New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here


by: Daryl Gulgowski


Daryl Gulgowski
GPA 3.71


Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

Class Notes
25 ?




Popular in Course

Popular in Agricultural & Resource Econ

This 2 page Class Notes was uploaded by Daryl Gulgowski on Saturday September 26, 2015. The Class Notes belongs to AGRON 317 at Iowa State University taught by Staff in Fall. Since its upload, it has received 21 views. For similar materials see /class/214424/agron-317-iowa-state-university in Agricultural & Resource Econ at Iowa State University.

Similar to AGRON 317 at ISU

Popular in Agricultural & Resource Econ




Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 09/26/15
Principles of Weed Science Agronomy 317 Vegetative Reproduction De nition A Production of new individuals without formation of seeds or spores B No recombination of genes resulting in clones C Vegetative reproduction most common in perennials but some annual weeds can form new plants through fragmentation common purslane Types of reproductive structures A Stem structure possessing nodes and internodes 1 Rhizome underground horizontal stem quackgrass swamp smartweed 2 Stolon aboveground horizontal stem bermudagrass 3 Tuber swollen stem tissue yellow nutsedge 4 Bulb stem with shortened internodes and fleshy modi ed leaves wild garlic B Vegetative rootstocks common milkweed Canada thistle 1 2 Lack nodes and internodes Adventitious buds form to produce new plants Advantages A Tolerance to control tactics 1 l Most vegetative reproductive structures have considerable more energy reserves than seed thus newly emerged perennials can survive more stress than annual weeds If the shoot ofa perennial is removed by mowing grazing or herbicide the plant can regenerate via the stored energy reserves in the vegetative reproductive organs whereas most annuals would simply die Perennials often are able to emerge from greater depths in the soil profile due to the high level of energy reserves This allows them to survive control tactics such as tillage that typically only disturb the upper area top 46 ofthe soil profile B Enhanced competitiveness 1 The large energy reserves available to each bud allows the plant to grow very rapidly immediately following emergence whereas seedlings developing from small seeds generally have low relative growth rates when transitioning from stored reserves in the seed to energy produced via photosynthesis The rapid growth of perennials allows them to get a head start on the crop plant and provides them a competitive edge for the growing season Many perennial weeds can form new reproductive structures ie rhizomes etc within a few weeks of emergence whereas an annual typically requires a full growing season to produce new seed O E Perpetuate successful genotypes since a plant that forms from a bud on a rhizome stolon or a vegetative rootstock is a clone of the parent plant genotypes that are best adapted to the current habitat will be maintained and reproduce more rapidly than less adapted geneotypes Disadvantages A Most perennial weed species produce far fewer reproductive units seeds buds nodes w 0 lt w 0 U than annual weeds Example 1 Quackgrass perennial grass 200 buds 2 Giant foxtail annual grass 4000 seed Perennial weeds typically spread less rapidly than annual weeds since the perennial reproductive structures are less adapted to longdistance dispersal than seeds Because ofthis perennial weeds are often found in distinct patches within fields However if left unmanaged a perennial can eventually cover an entire field Most perennial weeds reproduce within a field primarily via vegetative reproductive structures thus there typically is much less genetic variation within the population than is found with annual weeds This makes them much less adaptive to change than annuals However most perennials do produce seed thus there is a source of recombination of genes to create different biotypes Management of perennials A Perennial weeds are often the most difficult weed species to manage due to the large energy reserves stored within the soil profile In order to bring the plant under control the energy reserves must be depleted Prior to systemic herbicides it wasn t unusual to take land heavily infested with troublesome perennials Canada thistle eld bindweed Johnsongrass out of production for 23 years and repeatedly till the eld every 34 weeks whenever new shoots developed in an attempt to drain the energy reserves of the vegetative reproductive structure Systemic herbicides offer an opportunity to control perennials since the chemical can be translocated from shoot to the perennial root system However for effective control herbicide must be applied at a time when shoots are transporting energy reserves into the root This often doesn t coincide with typical herbicide application timings in cropping systems thus reducing the effectiveness of the herbicide In addition there is limited translocation to dormant buds which in an established perennial patch there are lots of thus complete control usually is not achieved with a single application even at optimum timings Smother crops typically plants with rapid growth rates and dense canopy characteristics have been used to suppress perennial and reduce energy reserves They provide an alternative to the repeated tillage described above and are usually beneficial to soil quality rather than detrimental as is tillage Most commonly used in organic systems


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Jim McGreen Ohio University

"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Kyle Maynard Purdue

"When you're taking detailed notes and trying to help everyone else out in the class, it really helps you learn and understand the I made $280 on my first study guide!"

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.