Exam 1 Flashcards
2019
What was White Snakeroot known to cause?
“Milk Sickness”
What well-known person was killed by White Snakeroot?
Abraham Lincoln’s mother (Nancy Lincoln)
Who identified White Snakeroot?
Dr. Anna
Where was White Snakeroot found identified at?
Rock Creek, IL
What method of weed control is still the most popular globally?
handhoeing
What did handhoeing previously cost per hour and acre?
$0.10/HR; $3.00/Ac
What does handhoeing cost not per hour and acre?
$9/HR; $270/Ac
What herbicides are currently approved for Hemp?
None!
What percent of plant species are considered “true weeds”?
Less than 0.1%/
What are the characteristics of true weeds? (2)
- Persistent- continually return
2. Pernicious- are a problem (highly destructive)
How many weeds are usually a major problem for any given crop?
25
What is the definition of a weed?
A plant that causes economic losses or ecological damage, creates health problems for humans, animals ,or is undesirable where it is growing.
What are some traits weeds display? (7)
- the ability to grow in habitats disturbed by mankind
- rapid seedling growth
- quick maturation
- dual modes of reproduction
- highly adaptable
- self compatible
- seed dormancy
What do weeds cause in crops? (4)
- loss of yield
- added protection costs
- Reduced quality of farm products
- Reduced quality of animals
What percent yield loss are weeds responsible for?
12%
What is harbored in Johnsongrass?
Maize Dwarf Mosaic Virus
What weeds harbor nematodes? (2)
Polk weed
henbit
What does Johnsongrass do when it grows near Sorghum?
Hybridizes with to form Shattercane.
What weed results in docks when mixed with Wheat?
Wild Garlic (known at home as wild onion)
What weed must be cleaned from Soybeans?
Balloonvine
What weed is toxic to livestock and is common in KY?
Perilla Mint (Beefsteak Plant)
What weed is thought to cause extensive damage in rangeland out west but is not found here? How many acres does it take up?
Leafy spurge; 5mil.
What weed impairs the harvesting of corn and cotton?
Morningglory
What weeds cause significant head, threshing, and separating loss? (2)
Redroot pigweed
Giant foxtail
What were examples of weeds poisionous to humans?
- poison ivy
- poison hemlock
How do you calculate expected yield loss because of weeds?
You will be given the following information:
- Expected yield of planted crop
- Weed or weeds present and their loss percentage
- current market price for your crop
You will plug your information into the following formula:
(Expected yield x loss percent as a decimal) x current market price= loss
What are the 5 varieties of pigweeds that we went over?
- Redroot Pigweed
- Smooth Pigweed
- Spiny Amaranth
- Palmer Amaranth
- Waterhemp
Which 2 pigweeds are known to be resistant to glyphosate?
Palmer Amaranth and Waterhemp
How to ID the pigweeds?
1. Does it have spines? (Y/N) Y- Spined Amaranth N-Go to 2. 2. Does it have fine hairs on the stem? Y-Go to 3 N-Go to 4 3. are the sepals longer than the leaves? Y-Redroot Pigweed N-Smooth Pigweed 4. Are the petioles long and the leaves pointy? Y-Palmer Amaranth N-Waterhemp
Define Winter Annual.
A plant that:
- grows in the fall and through the winter
- flowers the following spring
- lifecycle is less than or equal to 1yr
What are 3 examples of a winter annual?
- Cheat
- Henbit
- Annual Bluegrass
Define Summer Annual
A plant that:
- germinates in the spring
- grows through the summer
- flowers and dies in the fall
- lifecycle is less than or equal to 1 year
What are 3 examples of a summer annual?
- Pigweeds
- Goosegrass
- Cocklebur
Define Biennial
A plant that:
- has a lifecycle that is longer than 1 year but less than 2 years.
- If often vegetative during its 1st year and reproductive during its last. (will bolt and flower the 2nd)
What are 3 examples of a biennial?
- Bull Thistle
- Musk Thistle
- Common Burdock
Define Simple Perennial
A plant that:
- usually progresses like a summer annual but returns yearly
- lifecycle is more than 2 years
- these are non-spreading and non-creeping
What are 3 examples of simple perennials?
- Dandelion
- Polkweed
- Buckhorn Plantain
Define Creeping/Spreading Perennial
A plant that:
-follow same life as simple perennial and summer annual but has a method of creeping or spreading
What are the 6 methods that creeping/spreading perennials may spread? What is an example of each?
- Rhyzomes
- Johnsongrass - Stolons
- Bermudagrass - Tubers
- Yellow Nutsedge - Bulb/Bulbets
- Wild Garlic - Creeping Roots
- Horsenettle - Taproot Reproduction
- Dandelion
What are 3 examples of parasitic weeds?
- Dodder
- Witchweed
- Mistletoe
When was witchweed introduced into the Carolinas?
1957
How does witchweed attack its hosts?
By attacking the host plants roots.
What does dodder use to “tap” into host? What is it?
Haustoria- a simple branched projection that grows into host plant cells and acts as absorbing organ.
How do the following 3 tillage methods affect weed seed dispersion?
(moldboard plowing, chisel plowing, no-till)
Moldboard plowing- distributes weed seed evenly throughout soil depth
No-till- keeps weed seed at soil surface
chisel plowing- is intermediate between the other 2
What is the most common tillage method today?
Chisel plowing
What is a “weed seed bank”?
The number of viable weed seedin the top 6in. of the soil.
- it is different for every field
- every field has one
You can never eliminate all of weed seed population. (T/F)
T as evidenced by 1984 study. remaining 3% of pop reestablished infestation
What is the percent range of dead weed seed as determined by a study? What was still the count of viable weed seed per square foot?
50-90% dead; 60-1500 viable seeds per sq. ft.
What is fatal germination?
When seeds germinate at a depth that is too deep for emergence to occur.
What is the dominant factor that determines the species composition of weed seed bank?
cropping sequence
What type of weed does no-till favor?
Perennials
How many seeds per plant does palmer amaranth produce?
Up to 600k, rumored up to 1M.
What are the characteristics of Redroot Pigweed?
- No spines
- Fine hairs on stem
- Short and thick branches
- sepal 2x the length of the seed
What are the characteristics of Smooth Pigweed?
- No spines
- fine hairs on stem
- can have longer branches
- sepals same length as seed
What are the characteristics of Spiny Amaranth?
- has spines on stem
- no hairs on stem
- can appear with green or purplish stems
What are the characteristics of Palmer Amaranth?
-no spines
-no hairs on stem
-long petioles and oval shaped leaves
is dioecious
-RR resistant
What are the characteristics of Waterhemp?
- no spines
- no hairs on stem
- dioecious
- long slender leaves and shorter petioles
- RR resistant
