Techniques to check the spread of pest by seeds, corms, cuttings and cut flowers

By : JAYANT YADAV, CCSHAU, HISAR, HARYANA

INTRODUCTION• Most plants reproduce sexually from seeds, but some can be reproduced (or multiplied) by vegetative parts such as stems, roots, and leaves.

• some plants produce modified stems and/orroots, referred to here as specialized structures that accumulate food reserves and therefore have built-in regeneration potential and are valuable as vegetative propagules. Plants with specialized structures are well-suited for asexual propagation.eg. corms, cuttings, rhizomes, tubers, bulbs.

• Examples of vegetative propagated crops.• Corms-Banana, Gladiolus, Crocus spp.

(saffron),Taro(Colocasia spp.).• Rhizomes-banana, ginger, turmeric.• Cuttings-rose, hibiscus, lavender, geranium,

chrysanthemum, aster, stevia.• Bulbs- daffodil, dahlia, onion, garlic.• Stolon-sweet potato.• Tubers-potato.• Runners-Strawberry.

Importance • Knowledge about modes by which pathogens are

dispersed are helpful to devise suitable and effective disease management practices.

• Knowledge about modes by which pathogens are dispersed helps to reduce further spread of disease inoculum.

• Prior knowledge of disease spread can help the farmer to devise situational management practices i.e. prophylactic and curative practices.

Continued…….• Better knowledge of disease spread by vegetative

propagules can help to prevent entry of disease into the country i.e. better quarantine regulations.

• As over 40% of bacterial pathogens are transmitted over by veg. propagating materials, control in initial stages can help ensure better growth of the crop. Eg. X.compestris (c.canker)(c stocks),cuttings-A.tumefaciens(crown gall),potato tubers.

• Viruses and other related agents are invariably transmitted by vegetative propagules hence, viral diseases are particularly serious in horticultural crops.

Diseases spread through corms, cuttings and cut flowers

Disease causing agents

Insects/Mites Bacteria Fungi Virus Nematodes

cropsBanana Banana weevil Rhizome soft

rotPanama wilt, leaf spot, sigatoka

Banana bunchy top, Banana bract mosaic

-

Cassava - Erwinia soft rot Shot hole leaf disease

- -

Gladiolus Bulb mites scab Botrytis blight, curvularia leaf spot, fusarium yellows

Bean yellow mosaic,cucumber mosaic,tomato ring spot

Bulb nematode(Meloidogyne spp.)

Saffron Bulb mites - Root rot - -

turmeric Rhizome scale - - - -

cuttingsDisease causing agents

Insects/Mites

Bacteria Fungi Virus Nematodes

crops

Rose - Crown gall Stem canker, Botrytis blight

Mosaic virus -

chrysanthemum

- - Leaf spot, wilt - Foliar nematode

Seed borne pests and diseases Seed transmitted insect pests• Pulse beetle(Callosobruchus chiiensis)• Pink boll worm(diapause in third instar).• Coffee seed borer

Seed transmitted diseases of nematodes• Ear cockle of wheat• Potato cyst nematode.• Rice white tip nematode.

Seed transmitted diseases Internally seed borne diseases• Loose smut of wheat and barley• Ascochyta blight of chickpea• Phomopsis blight of brinjal

Externally seed borne Covered smut of barley, oats. Grain smut of sorghum Bunts of cereals

Management practices for control of pests and diseases of seeds, corms, cuttings and

cut flowers

Cultural control• Proper field sanitation.• Healthy plant material ,seeds free from pest and disease inoculum

should be selected.• Deep ploughing in summer with the help of a disc plough helps to

expose the planting material exposes hibernating stages to sunlight.

Physical control• Hot water or hot air treatment at 50 -55 degrees celsius of plant

propagating materials like corms, rhizomes, bulbs etc. help to control pest like bulb fly, rhizome weevil , nematodes etc.

• Steam sterilization of soil is done to kill soil insects and nematodes.

• Exposure of cotton seeds to sun heat in thin layers for 2-3 days during April helps to kill diapausing larvae of pink boll worm.

• Storage of seeds to low temperature of <4 degrees helps to prevent damage.

Mechanical control• Manual removal of infested plant parts such as pink boll worm attacked

rosetted flowers, adults of rhizome weevil, help to reduce pest infestation.

• pruning and destruction of infested corms, flowers, cuttings etc to check the multiplication of scales, mealy bug, etc.•Pheromone traps can be used to control the pests eg. Cosmolure for rhizome weevil , gossyplure for pink boll worm.

Chemical control• Application of Carbofuran 3G or Phorate 10 G @ 10-15 kg/ha, for

soil incorporation at the time of sowing.• Treatment of Chlorpyriphos 20 EC @0.1% in soil before planting

affords control.• Seed treatment with Imidacloprid 17.8 SL(Gaucho),70 WS @5-10

g/kg to control pests.• Application of 500 ml of Dimethoate 30EC in 500lt of water/ha to

control pests of flower bud, cut flowers.

Continued• Application of dicofol(kelthane) at 0.04%,propargite(O

mite)@1ml in 4litre of water for control of mite pests.• Application of EDB(Ethyl dibromide) @60 ltr/ha, DBCP(di

bromo chloro propane) @20-50 ltr/ha for control of nematodes.

• Seed treatment with systamic fungicide vitavax in protection with thiram, kerathane@0.04%,sulfex @0.35% for controlling fungal pathogens.

Continued• Soaking seeds in Agrimycin(0.025%) for 8hrs,spray of copper

fungicides alternatively with copper fungicides gives effective control to bacterial diseases.

Sources……

• Crop diseases and their management-Dr. H.S. Chaube and Dr. V.S. Pundhir.

• Agricultural pests of south asia and their management-A.S. Atwal and G.S. Dhaliwal.

• Introductory plant nematology- Dr. H. K. Bajaj and Dr. R. K. Walia.

• Internet

Thank you