Virginia Grape Disease Updates

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 c...

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.)

It finally stopped raining, but we (Winchester area) are having an on-going wet event since 10/9/13.  I counted >108 hours of wetness with an average temperature of 54F (ranging from 48F to 60F).  It has been a long enough for Botrytis, and although the temperature was bit low, downy mildew probably had some chances as well. Here is a list of things to be considered: 1) Time to harvest (if you are picking in a few days, I do not see the benefit of spraying now) 2) Current Botrytis situation in your vineyards 3) Variety (red with loose cluster ~ lower Botrytis risk) 4) Canopy management (Open fruiting zone is always helpful!) 5) Birds/insect damages (more damages, higher the Botrytis risk) 6) Fungicide effect on wine quality As I mentioned earlier this week, we had Botrytis risk event on last Monday; however, it had been dry for several weeks until that rain.  Thus, the Monday's risk might not have resulted in many infections.  On the other hand, Botryti...

Rain on this Monday resulted in 10 hours of wetness with an average temperature of 62F.  It was warm and long enough for both downy mildew and Botrytis.  Once again, downy mildew risk is for leaves only.  Risk of Botrytis depends on your variety, cluster architecture, and canopy management too.  Most of varieties still hanging are red (with some exceptions, of course), which has lower risk of Botrytis.  Also, if you have an open canopy, the risk are lower too.

Since 9/2 or so, we are observing dew events that were wet enough to make our leaf wetness sensor wet almost every night.  Since our sensors were located about the same height as the lower part of the canopy, leaves were probably wet as well.  Each events were about 6-9 hours.  Most of time, temperature was low (in 50F), but sometimes were in lower 60F.  What this condition promote can be downy mildew.  They tend to sporulate under dark condition, and since their spores can swim, these dews probably are enough for them to infect new tissues.  Due to low Brix, many people are tying to hang their berries longer this year.  Please make sure to have some protection on your foliage so that it can help maturation of berries (+ store carbohydrate for the winter!).  If you are concerned about potential effect of spray materials on wine quality, you can aim your sprayer nozzles to upper part of the canopy so that fungicides won't hit the berries.