Role of seed treatment in insect pest management

Role of seed treatment in insect pest management

Seed treatment is an application of chemicals to the seeds either at
the time of sowing or before sowing which is an alternative to
traditional foliar or soil treatment.

Efficient function
Application of insecticides to seeds before or at the time of sowing
offers the most effective means of protecting the germinating seed or
seedling.
The chemical insecticide is absorbed by the plant tissue and
transported in the sap through the entire plant through the vascular
system, right up to the top leaf.

Natural enemies
The pest ingests the chemical compounds along with the plant juice
that is lethal for them.
Natural enemy population such as coccinellids, spiders and chrysoperla
remain unharmed.
The efficacy of seed treatment depends upon a mulltitude of
interacting factors such as seed type, chemical formulation,
compatibility of materials, adjuvants and species of insects etc. Seed
treatment with lower doses of imidacloprid, at 5g/kg seed was found
effective in controlling jassids up to 60 days after emergence of crop
and higher seed cotton yield.

Treatment method
Treatment with marshal 25 DS at 80g/kg of seeds has recorded least
population of sucking pests and resulted in higher yield of sunflower.
Acetamiprid 20 SP at dosage of 25g a i/kg of seed protects cotton crop
up to 35 days against pests.
Seed treatment of sorghum with imidacloprid 70 WS at 15g/kg seeds or
thiamethoxam 70 WS at 10g/kg followed by foliar sprays after 30 days
with imidacloprid 17.8 SL at 0.01 per cent or thiamethoxam 25 WG at
0.01 per cent were found highly effective for the management of shoot
fly and stem borer.

Sharanabasappa
D. Satish
& Satyanarayan

Regional Agricultural Research Station, Raichur
& Department of Genetics and Plant breeding
College of Agriculture
UAS Dharwad

Control of late blight disease in tomato

Control of late blight disease in tomato
Late blight, caused by a fungus Phytophthora infestans, is one of the most devastating diseases of potato and tomato worldwide.
It first appears on the leaves and stems, and later on the fruits. Symptoms appear on leaves as pale green, water-soaked spots, often beginning at leaf tips or edges. The circular or irregular leaf lesions are often surrounded by a pale yellowish-gree n border that merges with healthy tissue. White mould growth
Lesions enlarge rapidly and turn dark brown to purplish-black. During periods of high humidity and leaf wetness, a cottony, white mould growth is usually visible on the lower leaf surface at the edges of lesions. In dry weather, infected leaf tissues quickly dry up and the white mould growth disappears.
Infected areas on stems appear brown to black and entire stem may be killed in a short time when moist weather persists.Fruit lesions
The fungus produces grey-green water-soaked spots which enlarge, coalesce, and darken, resulting in large, firm, brown, leathery-appearing lesions on fruits.
Cool nights and warm days with moist weather, which prevail during October-November, are the best conditions for development of the disease. Rain, fog or heavy dew are also ideal.Some management tips
— The disease is soil borne and can be managed by using integrated approaches to crop production and protection.
— Plant only healthy tomato transplants. Check to make sure plants are free of dark lesions on leaves or stems.
— Planting at recommended space (100 x 60cm), raising the crop in raised beds, removing infected fruits and staking of plants to avoid contact of fruits with soil for good air circulation is advisable.
— Spray at regular intervals. Begin chemical control programs before symptoms appear.
Copper hydroxoide(2g/lit) chlorothalonil (2g/liter) and mancozeb (2.5 g/liter) fungicides are the standard protectants used for control. They are usually applied every seven to ten days for best protection.
P.Chowdappa
Girija Ganeshan
& N.Ramachandran
Division of Plant Pathology
Indian Institute of
Horticultural Research
Bangalore

Management of downy mildew in sunflower

Management of downy mildew in sunflower
Sunflower crop is among the top five commercial oilseed crops grown all over India.
Its cultivation is mainly hindered by diseases and pests. Among the diseases downy mildew is a serious obstacle in sunflower cultivation due to its systemic nature of infection.
Typical symptoms occur in seedling stage. Infested seedlings die, but those that survive produce stunted plants with erect, platform heads with no flowers. Drought stress
If any flowers are produced they remain sterile and bear no seeds. The infested plants serve to perpetuate the fungus in the soil and are more prone to drought stress and lodging.
The disease is initiated by soil borne dormant structures called oospores or infected seeds.
Oospores germinate during spring in wet soils. They can survive in the soil for five to 10 years.
Cool, water-saturated soil during this period greatly favours the infection spread.
Plants become increasingly resistant to infection with age, so systemic infections occurs over a short period (two to three weeks) after germination.
Irrigation water running through an infested field also may carry mildew spores into a previously disease-free field. Management
— Plant high quality certified seeds free from downy mildew pathogen.
— Practise a five-year or longer crop rotation between sunflower crops with non-hosts such as corn and small grains.
— Eliminate weeds that can serve as alternate hosts of downy mildew.
— Avoid reuse of irrigation water from sunflower fields and provide adequate but not excessive irrigation, especially early in the season.
— Seed treatment with metalaxyl 6gm/kg seed will reduce the infection during the seedling stage. Spraying of rydomil MZ 3gm/lit or metalaxyl 3gm/lit water helps in controlling foliar infection.
— Using resistant varieties. is a good practice.
Mallikarjun Y, Kenganal, Hemavati, Ranebennur & Byadgi, A. S.
Department of Plant Pathology
University of Agricultural Sciences,
Dharwad, Karnataka

Mealy bug — a new threat to cotton cultivation

Mealy bug — a new threat to cotton cultivation
Cotton crops in Punjab, Rajasthan, Maharashtra, Andhra Pradesh, Gujarat and Tamil Nadu are being seriously infested with mealy bugs during the last 2-3 cropping seasons.
In Tamil Nadu the pest has been observed in Salem, Coimbatore, Perambalur, Erode, and Virudhunagar districts.
Mealy bugs are small, soft bodied sucking insects which suck the sap from the stem, twigs, leaves, flower buds and young bolls. Sooty mould
A sugary liquid secreted by these insects falls on the leaves and serves as a medium for the growth of sooty mould, a fungus that reduces photosynthetic ability of the plant.
Adult female lays 400-600 eggs in a thin bag called ovisac and within 3-9 days young mealy bugs called crawlers emerge from the ovisac.
The crawlers actively spread through various means and settle down in 25-30 days.
The pest causes premature leaf drop, dieback and death of plants if unchecked.
Serious attack of the pest results in bunchy growth, plants remain stunted and produce fewer bolls. Heavy clustering of mealy bugs can be seen on lower surface of leaves giving the appearance of a thick mat with waxy secretion.
The honeydew excreted by the mealy bugs attracts ants which help in spreading of the pest and provide protection from predators and parasites.Management
—Field borders should be free from weeds.
—Crop residues with infestation should be removed and burnt.
—Plough the infested fields to expose the immature stages in the soil to the biotic and abiotic factors.
—Discourage growing alternate host plants such as hibiscus, okra, custard apple, guava in nearby cotton fields.
— Encourage cowpea as border crop on bunds and irrigation channels to enhance the multiplication of predatory insects.
— Ant fences should be treated with chlorpyriphos 20 EC at 2.5 ml/lit through drenching (or) by application of malathion dust 5 per cent at 25 Kg/ha .
B. Dhara Jothi &
N. Gopalakrishnan
Central Institute for Cotton Research
Regional Station
Coimbatore, Tamil Nadu Mealy bug — a new threat to cotton cultivation
Cotton crops in Punjab, Rajasthan, Maharashtra, Andhra Pradesh, Gujarat and Tamil Nadu are being seriously infested with mealy bugs during the last 2-3 cropping seasons.
In Tamil Nadu the pest has been observed in Salem, Coimbatore, Perambalur, Erode, and Virudhunagar districts.
Mealy bugs are small, soft bodied sucking insects which suck the sap from the stem, twigs, leaves, flower buds and young bolls. Sooty mould
A sugary liquid secreted by these insects falls on the leaves and serves as a medium for the growth of sooty mould, a fungus that reduces photosynthetic ability of the plant.
Adult female lays 400-600 eggs in a thin bag called ovisac and within 3-9 days young mealy bugs called crawlers emerge from the ovisac.
The crawlers actively spread through various means and settle down in 25-30 days.
The pest causes premature leaf drop, dieback and death of plants if unchecked.
Serious attack of the pest results in bunchy growth, plants remain stunted and produce fewer bolls. Heavy clustering of mealy bugs can be seen on lower surface of leaves giving the appearance of a thick mat with waxy secretion.
The honeydew excreted by the mealy bugs attracts ants which help in spreading of the pest and provide protection from predators and parasites.Management
—Field borders should be free from weeds.
—Crop residues with infestation should be removed and burnt.
—Plough the infested fields to expose the immature stages in the soil to the biotic and abiotic factors.
—Discourage growing alternate host plants such as hibiscus, okra, custard apple, guava in nearby cotton fields.
— Encourage cowpea as border crop on bunds and irrigation channels to enhance the multiplication of predatory insects.
— Ant fences should be treated with chlorpyriphos 20 EC at 2.5 ml/lit through drenching (or) by application of malathion dust 5 per cent at 25 Kg/ha .
B. Dhara Jothi &
N. Gopalakrishnan
Central Institute for Cotton Research
Regional Station
Coimbatore, Tamil Nadu

Management of mango hoppers in orchards

Management of mango hoppers in orchards
Mango hoppers are the most serious pests of mango.
Hoppers have small sized wedge shaped body. Both nymphs and adults suck the sap from tender leaves, buds, flowers, flower stalk and fruits.
Severely infested leaves become curled and inflorescences get dried. In addition to direct damage, hoppers excrete honeydew on the infested plant parts which encourages the growth of fungal pathogen that form a sooty mould on the infested areas.
Favourable season
They are present throughout the year but are abundant only during the flowering season. The nymphs mature during June to October (feed and breed on the vegetative shoots) and January to March (breed on the flowers and inflorescence).
Egg laying
Adult female lays about 200 eggs singly by penetrating them into the midrib of the young leaves, shoots, flower stalks and unopened flowers.
Eggs are dull white in colour initially which later turn into light brown. The incubation period varies from 4 to 8 days.
After hatching from eggs, the nymphs are pinkish in colour which later turn into pale brown with prominent red bulged eyes along with long black coloured bristles on abdomen.
Nymphal period is 10-14 days. Female can be identified with the sickle shaped ovipositor. Adult longevity varies between three and four days.
Pest management
Avoid dense planting. Adopt resistant varieties and avoid susceptible varieties such as Baneshan, Chinnarasam, Bangalora, Khadar, Gaddemar, Rumani and Himayuddin ( Padiri, Neelam, Mulgoa, Peter and Sindura varieties are highly susceptible).
Orchards must be kept clean by ploughing and removal of weeds.
Remove over crowded, overlapping and infected branches.
Spray Phosalone 35 EC 1.5ml/ litre (or) Carbaryl 50WP 3gm/litre (or) Monocrotophos 36 WSC 1.25 ml/ litre.
Two rounds, first at the time of panicle emergence and the second two weeks later.
Spray 3 per cent neem oil or neem seed kernel powder extract 5 per cent.
M. KANNAN, M. KALYANASUNDARAM & P. SIVASUBRAMANIAN
TAMIL NADU AGRICULTURAL UNIVERSITY, COIMBATORE,

Management of bacterial wilt in tomato

Management of bacterial wilt in tomato
Diseases are a major hurdle in tomato cultivation, both under controlled and field conditions.
Among them bacterial wilt is most devastating on tomato causing yield losses up to 90 per cent.
The disease is also known as southern bacterial blight or solanaceous wilt. Rapid and complete wilting of normal grownup plants is a characteristic symptom of bacterial wilt.
During warm and wet climatic conditions most conspicuous symptom of sudden drooping of leaves, without yellowing, often accompanied by rotting of the stem are seen. The roots appear healthy and well developed. Cultural management
The disease can be kept under check if crop rotations are followed with crops such as maize, ragi and okra, since they can reduce the pathogen population significantly.
Soil solarisation combined with fumigation reduces the pathogen considerably.
Destruction of weeds, collateral hosts and other off season hosts will reduce the innoculum potential. Application of sawdust
Application of sawdust, peatmoss are efficient in reducing the incidence.
Application of nitrite form of fertilizers is also capable of reducing the bacterial population.
Calcium concentration in soil should be increased to have better control of wilt disease.Chemical control
Soil treatment with chloropicrin, methyl bromide or mixture of both were found effective in retarding the wilt development.
Application of bleaching powder (15kg/ha) has also been found effective against this disease.
Seedling dip with streptocycline avoids early invasion and infection by the pathogen through wounds formed during transplanting.
Bacterinol-100 can be used as dry seed dresser, for nursery spray and field application. Streptomycin sulphate or oxytetracycline when sprayed at 200ppm at 7 days interval provides good control.
Tomato varieties such as Arka Abha, Sonali, DPT-38 and Arka Alok which are resistant to bacterial wilt can be used for cultivation.Biological management
Several biological control agents such as Pseudomonas fluorescens, Bacillus licheniformis, B. cereus, B. subtilis and mycorrihiza are very effective in delaying and reducing the wilt development.
Mallikarjun Y
, Kenganal
& Byadgi, A. S.
Department of Plant
Pathology, UAS, Dharwad