Pests of Soybean and their Management by agrifunda


Hi friends. Welcome to agrifunda today post on ‘Pests of Soybean and their Management’. Soybean is one of the major pulse crop sown in India. The crop is attacked by a number of insect as well as non-insect pests. So far more than 300 pest species have been recorded on this crop. Of which few of them causing serious damage or economic damage. It includes stem fly, leaf miner, leaf defoliators like tobacco caterpillar and semi loopers. Let us understand these pests in details. Particularly on host range, identification character, biology, nature of damage, damaging symptoms and management practices.



Pests of Soybean and their Management by agrifunda


Pests of Soybean and their Management

1.Stem fly.


We will start with stem fly. Scientific name is Melanagromyza sojae. It belongs to family Agromyzidae of the order Diptera. It occurs in the early stage of the crop. That is when the crop is 15 to 20 days old. Thereby it affects the establishment of the crop. Besides soybean it also attacks other pulses, where it acts as a minor pest.Coming to adult identification. Adult is very small, shining black colored fly. Adult female lays eggs on uni-trifoliate leaves. Maggot is pale yellow in color. Pupation occurs inside the stem at lateral burrows.

Nature of damage:


coming to nature of damage. Maggot is the damaging stage. It enters into the stem through the petiole and feeds within by making tunnel downwards, causing partial drying and drooping of leaves. Followed by complete drying and drooping of plants. If you split open the affected stem, you can see the distinct tunnel with lot of fross material and amateurs particularly pupa and maggots.

Management:

Coming to management as a preventive measures. Go for early sowing to escape from the incidence of this pest. As a curative measures, collection and destruction of affected plants, thereby you can reduce the further multiplication of the pest. Then spray azadirachtin @ 2ml per liter of water. As a last option you can spray newer insecticide molecules like thiamethoxam @ 0.3g per liter of water, or you can use imidacloprid @ 0.3ml per liter of water.

2.Leaf miner:

Then coming to another major pest on soybean is leaf miner. That is Aproaerema modicella. It belongs to the family Gelichiidae of the order Lepidoptera. It occurs in the early stage of the crop. Besides soybean it also attacks groundnut, redgram etc. Adult is very small. Dark brown to greyish brown colored moth with white spots on the front wings. So here adult female lays eggs on leaves. On hatching, neonate larva mines into the epidermis of the leaf tissues and feed within. So here first two instars remains in the mines. They act as a leaf miner. The third instar larva comes out from the mine and webs 2 to 3 leaves together, and feed within by scraping the chlorophyll content of the leaves. As a result of which mine is formed in the leaves. Further webbing can be seen on the plant. Under severe infestation, whole plant looks burnt up appearance. Ultimately yield will get reduced.



Management.


As a preventive measure go for early and synchronized sowing. Then go for crop rotation with non-leguminous crops. As a curative measure, spray NSKE @ 5%, or use commercial neem products containing azadirachtin @ 2ml per liter of water. As a last option you can spray either Spinosad or Flubendiamide or Lambda-cyhalothrin at the recommended dose.

3.tobacco leaf eating caterpillar:

Then another major pest on soybean is tobacco leaf eating caterpillar. That is Spodoptera litura. It belongs to the family Noctuidae of the order Lepidoptera. It is a polyphagous pest. Adult is medium sized moth. Forewings are dark brown to greyish brown in color with white patterns. Hindwings are dull white in color. So here adult female lays eggs on leaves in groups. Eggs are covered with brownish hairs. Early instars usually dark green in color with black spot on either side of the first abdominal segment. Grown up larva having crescent shaped marking with yellow or orange longitudinal lines on the body. Pupation occurs in the soil.

Nature of damage:

Then coming to the nature of damage. Larva is the damaging stage. Neonate larva or early instar larva feed gregariously by scraping the green tissues from lower surface of the leaves. As the larva grow, they spread to the entire field and feed voraciously. Sometimes larva feeds on pods. As a result of which skeletal leaves can be seen on the plant. Even symmetric holes can be seen on the plant or particularly on the leaves. Under severe infestation, defoliation of the plant occurs. On plants you see the regular holes. Ultimately the yield gets reduced.

Management -

As a monitoring, a set of sex pheromone traps @ 2 to 3 traps per acre. As a preventive measure, go for deep summer ploughing, to expose pupa to hot sunlight or to the insectivorous birds. As a curative measure, collect the egg masses as well as the early instars; since they are in group and destroy them. Thereby you can reduce the further multiplication of the pest. Then spray anyone of the bio-pesticides. Either Metarrihizium rileyi or Beauveria bassiana. Or B.t products. As a last option you can spray synthetic insecticides like emamectin benzoate @ 0.4 g per liter of water. Or you can use chlorantraniliprole @ 0.2ml per liter of water.

4.Semi loopers:

Then other major pest on soybean is semi loopers. So here 2 species of semi loopers are commonly occurring. One is Thysanoplusia orichalcea, another one is Trichoplusia ni. Both belongs to family Noctuidae of the order Lepidoptera. They are both polyphagous. So here Thysanoplusia orichalcea is the main species. It can easily be identified with the presence of triangular golden patch on the front wing. So here adult female lays eggs singly on the leaves. On hatching, larva feeds on leaves voraciously leading the defoliation of the plant.

Management.


Spray anyone of the bio-pesticides. Either Metarhizium rileyi or Beauveria bassiana or B.t. products. As a last option you can spray anyone of the insecticide, either emamectin benzoate or Chlorantraniliprole at recommended dose.
Thank You.

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