A handbbok on Weed Control in Rice.pdf

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Surfactants are often added to herbicide formulations by the manufacturer, but additional surfactants may be needed for some postemer- gence herbicides or in some environmental conditions (e.g., bentazon under low temperatures). The herbicide label indicates how much surfactant to use when an additional surfactant is required. When surfactants are not recommended, their use with foliage-applied herbicides can result in loss of selectivity. Herbicide labels The best source of information con- cerning safe and effective herbicide use is the product label (Fig. 4.1) printed on or attached to the herbicide container. It gives directions on effective, safe use of the herbicide. The label should be read carefully and under- stood before any herbicide is used. The herbicide label is a legal document that in many countries has government approval. Every herbicide product label should contain the following information: Trade or brand name. The trade or brand name identifies a herbicide of one company and differentiates it from those of other companies. Like common weed names, trade names of herbicides may change from country to country. Thus, the trade name is not always adequate for identifying a herbicide or determining correct rates of application. When an application rate is recommended with a trade name, the rate normally refers to the amount of formulated product, and not the rate of active ingredient or the acid equivalent. Chemical and common names. Herbi- cides have complex chemical names. Rules for selecting suitable chemical names are given by appropriate chemical associations (e.g., the Interna- 54 Weed control handbook tional Union of Pure and Applied Chemistry [IUPAC]). The chemical name refers to the active ingredient. In addition to the chemical name, each herbicide is given a common name which also applies to the active ingredient. The common name is not the same as the trade name of the same herbicide. Common names for herbicides are approved by appropriate pro- fessional bodies, such as the Interna- tional Standardization Organization 4.1 All herbicide labels are required to provide important information. Users should read and understand the label before opening any herbicide container.
Table 4.1. Meanings of signal words found on herbicide formulation labels, to state danger to humans. Lethal oral dose Approximate lethal (LD 50 ) for rats Signal word Acute toxicity oral dose for an (mg/kg body adult human weight) (See p. 62 for discussion on Danger/Poison Warning Caution No signal word Highly toxic Moderately toxic Low to relatively nontoxic Relatively nontoxic (ISO). A herbicide may be produced or formulated by more than one company and thus be sold under several brand names, but the common name or chemical name should always be the same on all products. For example: Trade or brand names: Machete, Butanex, Lambast Chemical name: N-(buthoxymethyl)-2- chloro-N-(2,6diethylphenyl) acetamide Common name: butachlor Active ingredient. Each label specifi- cally names the active ingredient present in the herbicide. The amount of active ingredient may be given in percentage by weight or in grams per liter, and may be listed by its common name or by its chemical name. The inert ingredients need not be named, but the label should specify their percentage of content. Formulation. Some labels spell out the formulation, others use abbrevia- tions, such as EC or E for emulsifiable concentrates; WP or W for wettable powder; FW, F, or L for flowables; G for granules; and S for solubles. Content. Each label gives the total amount of herbicide in the container (eg, in liters [L] or kilograms [kg]). A taste to one teaspoonful (5 ml) One teaspoonful to 2 tablespoonfuls (30 ml) 30-450 ml LD 50 ) 5-50 50-500 500-5,000 Signal words and symbols. Herbicide labels state how poisonous the product is, using specific signal words and symbols. Examples are shown in Table 4.1. Labels of all highly toxic products have, in addition to the word poison, the skull and cross-bones symbol. Pictograms-graphically definitive symbols-are also recommended for inclusion on agrochemical labels (Info Letter 1988). Examples of pictograms are drawings of a pair of pants in boots and a pair of hands in gloves, to convey the need to wear footwear and gloves for safe handling of chemicals. These labels also include the statement Keep out of reach of children. Directions for use. Directions for use provide instructions on how to use the herbicide. This includes information on weeds that the herbicide controls, crops on which application of the herbicide is safe, application rates, application time, and application method. All directions for use must be followed. Name of manufacturer. The name and address of the manufacturer or distributor of the product often is required by law to be on the label. Hazards to humans and domestic animals. The hazards portion of a label indicates how the herbicide may be harmful to man and domestic animals. It gives information on how to avoid poisoning or contamination, such as the type of protective clothing required. Environmental hazards. To help reduce undesirable effects on the environment, the label also provides environmental precautions. It may include warnings that it is harmful to birds, fish, and wildlife, and advice on how to avoid contaminating water bodies. Harvesting statement. A harvesting statement is printed on labels when there is a chance that the treated crop may be fed to animals or handled by humans. Because residues of a herbicide require a minimum number of days to degrade, a harvesting statement specifies the number of days between the last herbicide application and the time when the crop can be safely cut, threshed, or eaten. Herbicide applicators A herbicide applicator is any device used to apply herbicides on plant and soil surfaces. Applicators distribute an exact quantity of a herbicide uniformly over a given area. They can be classi- fied as nonpressurized or pressurized. Nonpressurized applicators include the water can, granular applicator, controlled-droplet applicator, and direct-contact applicators such as rope wicks and wipers. Hydraulic (pressurized) applicators usually need water to work. A pressurized applicator may be manually operated (such as the lever-operated knapsack sprayer), motorized, or ground-driven (Fig 4.2). Herbicide use 55
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 and 12: Chapter 2 Rice weeds of worldwide i
Page 13 and 14: Lowland rice weeds ASTERACEAE (Comp
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 behavior in the crop environmen
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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