All about potatoes.pdf - Vegetableipmasia.org
All about potatoes.pdf - Vegetableipmasia.org
All about potatoes.pdf - Vegetableipmasia.org
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6.<br />
INSECT ECOLOGY<br />
water or may already be dissolved in an <strong>org</strong>anic solvent (alcohol for example)<br />
making them water-soluble. The consistency and color of these pesticides are<br />
similar to EC, but become clear after being diluted with water. The important<br />
components in these formulations are active ingredients and <strong>org</strong>anic solvents.<br />
Solvents used are types of alcohol.<br />
• Wettable powder (WP): WP contains active ingredients, a wetting agent and other<br />
materials such as adhesives. The wetting agent allows an even mixture of powder<br />
and water when it is diluted for spraying. Without the wetting agent, the active<br />
ingredients would not mix with water, but float on the surface. Carriers are<br />
generally in the form of mineral powder such as talc or clay. This talc or clay<br />
settles at the bottom of the tank and needs continuous shaking to maintain<br />
suspension.<br />
• Flowable (F): In these formulations, active ingredients are mixed with a carrier (a<br />
mineral powder) and a small amount of water producing a formulation fine but wet<br />
granules. This "wet mixture" is easy to mix evenly with water and can be sprayed<br />
using the same type of sprayers as used for WP formulations. This formulation<br />
requires continuous stirring.<br />
• Soluble Powder (SP): Active ingredients in SP formulations are either in a powder<br />
form that dissolves in water or formed into pellets containing small amounts of<br />
wetting agent to increase water solubility. Different from WP and F formulations,<br />
SP formulations do not require continuous stirring when spraying as the mixture<br />
remains in continual suspension.<br />
• Granules (G): The components of this formulation are an active ingredient, carrier<br />
and adhesive. This mix of materials is made into small granules. Active<br />
ingredients make up around 2-25%. Carriers are clay and mineral substances.<br />
Based on their mode of action:<br />
• Contact pesticides: There are pesticides that kill their intended targets by coming<br />
into contact with them. These pesticides remain on plants just after application,<br />
but are generally only effective for short periods of time and are easily affected by<br />
weather factors, particularly temperature and sunlight. They must be applied<br />
directly to the plant parts where pests and diseases are often found.<br />
• Systemic pesticides: These are pesticides that can enter and spread through all<br />
parts of a plant and affect the pest or disease after it consumes plant parts.<br />
Systemic insecticides generally poison stomachs or nerves, and are effective for<br />
controlling pests that suck, eat plant tissue or bore. Spraying needs not<br />
necessarily be on the affected parts of plants as these pesticides spread to all<br />
parts including the roots. Toxicity of these pesticides is generally long-lasting.<br />
These should not be used before harvesting as they can pollute crop produce and<br />
pose toxicity hazards to consumers.<br />
C. Pesticide toxicity classification<br />
The WHO (World Health Organization) has classified pesticides based on their<br />
toxicity. Pesticide classes depend on how hazardous they are to humans:<br />
• EXTREMELY HAZARDOUS (Class Ia): Pesticide formulations with, for example,<br />
the active ingredients parathion-methyl, mevinphos, alachlor.<br />
• HIGHLY HAZARDOUS: (Class Ib) Pesticide formulations such as those containing<br />
the active ingredients methamidophos, edifenphos, dichlorvos, monocrotophos, or<br />
methomyl.<br />
• MODERATELY HAZARDOUS (Class II): Pesticide formulations with the active<br />
ingredients ofatox, dimethoate, cypermethrin, fenvalerate, deltamethrin,<br />
fenobucarb, cartap, fipronil, endosulfan, fluvalinate and paraquat.<br />
36<br />
ALL ABOUT POTATOES