Unit 13 Agri-science Biological and chemical control Of Pests
The control of pests has afforded the population of the United State The best quality food products in the world, at the cheapest price. How we choose to control the pests sometimes is determined by being Able to identify the pest and know its qualities. The three most common types of pests are: Plants-Weeds Insects disease
Know the plant life cycle to help control them. Annual – completes life cycle in one year (seed) Bi-annual – completes life cycle in two years First year produces vegetatively Second year produces seed Perennial – lives longer than two year.
Insects – insects can cause physical damage to the crop or human or they can be a vector (carrier) of disease. Insects can be classified by the type of mouthpart they feed with. Chewing mouth parts means they will defoliate the leaf (remove it) Sucking mouth parts mean they will remove liquid from the plant causing wilt During different stages of metamorphosis insects will have different Mouthparts. Insects can also be classified by their life cycle. Gradual or incomplete metamorphosis is where the insect grows from Egg to a nymph (small adult) to adult. (grasshopper) Complete metamorphosis the individual goes through 4 stages Egg Larva Pupa Adult (butterfly)
Disease can be broadly defined as anything that causes abnormal plant growth. Abiotic diseases are caused by environmental factors, such as too much salt, air Pollution, drought stress. Biotic diseases are caused by living things and include these common causative Agents. Fungi produce spores that may be toxic and mycelium Bacteria that cause blights (take all) in corn and potatoes. Viruses that invade the plant and produce mosaics (leaf disorders) in Tobacco and wheat. Nematodes are animals that have specialized mouth parts to suck fluids From plants many times from the roots.
IPM – Integrated Pest Management (the use of many strategies to control pests. First you must identify the pest that is causing the problem, sounds easy, but It may be a combination of pests or a symptom may be common to more than One pest. After you identify the pest you must understand its life cycle and Morphology. Then identify the crop and the ecosystem you are dealing with. The crop should Be fairly easy the ecosystem (too wet a year, too dry, host crops) may be Harder to identify how it affect the pest. The ecosystem may be able to be Manipulated by type of crop and farming practices. You also have to determine the threshold at which it will become economically Important to control the pest (all alfalfa fields have some weevils, how many Do you have to have before they have to be controlled)
IPM cont. Strategies to control the pest may include Regulating the number of pests with chemical, biological controls etc. Quarantining the area so the pests do not move out of the area (hard to do with Insects) ( fruit entering California) Eradicating is the complete removal of the pest, very costly, and not 100% Forever (fruit fly) Host resistant plants may be engineered so part of the life cycle may be broken Biological control is the use of natural predators on pests (ladybird beetle) Cultural practices include tillage to destroy seeds, plants, larva Physical containment or protection may include insect proof containers (silos), Or “clean” rooms used to produce virus free seeds or plants. Chemical use is usually the last part of an IPM program. Insects and plants Form resistance to chemicals and they can cause great damage to the Environment.