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INTEGRATED MANAGEMENT OF INSECT-PESTS OF RICE
H S Randhawa, S S Aulakh and P S Sarao*
PAU, Regional Research Station, Gurdaspur
* Rice Section, Department of Plant Breeding and Genetics, PAU, Ludhiana
Rice is the major Kharif crop, in Punjab, state. The climate of Punjab is too much suitable for production of rice and it is more economical crop as compared to other Kharif crops. Therefore, farmers of Punjab preferred to grow rice crop in Kharif season. In Punjab rice is cultivated over an area of 29.75 lac hectares with an average yield of 23.84 quintal/acre during the year 2015-16 that was not enough. There are several reasons such as improper selection of seed, varieties, less plant population, excessive use of fertilizers & irrigation water, growth of weeds, attack of insect-pests and diseases are involved for lower productivity. But insect-pests play major role for lower productivity of rice crop. There is need to follow management for proper control of insect-pests. For integrated management we should need to use those control measures which are safer for our environment and society.
The detailed information is given below to apply different control measures for management of major insect-pests of rice
1. Stem borers
These bores (yellow, pink and white stem borers) are most serious pest of rice in Punjab which covers two generations in crop season (July -October). The adult females lay eggs on lower side of the plant leaves. The eggs are hatched within few days and newly emerged larvae, firstly attack on the leaves. The full grown larva bore into the stem and start feeding the internal portion from upper to lower side. The affected young plants show dead hearts (yellowing and drying of central shoots) whereas, the old one produce empty earheads which turn white and stand erect (Fig.-1).
Fig. 1- Adult and larva of stem borer Dead hearts and white ears
Strictly follow recommended sowing (second fortnight of May) and transplanting (second fortnight of June) time of paddy crop. With continuous early to late transplanting of paddy, the crop period was also increased that help to covers more generations of stem borers. The insect population increased too much that is very harmful for late transplanted paddy crop.
Collect egg masses covered with brown cotton like material from the leaves and destroy them regularly. This process starts from July to onward to reduce this insect population. Do not allow to stand the stubbles in the field after harvesting.
Use Biological agents
Natural enemies like Trichogramma chilonus and Trichogramma japonicum are those biological agents which destroy the eggs of harmful insects. These biological agents can be released in the field @ one lac per hectare. Tie the different trichocards of both the biological agents (50:50) those have capacity to release the nearly 1000 biological agents, on lower side of leaves at 100 places in per hectare (40 trichocards/ac of each biological agents). This process starts in field 30 days after transplanting of paddy nursery at weekly intervals till mid September and this ways it needs to repeat the process for 7-8 times. But it was recommended only in the organic cultivation of rice due to higher cost of trichocards.
The field showing more than 5% dead hearts (Economic threshold level) should be sprayed with 170 gm Mortor 70 SG (cartap hydrochloride) or 350 ml Sutathion 40EC (trizophos) or 560ml Monocil 36SL (Monocrtophos) or one litre Coroban/Dursban/Lethal/Durmet/Classic/Chlorgaurd/ Force 20 EC (Chlorpryiphos) in 100 litres of water/acre.
2. Leaf folder
This caterpillar rolls the leaves, feeds on green matter and white streaks are formed that reduces the photosynthetic activities of plants. The overall losses due to these insect-pests damage have been estimated at 25 per cent. This insect causes maximum damage from August to October. Higher application of nitrogenous fertilizers can increase the incidence of this pest (Fig: 2)
Fig. 2: Adult larva Damage due leaf folder
After the incidence of leaf folder, pass the 20-30 meter long coconut made rope on the upper surface of the crop to dislodge the leaf feeding larvae. The rope should be passed from one side to the other side of the field and come back to same direction of the field. The sufficient water should be standing in crop field.
Apply recommended dose of fertilizers. If possible apply need based nitrogenous fertilizers by using leaf color chart (LCC) or soil testing base at right time.
Follow recommendations as against stem borer.
Spray the crop when leaf damage reaches at 10% (Economic Threshold Level) with insecticides as recommended against stem borer.
3. Plant hoppers
These hoppers include white backed plant hopper, brown plant hopper and green leaf hopper. Both nymphs and adults suck plant sap particularly from leaf sheath from July to October. The infested crop dries up in patches. It is also called hopper burn. As the plant dry up the hopper migrate to the adjoining plants and kill them. In few days, the area of dry patches enlarge.
Fig 3: Planthoppers and their hopperburn
Choose resistant varieties for transplanting.
Apply recommended dose of fertilizers.
Installation of light traps near paddy field is very helpful to reduce the insect population.
About month after transplanting, the few plants in the field should be slightly tilted and tapped for 2-3 times at the base at weekly interval. If minimum five plant hoppers are seen floating on water, only then crop should be treated with insecticides. The plant hoppers can be controlled with application of 40 ml Confidor 200SL/Crocodile 17.8 SL (Imidacloprid) or 800 ml Ekalux/Quingaurd 25EC (quinalphos) or one litre Coroban/Dursban 20 EC (chlorpyriphos) in 100 litres of water per acre. For better effectiveness, direct the spray towards the base of plants. If damage noticed at hopper burn stage, treat the affected spots along with their 3-4 meters periphery immediately as these spots harbour high population of insects.
4. Grass hoppers
The adults and nymphs of these hoppers eat leaves of plants especially nursery. The photosynthetic activities are reduced which results lower crop yield.
Fig 4 Grass Hopper
The female insects deposit their eggs in the soil on water channels and ridges. Therefore, it is recommended to expose the eggs to sun by ploughing the water channels and ridges during the month of May and June. Keep the water channels and boundary ridges of fields free from weeds.
Insecticides recommended against plant hoppers are also effective against grasshoppers.
5. Rice hispa beetle
Earlier this pest was confined to Gurdaspur and Amritsar districts only, but presently the incidence of this pest increased to other areas of Punjab. The grubs feed the green matter of the leaves by making tunnels and produces bold, white streaks on leaves. Whereas the adult beetles are external feeders (Fig.-4).
Fig. 5- Hispa beetle and its incidence on rice
If incidence of this insect starts in the nursery, clip-off and destroy the leaf tips of seedlings before transplanting.
If incidence appeared on transplanted crop then spray 120 ml Methyl Parathion 50 EC (methyl parathion) or 560 ml Monocil 36 SL (Monocrotophos) or one litre Dursban/Coroban 20 EC (chlorpyriphos) or 800 ml Ekalux/quingaurd 25 EC (quinalphos) in 100 liters of water per acre with manually operated knapsack sprayer. Repeat the spray if the attack persists.
6. Rice-ear- cutting- caterpillar/Army Worm
The larvae of this insect are gregarious in habit and are commonly known as ‘army worm’. The young larvae feed on leaves, leaving only mid-ribs and stems. The old larvae cut-off the panicles mostly at the base, hence name as “rice ear-cutting caterpillar”. This stage of insect causes serious loss to crop. The larvae are shy of sunlight and generally feed at night. The insect damage to crop caused during September to November.
Fig. 6: Larvae of ear cutting caterpillar
The larvae of this insect hide in the cracks and crevices in the soil during the day time and later on these also pupates in the soil. After harvesting of crop, the fields should be ploughed deeply and exposed larvae are to be killed by sunlight or can be eaten by birds.
Spray the crop with 400 ml Ekalux/Quingaurd 25 EC (quinalphos) in 100 liters of water per acre with manually operated knapsack sprayer. As the insect is nocturnal in behavior, spray should be given in the late evening hours for getting better results.
7. Rice root weevil
It is a localized pest in the rice area around Rajpura (Patiala). However this pest also been observed in some other areas in the state. Its white legless grub feeds on roots in the soil from July to September. The infested plants turn yellow, stunted and produce only a few tillers.
Rice Root Weevil
The grubs of this insect remains in the soil, therefore it recommended to plough field deeply after harvesting of crop.
Apply 3 kg Foratox/Thimet 10G (phorate) per acre in the standing water.
Precautions: Use gloves while applying granular insecticides.