Diseases of fruit plantation medicinal and aromatic crops (2+1)

Mango anthracnose

Anthracnose is also known as blossom blight, leaf spot, fruit rot and twig blight. This disease is severe both in field and storage. The disease is present all mango area of India The verities neelam and bangalora are highly susceptible to this disease.
Symptoms

Leaf spot

• The fungus attacks tender shoots and foliage. Brown or dark circular or irregular spots are formed on the leaves and such leaves are crinkled.
• The affected portion dry up and fall off and leaf ragged margins. Often these leaves are shed leaving the twigs bare.
Die back

• The infection spreads to the green twigs and forms dark brown lesions on them. Young branches dieback.
• On the lesions and dead portions, minute, pink, cushion-shaped fructifications of the pathogen are seen during moist weather.
Blossom blight

• Small dark spots are formed on the main stalk and lateral branches of the panicle. Individual flower stalks are also infected.
• The flowers wither and shed. When severely infected. All the flowers destroyed and no fruits are formed.
Fruit rot

• The tender fruits turn black and fall off. Often dark lesions develop on the fruits and cause partial of complete shriveling, blackening and shedding.
• Matured fruits are also infected. Black, round or irregular, sunken spots are formed on the skin. as the fruit ripens the spots extend over the whole surface accompanied by the softening and rotting of the fruits.
• This type of injury is observed while the fruits are on the trees. it also occurs during transit and in storage. Spoilage of ripen fruits is common.
• Fructification of the pathogen is formed on the spots.


Etiology

• Acervuli developed on diseased parts of the plants.
• They are irregular and appear as brown to black dots. Setae are common on twigs but not on fruits.
• The acervuli when mature exude pink masses of conidia under moist conditions. Marginal setae are rare.
• Conidia are borne on hyaline conidiophores. The conidia are straight, cylindrical or oval, hyaline with two oil drops and are non-septate with round ends.
Mode of spread and survival

• Inoculum remains on dried leaves, defoliated branches, mummified flowers and flower brackets and they serve as primary inoculum.
• Secondary spread is through air born conidia. The fungus can enter the pores of green fruits.
• The latent infection of mature fruits may takes place through lenticels. The fungus apparently infects the fruit while it is green and develops in flesh during ripening.
• The latent infection is carried from the field to storage. Healthy fruits develop infection after in coming in contact with disease ones.
• The latent infection does not begin to spread until it reaches eating maturity.
Epidemiology

• The acervuli are abundant on the dead twigs and 80% of the spores on them are viable. Fresh acervuli continued to appear on dead twigs and persist on the tree.
• The optimum temperature for infection was found to be 25oc and relative humidity 95-97%. The perithecial stage of the fungus is not very common.
• There is no evidence to show that fungus perpetuates through ascospores.
Management

• Diseased twigs, leaves and fruits, which fall on the ground in the orchard, should be collected and all infected twigs should be pruned and burnt.
• Spraying of Bordeaux mixture 0.6% in the young plants during Feb, April and sept controls the disease. Spraying carbendazim 0.1% or thiophanate-methyl0.1% or chlorothalonil 0.2% for 15days interval until harvest effectively controls anthracnose.
• Before storage, fruits should be treated with hot water at 50-550 c for 15min. or thiabendazone 1000ppm for 5min. Spraying of coc +zineb after completion of heavy showers followed by wettable sulphur 0.2% before flowering and carbendazin 0.1% at 15days interval from fruits formation proved effective.