “when to spray what to protect your crop at the last stretch”.   Unfortunately (as with everything else), my answer to the question is “it depends.”  But it won’t help anybody, so, let’s go over several potential scenarios and see one of them makes sense to you.

Case 1: you are expecting harvest in 2-3 weeks
I think many of Chardonnay and other early white cultivars are about to be harvested.  Luckily, around Winchester area, we have had a good stretch of relatively dry weather.  We had rain showers came in several times, but only two of them, one at 8/4 and another one on 8/20 were long enough to initiate major late season diseases, such as Botrytis.  We have three Botrytis trials, but we have not seen evidence of Botrytis outbreak.  Moreover, at Winchester area, a forecast of next rain is on next Tuesday, and it looks like a case of another thunderstorm.  

Thus, at this point, only concern I have is powdery mildew, and maybe Botrytis and sour rot.  For the powdery mildew, it may show up on the upper part of the canopy where young foliage is available; however, it won’t affect your berries at this point of the season.   It will take at least a week from infection to the production of spores, so, with 2-3 weeks to go, it is less likely to see powdery mildew being a big issue for our harvest.

As I noted earlier in this blog, the first line of defense against Botrytis and sour rot is a good canopy management, and management of insects (e.g., grape berry moth) and birds that can cause wounds on berries.  If you have been successful on these, there are low chances of getting into trouble at this point.  Even if there are some Botrytis, with the dry days in the forecast, I am not sure how much damages can Botrytis cost, unless of course, you have not keep up with canopy management.  Botrytis really likes humidity that can be created by a poorly managed dense canopy.

So, what to do?  If you have not seen any sign of powdery, Botrytis, and sour rot issues with your vines, I may say that you probably do not need to worry about applying another fungicides, unless there is a tropical storm coming up from the south (it does not look like it as of today).  But if you are concerned about powdery or Botrytis based on the current status or the history of your vineyard, it is probably better to apply something before the Tuesday’s expected rain.  For the specifics, please refer to the end of this posting.

Case 2: You still have more than 4 weeks to go.
Many of reds probably still have at least 4 weeks to go.  In addition to powdery mildew and Botrytis, downy mildew can become an issue.  As temperature during the night goes down, the relative humidity goes up.  This humid dark condition stimulates downy mildew pathogen to produce spores.  Young leaves are more susceptible to downy mildew infection; thus, you will see the development of late season downy mildew at the top part of the canopy.  If it stays in the upper canopy, I do not see any major threats; however, things can go bad if we have many rain events and even more resistant older leaves become infected.  Although berries are resistant to downy mildew infection at this point, heavy infection on foliage can result in defoliation. 

There are concerns on the effect of certain fungicides, such as copper, captan, and sulfur on fermentation or quality of wine.  Thus, often time wine makers do not want to see the use of these chemicals within a month of harvest.  Thus, if you want to have a last shot of these fungicides, next week or so might be the best timing.

Since there are more weeks to go, what I would recommend is use of good downy and powdery mildew materials in the near future to keep foliage clean, and use Botrytis material as needed (i.e., if a tropical storm is coming up north).

Case 3: You have on-going disease issue(s)
Some of you might have been having a difficulty containing some of diseases, and hoping to get something out from the bad situation.  Due to concerns on fungicide resistance, what we typically recommend is the use of relatively low fungicide resistance risk materials.  Copper, captan, and phosphorous acid (Prophyt etc., but tank mix with other downy mildew material) for downy mildew, sulfur, potassium bicarbonate, and (Kaligreen, Armicarb, etc.), and stylet oil (use with a caution: no oil spray within two weeks of sulfur or captan spray!) for powdery mildew, and copper and captan for Botrytis.   Also, make sure to contact your local extension agents and/or attend one of our IPM meetings so that you will have a better plan for next season.

Select list of materials and their PHIs
Powdery mildew:  DMIs (Rally, Elite, Luna Experience, etc.), Quintec, and Vivando, have 14-day PHI, Torino has 3-day PHI, and sulfur has 0-day PHI

Downy mildew: Revus, Revus Top, and Adament (need to be tank-mixed with captan or copper or Phosphorous acid) have 14-day PHI.  Revus has a very good protective activity against downy mildew; thus, it could come in handy this time of the season.  Unfortunately other good downy material has longer PHIs.  Phosphorous acid (Prophyt, Phostrol, etc.), captan, and copper have 0-day PHI.

Botrytis: SDHIs (Luna Experience and Tranquility, Pristine (note: Pristine and Eudura have higher risk of resistance development), etc.) and Inspire Super have 14-day PHI.  Scala, Meteor (= Rovral), Switch, and Vanguard have 7-day PHI, and Elevate has 0-day PHI.  (Note: canopy and bird management are very important too!)

Ripe rot and bitter rot: QoIs (Abound, Flint, etc., PHI=14 days) and captan have a good efficacy.  Please make sure to rotate between them.

Tuesday, July 28, 2015

Late season disease management considerations

Some of our early cultivars such as Alandale is changing it color.  It is just a matter of time to see other cultivar to enter phase of veraison.  Hopefully, we will keep seeing dry weather with little bit of rain here and there....

There are several diseases to be considered at this stage.  One of them is Botrytis.  The spray timing for Botrytis is at bloom, bunch closure, and veraison.  The pathogen seems to be active throughout the season, but Botrytis likes berries when they get mature and accumulate more sugar.   As usual, canopy management is the first line of defense against grape disease management and this is particularly true for Botrytis since it tends to develop after a long period (15-17 hours) of high humidity condition.

Please keep in your mind that Botrytis is very well known for its capability to overcome fungicides.  Thus, a rotation of mode of action groups is very important aspect for Botrytis management.  The mode of action for a particular fungicide can be found as a FRAC code, which you should be able to locate on the label.  For example, Rovral belongs to FRAC code 2.  Two different fungicides with two different chemical names may have the same FRAC code; therefore, when you are in doubt, please make sure to rotate among the FRAC codes.  Moreover, many new materials have more than one modes of action together.  For instance, both Pristine and Luna Experience (or Tranquility) are mixed products and both contain SDHI (FRAC code = 7).  Thus, if you use Pristine for one spray, application of Luna Experience won't be considered as a rotation of mode of action.

These are some of chemical (and FRAC code) that you can use for Botrytis management: Elevate (17), Scala (9), Vangard (9), Switch (9+12), Inspire Super (9+3), Luna (Tranquility 7+9, Experience 7+3), Meteor/Rovral (2),  Endura (7), and Pristine (7+11).  Since captan has moderate efficacy against Botrytis, it is always a good idea to tank mix a Botrytis material with captan for resistance management.

If you think one of fungicides you are using is not providing sufficient control, please contact Dr. Baudoin or me.

It is also important to avoid risk of wounding 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 fruit skin is damaged.  Thus, management of insect such as grape berry moth, or birds, or powdery mildew at early in the season, can lower the risk of Botrytis development.  Moreover, sour rot pathogens also really like going after wounds; so, wound management would be the key for the sour rot management as well.  

Another diseases to be considered at this time of the year are ripe rot and bitter rot.  Both are considered as a warm season diseases, and 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.  You will see a round dark brown lesions on the top portion of an infected berry (as you see on the picture above); however, the difference between sun burn and ripe rot is that 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.  With a severe infection, you may see many shriveled berries on a cluster.  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, you need to protect berries from infection, 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 three mode of actions because some of isolates causing ripe rot are not sensitive to one of these materials.

Monday, July 13, 2015

You start to see black rot now, so, what should you do?

I have received several emails about black rot recently.  With the frequency of rains we observed so far, it is not surprising to see small amount of black rot even if you had a very good coverage of fungicide. Typically black rot starts off as brown discoloration on the berry, and associated with production of fruiting bodies which are often look like black dots (the size of ground black pepper?).  The picture above is not the best, but you see black dots on the one at the top of the picture.  Eventually, the infected berry will become hard and dry mummified berry with a lots of fruiting bodies, which you can see here and there in the picture.

If you are seeing something like the picture above, chances are the infection happened at least two weeks ago when berries were susceptible to the infection by black rot pathogen (and so as by powdery mildew or downy mildew pathogen).  I can say that because it takes about 2 weeks after infection for black rot pathogen to cause symptoms.  However, at this point of the season, your berries are matured and should be resistant to new infections.  Thus, spores from the infected berries should not cause further infection on healthy berries.  But I should note that if the vine had multiple infection events in the past, you may see increase in black rot.  Often time, infection happened at the end of the critical period for black rot tends to take time to show its symptom.  However, there is nothing we can do about the infected berries.

So, the question is what to do.  Since it should not cause further new infections on berries, I do not see the need for a black rot specific fungicide application.  However, if you insist, or if you have a late maturing varieties that may still be in the edge of the critical period, or more importantly, if you have a concern on ripe rot, you can include either a QoI (Abound, Flint, etc) or DMI (Rally, Elite, etc) to your next fungicide application.  Please note that captan won't be effective against black rot.  Unlike black rot, grape berries seem to be susceptible to ripe rot pathogen throughout the season. 

If you are considering removal of infected berries, you may want not only to remove them from the vine, but also take the infected berries out from your vineyard.  Even if you drop them on the ground, these infected berries will survive over the winter and become a source of spores in coming spring.  This pathogen can produce airborne spores, thus, spores on the ground can be blown off to leaves.  The mummies are small in size, thus, I doubt that a lawn mower will break them down.  Moreover, sending people to pick infected berry will cost you quite a bit. 

Thus, what I would do is just leave them as is.  The healthy berries won't get new infection, thus, I do not see the risk on yield reduction beyond what have been infected at this point.  By the time of harvest, the infected berries should become dry mummified berries that are easy to spot on a sorting table, and even if they are mixed into a must, this disease is not known to affect the quality of wine.

Lastly, if you had observed a fair amount of black rot this year, please make sure to have a good protection program next year, especially if it ended up like a rainy one like this year.

Sunday, June 28, 2015

Handout from Loudoun county meeting

Looks like we have openings in the sky today and tomorrow.  What a wet year!

Here's a copy of handout from the extension meeting held at Loudoun county last week.  It covers weather condition at Winchester, seasonal updates, and fungicide updates.

Friday, June 26, 2015

For this Saturday's and next week's rain events

Since we are expecting heavy rain event on Saturday, plus about to be done with the critical time for cluster infection by downy mildew, powdery mildew, and black rot (which last 4-5 weeks after bloom), I received a several emails about the application timing. 

As with other timings, it really depends on so many factors, but here's my take on it.
     If you have a history of black rot and downy mildew in your vineyard, you may have a higher disease risks.  If you are in this situation, AND if you think that your previous application was waring off, then you may need to apply some protection before the rain.  However, if your previous application was within 7-day or have not seen many rains, or not having much issue with downy or black rot, then you probably do not need to panic.
    A good news is that it looks like we have an opening after the Saturday's rain event.  (then a few more days of rain in the early part of the week)  Thus, unless if you have in the high risk situation, I think you can wait until the rain is over.  Then the question is what to apply, and here's my two cents.

If you have black rot issues:
Mancozeb + Sulfur + DMI (Rally, Elite, etc)  or Mancozeb + Sulfur + QoI (Abound, Pristine, etc)

It depends on how many times you have used either DMI or QoI, please limit the use of them to 2-3 times per season, and less is better due to their risk against fungicide resistance.  Also, this is most likely to be one of the last application timing for mancozeb due to its 66-day PHI.  If you cannot use mancozeb, use captan or fixed copper, or other downy mildew material (Zampro, Ranman, etc please see below), but make sure to tank mix with either DMI or QoI, since captan, copper, and these downy mildew materials does not have much efficacy against black rot pathogen.

If you have downy mildew issues:
Mancozeb + Sulfur + Phosphorous acid (Prophyt, Phostrol, etc) or Mancozeb + Sulfur + Ridomil (Gold MZ or Copper)

Once again, the choice depends on how many times you have used either Ridomil, please limit the use of them to 1-2 times per season, less is better.   Prophyt is less prone to have fungicide resistance issues than Ridomil, but as usual, don't rely on it too much.  It has its own issues such as phytotoxicity.  Also, even if your main target is downy, do not forget to add a material for black rot.  It can sneak up on you!

The other newer downy mildew materials such as Revus, Zampro, Ranman, etc., are excellent materials, but they work as protective manner, thus, you cannot expect a kick-back activity with them, but with the expected rains in next week, it maybe a good idea to add these materials to the tank, in addition to the Phosphorous acid or Ridomil, especially if you do not want (or cannot) use mancozeb (but it will be an expensive spray!)

If you have concerns on both black rot and downy mildew, you can mix and match.  Also, if your vines are about to be bunch closure (some of our cultivars are), do not forget to add a Botrytis material (Rovral, Vanguard, etc).

On the plans above, I am adding sulfur for powdery mildew.  Since we had many rain events, I think many of you have not seen many powdery mildew, but it is a good idea to have sulfur as an insurance.  If you have seen powdery, especially on clusters, you can use a potassium salt product (Kaligreen, Armicarb, etc.) which should stop the spread.

We are almost done with the critical time!  Good luck!

Tuesday, June 23, 2015

Handout from VVA summer technical meeting

Most of us are about to see the end of critical time for berry infection by black rot, powdery mildew, and downy mildew.  Please keep up as much as you can with protection of vines for next few weeks.  I know many of us experienced some degree of flower and berry infection by either black rot or downy mildew due to frequent rain events, but once we pass the critical period (4-5 weeks after bloom for most of cultivars, and maybe 5-6 weeks for some susceptible varieties), these pathogen cannot cause disease on mature berries.

The next critical spray is for Botrytis at bunch closure and veraison.  Make sure to remember about rotation of mode of action groups as well as tank mixing.  Since many of Botrytis specific materials are prone to have fungicide resistance issue, it is better to mix with a broad spectrum material such as captan or copper.  (Mancozeb can be used too, but we are approaching to the 66-day PHI.) 

Another important IPM component for Botrytis management is the control of grape berry moth (or other insects or birds that can damage berries) and proper canopy management.  Although Botrytis is known to cause infection in relatively short amount of time (~4 hrs) in the lab setting, infection in the field often requires a lot longer wetness or high humidity event (15-17 hrs is often discussed as a threshold), thus, proper canopy management can have a very high impact on Botrytis management.

Also, here is a handout from VVA summer technical meeting, which covers results from recent fungicide trials, information on newer fungicides, management tips for major fungal diseases, etc.

We will see you tonight at Zephanirah!

Thursday, May 28, 2015

Bloom time fungicide considerations

The warm May pushed our vines forward rather quickly.  Many people in northern VA are about to see blooms (our 3-year old young Chardonnay vines are trace bloom), and I am sure rest of regions are going through bloom by now.  This means that 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.  (Note: recent warm and humid night time conditions are favoring spore production of downy mildew pathogen)  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 translate into 3-4 sprays for V. vinifera, and 2-3 sprays for V. labrusca.  If you have hybirds, they are somewhere in between, so, 4-5 weeks to be protected.  As usual, please make sure to rotate mode of action groups.

Here are three examples from our experimental vineyards.  (Note:  I will add a Phosphonate product for downy mildew whenever we have many rains)

Plan A (my "standard" program)
  1. At bloom: mancozeb + sulfur + myclobutanil or another DMI + Vangard
  2. First cover: mancozeb + sulfur + Quintec (or other PM material, such as Vivando or Torino)
  3. Second cover: mancozeb + sulfur + myclobutanil or another DMI
  4. Third cover: captan + sulfur + Quintec (or other PM material, such as Vivando or Torino) (Note: if I do not see any evidence of powdery mildew, I may omit Quintec from this spray) 
 Plan B (if your major concern is downy mildew)
  1. At bloom: mancozeb + sulfur + Revus Top + Vangard (or another Botrytis material) (Revus Top contains a DMI)
  2. First cover: mancozeb + sulfur + Quintec (or other PM material, such as Vivando or Torino)
  3. Second cover: mancozeb + sulfur + Revus Top
  4. Third cover: captan + sulfur + Quintec (or other PM material, such as Vivando or Torino) (Note: if I do not see any evidence of powdery mildew, I may omit Quintec from this spray)
 Plan C (if your major concern is Botrytis)
  1. At bloom: mancozeb + sulfur + Luna Experience  (Luna Experience contains a DMI)
  2. First cover: mancozeb + sulfur + Quintec (or other PM material, such as Vivando or Torino)
  3. Second cover: mancozeb + sulfur + myclobutanil or another DMI
  4. Third cover: captan + sulfur + Quintec (or other PM material, such as Vivando or Torino) (Note: if I do not see any evidence of powdery mildew, I may omit Quintec from this spray)
The spray interval depends on the weather conditions; so, I cannot give you a specific number.  However, in general, I would aim for shorter intervals for sprays #1, #2, and #3 (7 to 12 days), but I may relax a bit for #3 and #4 (10 to 14 days), especially if weather conditions do not favor downy or black rot.  Please note that I am saving my DMI and Quintec (or Vivando, or any other new powdery material) usages for the critical period, thus this is the only time we spray these materials.

I would like to use a mancozeb product around bloom because it has activities against multiple pathogens including pathogens for black rot and ripe rot.  Captan is not as effective as mancozeb when it comes to black rot management.  The third cover may become too close to the 66-day PHI, so, you need to be careful with the usage of a mancozeb product.

Of course the examples above are just examples, and there are many other options.  For example, there are many materials available for both downy and powdery mildew management in recent years.  Please refer to our PMG for more details.

Thursday, May 21, 2015

More on fungicide (re)application timing topic

I posted general "rule of thumb" about application (or re-application) earlier this season.  Dr. Annemiek Schilder at Michigan State University recently published a very nice write up about it.

She answers many of questions we have in our mind, when the fungicide residues to be washed off from the rain, efficacy of spreader-stickers, and systemic fungicides.  Please check it out.

Monday, May 18, 2015

Mealybugs are on its move too!

Today is the one of the days when you find many things in the vineyard!  Mealybugs (white one in the middle of the picture) are also observed, mainly at the base of the shoot (or a spur in this case).  You also see a scale insect on this picture.  Please note that both mealybugs and scale insects can transmit several virus pathogens, including the ones cause grapevine leafroll disease.   Unfortunately, once the vine is infected, only remedy is removal of the infected vine.  (However, please note that the presence of leaf roll virus does not always results in immediate loss of crop.) 

If you have both mealybugs and virus infected vines, and have a plan of expansion, it is probably a good idea to protect new vines using insecticides.  However, you have to make sure you have both the virus and mealybugs to justify your action since insecticides for mealybugs are relatively expensive, and as with other chemicals, application of unnecessary insecticide is not recommended.  If it is not properly applied, that extra application of insecticides may results in the outbreak of other insect pests or development of insecticide resistance.

If you are aware of mealybugs, or having a suspicious vines, it is best to submit samples to one of the labs that test vines of viruses. 

* Eurofins STA Laboratories in Gilroy, CA
(http://www.eurofinsus.com/stalabs/products-services-grapevine-testing.html).  The contact person is Judit Monis (phone: 408-846-9964; email:juditmonis@eurofinsus.com)
* AL&L Crop Solutions, in Davis, CA
(http://www.allcropsolutions.com/diseasetesting/).  The contact person is Anna-Liisa Fabritius (phone: 530- 759-9460; email: info@allcropsolutions.com)
* Agri-Analysis, W. Sacramento, CA. (http://www.agri-analysis.com/).  The contact person is Alan Wei 800-506-9852, email info@agri-analysis.com

Updates on the previous post (Downy mildew)

On the previous post, I mentioned that "At this time of the season, what we typically recommend is either mancozeb or captan mixed with sulfur to protect young shoots and leaves.  The reason why I typically do not recommend a use of newer materials such as Revus or Phosphite for downy or Luna or Rally for powdery is because we want to keep it for the critical time for cluster infection, which is from bloom to 4-5 weeks after bloom."

However, it looks like at out site, the downy mildew pathogen is taking advantage of the weather conditions.  Although our last application of mancozeb and sulfur was only 6 days ago, I noticed that some of older leaves show symptoms of downy mildew (i.e., the infection might have happened prior to the previous application).  At this point, many of leaves look like the first picture, and disease incidence is probably less than 0.5%, thus, it is difficult to find them; however, we came across with a few leaves with clear symptoms as in the second picture.

Thus, I will probably add a phosphite material (Prophyt, Phostrol, etc.) to next round of fungicide application in this week to stop further spread of the disease.  Based on the look on the clusters and warm weather in the forecast, we are speculating that bloom for our Chardonnay will happen in 10-14 days from now.

Warm and wet weekend

Winchester area received a series of rain over the weekend, and it looks like we may see more coming in the next few days.  There were three days of low and moderate Phomopsis infection risk events over the weekend.  Also, humid and warm nights can promote development of downy mildew spores. 

At this time of the season, what we typically recommend is either mancozeb or captan mixed with sulfur to protect young shoots and leaves.  The reason why I typically do not recommend a use of newer materials such as Revus or Phosphite for downy or Luna or Rally for powdery is because we want to keep it for the critical time for cluster infection, which is from bloom to 4-5 weeks after bloom.  If this warm temperature continues, the bloom may comes soon, though!!

Thursday, May 7, 2015

Low Phomopsis risk

Two days of intermittent rain brought a low infection risk event for Phomopsis.  Also, these spring rain events can be precursor events for both downy and powdery mildew.  As noted in the previous posts, keep protecting young shoots from these pathogens.  At this point, you can use mancozeb, captan, and sulfur.

(Note: for some reason, this post was not posted in a timely manner.  Sorry!)

Friday, May 1, 2015

On-going disase risk

As usual, we start our season with rains.  It has been more than 13hr of wetness so far at Winchester with an average temperature of low 50s.  It has accounted for a low risk of Phomopsis infection, and a line of rain just passed the area too.  We will see how it will turn out over the weekend.

As shoots extend rapidly in the early part of the season, the new tissues are not protected by the previous application of fungicide(s).  Keep in your mind to protect these new tissues.

I often am asked about when to reapply fungicide(s) after rain.  An often discussed rule of thumb is:
  1. < 1 inches of rain: Continue with intended spray interval
  2. 1-2 inches of rain: Consider shortening your spray interval in half.  (E.g., if there is 7 days remaining for the normal spray interval, shorten it to 3-4 days)
  3. >2 inches of rain: Consider re-application soon.
However, please note that it also depends on the history of your vineyard(s), cultural practice, and also cultivar selection too.  For example, if you have not seen downy mildew in the past 4-5 years, have a nicely kept canopies for air movement, and you have relatively downy mildew resistant hybrids, say, Chambourcin or Norton, you may have less issue with downy mildew even if the fungicide coverage is not perfect.

Tuesday, April 28, 2015

Vineyard Meeting at Early Mountain

We will have a vineyard meeting tomorrow (sorry for a late notice...  I have been bit busy...) at Early Mountain vineyards.

We will start from 11 and finish around 3.  There will be vineyard tour and seasonal updates from us.  You can either bring your own lunch or purchase it from the winery ($11 or so).

Here is my handout for the meeting.

See you tomorrow!

Wednesday, April 22, 2015

Start of the season!

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.

Friday, April 10, 2015

Early spring rains can promote Phomopsis development

Our young 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 infection on shoots and rachis.  It also causes berry infection, which is not common with wine grapes because of our spray programs.  Materials for black rot and downy mildew are often effective against Phomopsis, thus, coverages for these diseases are also working as management of Phomopsis, especially later in the spring/summer.

Phomopsis tends to appear as a vineyard gets older because this disease 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, are more susceptible to Phomopsis than others. 

The fungus survives in canes and trunks that were infected in previous years.  During the spring, it will produce spores that are splashed by rain onto new tissues.  Phomopsis spores can cause infection under relatively cooler environment (upper 40s).  Thus, 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.

Sunday, March 1, 2015

2015 IPM workshop 3/10 @ King Family Vineyards

2015 Integrated Pest Management (IPM) meeting announcement

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 2015 growing season.

We will have only one IPM meeting this year, centrally located at King Family Vineyards in Crozet, VA on March 10, 2015.  http://www.kingfamilyvineyards.com/
The meeting will begin at 9 am and should conclude by 4 pm.  Please bring your own lunch – we plan to have discussions during lunch.

What: 2015 vineyard IPM Workshop
When: March 10 2015, beginning at 9am – we will finish by 16:00
Where: King Family Vineyards; Carriage House
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; please confirm your participation by sending a message to Tremain Hatch Thatch@vt.edu by 6 March. 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

Tuesday, February 10, 2015

My Presentations from 2015 VVA meeting

It was nice to see you all at the VVA meeting.  Here are slides of my presentations.  The links should open up files in my Google Drive (pdf files).

1) Beginner's workshop
2) Interactive Disease Management Planning
3) Winter-time disease management of trunk diseases

We are currently planning an IPM workshop at Nelson county on March 10th.  If you are interested in, please keep the day open.  It will be a whole day event with a series of presentations from our experts on viticulture, insect management, weed management, and of course disease management.  I am hoping to have the interactive session again with more time to actually finish the season.  ;)

Wednesday, January 14, 2015

Information on VVA 2015 (re-post)

Here comes information on this year's VVA meeting!

If you are new to the industry, please consider attending VA vineyards association’s annual meeting.  This year, we have a half-day beginner’s workshop on Thursday the Feb 5th

Introduction to mid-Atlantic wine grape production
When: 5 February 2015
Where: Omni Hotel, Charlottesville VA (part of the VVA’s winter technical meeting) Registration: At VVA website (http://www.virginiavineyardsassociation.com/)
Details: This will be a team-taught program designed for those either exploring grape production or recently engaged in wine grape growing. Program will be followed by a reception with experienced grape growers and winery representatives.

Virginia Vineyards Association’s winter technical meeting When: 6 -7 February 2015
Where: Omni Hotel, Charlottesville VA
Registration: At VVA website (http://www.virginiavineyardsassociation.com/). The meeting is open to all, not just VVA members. The program timing details are provided at the VVA website. The following provides a bit more explanation as to what each topic will cover, day by day.

There will be many good talks in viticulture and enology as usual.  In terms of disease management, there will be several sessions: 1) Virus panel (Friday), 2) Research updates (Saturday), 3) Interactive discussion session (Saturday), and 4) Winter injury/disease. 

Hope to see you soon!

Pruning workshops (re-posting)

It looks like there were some errors with my previous posting, so, here you go again!

2015 Virginia Cooperative Extension pruning workshops

Specialists with Virginia Tech’s AHS Jr. AREC and local Virginia Cooperative Extension agents will conduct two commercial viticulture pruning workshops in January. These workshops will involve classroom style presentations followed by guided practice in the vineyard. Both programs will provide a review of the fundamentals of dormant pruning. Moving to the vineyard we will then focus on pruning strategies for vines with winter injury and crown gall where trunk-renewal and retraining are necessary to compensate for injury sustained in the 2013/2014 winter.

There will be two meetings!

Meeting #1
When: January 19th 2015 (Central Virginia) @11:30am
Where: Democracy Vineyards http://democracyvineyards.com/
585 Mountain Cove Rd.,
Lovingston VA 22949

Meeting #2
When: January 23rd 2015 (Northern Virginia) @ 11:30 am
Where: Desert Rose Ranch and Winery http://desertrosewinery.com/
13726 Hume Road
Hume VA 22639

Details for both pruning workshops:
  • Meet at 11:30 am at the winery
  • Bag lunch indoors at the winery (bring your own lunch)
  • Session ends by 16:00
  • No registration or cost; open to all
  • Bring pruning shears and prepare to be outside rain or shine

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.