OTHERS

Integrated pest management for mango

MANGO MANGIFERA indica is the most important fruit crop of India. The yield is affected by various biotic and abiotic factors.

Leaf cutting weevil Deporaue marginatus, stem borer Chlumetia transverse are the major pests attacking mango nursery. These pests are more serious during the first six months of the newly prepared nursery. The freshly prepared grafts could be protected effectively by spraying 0.05 per cent endosulfan against leaf cutting weevil, 0.01 per cent fenvalerate, 0.02 per cent monocrotophos or 0.02 per cent quinalphos for the control of stem borer. Removal of shoot borer affected grafts/ seedlings followed by spraying either 0.04 per cent monocrotophos, 0.05 dimethoate or 0.1 per cent carbaryl 50 WP is recommended for the effective control of shoot borer.

The nymphs and adults of mango hopper suck the cell sap from inflorescence and flower buds. The infected flowers shrival, turn brown and ultimately fall off, thereby, affecting the yield adversely. During severe attack, the pest may destroy the entire crop. The peak population occurs when fruits are of pea size. At post bloom stage, a population of two adult insects per inflorescence is enough to cause yield reduction.

The nymphs and adults of mealy bugs suck the cell sap from tender shoots, fruits, as well as roots. As a result, the shoots dry up and fruits remain undersised. In case of severe infestation on roots, the trees up to 5 years may die. Control measures include digging or ploughing repeatedly around the trees during summer to kill the pest by exposing them to sun's heat, ants and birds.

Adult of stem borer do not cause any damage except feeding on tender shoots and buds or making irregular scratches on stem by bitting and chewing. Grubs cause maximum damage particularly in neglected orchards by tunneling inside the main trunk and branches. The branches show signs of wilting and masses of refuse/excreta exude from the bored holes. When the root of trunk is damaged the entire tree may die. It can be controlled by injecting borer solution containing two parts of carbon disulfide and one part of chloroform: cresote mixture (1:1) with an injecting syringe.

Grubs of stone weevil enter into the stone of the mango fruit and feed on the internal contents. As a result, the fruit pulp adjacent to the stone get discoloured. It is a major problem in export of mangoes. Thotapuri variety is the most susceptile one and is damaged severely every year. The parthenocarpic hybrid variety Sindhu (Ratna x Alphonso) is totally resistant to the pest. Disposal of fallen fruits would help to reduce the pest infestation.

The maggots of fruit fly feed on the pulp of the fruits. Brownish rotten patches develop on the fruits as a result and such fruits fall down. The late maturing varieties are affected severely by fruit fly. Sanitation in the orchard is the most important preventive measure for fruit fly infection. Collection and destruction of fallen fruits would help to reduce pest infestatin. Bagging of fruits with cloth or paper bag may be resorted to. But this is very expensive in large orchards.

Use of chemical traps containing citronella oil (10 drops in 0.5 litre water) is found to be useful to reduce the pest incidence. Three sprays of 0.1 per cent fenthion or malathion at monthly intervals starting from one and a half months after fruit set helps in reducing the pest. Chemical traps containing methyl eugenol has been successfully used.

Termites remain underground and feed on the roots and then move upwards making the trunks completely hollow or construct earthen galleries on tree trunks and feed on the bark.

The damage is more severe in nursery and newly planted orchards where the entire saplings may die. Control measures include destruction of termitoria along with the queen. Fumigation with EDCT mixture, cynogas dust or petrol, soil application of 5 per cent aldrin/ chlordane/ heptachlor dust (200 to 300 g per tree) will effectively control the termites. Painting the trees with tar and prompt removal of the galleries as soon as they appear may be carried out regularly.

N. Manikandan

Agricultural College & Research Institute

Madurai 625 104