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Plantwise Technical Factsheet

powdery mildew of rose (Podosphaera pannosa)

Host plants / species affected
Catharanthus roseus (Madagascar periwinkle)
Cotinus coggygria (fustet)
Eucalyptus
Forsythia (golden bells)
Prunus amygdalus
Prunus armeniaca (apricot)
Prunus cerasus (sour cherry)
Prunus laurocerasus (cherry laurel)
Prunus persica (peach)
Prunus salicina (Japanese plum)
Rhododendron (Azalea)
Rosa (roses)
Rosa canina (Dog rose)
Rosa damascena (Damask rose)
Rosa foetida
Rosa moschata
List of symptoms/signs
Fruit  -  discoloration
Fruit  -  extensive mould
Leaves  -  abnormal colours
Leaves  -  abnormal forms
Leaves  -  abnormal leaf fall
Leaves  -  fungal growth
Stems  -  mycelium present
Symptoms
P. pannosa is well characterised by forming dense, pannose, persistent, white, greyish to greyish-brown patches on leaves, stems, inflorescences and fruits, causing leaf disfigurations, distortions, discolorations and premature leaf fall. Leaf symptoms on rose and peach are similar. On fruits of peach, this fungus often causes fissures of the hymenium, preventing further normal development.
Prevention and control
Host-Plant Resistance

Resistant varieties have been reported for roses as well as peach (Anon., 1996, 2001).

Biological Control

Ampelomyces quisqualis Ces. (AQ10) and Bacillus subtilis (Serenade) have been used as biological agents to control P. pannosa (Anon., 2001; Flint, 2001; Kiss, 2003; Kiss et al., 2004).

Chemical Control

Benzimidazoles (benomyl, thiophanate-methyl), propiconazole, triadimefon, triforine and sulfur fungicides have been recommended for powdery mildews in general, including rose powdery mildew (Anon., 1996). The following additional fungicides have been used to control powdery mildew: dinitrophenols, quinomethionate, drazoxolon, ditalimfor, 2-Amino-pyrimidines, pyridine and pyrimidine carbonols, morpholines, pyrazophos (Bent, 1978; Lyr, 1987).

Several less toxic fungicides are also available (horticultural oils, neem oil, jojoba oil, potassium bicarbonate, bicarbonate of soda), which are mainly preventive, with the exception of oils that work best as eradicates (Anon., 2001; Flint, 2001).
Related treatment support
Plantwise Factsheets for Farmers
Osinaga, C.; Antezana, O.; CABI, 2011, Spanish language
 
Pest Management Decision Guides
Masinde, B.; Okeno, M.; Otipa, M.; CABI, 2015, English language
 
External factsheets
University of California IPM Pest Management Guidelines, University of California, 2009, English language
West Virginia University Extension Service Factsheets, West Virginia University Extension Service, English language
University of California IPM Pest Management Guidelines, University of California, 2010, English language
University of California IPM Pest Management Guidelines, University of California, 2009, English language
Ontario CropIPM factsheets, Ontario Ministry of Agriculture, Food and Rural Affairs, Canada, 2015, English language
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