WEEDS, BUGS AND OTHER

PEST

Weeds•Weed-plants that are considered to be growing out of place.•What is a weed to some is not a weed to others•The key is where it is growing•Undesirable plants•They compete with desired plants for water, nutrients, light and space.•They decrease crop quality•They reduce aesthetic value•They interfere with maintenance along right-of-ways•They harbor insects and disease pathogens

Annual Weeds

Prickly Lettuce

Common Chickweed

Annual Weed-a plant that completes its life cycle within one year.Two Types of annual weedsWinter annual-germinates in the fall and actively grows until late spring

Summer annual-germinates in the late spring and grows in hot summer months

Biennial Weeds-are weeds that live for 2 years. First year only produces vegetative growth-leaves, stem and root tissue

Second year produces seeds and flowers and then dies.

Wild Carrot

Bull Thistle

Burdock

Perennial Weeds-can live for more then two years and may reproduce by seed and/or vegetative growth.

Rhizomes-a stem that runs underground and gives rise to new plants at each joint (node).

Stolen-a stem that runs on the surface of the ground and gives rise to new plants at each node.

Bermuda Grass

Canada Thistle

Dandelion

Noxious WeedsNoxious Weed-a plant that causes great harm to other organisms by weakening those around it.

Most states have a noxious weeds list.

Great effort is made to control or eradicateCan be very difficult to kill and need several

treatments of herbicidesSpread by various methods

Seeds become airborneSeeds enter flowing waterwaysSeeds become attached to humans or

animals and travel Seeds are eaten and distributed by birds

Idaho Department of Agriculture has a list of 64 noxious weeds. The State is divided into 30 Cooperative Weed Management Areas (CWMA).

In each of these areas land owners and government agencies work together to ensure that noxious weeds are controlled and eradicated.

Black Henbane

Yellow Devil Hawkweed

KnotweedPuncture vineBuffalobur

DiseasesPlant disease is ANY abnormal plant growth.

Plant diseases are more the rule then exceptionMost plants tolerate the diseasesThere are two types of disease causing agentsAbiotic (nonliving)Nutrient deficienciesWater stressTemperature stressCombination of water and temp stressBiotic (living)Fungi BacteriaViruses Nematodes

It is important to understand the difference between infectious diseases caused by biotic agents and noninfectious diseases caused by abiotic diseases.

There are various symptoms caused by the pathogens on plants:

Dwarfing of growth Yellowing of foliageLeaf spotting Blasting of grain headsStem cankers Fruit rotSeed decay Destruction of

seedlingsWilt DefoliationRoot rot Galls

Growers need to know what the symptoms are and the causes to be able to effectively treat and eradicate the disease.

Disease TriangleThe occurrence and severity of the plant disease is based on the following factors:

1. A susceptible plant or host must be present

2. The pathogen organism, or causal agent, must be present. A casual agent is an organism that produces a disease.

3. Environmental conditions conducive to support the causal agent must occur.

The relationship between these factors is known as the disease triangle

*Understanding how the relationship works is how we can effectively treat plant diseases and learn to stop the growth of the new diseases.

Fungi are the principal causes of plant diseases.

Fungi are plants that lack chlorophyll.

Fungi causes diseases by producing spores or mycelium

These spores can be dispersed by wind, water, insects and humans.

Bacteria: one-celled or unicellular microscopic plants.

Bacteria can enter a plant only through wounds or natural openings.

Bacterial diseases are the causes for things like stem and root rot as well as many blights.

Viruses: pathogenic or disease-causing, organisms

Viruses are composed of nucleic acids surrounded by protein sheaths. They effect the plant’s metabolism by effecting protein synthesis. Plant viruses are transmitted by seeds, insects, nematodes, fungi, grafting and mechanical means, including sap contact. Produces several well-known symptoms- a visible change to the host. Symptoms include ring-spots, stunting, malformations and mosaics-light and dark green leaf patterns.

Nematodes: tiny roundworms that live in the soil or water, within insects, or as parasites of plants or animals. These parasites are very small and produce damage by feeding on the host plant. Main symptom is plant growth issues from feeding on the roots and stems.

Other PestInvertebrate pest: organisms that do NOT have a vertebrate.

Insects, nematodes, snails and slugs

Insects have three body parts: head, thorax and abdomen and have 6 legs.

Ticks, mites and spiders have only two body parts and 8 legs.