This document discusses shifting weed management to an ecological systems approach using integrated weed management (IWM). IWM combines chemical, mechanical, biological and cultural control methods. The document outlines several new ecological solutions for weed control, including preventing propagule spread, seedbank management, crop rotation, tillage, cover crops, and enhancing crop competitiveness. It also discusses using biological controls and new technologies like RNA interference. The conclusion states that with advancements in herbicides, precision agriculture and ecological approaches, there are new possibilities that do not rely solely on chemicals, but more knowledge is still needed to implement ecological practices into IWM systems.

1. Shifting the Paradigm:
An Ecological Systems
Approach to Weed
Management
Joseph odingo
A56/37223/2020

2. Introduction
• Weeds are the primary and most important pest in agriculture.
• Several mechanisms of weed control are in place but integrated
weed management IWM combines all these mechanisms.
• Ecological system approach aims at increasing yield while
reducing economic loss
• Reliance of herbicides in modern farming has changed the
process of weed control from acquiring knowledge of weed to
quick use of chemicals.

3. • IWM is the practice of using chemical, mechanical and
biological control methods in combination with cultural weed
management practices.
• Ecological management requires proper knowledge of the local
environment and the use of herbicide has changed the type of
skill and knowledge used to manage weeds.
• These ecological approaches serve as components of an IWM.

4. New angles on ecological
solutions
i. Prevention of contamination and propagule spread.
Weed propagule movement is facilitated by
• Machinery movement across farms
• Grain contamination with weed seed
Proper sanitation and planting of clean seeds prevents the spread

5. ii. Seedbank management
• The persistent use of cultivation and herbicides will often
reduce the weed seed bank, but with the increase in HR weeds
or less than perfect weed control, eliminating them altogether
is rarely achieved.
• Harvest weed seed control (HWSC) is a non-chemical weed
management tactic that targets weed seeds at harvest, which
results in reducing the number of seeds entering the soil seed
bank.
• There are six forms of HWSC implemented today: chaff carts,
bale-direct systems, narrow windrow burning, cha lining, chaff
tramlining, and seed destructors

6. iv. Crop rotation
• The current rotational system is simplified, which favors weed
survival and promotes the evolution of superior competitive
ability of weeds over time.
• Simplified rotational practices may be heavily dependent upon
herbicides to control weeds and maintain crop yields
iv. Tillage
• Traditional organic agriculture has been highly reliant upon
tillage to provide weed control. Typical practices in organic
grain production involve moldboard plow or disc tillage, the
use of a tine weeder or rotary hoe, and interrow cultivation
• However tillage may negatively impact soil conservation,
promote soil erosion, reduce root colonization by arbuscular
mycorrhizal fungi , and lead to soil carbon loss from the soil

7. v. Cover Crops
• Helps in Weed suppression in organic no-till systems using
cover crop biomass
• High-residue cover crop options besides cereal rye are needed
to diversify this practice.
vi. Competitive Ability of Crops
• Crop competition is an approach that can be used to manage
weeds
• Enhanced crop competition can be achieved through various
cultural practices, such as competitive crop cultivars, increased
seeding rates, narrow row spacing, and altered row orientation

8. Biological Weed Control
• There are two approaches to biological weed control, whether
the control agent is bacterial, fungal, insect, or other: classical
biological control and inundative biocontrol
• Classical control relies upon the introduction of a pathogen,
herbivore, or predator of the target pest
• Inundative biocontrol may be more amenable to agricultural
systems, such as bioherbicides

9. New (Currently Proposed)
Solutions
a) Technological Advancements
• A potential new technology is the use of RNA to silence key
genes through the process of RNA interference (RNAi). This
technology would potentially be applied as a spray to enhance
weed susceptibility to herbicides or direct death of the weed.
b) Altering Sex Ratios
• Some species of flowering plants are dioecious, meaning there
must be male and female plants present and subsequent gene
exchange in order for reproduction to occur.
• Environmental stressors may impact male and female
phenologies differently, leading to asynchronous flowering

10. Conclusion
• With advancements in ecological approaches, herbicides, and
precision agriculture, there are new possibilities for the future
that do not rely solely on the use of chemical control.
Moreover, ecological interactions are not well documented and
understood, and success of methods may rely heavily upon
geographically-specific factors (soil type, OM, pH, climate and
climate variability, species present, etc.).
• Knowledge is still needed for the implementation of ecological
practices in an IWM system at local, regional and landscape
levels.