this month in diseases
geraniums
By A.R. Chase and Margery Daughtrey
Disease Pathogen Stage of crop Best cultural controls Best product controls,
based mainly on
Chase Research trials
Botrytis blight Botrytis cinerea Any time Manage irrigation; avoid Daconil Ultrex (before
In this issue,
and stem rot from rooting wounding; don’t grow fl owering starts),
to fi nishing plants under hanging Chipco 26019,
we present
(leaves, baskets that drop petals Decree, Pageant
a summary
stems and of diseases
fl owers)
that occur in
Oedema None, spider mite Finishing Choose oedema-resistant Use appropriate
geraniums.
feeding can cause cultivars; control spider miticides if oedema is
Remember:
this symptom mites; manage water due to mites’ feeding
Product
carefully during the winter
controls are
based on
Pseudomonas Pseudomonas Plugs to Use pathogen-free seeds Copper products (e.g.,
research
leaf spot cichorii fi nishing and plugs; avoid letting Camelot and Phyton
trials and do
leaves sit wet 27), Cease
not refl ect an

endorsement
of any sort.
— A.R. Chase is
Pythium Pythium irregulare Plug Use well-draining Subdue MAXX
president and
pathologist of Chase
damping-off production, potting media; manage (resistance is
Horticultural Research,
mainly irrigation; use new possible), Terrazole
Inc. and can be
media and pots; choose (or Truban), FenStop reached at archase@
pathogen-free plants (at lower labeled chaseresearch.net.
rates), Segway
Margery L. Daughtrey
is senior extension
Rhizoctonia Rhizoctonia solani All stages of Use new rooting media 3336 sprench, Chipco
associate at Cornell
University’s Long
cutting rot production and fl ats 26019 (not always
Island Horticultural
effective), strobilurins
Research & Extension
(e.g., Compass O, Center and can be
Heritage, Insignia)
reached at mld9@
cornell.edu.
Rust Puccinia Finishing Use pathogen-free Strobilurins
pelargonii-zonalis cuttings; space plants (especially Heritage),
to improve drying DMIs (e.g.,
Hoist=Eagle)
Southern wilt Ralstonia Finishing Avoid recirculating For race 1, phos-
solanacearum water systems acids (e.g., Aliette)
Xanthomonas Xanthomonas Later in Use pathogen-free Copper products (e.g.,
campestris pv. production, seeds and plugs; avoid Camelot and Phyton
pelargonii mainly overhead irrigation 27), Cease
www.gpnmag.com February 2010 GPN 15
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