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State of California Department of Pesticide Regulation - page 16 / 104





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How Bacteria Spread

Anything that moves and comes in contact with bacteria or bacterial spores can spread them to other areas. This includes air (bacterial spores), water, equipment, rodents and other animals, insects, and people. Unlike viruses, bacteria can survive off their hosts for relatively long periods.


Fungi are a large group of non-green plants that live by feeding on either living or dead organisms. They cannot make their own food because, like bac- teria, they lack the green plant pigment, chlorophyll. Some fungi, such as yeasts, are tiny single-celled organisms. Others, such as mushrooms, are multicelled and

become very large. Fungi and bacteria often occur together in nature.

Fungi reproduce in several different ways. Some multiply from cell fragments. Others produce spores that function like plant seeds. Many species of fungi produce more than one type of spore. Some act as resting structures to carry the fungus through adverse con- ditions, while others are responsible for the ongoing secondary spread of the organism. Spores of fungi are not as resistant to chemicals, heat, or drying, as are bacterial spores.

Although many fungi are beneficial in breaking down organic mat- ter and for making bread, cheese, wine, and beer, some types cause diseases in humans, other animals, and plants. Ringworm, for example, is a fungal infection of the skin or nails. Serious forms of fungal disease include coccidioidomycosis (a disease of the respiratory system accompanied by fever and skin eruptions) and histoplasmosis (a disease affecting the lungs, spleen, and central nervous system). Several types of fungi cause decay and mildew of wood, fabrics, and paper products.

Fungi that invade water cooling towers and similar structures have a vegetative body, called the mycelium, that is composed of tiny filaments called hyphae. The mycelium grows through the fibers of wooden portions of the cooling equipment. This structure is usually large enough to be visible without magnification.

Characteristics of the mycelium and fruiting bodies aid specialists in identi- fying fungi. Fruiting bodies are the structures that produce spores, so finding these structures in damaged wood confirms a fungal infection.

How Fungi Spread

Spores of fungi spread by air, water, insects, and any practice that moves the infected host from one location to another. A fungal organism requires certain en- vironmental conditions to begin to grow and infect objects. These conditions often include high humidity or presence of water and warm temperatures.


Algae are primitive plants closely related to some fungi and protozoans. They differ in that they contain chlorophyll and other pigments. Algae reproduce by means of spores, cell division, or fragmentation. They range from microscopic single-celled organ- isms to 200 foot-long seaweeds. Algae occur in fresh and salt water and on land. There are more than 17,000 identified species of algae.


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