A Working Definition of “Pest” An injurious and noxious or troublesome living organism [that] does not include a virus, bacteria, fungus or internal parasite that exists on humans or animals (British Columbia Pesticide Control Act,1997) Includes insects, weeds, plant pathogens, birds, non-human mammals and other organisms which pose non-medical problems to humans and non-veterinary problems to animals
A pest must cause injury In nature, there are no pests. Humans label organisms as “pests”. In order for an organism to be considered a pest, a damaging stage of the organism must be present in high enough numbers to cause actual injury to something valued by people. Being a pest is not an inherent property of a species but, rather, a species (along with its population and age distribution at a given time and place) and a human valuation of the item being injured or damaged.
History of Pesticide Pesticides are not new. Ancient Romans killed insect pests by burning sulfur and controlled weeds with salt. In the 1600s, ants were controlled with mixtures of honey and arsenic. By the late nineteenth century, U.S. farmers were using several materials to control insect pests in field crops, but often results were unsatisfactory because of the primitive chemistry and application methods.
Pesticide Use In the United States, pesticides are used on 900,000 farms and in 70 million households. Herbicides are the most widely used type of pesticide. Agriculture uses 75% of all pesticides, but 85% of all U.S. households have at least one pesticide in storage.
During the Early 19 th Century Great strides in biological knowledge (e.g. germ theory, evolution, genetics). Industrial revolution leads to large scale farming and commercial markets Modern pest groups are recognized (insects, weeds, pathogens) Potato famine creates incentive for government funding of pest controls.
By WWI Lack of good options Modern pest tactics were available but only a few were economical Increasing issues Developed countries were being invaded by major foreign pests, due to increased international commerce
During the 1940’s Better Living through Chemistry 1940 – DDT patented as an insecticide 1942 – BHC found insecticidal 1943 – 2,4-D found effective as a herbicide 1946 – Gerhard Schrader hired by Bayer 1946 – Houseflies found resistant to DDT
Green Revolution Series of research, development, and technology transfer initiatives, occurring between the 1940s and the late 1970s, that increased agriculture production around the world, beginning most markedly in the late 1960s During the Green Revolution in India, for example, crop yields routinely grew at 4% to 6% a year Led by Norman Borlaug, the "Father of the Green Revolution" credited with saving over a billion people from starvation. They used: high-yielding varieties of cereal grains expansion of irrigation distribution of hybridized seeds, synthetic fertilizers, and pesticides to farmers. Synthetic nitrogen, along with mined rock phosphate, pesticides and mechanization, have greatly increased crop yields in the early 20th century.
During 1950’s Organic chemical pesticides become routine on all crops Viewed as “modern” farming Low risk, “cost of business” Few/no regulations High prices/demand for US exports Problems would not be addressed until 1962
Problems Arising During the 1950’s Pest Resistance Bird/Fish Kills Human Poisonings Secondary Pests Biomagnification
“Pesticide Treadmill” 1.Spray, kill pest & natural controls. Pest comes back. Repeat until… 2.Resistance in primary pest. Increase application rates. Kill broader range of natural controls. 3.Induce secondary pest 4.Begin spraying for secondary pest until… 5.Resistance in secondary pest 6.Change chemicals. Repeat sequence.
Silent Spring in Context of its Time In the 10 years before Silent Spring… Many new innovations were introduced. Pesticides were viewed as one of them. Widespread attitude was that man could control nature. Pesticides were a manifestation of that view. Pesticides were applied liberally and often. “More is more” attitude
Silent Spring DDT was capable of killing hundreds of different kinds at once. Eradicated malaria-causing mosquitoes and an effective delousing powder Silent Spring described how DDT entered the food chain and accumulated in the fatty tissues of animals, including human beings, and caused cancer and genetic damage. DDT is persistent in the environment and does not get diluted or break down We will read part of Silent Spring later…
What is involved in the management of greenhouse pests? Healthy greenhouse crops are essential to a successful greenhouse business. Plant health refers to the condition of plants. Healthy plants are free of pests and disease. They have clean foliage and flowers, along with a good rate of growth. It is important that plants be healthy while they are growing and developing. It is also important that their health be maintained after they are sold.
What is involved in the management of greenhouse pests? Healthy plants have a greater capacity to defend themselves against plant pests than plants under some type of stress. Plant stress is usually associated with environmental conditions. Improper watering weakens a plant’s ability to fight off infectious diseases, including root rots. High humidity in greenhouses is ideal for many fungal diseases.
What is involved in the management of greenhouse pests? Growers have control over many environmental factors that can keep plants healthy. 1. Care can be taken to provide a growing medium with the desired drainage, aeration, and pH. 2. Plants can be planted at the proper planting depth. 3. Optimum nutrient levels can be maintained with fertilizers. 4. One of the most important factors is to follow recommended watering practices. 5. Temperature, light intensity, and air quality can also be adjusted to meet the needs of the specific crop.
What is involved in the management of greenhouse pests? No matter how well crops are grown, pests and diseases will become problems from time to time. The very nature of greenhouse crop production leads to some disease problems. In most cases, crops are of the same species, variety, or cultivar. Being of identical genetic makeup, they are vulnerable to infectious disease that can easily spread from one plant to another.
Common Pests Spider Mites Whiteflies Mealybugs Caterpillars & Foliage Worms Scales Aphids Slugs & Snails Pest Flies Beetles Thrips
Spider Mites First Sign: Little yellow speckles on leaf surfaces. When you turn a leaf over, tiny, oval shaped mites, about pin head in size, are scurrying around. Spider Mites are arachnids, so they usually have 8 legs. Spider Mite eggs are all perfectly round, the same size, ranging from clear to amber in color. With larger infestations a fine webbing, crawling with mites, covers the plant tops. Soon, the leaves are browning and dying.
Whiteflies First Sign: Tiny, pure white "moths" resting on leaf surfaces. When disturbed, these moth-like flies quickly flutter up, then settle back down onto plants. Leaves may appear shiny with honeydew. They are insects, so they have 6 legs and they have wings. They tap into the phloem of plants introducing toxic saliva which causes black mold to grow on plants
Mealybugs Distorted leaves, generally weakened plants. Clusters of Mealybugs look like a cottony mass. It's only on close examination that they're seen to be individual, soft bodied, very slow moving insects. They gather at the joint of a leaf to a stem. They feed on the phloem and can induce leaf drop.
Caterpillars & Foliage Worms First Sign: Chunks chewed right out of leaves. You may also see little piles of fecal material scattered about. Look closer and you'll detect worm-like larvae crawling slowly around, feeding. The caterpillars are the larva of moths. They are insects, the adults have 2 pairs of wings and 6 legs.
Scales Distorted leaves, generally weakened plants. Look like raised dots on the plant, but they are insects. The adult insect are very slow moving or sessile. They feed on the phloem and can kill the plant in severe cases.
Aphids First Sign: Wilted-looking plants that aren't thriving. Looking closer, dense colonies of tiny (1/32" - 1/8") soft bodied, pear-shaped insects are seen, especially on tender growing tips and undersides. Young Aphids look like miniature adults. And the whole family will be found feeding together. Aphids have the ability to reproduce very rapidly. Astonishingly, they give birth to live young that are pregnant! Ladybugs are a good control measure.
Slugs & Snails First Sign: Chunks chewed right out of leaves. You may see silvery trails left behind on leaves. Slug is a common name for a shell-less terrestrial gastropod mollusc.
Pest Flies Often found in compost and can be responsible for disease transmission Control with removal of habitat like standing water and decomposing plants
Beetles Can chew plant leaves Predatory beetles are good, like ladybugs. Beetles with chewing mouthparts are bad. Insects with 6 legs, wings, and hard covering over wings.
Thrips First Sign: Leaf surfaces finely speckled with yellow spots. Later, a silvery metallic looking sheen may cover leaf surfaces. Not all Thrips create this sheen. With or without the sheen, you'll also see black specks (Thrip fecal material). Only on close inspection is the pest itself found. About 1/16" long, thrips can move quite quickly for their size. Many gardeners report thrips as a small "worm with legs". Larvae and adults look similar, but adults have wings and can fly.
GOOD INSECTS Ladybugs Ladybug larva Pirate bugs Spiders