Unit 4 12/5/22 Flashcards
Why is weed control important?
- Livestock producer
- Home
- Medical
- Recreational
- Aesthetic
- Hort/turf/agronomic
- Preserving native species
Generally ______________ produce the most amount of seed in one year
Annuals
How do we
influence
weeds?
- Annual weeds are adapted to growing in any
soil with characteristics favorable for crop
growth (most data indicates) - However, there are economically important
weeds that are perennial - Dandelion, Canada thistle, curly dock,
common milkweed, etc.
one plant can produce how many seeds
60-80 thousand
What are the tree main weed groups?
Annuals
Biannual
Perennials
What is the annual weed group?
- Annuals (summer and winter) – Should be managed before they can produce seed
for the following year
Biennials
- Biennials – Reproduce by both vegetatively or by seed (seed not produced until the
second year)
Perennials
- Perennials – Survive for many years and produce seed. However, many primarily
produce vegetatively by creeping stems (rhizomes and stolons). Hardest to control
once established.
How are weeds dispersed?
- Wind
- Water
- Animals
- Humans
- Equipment
- Plant mechanisms (barbs, hooks,
spines, awns, sticky secretion,
cottony lint)
What is an example of a weed dispersed by animals?
Buckthorn, birds eat seeds and poop
What makes weeds so
successful?
- Abundant seed production
- Rapid population establishment
- Seed dormancy
- Long-time survival of buried seed
- Adaption for seed dispersal
- Vegetative reproductive structures
- *Ability to thrive in disturbed soils
What do weeds compete
light
water,
nutrients
space
Would you expect more dormancy for weeds or crops
Weeds
What are the two vegetative structures
Stolons and rhizomes
What is GDD
Growing Degree Day
Why is understanding Weed Emergence Sequence important?
*improve weed management by determining when to scout fields
- GDD = are heat units required to reach 10%
emergence - For some species, the majority of emergence
occurs in a short time period (2-3 weeks). Other
plant species may emergence over a prolonged
period (8-10 weeks)
Emergence date of group 0
Emergence date of group 1
Emergence date of group 2
Emergence date of group 3
Emergence date of group 4
Do weeds grow more when they are younger or older
Weeds will grow more as they get older
How long can weed seeds survive?
5-10 years in soil
Weeds in your field (seed bank) can go up to 142 years
Seed bank viability
- 142-year-old experiment at Michigan State University
- Moth Mullein
How many weeds in the United States are Native?
40 percent of the weeds found in the United States are native
60 percent are considered exotic or imported.
Cost of Invasive Plants in USA
Invasive species cost the United States an estimated $34.7 billion each year in control efforts and agricultural losses.
Is their any utility for these weeds?
Can we produce another type of crop?
Agriculture has not found
another major food crop
since the soybean was
rediscovered in the
western world in the 20th
century.
What foods provide about 60% of the human diet?
Wheat, rice, and corn
What is the difference between summer and winter annual weeds
What is the advantage for a weed to be a winter annual
What was the latest major food crop added in agriculture
soybean
What does soil do for plants?
Anchorage: root systems
Oxygen: the spaces among soil particles
contain air that provides oxygen
Water: the spaces among soil particles also
contain water
Temperature modification: soil insulates roots
from drastic fluctuations in temperature
Nutrients: soil supplies nutrients and hold the
nutrients that we add in the form of fertilizer
Soil
- Primary source of nutrients and physical support
for plants - Comprised of minerals (inorganic compounds) and
organic compounds - Soils vary in their texture: a ratio of sand, silt and
clay
What is organic?
plant material
Water-holding capacity
soil’s ability to hold
water is called its water-holding capacity
Cation exchange capacity (CEC
expression of the
soils ability to hold and exchange cations
pH
is a description of the soil’s acid/alkaline
reaction
- Soils generally range from pH 4.0 to pH 8.0
pH
- Northeastern forest soils can be very acid (pH 3.5)
- Western soils can be very alkaline (pH 9)
- Products can be added to soil to adjust pH
- Example applying lime can increase soil pH for crop
production
Soil texture is defined as?
the percentage of sand, silt, and clay particles in a soil.
Each plant has an optimal Ph range
What are essential nutrience
needed to complete life cycle
macro and micro nut
macro
essentrial nutrience
Macro - Nitrogen
Micro - iron
what can a plant look like if it has a deficienty
- Stunting
- Chlorosis
- Necrosis
- Purpling
Fertilizers
Most soils have at least some
residual nutrients (only a soil test
can assess this)
* Fertilizing without the results of a
soil test leads to a waste of
money and product
* Sometimes nutrients are present
but unavailable to plants because
of too high or too low pH
Fertilizers
can be
banded
- Vegetable gardens can be
fertilized by banding or placing
fertilizer alongside the crop row
Compost
- Compost is cheaper than
traditional ingredients, holds
water well, provides nutrients,
and can be produced at home - Quality of compost will depend
on the quality of the materials
that were composted - Organic
Why not use
garden soil?
- Garden soils are too dense to
allow good air and water
movement when added to a
container - Insects
- Diseases
- Weeds
Fertilizing a
lawn
- Determine the level of growth
desired - If a low-maintenance lawn is
desirable, no fertilizer may be
needed - Slow-release fertilizers are
preferred over soluble fast-
release formulations
How do you know what type of media to select?
listed on soil bags
