Introduction to Plant Pests Margaret Chapman Cal Poly, San Luis Obispo AgEd 410 Spring 1999 Modified by Georgia Agricultural Education Curriculum Office July, 2002

Four main groups of plant pests: 1. Weeds 2. Invertebrates 3. Vertebrates 4. Disease Agents

Plant Pests * Organisms that compete with people for food or fiber, interfere with raising our crops and livestock. * Proper identification is important in controlling pests.

Weeds * Undesirable plants, sometimes defined as “any plant growing out of place.” * Adapt well to local climates and soils and can compete successfully with cultivated plants.

* Most weeds produce a large number of seeds. * Some weed seeds can remain dormant for 20 years before germinating.

* Weeds can be persistent and difficult to eradicate, because some have vegetative means of reproduction in addition to seeds. * Weeds compete with agricultural crops for water, nutrients, light and space.

* Weeds can interfere with farming operations, and can harbor insects and plant diseases. * Some weeds are toxic to livestock.

* A simple way to identify weeds is to compare them to colored photographs and drawings. * Become familiar with plant classification system and the weeds physical features, developmental stages,and life cycles.

* We will discuss weed and other pest control measures in upcoming lessons.

Invertebrate Pests * Includes insects and their relatives, nematodes, snails and slugs. * “Invertebrate” signifies animals without backbones (no vertebrate).

* Insects have three body parts: head, thorax and abdomen and six legs.

* Ticks, mites and spiders have only two body parts and eight legs.

* Nematodes are a large group of unsegmented worms that can be plant parasites.

* Snails and slugs are mollusks that prefer cool, moist surroundings.

Vertebrates * Animals with backbones * Includes fish ,amphibians, reptiles, birds and mammals. * Most of our concern is with birds and mammals.

Pest birds * Harbor pathogens, disease causing organisms * Eat or damage crops * Cause damage to buildings * Make too much noise

* Rodents are mammals that interfere with people, or cause harm to crops and livestock. * Animal pests are similar to weeds, those that are out of place are considered pests.

Most of our vertebrate problems are caused from: * Rats * Squirrels * Mice

Disease Agents * Cause disease in plants and animals. * Many are submicroscopic, making identification difficult. * If you can’t see the pest, then it may be identified by the type of symptoms caused or damage done.

* Included in this group of pests are: 1. Bacteria Bacterial citrus canker symptoms on citrus leaves

2. Fungi orange fruit caused by the fungus Elsinoe fawcetti * Scab symptoms on orange fruit caused by the fungus Elsinoe fawcetti

3. Viruses veins and shoots * Citrus tristeza Virus on grapefruit * Potato Virus on veins and shoots * Citrus tristeza Virus on grapefruit

Problems growers face * Energy, time and expense to combat problems. * Losses of food to our world food supply can become disastrous. * Farmers are focusing on controlling pests while dealing with environmental pollution problems.

* New methods and concepts continue to evolve each day to keep our crops healthy and abundant.