PA Map: 2007 Late Blight Spray Dates Based on BLITECAST, Sep 24
=============================================================================
* = QUALITY DATA SITES
*** ** = experimental data sites
********
***** *******************************************************************************************
* erie-1 * erie-2 * * POTTER * * LACKAWANNA **
May = ** none * none * * none * * none ** = May
Jun = ** 13 * 13,29 * * 13 * * 17,29 ** = Jun
Jul = ** 4,9 * 7,12 * * 27R * * 5,10,20,25,30 ** = Jul
Aug = ** 12,21,26 * 12,21,26 * * 12,22,27 * * 4,14,21,26,31 ** = Aug
Sep = ** * 10,15 * * 10,15 * * 13,20 ** = Sep
*******************************************************************************************************
** * LYCOMING * * luzerne * **
May = ** * none * * none * ** = May
Jun = ** * 6,30 * * 13R,23R * ** = Jun
Jul = ** * 5,18,24,29 * * 3R,13R * ** = Jul
Aug = ** * 4,14,20,25,30 * * 17R,22,27 * ** = Aug
Sep = ** * 4,14,20,25 * * * ** = Sep
*******************************************************************************************************
** butler * * CENTRE * northumberland * schuylkill * LEHIGH **
May = ** none * * none * none * none * none ** = May
Jun = ** 29 * * 9,14,28 * 6,29 * 10,29 * 8,13,18,23,28 ** = Jun
Jul = ** 27R * * 3,10,18,25,30 * 9,30 * 6 * 3,8,23,28 ** = Jul
Aug = ** 7,12,20,25 * * 4,14,19,24,29 * 8R,21,26 * 4R,21,26 * 2,12,17,22,27 ** = Aug
Sep = ** 11 * * 10,15 * * 15 * 1,6,11,16,23 ** = Sep
*******************************************************************************************************
** * CAMBRIA * huntingdon * * dauphin * berks * **
May = ** * none * none * * none * none * ** = May
Jun = ** * 9,18,28 * 13R,23R * * 29 * 10,20,30 * ** = Jun
Jul = ** * 3,8,16,21,26 * 3R,13R * * 6,21,26 * 7,21,26 * ** = Jul
Aug = ** * 5,10,15,20,25,30 * 3,10,20,25,30 * * none * none * ** = Aug
Sep = ** * 4 * 12 * * * * ** = Sep
*******************************************************************************************************
** WASHINGTON * * franklin * lancaster2 * lancaster1 * **
May = ** none * * none * none * none * ** = May
Jun = ** 14,20,25,30 * * 22 * 11,29 * 29 * ** = Jun
Jul = ** 7,12,19,26,31 * * 3,21,26 * 9,21,26 * 21,26 * ** = Jul
Aug = ** 11,16,21,26,31 * * none * none * none * ** = Aug
Sep = ** 12 * * 15 * 16 * * ** = Sep
*******************************************************************************************************
NOTE: Theoretical spray dates listed for COUNTIES in "upper case" CAPITAL letters are
based on quality environmental data measured at a local site.
Theoretical spray dates listed for Counties in "lower case" letters are based on
experimental data for a local site.
* Notes:
(1) e = Dates followed by "e" = early = before an initial threshold (CS18 or BFD10)
was reached.
R = Rain+Temperature based threshold (10BFD) = 10 Consecutive Blight
Favorable Days. If inoculum is present, symptoms are expected in
about 7-14 days.
H = Humidity+Temperature based threshold (CS18) = 18 Cumulative Severity
Values for the season. If inoculum is present, symptoms are expected
in about 7-14 days.
(2) These spray dates are based on environmental data monitored or calculated for a
specific site. Since environment varies, sometimes within relatively short distances,
the forecast information reported here should be considered in combination with
local environmental information. One way to evaluate how well forecast information
is likely to apply, is to record daily rainfall at the local site, and then compare
this with rainfall reported on the 1-800-PENN-IPM phone message line. If rainfall at
a farm is similar to rainfall reported for a nearby weather-forecaster site, then the
forecast could be quite accurate for use on the farm. When farm rainfall is higher
than at the nearby weather-forecaster site, disease conditions could be more severe
than reported, and more sprays could be necessary. Likewise, if farm rainfall is
lower, farm disease conditions could be less severe, and fewer sprays could be possible.
(3) 10BFD = 10 consecutive Blight Favorable Days. If inoculum is present, late blight
can be expected to appear 7-14 days later.
(4) The late blight forecaster (BLITECAST) is relatively conservative; when the forecast
is determined based on quality environmental data, the forecaster will usually suggest
more sprays than needed in some situations. This is because the forecaster assumes that
disease inoculum is always present. Growers who keep up-to-date on appearance of late
blight in surrounding counties and states, may be able to delay some sprays, but this
can be risky because late blight can wipe out a planting within a couple of weeks, and
sprays are not very effective after late blight is present.
(5) Some growers make a supplemental application whenever a forecaster does not
call for a spray for a period of 14-days. This could be appropriate throughout
the season wherever there is a history of late blight.
(6) Once any late blight is present nearby, fungicides should be considered weekly.
County and town site locations for environmental information used to
determine the forecast information:
Erie Co.; Site#1 = Fairview, near Lake Erie.
Erie Co.; Site#2 = Corry, inland from Lake Erie.
Potter Co.; Site#1 = Sweden Valley, north east of Coudersport.
Butler Co.; Butler, on the east side of town.
*Washington Co.; Finleyville, south of Pittsburgh.
*Cambria Co.; Loretto, east of Ebensburg.
*Centre Co.; Rock Spring, southwest of State College.
Huntingdon Co.; Maddensville, in southern Huntingdon Co. near Fulton Co.
Dauphin Co.; Gratz.
*Lycoming Co.; Jersey Shore, near the Susquehanna River.
Franklin Co.; north of Waynesboro.
Northumberland Co.; Montandon, near the Susquehanna River.
Luzerne Co.; next to the Susquehanna River at Forty Fort.
*Lackawanna Co.; Clarks Summit, north of Scranton.
Schuylkill Co.; near Ringtown.
*Lehigh Co.; Germansville, north west of Allentown.
Berks Co.; Kutztown, west of Allentown.
Lancaster Co.; Site#1 = Leola, northeast of Lancaster.
Lancaster Co.; Site#2 = Mount Joy, northwest of Lancaster.
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* Quality environmental data are measored at the sites marked with an
asterisk (*). Environmental data and resulting forecasts for the other
sites are experimental.
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developed by Dr. Alan A. MacNab, Professor, Plant Pathology
Penn State College of Agricultural Sciences
211 Buckhout Lab, University Park, PA 16802
Updated: Sep 24, 2007; EMH
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Where trade names are used, no discrimination is intended
and no endorsement by the Cooperative Extension Service is implied.
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