Diseases:
Mango is affected by a number of diseases. These may be M incited by fungi, bacteria, flowering parasitic plants, etc.
These are as follows:
(i) Anthracnose:
Causal organisms are Glomerella cingulata, Colletotrichum gloeosporiodies, Gloeosporium mangiferae. Anthracnose of mango is prevalent in many countries where mango is cultivated. High humidity, frequent rains and a temperature of 24-32°C at the time when the young shoots or flowers or fruits are produced are very favourable for its large scale infection and damage.
(ii) Powdery Mildew:
Causal organism is Odium mangiferae. Powdery mildew is a common disease of mango and is prevalent in many countries. In India, it is common in Uttar Pradesh, Maharashtra, Andhra Pradesh, Mysore and Madras. The disease usually occurs during December to March.
(iii) Sooty Mould:
Causal organism is Caponodium spp. This disease is of common occurrence in India and Israel. Actually, sooty mould in itself is not a disease. The mango trees with the infestation of scales or hoppers leave honey like exudates on leaves, on which the moulds causing blackening develop.
Litchi is almost free from fungal diseases in India. But there are a few rots which cause some damage. The rot caused by Helmenthosporium hawaiense and rotting of fruits after harvesting caused by Aspergillus sp., which can be controlled by spraying any copper fungicides such as 0.1 % Blitox 50.
These fungicides are applied immediately after the appearance of the symptoms. No fungicides should be applied on the trees or fruits at least 20 days before harvesting.
Banana is infected by many diseases.
It is following categorized:
These are as follows:
(i) Leaf Spot or Sigatoka Disease – It is caused by Mycosphaerella musicola. The disease is common and is distributed throughout the banana growing areas of the world.
(ii) Cigar End Rot – Its causal organism is Verticillium theobromae. The disease is transmitted by air-borne spores found in the debris of the banana field.
(iii) Panama Wilt – Panama wilt is caused by Fusarium oxysporum var cubense. It is a soil borne disease and is more serious in poorly drained soil. It is the most destructive disease attacking the plant at any stage of its growth.
These are as follows:
(i) Bacterial Wilt
(ii) Moko Disease
These are as follows:
(i) Bunchy Top – Bunchy top is one of the most destructive viral diseases, transmitted to healthy plants by the aphid Pentalonia nigronervosa. Dwarf bananas are very susceptible to the disease.
(ii) Mosaic or Infectious Chlorosis – This disease is caused by strains of cucumber mosaic virus transmitted by aphids. It is endemic in Western India.
Diseases:
The following diseases of guava are described here:
Guava wilt is a fungal disease and known to occur in Uttar Pradesh, Bihar, Rajasthan and Madhya Pradesh. It is a very serious and common disease of guava and occurs severely in alkaline soil.
The infection can be minimised by drenching the soil with Brasiol and spraying the plant with Bavistin (0.1%) at an interval of 15 days at the early stage of infection.
The disease is caused by Gloeosporium psidii. It is a serious disease of the Western districts and Terai regions of Uttar Pradesh. The conditions of high humidity and frequent rains favour the spread and intensity of the disease attack.
It is a serious bacterial disease of guava fruits caused by pesta/otia psidii.
It is also a serious disease and is common during rainy season. Causal organism is Phomopsis psidii.
Diseases:
There are two fungal diseases which attack on the tree:
(i) Powdery Mildew – This is a fungal disease caused by Odium sp. The disease appears on fruits during October-November in the form of small whitish spots, which later enlarge, coalesce and turn from brown to dark brown and finally cankerous.
(ii) Alternaria Leaf Spot – The disease appears in January-February showing small round and grey spots with red border.
1. Aonla Rust is caused by Ravenellia emblicae and can be prevented by spraying 0.2%, Dithane Z-78 at the interval of 7-20 days during July to September.
2. Blue mould is caused by fungus (Penicillium islandicuum).
3. Fruit rot is caused by fungus (Penicillium oxalicum).
4. Leaf rust is caused by fungus Phakospora phyllanthi. It is commonly seen on leaves in the months of July-August.
1. Die Back or Pink Disease:
This disease is caused by Corticium salmonicolor. The affected branches initially, show white patches on the bark and a film of silky thread mycelium develops on the branches during monsoon. Later, fungus develops pinkish growth. In due course, the bark splits and peels off and the affected shoots starts drying up from the tip.
This disease can be controlled by the pruning of the affected branches below the spot of infection and destroying them, protecting the cut surface by application of Bordeaux paste and spraying of Bordeaux mixture 1% twice in May-June before the onset of South-West monsoon and the second in October.
2. Damping Off of Seedling:
Under conditions of poor drainage in the nursery, the disease occurs. It is caused due to Pusarium sp., Pythium sp, Phytiophthora palmivora and Cylindrocladium scoprium. The fungi attack either on the root or the collar region or both of the seedlings.
It can be controlled by provision of adequate drainage in the nursery and drenching the beds/polybags with 0.1% Cersen, Bordeaus mixture 1% Diathane-M-45 0.25% or Feltef 0.1%. .
Fungal, bacterial and viral diseases of plum are given here:
(i) Bacterial Canker – The disease is caused by bacteria (Xanthomonas pruni) form over-wintering cankers on the twigs.
(ii) Oak Root Fungus – The disease is caused by Armillariella mellea, which infects the roots and lower part of the trunk.
(iii) Brown Rot – It is caused by the fungus Monilinia fructicola which attacks peaches, apricots and cherries besides plums in orchard, transit, storage and market.
(iv) Crown Rot – High soil moisture leads to this disease. Cankers develop on the bark below the ground and infected trees appear pale after leafing.
Bordeaux paste (2 kg copper sulphate and 3 kg quick lime dissolved separately each in 15 L of water and mixed) should be applied on the tree trunks before the onset of the rainy season.
(v) Plum Pox or Sharka – It is transmitted by aphids and by budding and graft material, the disease is characterised by chlorotic leaves and shallow depressions on the fruit.
Among the diseases, the fungal diseases and the viral diseases are prevalent.
Some of the important fungal diseases are given here:
(i) Collar Rot or Stem Rot – This is a serious disease that occurs in the nursery, as well as main field. Its causal organism is Pythium aphanidermatum.
(ii) Root Rot – Its causal organism is Phytophthora palmivora. However, this disease of the young seedlings in the nursery is caused by Rhizoctonia solani and Fusarium sp.
(iii) Anthracnose – This is a fungal disease, necrotic spots are produced on leaves and stems. The disease is favoured by wet weather conditions.
Among the viral disease, papaya mosaic and papaya leaf curl diseases are common.
(i) Papaya Mosaic – This disease is of common occurrence in almost all parts of India. The affected plants become stunted in growth, show yellow mottling and distortion of leaves.
(ii) Papaya Leaf Curl – Its causal organism is tobacco leaf curl virus. The leaves are severely affected and show symptoms of curling, crinkling and distortion of leaves accompanied by vein clearing and reduction in leaf size.
The disease is transmitted through grafting and by white fly (Bemisea tabaci). In advanced stages, defoliation occurs and plant growth is arrested.
(i) Brown Root Disease – This disease is caused by the fungus Sclerotinia fructigena. The disease causes heavy losses of pears and apples in Punjab. Spray the affected fruit trees with lime sulphur (1:60) or bordeaux mixture (4 : 5 : 50).
(ii) Fire Blight of Pear – This disease affects flower panicles, branches and fruits. Affected panicles and fruits become blighted and fall down prematurely. Plants raised from ‘Pathernakh’ rootstock in plains and from Pyrus pashia in hilly regions are resistant against this disease.
Some important diseases are as follows:
This disease is caused by the fungus Plasmopara viticola. It causes extensive damage to grape vines in all grape growing tracts except some parts of North India and mountainous zones.
Leaves, shoots, tendrils, flowers and fruits of the vine are infected. White growth in patches appears on the lower surface of the leaves.
This is a dreaded disease of grapes that develops in an epidemic form during rainy season under high humidity and high temperature conditions. This disease is caused by the fungus Gloecosporium ampelophagum. Almost all commercial cultivars of grape except ‘Bangalore Blue’ are susceptible to this disease.
This disease is caused by the fungus Uncinula necator. It is highly virulent in South India and Kinnaur district of Himachal Pradesh.
This disease is caused by the fungus Uncinula necator. It is highly virulent in South India and Kinnaur district of Himachal Pradesh.