green and blue mold of citrus

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1. USAMA MAQSOOD BAGF16M079 University college of agriculture university of sargodha

2. Green mould of citrus

3. History and introduction: Penicillium digitatum  is a species within the Ascomycota division of Fungi. The genus name  Penicillium  comes from the word "penicillus" which means brush, referring to the branching appearance of the asexual reproductive structures found within this genus P. digitatum  was first noted as  Aspergillus digitatus  by Christiaan Hendrik Persoon in 1794 

4. Green mould of citrus: Etiology Class : Eurotiomycetes Order : Eurotiales Family: Trichocomaceae Genus: Penicillium Species: P.digitatum Binomial name: Penicillium digitatum

5. symptoms: P. digitatum causes a destructive fruit rot of citrus. Soft water-soaked area on the peel, followed by the development of a circular colony of white mould, up to 4 cm diam. after 24-36 hours at 24°C. Green asexual spores (conidia) form at the centre of the colony, surrounded by a broad band of white mycelium. The lesion spreads more rapidly than those caused by P. italicum. The fruit rapidly spoils and collapses (Brown and Eckert, 1988; Snowdon, 1990).

6. Epidemiology: Penicillium digitatum  is a  mesophilic  fungus, growing from 6–7 °C to a maximum of 37 °C , with an optimal growth temperature at 24 °C . With respect to  water activity   P. digitatum  has a relatively low tolerance for osmotic stress.  Germination does not occur at a water activity of 0.87.  In terms of chemicals that influence fungal growth, the minimum growth inhibitory concentration of sorbic acid is 0.02–0.025% at a pH of 4.7 and 0.06–0.08% at a pH of 5.5.

7. Thiamine on the other hand, has been observed to accelerate fungal growth with the effect being co-metabolically enhanced in the presence of tyrosine, casein or zinc metal.  In terms of carbon nutrition, maltose, oxalic acid and tartaric acid support little, if any, growth.  However, glucose, fructose, sucrose, galactose citric acid and malic acid all maintain fungal growth

8. Disease Triangle:

9. Life cycle:

10. Host plants of green mould: Citrus x paradisi ( grapefruit ) Malus domestica (apple) Oryza sativa (rice) Pistacia vera (pistachio) Prunus domestica (plum) Solanum lycopersicum (tomato) Sorghum bicolor (sorghum) Vitis (grape) Zea mays (maize)

11. Ecology: Penicillium digitatum  is found in the soil of areas cultivating citrus fruit . In nature, it is often found alongside the fruits it infects, making species within the genus  Citrus  its main ecosystem. It is only within these species that  P. digitatum  can complete its life cycle as a necrotroph .  However,  P. digitatum  has also been isolated from other food sources. These include  hazelnuts,  pistachio nuts, kola nuts, black olives, rice, maize and meats .  Low levels have also been noted in Southeast Asian peanuts, soybeans and sorghum.

12. Blue Mould of Citrus

13. Blue mould of citrus: Etiology Class: Eurotiomycetes Order: Eurotiales Family: Trichocomaceae Genus: Penicillium Species: P. italicum Binomial name: Penicillium italicum

14. History and introduction: Penicillium italicum , the cause of citrus blue mold was described by Wehmer in 1894 Penicillium italicum is a species within the Ascomycota division of Fungi Penicillium italicum is the first phytopathogenic penicillium species whose complete genome has been entirely sequence .

15. Symptoms: P. italicum causes a destructive fruit rot of citrus. 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 (Brown and Eckert, 1988, Brown, 1994).

16. Host plants of blue mould: Allium cepa (onion) Allium sativum (garlic) Citrus Citrus aurantium (sour orange) Citrus bergamia (bergamot) Citrus limon (lemon) Citrus maxima (pummelo) Citrus nobilis (tangor) Citrus sinensis (navel orange) Citrus x paradisi (grapefruit) Cucumis sativus (cucumber) Dioscorea (yam)

17. Management: green and blue mould initially relies on the proper handling of fruit before, during and after harvesting. Spores can be reduced by removing fallen fruit. Risk of injury can be decreased in a variety of ways including, storing fruit in high humidity/ low temperature conditions, and harvesting before irrigation or rainfall in order to minimize fruit susceptibility to peel damage. Degreening practices can also be conducted at humidities above 92% in order to heal injuries

18. Control: Chemical control : in the form of fungicides is also commonly used. such as   imazalil   thaibendazole     biphenyl All of which suppress the reproductive cycle.  Post-harvest chemical treatment usually consists of washes conducted at 40–50 °C (104–122 °F), containing  detergents , weak alkalines and fungicides .  Californian packinghouses typically use a fungicide cocktail containing sodium o-phenylphenate , imazalil and thiabendazole .  

19. In Australia, guazatine is commonly used although this treatment is restricted to the domestic market.  In terms of the export market, Generally recognized as safe (GRAS) substances are currently being explored as alternatives. GRAS substances such as sodium bicarbonate, sodium carbonate and ethanol, have displayed an ability to control  P. digitatum and P. italicum decreasing germination rate

20. Biological control: veral yeasts and bacteria have been demonstrated to have antagonistic abilities against P. digitatum and P. italicum . The yeast antagonists are assumed to operate by inducing phytoalexins (Rodov et al., 1994) or by competition for nutrients (Droby et al., 1989); no antibiotics are known (Cheah et al., 1995). The mechanism of biocontrol for Bacillus spp. is assumed to be antibiotic production (Rodov et al., 1994). Some strains of Pseudomonas cepacea, while being antagonistic towards P. digitatum and P. italicum , also retard wound healing in orange fruits (Huang et al., 1991).

21. 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 natural products have been tested for their effectiveness at controlling P. digitatum. An 'essential oil' from Thymus capitatus had similar effectiveness in vitro to thiabendazole (Arras et al., 1994); gel from Aloa barbadensis slowed and reduced infection of inoculated gSerapefruit (Saks and Barkai-Golan, 1995). Similar results have been obtained with extracts from a variety of herbs

22. Cultural control: Minimizing fruit injury and the efficient removal of infected fruit are the most effective ways to control this disease. Disinfectants can be used to clean equipment in packing and storage facilities (Brown and Eckert, 1988). Ripening or degreening of fruit at 30°C and 95% RH promotes healing of wounds before fungal colonization can occur (Snowdon, 1990).

23. Cont… The disease develops most rapidly at temperatures near 24°C and fruit is thus usually refrigerated during storage (Brown and Eckert, 1988). Postharvest washing at 40-50°C in detergent or weak alkali solutions, usually including some fungicides , reduces decay. Individual wrapping of fruit in wax paper, or packaging in trays, prevents spread from infected to uninfected fruit during transport or storage. Storage at 5°C in a high carbon dioxide atmosphere reduces rot (Amarjit-Singh et al., 1992). Inclusion of a pouch of KOH in polyethylene wrapped fruit reduces rot (Piga et al., 1997).

24. Ultraviolet light and higher temperatures induce formation of the phytoalexin scoparone, which promotes healing of wounded tissues (Pitt and Hocking, 1997. Gamma irradiation of grapefruits with 0.3 kGy reduced decay, but higher levels may cause peel damage (Miller and McDonald, 1996).

25. References :   Pitt, John I.; Hocking, Alisa D. (1985). Fungi and food spoilage (3rd ed). Dordrecht: Springer.  ISBN   9780387922072 .   Onions, A.H.S.  "Penicillium digitatum. C.M.I. Descriptions of Fungi and Bacteria No. 96" . Descriptions of Fungi and Bacteria. CAB International Wallingford UK.   Smith, I.M. (1988). European handbook of plant diseases ([Online-Ausg.] ed.). Oxford [Oxfordshire]: Blackwell Scientific Publications.  ISBN   978-0632012220 .   Wilson, Charles L.; Wisniewski, Michael E.; Biles, Charles L.; McLaughlin, Randy; Chalutz, Edo; Droby, Samir (1991-06-01).  "Biological control of post-harvest diseases of fruits and vegetables: alternatives to synthetic fungicides" . Crop Protection.  10  (3): 172–177.  doi : 10.1016/0261-2194(91)90039-T .   Marcet-Houben, Marina; Ballester, Ana-Rosa; de la Fuente, Beatriz; Harries, Eleonora; Marcos, Jose F.; González-Candelas, Luis; Gabaldón, Toni (2012-01-01).  "Genome sequence of the necrotrophic fungus Penicillium digitatum, the main post-harvest pathogen of citrus" . BMC Genomics.  13 : 646.  doi : 10.1186/1471-2164-13-646 .  ISSN   1471-2164 .  PMC   3532085 .  PMID   23171342 .

26.   Brown, G. Eldon.  "Citrus Diseases-PostHarvest"  (PDF). University of Florida: IFAS Indian River Research and Education Center. University of Florida. Fergus, Charles L. (1952-03-01). "The Nutrition of Penicillium digitatum Sacc". Mycologia.  44  (2): 183–199.  doi : 10.1080/00275514.1952.12024184 .  JSTOR   4547585 .   Issues in General Food Research: 2013 Edition . ScholarlyEditions. 2013-05-01.  ISBN   9781490106892 . Barron, George.  "Penicillium italicum and Penicillium digitatum on Orange" . George Barron's Website on Fungi.