Mr Gomes Seed Production A live source of life A mature fertilized ovule embryo that has stored energy reserves A small plant packaged for shipmentjust needs the right environment to go Prevention of seed production especially in annuals is one of the biggest keys to reducing weed pres ID: 754345
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Slide1
Weed Control
Plant Science 280
Mr. GomesSlide2
Seed Production
A live source of life! A mature fertilized ovule (embryo) that has stored energy reserves
A small plant packaged for shipment…just needs the right environment to go
Prevention of seed production, especially in annuals, is one of the biggest keys to reducing weed pressureSlide3
Seed Size/Abundance
Seed size is generally extremely small, most weeds can produce a tremendous amount
Shepherd’s purse can have as many as 5 million seeds/pound!!
Weed seed has a unique ability to survive in the soil based on archaic genetic traits
Estimates vary, but numbers vary anywhere from 120 million to as high as 1.4 billion seeds/acreSlide4
Seeds Produced by Common Weeds
Common Name
Barnyardgrass
7,160 seeds/plant 324,286 seeds/lb
Common cocklebur 440 seeds/plant 2,270 seeds/lb
Curly Dock 29,500 seeds/plant 324,286 seeds/lb Slide5
Weed Categories
Divided into three categories:
Broadleaves
Grasses
SedgesSlide6
Broadleaves
Broadleaf
Dicots
Veins in Leaves
Are Netted
Herbaceous or WoodySlide7
Grasses
Narrowleaf – Blade
Monocot
Veins are parallel Slide8
Sedges
Members of the family
Cyperaceae
Bear a close resemblance to grasses and can be distinguished by a thin triangular stem, the absence of a ligule, and the fusion of leaf sheaths forming a tube around the stem
Perennial sedges have underground tubers and/or rhizomesSlide9
Other Classifications
Summer Annual
Germinate in Spring, grow during summer, mature and die in the Fall
Winter Annual
Germinate in the Fall and Winter, Mature and die in Spring or early SummerSlide10
Life Cycles
Annual
Biennial
PerennialSlide11
Annuals
Annual Weeds germinate and spread by seed, having an average lifespan of one growing season. These include both winter and summer types. Winter annuals, like chickweed, germinate in late summer/early fall, go dormant in winter and actively grow during spring. Summer annuals, such as
lambsquarters
, germinate in spring, grow throughout the summer and are gone with the arrival of cold
weatehrSlide12
Lifecycle of an Annual Weed
germination
flowering
pollination
seed
set
plant
dies
growth
Shallow, tap root system
Reproduce by seed
Don’t need food reservesSlide13
Biennial Types
Biennial Weeds complete their life cycle in two growing seasons, germinating and forming rosettes their first year and producing flowers and seeds their second year. Examples of these types include bull thistle and garlic mustard.Slide14
Perennial Types
Perennial Weeds return every year and normally produce long tap roots in addition to seeds. These weeds, which include dandelions, plantain, and purple loosestrife, are the most difficult to controlSlide15
Perennial Types
Characteristics affecting timing
Deep root system
Rhizomes, tubers
Reproduce primarily by the above
Need food reserves to sustain plant through dormancySlide16
Life Cycle of a Perennial
germination or sprouting
growth and rhizome,
stolon, and/or
tuber production
Lowest amount
of stored carbohydrates
(flowering)
(pollination)
seed set or vegetative structure maturation
Highest amount
of stored carbohydratesSlide17
Managing Weeds
Maintain healthy orchard or fields
Prevent seed production
Prevent seed germination
Eliminate weed seedlings
Target susceptible growth stagesSlide18
Plant Development Stages
1. Seedling
Tender and vulnerable to stresses
2. Vegetative
Great uptake of water and nutrients
3. Seed Production
Slow uptake of water and nutrients directed to flower, fruit, seed
4. Maturity
Little uptake of water and nutrients
Low energy productionSlide19
What you need to know prior to developing a plan to control weeds
Be able to identify the weed
Know the weeds life cycle
Know the weeds habitat
Now a proper plan can be developed!!!Slide20
Types of Weed Control
Preventative
Cultural
Mechanical
Chemical
Biological Slide21
Preventative Weed Control
Preventative weed control refers to any control method that aims to prevent weeds from being established in a cultivated crop, a pasture, or a greenhouse. Examples of preventative weed control would be using certified weed free seed, only transporting hay that is weed free, making sure farm equipment is cleaned before moving from one location to another, and screening irrigation water to prevent weed seeds from traveling along irrigation ditchesSlide22
Cultural Weed Control
One of the easiest ways to control weeds is through prevention or cultural control. Close planting in the field can reduce weed growth by eliminating open space. Cover crops are good for this as well. Adding mulch will prevent light from getting to weed seeds and prevents growthSlide23
Mechanical Weed Control
Mechanical control of common weed plants can be accomplished through hand pulling, hoeing, digging or mowing (which slows growth and reduces seed formation). While these methods are effective, they can be time consuming and expensive.
Tillage such as discing and plowing
Mowing
Mechanical cultivator such as inline bed prepSlide24
Chemical Weed Control
Since many weeds, like dodder, hairy flea bane, spurge, and nut grass can become aggressive to the point of taking over, chemical control is sometimes necessary, and used normally a last resort. There are numerous herbicides, like glyphosate, available to help eliminate common weed plantsSlide25
Herbicide Classification
Selective
Kills some plant species, but does not damage other
Ex. Simplicity, Shark, Laudis, Weed-B-Gon
Nonselective
Generally kills all plant species.
Ex. Roundup, Goal
, RelySlide26
Herbicide Classification
Contact
Causes localized injury to plant tissue
Does not readily translocate.
Ex. Diquat
Systemic
Readily translocates on plant tissue
Ex. RoundupSlide27
Herbicide Classification
Pre-emergence – ex. Dual Magnum, Preen
Applied before weed seed germination.
Do not control emerged weeds
Post-emergence – Ex. Roundup,
Treevix
Applied after weed emergence.
Do not control un-emerged weedsSlide28
Herbicide Selection Factors
1. Identify the problem species
2. Identify the herbicides labeled for the site
3. Determine tolerance of desirable plants
4. Integrate management objectives
5. Obtain suitable safety and application equipment Slide29
Before you use herbicide
Identify desirable plant and weed
Read and UNDERSTAND herbicide label
Follow mixing, application, storage, disposal, etc. directions carefully
Use only recommended amount
Maintain and calibrate equipment
Do not use on desirable plants not listed on label (Off
LabelApplications
)Slide30
Biological
Biological weed control refers to any technique that involves the use of natural enemies of weed plants to control the germination of weed seeds or the spread of established plants. This is a rapidly expanding area of weed control with many examples. Examples of biological weed control include to sheep to control tansy ragwort or leafy spurge, cinnabar moth and the tansy flea beetle to control tansy ragwort, the chrysolia beetle to control St. Johns Wort, and the use of goats to control brush on rangeland.