A handbbok on Weed Control in Rice.pdf

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Dicotyledons The seeds of dicotyledonous weeds have two cotyledons. Mature leaves are broad and usually net-veined. The root systems have tap roots. The dicotyledons have a branched growth form. Not all broadleaf weeds however, are dicotyledonous. Commelina benghalensis, Monochoria vaginalis, and Eichhornia crassipes have broad leaves but are monocotyledonous weeds. Habitat Weeds in rice can be grouped on the basis of their adaptation to submerged conditions as lowland or upland weeds. Lowland weeds may be semiaquatic or aquatic; upland weeds are adapted to dry sites. Information on yield loss from uncontrolled weeds from different experiments around the world is given when available to indicate the weed's potential competitive ability. The losses will differ from one locality to another because they are affected by environmental factors such as nu- trient, moisture, temperature, time of weed emergence, and density. The yield loss information is not meant to show the relative competitiveness among the different weeds, and the yield loss figures should not be used to target particular weeds for control, leaving others to compete with the crop. 8 Weed control handbook For further information on the biology of the weeds listed in this chapter, and on other weeds that may be of interest, readers can refer to the book The world's worst weeds - distribu- tion and biology (1977) by L.G. Holm and colleagues. Other references include Krantz et al (1977), Moody (1981), and Moody et al (1984). Approved computer codes for weeds Computer codes for weeds now available (Bayer Agrochemicals Division 1986) are useful for univer- sal identification in bibliographies and data bases. An approved computer code is a five-letter abbrevia- tion based on the scientific name of each plant. In general, the first three letters refer to the genus and the last two denote the species, the subspe- cies, or the variety. For example, the code for Echinochloa colona is ECHCO; for Echinochloa crus-galli, ECHCG; and for Echinochloa crus-galli P.B. var. kasaharae Ohwi, ECHCK.
Lowland rice weeds ASTERACEAE (Compositae, sunflower family) Weed name: Eclipta prostrata (L.) L. Synonyms: Eclipta alba (L.) Hassk., Eclipta erecta L., Verbesina alba, Verbesina prostrata L. Local names: Country Common name Argentina yerba de tago (Spanish) Bangladesh keshuti (Bengali) France eclipte blanche India bhangra, kesadura, ghuzi Indonesia urang-aring (Javanese) Japan takasaburo Malaysia aring-aring Mexico hierba-prieta (Spanish) Myanmar kyeik-hman Pakistan daryai buti Peru florcita (Spanish) Philippines higis manok (Tagalog) Sri Lanka sindu kirindi (Sinhalese) kaikechi (Tamil) Sudan tamar el ghanam Thailand ka-meng (Thai) USA eclipta Vietnam co muc Life cycle: An annual or perennial broadleaf weed that can grow as tall as 90 cm. Propagates by seeds, which show no dormancy. In the tropics, the seed germinates throughout the year. Habitat: Thrives in continuously wet soils but can grow at dry sites. Also found in poorly drained wet areas. Weedy nature: An adaptable weed with fast vegetative growth. Agricultural concern: Prevalent in lowland and upland ricefields. Rice yield losses of 25% have been recorded in the Philippines. Seedling Mature plant Seed, magnified Flower Weeds worldwide 9
Page 1 and 2: 1991 P.O. Box 933, 1099 Manila, Phi
Page 3 and 4: Foreword Farmers everywhere search
Page 5 and 6: Contents FOREWORD PREFACE 1 S IGNIF
Page 7 and 8: Table 1.3. Weeds as secondary hosts
Page 9 and 10: horizontal leaves. Tall plants have
Page 11: Chapter 2 Rice weeds of worldwide i
Page 15 and 16: Lowland rice weeds / CYPERACEAE (se
Page 17 and 18: Lowland rice weeds / CYPERACEAE (se
Page 19 and 20: Lowland rice weeds / ONAGRACEAE (ev
Page 21 and 22: Mature plant Inflorescence Seed, ma
Page 23 and 24: Lowland rice weeds/POACEAE (grass f
Page 25 and 26: Lowland rice weeds / POACEAE (grass
Page 27 and 28: Lowland rice weeds / PONTEDERIACEAE
Page 29 and 30: Upland rice weeds AIZOACEAE (carpet
Page 31 and 32: Upland rice weeds / ASTERACEAE (sun
Page 33 and 34: Upland rice weeds / CYPERACEAE (sed
Page 35 and 36: Upland rice weeds / POACEAE (grass
Page 41 and 42: Upland rice weeds / PORTULACACEAE (
Page 43 and 44: Deepwater weeds / CONVOLVULACEAE (m
Page 45 and 46: Wetland tillage is common in most t
Page 47 and 48: leaf size), with the resultant shad
Page 49 and 50: Economics of control The economic b
Page 51 and 52: Chapter 4 Principles of herbicide u
Page 53 and 54: Preemergence herbicide application
Page 55 and 56: and behavior in the crop environmen
Page 57 and 58: Table 4.1. Meanings of signal words
Page 59 and 60: 4.3 Controlled-droplet applicators
Page 61 and 62: amount after spraying is 8 liters,
Page 63 and 64:
The decision to spray should be mad
Page 65 and 66:
farmers, however, should wear cloth
Page 67 and 68:
Table 5.1. Susceptibilitles a of im
Page 69 and 70:
Propanil can be used at 3-4 kg ai/h
Page 71 and 72:
Thiocarbamates Thiocarbamates are a
Page 73 and 74:
Quinclorac. Quinclorac is a chino-
Page 75 and 76:
Planting method Transplanting into
Page 77 and 78:
Direct seeded on puddled soil In di
Page 79 and 80:
Table 6.2. Herbicides suitable for
Page 81 and 82:
6.4 Rice growth stages when herbici
Page 83 and 84:
Fertilizer Incorporating N and P fe
Page 85 and 86:
Nurseries Seedling nurseries should
Page 87 and 88:
Land preparation Leveling the puddl
Page 89 and 90:
Land preparation Land preparation s
Page 91 and 92:
Chapter 8 Weed control in upland ri
Page 93 and 94:
Hand weeding The weed-free period r
Page 95 and 96:
Chapter 9 Weed control in deepwater
Page 97 and 98:
Hand weeding Hand weeding is the mo
Page 99 and 100:
Chapter 10 Management of some diffi
Page 101 and 102:
Wild rices The important wild rices
Page 103 and 104:
Herbicides For effective control of
Page 105 and 106:
IRRI-International Rice Research In
Page 107 and 108:
B. Conversion table for granular fo
Page 109 and 110:
Index A Absorption of herbicide, 50
Page 111 and 112:
in deepwater and floating rice, 96
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