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Vineyard IPM Scouting Report for week of 19 July 2010
UW-Extension Door County and Peninsular Agricultural Research Station
Sturgeon Bay, WI
Grape Phylloxera FAQ
What is phylloxera?
• There are two forms of phylloxera based on the life
cycle of the pest with one form feeding within root
galls and the other feeding within leaf galls.
• In Wisconsin, the leaf gall form of phylloxera pre-
dominates, this is likely do to the fact that Vitis species
of American heritage are resistant to the root form.
Will phylloxera kill grapevines?
• Heavy infestations that result in a lot of leaf galls will
reduce photosynthesis and therefore reduce sugar production that may play an indi-
rect role in winter hardiness especially in young vines.
What is the threshold for phylloxera?
• No thresholds have been established.
Does applying a insecticide after galls first appear reduce further gall formation?
• Phylloxera has multiple generations per year, nymphs or crawlers will exit the galls
on the older leaves and move to the shoot tips resulting in more galling. Once crawl-
ers are within galls, most insecticides are ineffective.
Will phylloxera reduce yield?
• Only if severe galling results in more than 70% of the leaves infected. Phylloxera im-
pacts fruit production the greatest if severe galling occurs 2 weeks post-bloom.
Are some French American hybrids more susceptible to phylloxera than others?
• Frontenac has been most severely infested by phylloxera in the vineyards I have
scouted the previous 4 years.
When is the best time to manage phylloxera?
• Early season control is critical and insecticides should be applied during bloom.
Where can I get information on insecticides to manage phylloxera?
• See page 5 of the 2010 Midwest Small Fruit and Grape Spray Guide at
http://www.ag.purdue.edu/hla/Hort/Documents/ID-169-2010.pdf
Grape Phylloxera galls ap-peared on wild grapes this week at the Peninsular Research Sta-tion in Sturgeon Bay, WI
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What’s lurking
in or near the vineyard this week?
Downy mildew lesions or “oil spots” on the top of leaf (left) and the white downy spore masses on the bottom of the leaf.
Grape Phylloxera appeared for the first time this season on wild grapes at PARS. Even though the grape crop and de-gree days are much farther progressed this year com-pared to last, phylloxera ap-peared two weeks latter this year on wild grapes than last year.
Phylloxera galls on top of leaf
Phylloxera galls on bottom of leaf
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Brianna at PARS 7.19.2010 Brianna at WMARS 7.12.2010
Foch at PARS 7.19.2010 Foch at WMARS 7.12.2010
La Crescent at PARS 7.19.2010 La Crescent at WMARS 7.19.2010
Development of wine grapes at the Peninsular Agricultural Research Station (PARS) Sturgeon Bay, WI and the West Madison Agricultural Research Station (WMARS), Madison, WI. Buds damaged by frost at PARS on 5/8 and 5/9/2010
1.
1New buds selected at PARS this week for following phenology since buds featured in previous
issue (week of 5.10.2010) of the IPM report were damaged by frost.
7.12.10
7.12.10
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Development of wine grapes at the Peninsular Agricultural Research Station (PARS) Sturgeon Bay, WI and the West Madison Agricultural Research Station (WMARS), Madison, WI. Buds damaged by frost at PARS on 5/8 and 5/9/2010
1.
La Crosse at PARS 7.19.2010
Marquette at PARS 7.19.2010
La Crosse at WMARS 7.12.2010
Marquette at WMARS 7.19.2010
Wild grape at PARS 7.19.2010
1New buds selected at PARS this week for following phenology since buds featured in previous
issue (week of 5.10.2010) of the IPM report were damaged by frost.
7.12.10
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Date 2010 2009 5 Year Average2
7/18/2010 1207 951 1107
Degree Day1 (base 50) Accumulation since April 1, 2010 at Peninsular
Agricultural Research Station in Sturgeon Bay, WI
Date 2010 2009 4 Year Average2
7/18//2010 1538 1198 1332
Degree Day1 (base 50) Accumulation since April 1, 2010 at West Madison
Agricultural Research Station, Madison, WI
1Modified method. 2Average from 2006 to 2009.
Please scout your vineyards on a regularly scheduled basis in an effort to manage problem pests. This report
contains information on scouting reports from specific locations and may not reflect pest problems in your
vineyard. If you would like more information on IPM in grapes, please contact Dean Volenberg at (920)746-
2260 or [email protected]
1Modified method. 2Average from 2005 to 2009.
Year Degree days (base 50)
2010 42
2009 12
2008 0
2007 37
2006 9
2005 8
2004 9
Accumulated degree days1 (base
50) for the month of March at Pen-
insular Agricultural Research Sta-
tion.
1Modified method.
Date Low °F
5/3/2010 44
5/4/2010 48
5/5/2010 41
5/6/2010 37
5/7/2010 32
5/8/2010 291
5/9/2010 291
Low temperatures reported
at Peninsular Agricultural
Research Station, Sturgeon
Bay, WI.
1Frost damage reported to
some grape varieties in grape
variety trial.
