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Plantwise Technical Factsheet

blue mould (Penicillium italicum)

Host plants / species affected
Allium cepa (onion)
Allium sativum (garlic)
Chaenomeles japonica (Japanese quince)
Citrus
Citrus aurantium (sour orange)
Citrus bergamia (bergamot)
Citrus limon (lemon)
Citrus maxima (pummelo)
Citrus nobilis (tangor)
Citrus reticulata (mandarin)
Citrus sinensis (navel orange)
Citrus x paradisi (grapefruit)
Cucumis sativus (cucumber)
Cydonia oblonga (quince)
Dioscorea (yam)
Eucalyptus
Ficus
Fortunella (kumquats)
Juglans (walnuts)
Manilkara zapota (sapodilla)
Petroselinum crispum (parsley)
Phaseolus (beans)
Picea (spruces)
Raphanus sativus (radish)
Solanum lycopersicum (tomato)
Vitis (grape)
List of symptoms/signs
Fruit  -  extensive mould
Symptoms
P. italicum causes a destructive fruit rot of citrus. Early symptoms include a soft water-soaked area on the peel, followed by development of a circular colony of white mould. Bluish asexual spores (conidia) form at the centre of the colony, surrounded by a broad band of white mycelium. The lesions spread more slowly than those caused by P. digitatum. A halo of watersoaked, faded tissue surrounds the lesion. The fruit rapidly spoils and collapses, with sporulation sometimes occurring internally (Brown and Eckert, 1988, Brown, 1994).
Prevention and control
Host-Plant Resistance

Different cultivars of clementine oranges have shown differences in susceptibility to P. digitatum (Farih et al., 1995).

Cultural Control

Minimizing fruit injury and efficient removal of infected fruit are the most effective ways of controlling this disease. Disinfectants can be used to clean equipment in packing and storage facilities. Cull piles should be kept away from the packing area. The disease develops most rapidly at temperatures near 24°C and fruit is thus usually refrigerated during storage. However, P. italicum grows more quickly at temperatures below 10°C than P. digitatum and may predominate in cold storage. The latter is more prone to spreading in packaged fruits than green mould (P. digitatum), forming 'nests' of infection (Brown and Eckert, 1988).

Chemical Control

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:

Biological Control

A biocontrol product based on a formulation of Pseudomonas syringae strain ESC-10 is now commercially available under the trademarked name BIO-SAVE 1000.

Various plant extracts have been tested for their effectiveness at controlling P. italicum (Jiratko, 1994; Dixit et al., 1995) with extracts from Ageratum conzyoides being most effective (Dixit et al., 1995). An 'essential oil' from the herb Thymus capitatus (Arras et al., 1994) and neem oil (Ali et al., 1992) had a similar effect in vitro as thiabendazole.
Impact
P. italicum is prevalent in all citrus-growing regions of the world but less frequent than green mould caused by P. digitatum (Brown and Eckert, 1988).
Related treatment support
 
External factsheets
TNAU Agritech Portal Crop Protection Factsheets, Tamil Nadu Agricultural University, English language
TNAU Agritech Portal Crop Protection Factsheets, Tamil Nadu Agricultural University, Tamil language
Pestnet Factsheets, Pestnet, English language
TNAU Agritech Portal Crop Protection Factsheets, Tamil Nadu Agricultural University, English language
TNAU Agritech Portal Crop Protection Factsheets, Tamil Nadu Agricultural University, Tamil language
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