Diseases of Vegetable, Ornamental and Spice Crops

Exercise 16: POST HARVEST DISEASES

A) BOTRYTIS BLIGHT OR ROT :

Symptoms: This disease is considered most serious as post –harvest disease particularly in roses, geraniums. Floweres and flowering stems are generally attacked after harvest if proper storage facilities are not provided. Cut flowers becoming an increasingly troublesome problem. Cut flowers may be damaged by Bortytis fungus during storage and shipment. Healthy, symptomless flowers become badly decayed during transit and /or subsequent storage.

Mycelium: Grey to greyish brown mycelium (Fig. 1).
Asexual reproduction: Asexual reproduction occur through conidiophores and conidia. Conidiophores and conidia appear as bunch of grapes (Fig. 1).

Causal organism: Botrytis cinerea

Fig. 1: Microscopic details of Botrytis cinerea

B) FUSARIUM AND PYTHIUM ROT:

Symptoms: The fungus multiply very fast on the rhizomes of the medicinal and aromatic plants causes browning, discolouration of tissues leading to development of lesions of small sizes with somewhat depression area under improper storage conditions immediately after harvest. Rotting is accomplished with other pathogens of minor importance such as Penicillium and Aspergillus spp.

Causal organisms: Fusarium solani and Pythium spp.


C) SOFT ROT:

Symptoms: Generally infect the plants after harvest and infection usually resulted due to mechanical injury. The infection originates in the field as latent infection in inflorescence. Black and white to creamish growth covers the harvested plant parts in dual infection which causes browning and rotting of the infected parts.

Cuasal organisms: Aspergillus and Colletotrichum spp


D) GREEN MOULD ROT:

Symptoms: This disease appears in packing houses, transit, storage and market. The pathogen involved is a wound parasite but well spread by contact also. It requires low temperature during storage and is an efficient producer of ethylene. It forms spongy, watery and decolourized spots on infected portions.

Causal organisms: Penicillium spp (Fig. 2).

Fig. 2: Microscopic details of Penicillium