Cabbage Integrated Pest Management : An Ecological Guide.

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Major Cabbage Insect PestsJ Free biopesticides for aphid controlDuring a TOT in Mymensingh, Bangladesh, the newly transplanted eggplant field suffered from aphidinfestation. Participants from the TOT discovered aphids covered with fungus on various locationsaround their eggplant field. They collected as much diseased aphids as they could get, mixed themin water, and stirred firmly. This will release spores from the fungus into the water and this waterbecomes infectious for aphids. Then the solution was slightly filtered through a cloth (to remove largeparts) and sprayed on the eggplants using normal backpack sprayers (pers. comm. Prabhat Kumar,1999).· Localized sprays. There are insecticides that control aphids. However, spray applications ofinsecticides can kill lady beetles and many other natural enemies of the cabbage aphid and otherpest insects! Balance the benefits of spraying against the harm done to the beneficials! Whenapplying insecticides is considered necessary, apply only on those plants that have aphid colonies,not on all plants. This reduces the amount of pesticides needed and, may save at least part of thebeneficials present in the field.¤Points to remember about aphids:1. Aphids have many natural enemies.2. On small scale, aphids can be removed by hand rubbing, washed off with water spray, or destroyedby removing and destroying infested leaves.3. Localized (infested plants only) spray with soap solution (0.5%) controls aphids.4. Biopesticides, where available, may offer good control.5. Insecticides are usually not necessary for aphid control.Related exercises from CABI Bioscience/FAO manual4-D.1 Predation on sucking insects in insect zoo4-D.2 Cage exclusion of natural enemies in the field5.3 Flea beetle - Phyllotreta sp.The main host plants for flea beetles are cruciferous crops but they can also live on cotton and cereals.DescriptionThere are many species of flea beetles that damage cruciferous crops, most of them belong to the genusPhyllotreta. The adult beetles can be separated by color into two major groups: one in which the back isblack with two longitudinal yellow bands (the striped flea beetle) and the other group in which the back isof one color, usually black. All adults have backs with ametallic appearance and are about 1.5 - 3.0 mm long.Flea beetles are characterized by their enlarged hindlegs with which they make long flea-like leaps. As theirname implies, flea beetles have the habit of jumpingwhen disturbed.P. cruciferae P. nemorumLife cycle85 Cabbage Ecological Guide - 2000
Major Cabbage Insect PestsThe adults can overwinter in sheltered sites where leaf litter and plant debris is present. They becomeactive with temperatures rising above 20 o C. When the temperature is always high, like in tropical lowlands,the flea beetles will not have a resting phase but just continue reproducing.Adults disperse, frequently in large numbers, on prevailing winds. They can travel long distances. Whenthey locate a suitable host crop, they settle and start to feed, often on seedling tissues below ground.After mating, the beetles lay their eggs in the soil near host plants. The eggs are pale-yellow in color,about 0.3 mm long and 0.15 mm wide. The larvae of all species are generally white or pale-yellow in colorand have very short legs. The larval head is dark in color. The larvae of most species feed on the plantroots. After living in the soil for about 4-5 weeks, the fully grown larvae are about 5-6 mm long. Theypupate in the soil. The pupa is about 2.5 mm long, white to yellow in color at first but later turns darker.The duration of the pupal stage depends on climatic factors like the temperature, it may take up to 4weeks.Plant damage and plant compensationDamage by flea beetles is most evident on seedlings. Severe damage can be caused by beetles feedingon the seedlings below soil surface, before the seedlings emerge above the soil. With emerging seedlings,the beetles chew holes, particularly in the cotyledons (seed leaves), giving them a characteristic shotholeappearance. Occasionally, seedlings may be completely destroyed. Loss can be greatest in a dryperiod when the seedlings grow very slowly after germination.Flea beetles are especially damaging to Chinese cabbage, which is sometimes used as a trap crop tokeep flea beetles off other crucifers.Apart from the direct damage they cause, flea beetles can also transmit turnip yellow and turnip mosaicvirus. Crops are at risk mainly when the new generations of flea beetle emerge. Although the plants areby then large, damage may be severe if large numbers of beetles enter the crop.Plant compensation study example for flea beetle damageHow much leaf damage can cabbage seedlings sustain? When does crop injury result in yield orquality loss? How much damage can be tolerated before something has to be done to control fleabeetles? Find out in a compensation study!Select a number of seedlings (e.g. 100) in a separate area of the nursery. Cut different percentages ofthe seedleaves (cotyledons) and different percentages of the first true leaves at different times. Forexample: cut 10, 25, 50 and 75% of the cotyledons one week after emerging, another 10, 25, 50 and75% of all leaves per plant at 2 weeks after emerging, etc. Cutting the leaves will simulate the damagedone by flea beetle (and some other leaf-eating insects). Label the different “treatments” carefully toavoid mixing up. Transplant the seedlings in a separate area of the field and include plants that havenot been cut as the control. Compare plant vigor, yield and quality during growing and at harvest time.Natural enemiesThe rainy season is not favorable for flea beetles. When the soil is more or less permanently moist,seedlings establish quick and are soon large enough to tolerate most flea beetle infestations. The sensitivegrowth stage is shortened and damage is reduced. Rain can also have a direct impact on flea beetles,washing them off the leaves, disturbing emergence from eggs in the soil, or destroying the larvae in thesoil by washing them away.Except for general predators like spiders, there are no specific predators or parasites that control fleaCabbage Ecological Guide - 200086
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Why this guide?About this guideThis
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Introduction1.4 Cabbage: a bit of h
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Cabbage Crop DevelopmentPresently t
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Cabbage Crop Development2.2 Suscept
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Major Agronomic Practices3MAJOR AGR
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Major Agronomic Practices3.2.3 Seed
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Major Agronomic PracticesUse protec
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Major Agronomic Practices3.4.2 Soil
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Major Agronomic Practicesthan 7, th
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Major Agronomic Practices3.4.7 Soil
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Major Agronomic PracticesSome of th
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Major Agronomic PracticeslllCreates
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Major Agronomic PracticesWhen a com
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Major Agronomic PracticesIn additio
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Major Agronomic PracticesSome farme
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Major Agronomic PracticesEffects of
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Page 44 and 45: Major Agronomic PracticesTransplant
Page 46 and 47: Major Agronomic Practices3.9 Water
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Page 52 and 53: Ecology of Insect Pests and Natural
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Page 75 and 76: Major Cabbage Insect Pests5MAJOR CA
Page 78 and 79: Major Cabbage Insect PestsDiadegma
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Page 82 and 83: Major Cabbage Insect PestsThe sad s
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Page 106 and 107: Major Cabbage Insect PestsParasitic
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Major Natural Enemies of Cabbage In
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Disease Ecology7.1 Plant diseases a
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Disease Ecology7.3 How diseases spr
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Disease EcologyThe disease triangle
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Disease Ecologygrowth malformations
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Disease Ecology7.8 Control or manag
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Disease Ecologycontaminated seeds :
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Disease EcologyTrichoderma species
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Major Diseases of Cabbage8MAJORDISE
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Major Diseases of CabbageRole of en
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Major Diseases of CabbageOnce there
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Major Diseases of Cabbage· Practic
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Major Diseases of Cabbage¤Points t
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Major Diseases of Cabbagespores wit
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Major Diseases of Cabbage¤Points t
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Major Diseases of Cabbagebut does n
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Major Diseases of Cabbage8.7 Downy
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Major Diseases of Cabbage8.8 Black
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Major Diseases of CabbageNitrogen (
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Weed Management9WEEDMANAGEMENTSUMMA
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Weed ManagementBroadleaf weeds or g
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Weed Managementcompost or it may be
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Weed Management· Check details of
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Weed ManagementTherefore, to date,
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Rodent ManagementRats are a common
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Rodent Management10.4 Rat managemen
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Rodent Management10.4.4 Biological
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Key to Some Common Cabbage Insect P
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Literature and Internet Reference L
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PESTS & DISEASES COMMON TO CABBAGEP
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Plate 3Fig. 13 : Advanced symptoms
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deficiency symptoms ---------------
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chemical --------------------------
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