Assignment Submitted by: Muhammad Mazhar Iqbal Submitted to: Dr. Mirza Abid Mehmood Coarse code: PP-605 Coarse Tittle: Seed and Post-Harvest Pathology Reg. No: 2019-uam-069 Department: Plant Pathology Assignment Tittle: Post-harvest Disease of Citrus MNS-University of Agriculture Multan Postharvest diseases of Citrus Anthracnose Septoria spot Blue and Green Mould Sour rot Stem end rot Black rot Brown rot Botrytis rot etc Anthracnose Causal organism Colletotrichum gloeosporides Symptomology Brown to black spots of about 1-1.5” start appearing on the surface of fruits. Superficial leathery appearance, silver to grey colored lesions, and tear staining pattern can easily be observed on fruits. Brown to black colored spores gives us the signs of pathogen under humid conditions which can later turn to pink. Disease cycle Management The bio-control agents that can be used for controlling the postharvest fruit diseases include antagonist fungi Trichoderma, bacteria with PGPR activity and yeasts as bio-protectant. And the chemical management includes, spraying the copper based fungicides, hot water treatment or fungicide solution or treatment with lime solution. Benzimidazol fungicides are also used to minimize the fruit losses. Septoria spot Causal organism Septoria depressa Symptomology Small spots are converted into large blotches during storage and transportation of fruits. Other symptoms includes dark collapsed lesions with purple tinges and back specks are also developed on the decayed surface of the fruits. Fruits are more susceptible after frost. Management Copper based fungicides are mostly used to for field applications. It is now present in the few areas of the world so proper quarantine and inspection measures should be followed so that it should be not transferred to the new areas. And also not to import the fruits from prohibited areas. Blue and Green Moulds Causal organism Penicilium digitatum (Green Mould) P. italicum (Blue Mould) Symptomology Late season fruits are more susceptible to pathogens. The fungal growth varies directly with the storage temperature. White fungal growth can easily be seen on the fruits surface which then progressively turns blue and green as spores develops. And the damaged tissues become soft with the passage of time. Management Chemical management Pre-harvest sprays of fungicides are applied to control the pathogen growth within 24 hours. Good hygiene conditions are very necessary. Sanitation practices destroys the fungal spores. Store the fruits at proper temperature. Sour Rot Causal organism Galactomycetes citri-aurantii Symptomology Early stage symptoms are closely related to the blue and green moulds. It causes the very soft watery decay of the fruits. Clear and distinct margin can easily be observed between decayed and healthy tissues. In case of high humidity, yeast can cover fruit lesions. Management Carefully handle the fruits so that there should be any type of rind damage. Application of Guazatine fungicide within 24 hours of harvest can also minimize the risk of infection. Stem end rot Causal organism Lasiodiplodia theobromae Symptomology A dark rot start developing from the stem end of fruit and it start proceeding to the healthy end. This rot produces the dark colored streaking of the water conducting tissues of fruits. Management Fruits are provided with the proper sanitation conditions. They should be stored at low temperature i.e. 10 degree Celsius. Remove all the rotten or diseased fruits so that to minimize the level of pathogen inoculum. Allow fruits to ripen on trees longer and less use of ethylene. Black rot Causal organism Alternaria alternate Symptomology Mostly disease develops after harvest and during storage. Dark brown to black areas can easily be seen on the fruit surface which have huge effect on the quality of fruits. Management Guazatine and imazalil have ability to reduce the viability of pathogen. Proper hygienic conditions are very necessary to minimize the infection ratr. Brown rot Causal organism Phytophthora spp. Symptomology Tan to olive brown lesions on fruit surface. These lesions have the pungent smell. The whole fruit can become soft after the secondary infections. The pathogen can cause the pre and post-harvest disorder under the cool and wet conditions. Management Its management includes the proper hygienic conditions. All the rotten fruits are properly damped into the soil. Proper pre harvest fungicide application. Copper salts can be used as the protective treatment.
