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

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Downy mildew gallery

At Winchester, we had light rain events during the night of 6/12/09, but it was short events and the relative humidity was low (80% or so), thus it probably did not promote any infections. However, we are experiencing continuing favorable nights for downy mildew sporulation (average T>55F, high RH (80-100%)) for 10 days now. Yesterday, we conducted a formal disease assessment, and observed first incidence of powdery mildew for this season. We had plenty of infection events in last two months, so it was not surprising. At this point, it is a trace level of infection on untreated vines. Downy mildew was the major disease so far. We had up to 40% incidence on untreated vines. Next runner-up was black rot. It varies vine to vine, but some of vine had 10-15% incidence. Phomopsis was omnipresent as I expected from early May rain falls, but severity was low overall. We will examine diseases again in the near future, and I will update as the season goes. Here is downy mildew ga

Season's Greetings!

I hope you and your family have a good holiday season and a Happy (and safe) New Year! Thanks again for your support of our programs. Here are some recent media highlights. 😉 The link will open a new window. AHS AREC promotional video that highlights some of our activities. The link did not work... It asks you to log in to VT. I will request the IT people to change the setting, but in a meantime, here's the same video. We also appeared in the Library of Congress project “Winery Workers of Virginia”. One more announcement: I will be moving this blog to a new location ( ext.grapepathology.org ) early next year. I had to make a change due to the email subscription service, which has been terminated. You do not need to change your bookmark or your email subscription. The URL will be forwarded to a new site and your email subscription has been moved to a new site already.

Recent downy mildew risk events

It seems that several rain events have happened over the course of the past two weeks or so. Here is a summary of recent downy mildew risk events, based on the NEWA stations and DMCast. Bristol, VA Fifteen days with potential DM infection event(s) since Sept 1. The latest event happened last Sunday. Floyd, VA Eleven days with potential DM infection event(s) since Sept 1. The last event happened last Friday. Charles City, VA Twelve days with potential DM infection event(s) since Sept 1. The latest event happened yesterday. Central VA Since there was a wide variation among stations, I am listing several around Central VA. Tyro, VA Nine days with potential DM infection event(s) since Sept 1. The latest event happened yesterday. Red Hill and Crozet, VA Only one day with potential DM infection event(s) since Sept 1. Olympic Lake Thirteen days with potential DM infection event(s) since Sept 1. The latest event happened last Sunday. Washington, VA Eight days with potential DM infection event

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