PEST AND DISEASES

The fruit flies, Dacus ferrugineus and D. zonatus, attack the mango in India; D. tryoni (now Strumeta tryoni) in Queensland, and D. dorsalis in the Philippines; Pardalaspis cosyra in Kenya; and the fruit fly is the greatest enemy of the mango in Central America. Because of the presence of the Caribbean fruit fly, Anastrepha suspensa, in Florida, all Florida mangos for interstate shipment or for export must be fumigated or immersed in hot water at 115° F (46.11° C) for 65 minutes.
In India, South Africa and Hawaii, mango seed weevils, Sternochetus (Cryptorhynchus) mangiferae and S. gravis, are major pests, undetectable until the larvae tunnel their way out. The leading predators of the tree in India are jassid hoppers (Idiocerus spp.) variously attacking trunk and branches or foliage and flowers, and causing shedding of young fruits. The honeydew they excrete on leaves and flowers gives rise to sooty mold.
The mango-leaf webber, or "tent caterpillar", Orthaga euadrusalis, has become a major problem in North India, especially in old, crowded orchards where there is excessive shade. Around Lucknow, 'Dashehari' is heavily infested by this pest; 'Samarbehist' ('Chausa') less. In South Africa, 11 species of scales have been recorded on the fruits. Coccus mangiferae and C. acuminatus are the most common scale insects giving rise to the sooty mold that grows on the honeydew excreted by the pests. In some areas, there are occasional outbreaks of the scales, Pulvinaria psidii, P. polygonata, Aulacaspis cinnamoni, A. tubercularis, Aspidiotus destructor and Leucaspis indica. In Florida, pyriform scale, Protopulvinaria Pyrformis, and Florida wax scale, Ceroplastes floridensis, are common, and the lesser snow scale, Pinnaspis strachani, infests the trunks of small trees and lower branches of large trees. Heavy attacks may result in cracking of the bark and oozing of sap.
The citrus thrips, Scirtothrips aurantii, blemishes the fruit in some mango-growing areas. The red-banded thrips, Selenothrips rubrocinctus, at times heavily infests mango foliage in Florida, killing young leaves and causing shedding of mature leaves. Mealybugs, Phenacoccus citri and P. mangiferae, and Drosicha stebbingi and D. mangiferae may infest young leaves, shoots and fruits. The mango stem borer, Batocera rufomaculata invades the trunk. Leaves and shoots are preyed on by the caterpillars of Parasa lepida, Chlumetia transversa and Orthaga exvinacea. Mites feed on mango leaves, flowers and young fruits. In Florida, the most common is the avocado red mite, Paratetranychus yothersii.
Mistletoe (Loranthus and Viscum spp.) parasitizes and kills mango branches in India and tropical America. Dr. B. Reddy, Regional Plant Production and Protection Officer, FAO, Bangkok, compiled an extensive roster of insects, mites, nematodes, other pests, fungi, bacteria and phanerogamic parasites in Southeast Asia and the Pacific Region (1975).
One of the most serious diseases of the mango is powdery mildew (Oidium mangiferae), which is common in most growing areas of India, occurs mostly in March and April in Florida. The fungus affects the flowers and causes young fruits to dehydrate and fall, and 20% of the crop may be lost. It is controllable by regular spraying. In humid climates, anthracnose caused by Colletotrichum gloeosporioides (Glomerella cingulata) affects flowers, leaves, twigs, fruits, both young and mature. The latter show black spots externally and the corresponding flesh area is affected. Control measures must be taken in advance of flowering and regularly during dry spells. In Florida, mango growers apply up to 20 sprayings up to the cut-off point before harvesting. The black spots are similar to those produced by AIternaria sp. often associated with anthracnose in cold storage in India. Inside the fruits attacked by AIternaria there are corresponding areas of hard, corky, spongy lesions. Inasmuch as the fungus enters the stem-end of the fruit, it is combatted by applying Fungicopper paste in linseed oil to the cut stem and also by sterilizing the storage compartment with Formalin 1:20. A pre-harvest dry stem-end rot was first noticed on 'Tommy Atkins' in Mexico in 1973, and it has spread to all Mexican plantings of this cultivar causing losses of 10-80% especially in wet weather. Fusarium, Alternaria and Cladosporium spp. were prominent among associated fungi.
Malformation of inflorescence and vegetative buds is attributed to the combined action of Fusarium moniliforme and any of the mites, Aceria mangifera, Eriophyes sp., Tyrophagus castellanii, or Typhlodromus asiaticus. This grave problem occurs in Pakistan, India, South Africa and Egypt, El Salvador, Nicaragua, Mexico, Brazil and Venezuela, but not as yet in the Philippines. It is on the increase in India. Removing and burning the inflorescence has been the only remedy, but it has been found that malformation can be reduced by a single spray of NAA (200 mg in 50 ml alcohol with water added to make 1 liter) in October, and deblooming in early January.
There are 14 types of mango galls in India, 12 occurring on the leaves. The most serious is the axillary bud gall caused by Apsylla cistellata of the family Psyllidae.
In Florida, leaf spot is caused by Pestalotia mangiferae, Phyllosticta mortoni, and Septoria sp.; algal leaf spot, or green scurf by Cephaleuros virescens. In 1983, a new disease, crusty leaf spot, caused by the fungus, Zimmermaniella trispora, was reported as common on neglected mango trees in Malaya. Twig dieback and dieback are from infection by Phomopsis sp., Physalospora abdita, and P. rhodina. Wilt is caused by Verticillium alboatrum; brown felt by Septobasidium pilosum and S. pseudopedicellatum; wood rot, by Polyporus sanguineus; and scab by Elsinoe mangiferae (Sphaceloma mangiferae). Cercospora mangiferae attacks the fruits in the Congo.
A number of organisms in India cause white sap, heart rot, gray blight, leaf blight, white pocket rot, white spongy rot, sap rot, black bark and red rust. In South Africa, Asbergillus attacks young shoots and fruit rot is caused by A. niger. Gloeosporium mangiferae causes black spotting of fruits. Erwinia mangiferae and Pseudomonas mangiferaeindicae are sources of bacterial black spot in South Africa and Queensland. Bacterium carotovorus is a source of soft rot. Stem-end rot is a major problem in India and Puerto Rico from infection by Physalospora rhodina (Diplodia natalensis). Soft brown rot develops during prolonged cold storage in South Africa.
Leaf tip burn may be a sign of excess chlorides. Manganese deficiency is indicated by paleness and limpness of foliage followed by yellowing, with distinct green veins and midrib, fine brown spots and browning of leaf tips. Inadequate zinc is evident in less noticeable paleness of foliage, distortion of new shoots, small leaves, necrosis, and stunting of the tree and its roots. In boron deficiency, there is reduced size and distortion of new leaves and browning of the midrib. Copper deficiency is seen in paleness of foliage and severe tip-bum with gray-brown patches on old leaves; abnormally large leaves; also die-back of terminal shoots; sometimes gummosis of twigs and branches. Magnesium is needed when young trees are stunted and pale, new leaves have yellow-white areas between the main veins and prominent yellow specks on both sides of the midrib. There may also be browning of the leaf tips and margins. Lack of iron produces chlorosis in young trees.