Skip to main content

A quick note on Pierce's Disease management

Since the past winter was more or less steady and mild, in terms of temperature fluctuations, there are less likely that many of us saw the minimum temperature at 15F or lower. For example, at Winchester, we saw 14.5F on the 21st of February, and that's it for this winter. The risk of Pierce's disease will increase with a warmer winter. I.e., less than three nights with a minimum temperature of 15F or lower will decrease the risk of Pierce's disease. 

Thus, especially people in the south and eastern part of the state may need to prepare for the management of sharpshooter leafhoppers, which are the vectors of Pierce's disease. Some growers in the eastern VA use insecticides for sharpshooter leafhoppers from May to June, so, I thought it is probably a good idea to sent out a reminder. 

Entomology is not my area of expertise, thus, I will copy the information from our Pest Management Guide, page 8.

In some vineyards in the eastern part of the state, sharpshooter leafhoppers, the vectors of Pierce’s disease are of concern. While research is needed on the vector relationships and timing in Virginia, the neonicotinoids Admire Pro (1.0 fl oz). Assail 70WSP (1.1-2.3 oz/A), Assail 30SG (2.5-5.3 oz/A), Belay Insecticide (4.0-6.0 fl oz), Scorpion 35SL (2.0-5.0 fl oz), Venom 70SG (1.0-3.0 oz/A), and Venom 20SG (0.44-0.66 lb/A) are registered for control of sharpshooters. Use the higher rates for higher pressure. In addition, Scorpion and Venom are registered for soil application (9.0-10.5 fl oz; 5.0-6.0 oz/A respectively), as is Admire Pro (7.0-14.0 fl oz/A). Soil applications should be applied between bud-break and pea-berry stage and should be considered when there are three or fewer nights below 15˚F during the preceding winter. The neonicotinoids share a common mode of action; avoid overuse to avoid resistance.

Besides neonicotinoids, the following pyrethroids are registered for sharpshooter control: Esteem (5 oz/A), Danitol 2.4EC (10.67-21.33 fl oz/A), Brigade 2EC (6.4 fl oz/A), and Baythroid 2EC (1.6-3.2 fl oz/A). Danitol is limited to two applications, Baythoid to four applications, and Brigade to two applications at the low rate, one at the high. In blocks where Spotted-wing drosophila will need to be controlled, early use of pyrethroids will decrease the number of applications available in late season.

Consult http://www.virginiafruit.ento.vt.edu/PDsharpshooters.html for updated information

Labels:

Comments

Post a Comment

Please leave your comment here. In order to avoid spam messages, l moderate comments, thus it may take a few hours for your comment to be posted on the page.

Popular posts from this blog

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
Post a Comment
Read more

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. 
Post a Comment
Read more

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
Post a Comment
Read more