Cabbage Integrated Pest Management : An Ecological Guide.

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Major Cabbage Insect Pests¤Points to remember about cutworms:1. Cutworms can be a problem in nurseries.2. No effective biocontrol agents are available to date although the option of cutworm managementwith entopathogenic nematodes needs further study3. Weeding might prevent cutworm infestation.4. Use of baits can be an effective cutworm control measure.5.5 Armyworm - Spodoptera sp.The name ‘armyworm’ is the common name for a stagein the life cycle of certain moths. Most of them belong tothe genus Spodoptera but there are other caterpillars thatmay be classified as armyworms. “Armyworm” is more abehavioral term: when the supply of food for armywormsis running out, they may “march off” over the ground likean army to find new feeding locations. With very largepopulations, the ground may be completely covered with“marching bands” of caterpillars.Spodoptera lituralisThis behavior however, depends on the circumstances. For example, Spodoptera litura/littoralis in smallnumbers feed on the leaves of plants but will sometimes act as a cutworm (in rice) and at other times willswarm in groups and act as a typical armyworm.Armyworms attack many crops including cotton, tomato, rice, tobacco, maize, legumes and many othercrops.The main species of armyworms of importance for vegetables are:· Spodoptera exigua - lesser armyworm, beet armyworm· Spodoptera lituralis - common cutworm· Spodoptera litura (= Prodenia litura) - fall armyworm, cluster caterpillar, rice cutworm, cotton leafwormSpodoptera lituralis andSpodoptera litura haveonly recently beenseparated as differentspecies by the genitaliaof the adult moths. OneSpodoptera lituralisneeds a very good lensto be able to see theSpodoptera lituraSpodoptera exiguadifference. Thecaterpillars of the twoare not really separableas caterpillars of allarmyworms can havedifferent colors fromgreen to black, andchange this colour according to host plant tissue eaten. However, it is important to be able to separatethem into the right species. This is because effective NPV has been developed as biocontrol agent. NPVis very specific to the species and applying the “wrong” NPV will not give effective control.91 Cabbage Ecological Guide - 2000
Major Cabbage Insect PestsDescription and life cycleAdults of armyworms are gray to gray-brown in appearance, with a wingspan of about 25 mm. Theforewings are yellow-brown with white and black patterns. The hindwings are whitish. They do not usuallyfly far and lay their eggs close to the place of emergence. Eggs are laid in large masses on the undersidesof host plant leaves. Each egg mass has a fuzzy appearance because it is covered in fine hairs andscales from the body of the female. About 500 - 2000 eggs per female are deposited in batches of 50 -200 over a few days period. The eggs are ribbed, and range in color from green-gray when freshly laid,becoming very dark in color just before hatching.Egg hatch occurs 2 - 6 days after laying. Caterpillars of armyworms feed in groups together for a whilebut spread out when they become older. They usually feed at night.Newly hatched caterpillars are light green in color and about 1 mm in length with relatively large heads.They undergo five or six moults and reach a length of 35 - 50 mm before burrowing into the soil forpupation. When fully grown, caterpillars vary in color from light tan or green to almost black. Larvae of S.exigua are often green in color with a white line along the side; S. littoralis are often brown to black andcan have more black spots/stripes on the body. They are also usually a bit larger than S. exigua. Larvaeof S. litura and S. littoralis have a distinct black band on the first abdominal segment. The head is black.They feed together in groups. The pupa is dark red in color, 15 - 20 mm long. The pupal stage takes about12 days.Plant damageArmyworms skeletonize host plant leaves. Egg batches are laid closetogether and in a severe year clusters of many caterpillars may rapidlydefoliate of cabbage plants. This is usually a problem from seedlinguntil cupping stage. When the cabbage head is formed, usually notmuch damage is done.Natural enemiesGood results have been achieved with the use of nuclear polyhedrosis viruses (NPV) for the control ofarmyworms. These NPVs have become an important biocontrol agent in IPM systems. There are differentstrains of the NPV:SlNPV for control of Spodoptera lituraSeNPV for control of Spodoptera exiguaNPV is being tested at various locations in Asia, e.g. Vietnam, Philippines and Indonesia. Some countriesare already using it on large scale.Cabbage Ecological Guide - 200092
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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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Major Agronomic PracticesAn example
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Major Agronomic Practicesseed beds,
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Major Agronomic Practicesthis layer
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Page 75 and 76: Major Cabbage Insect Pests5MAJOR CA
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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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