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Weed Management Systems & Strategies


Weed Management Strategy
--> Management Skills
--> Goals & Expectations
--> Integrate Crop & Weed Management
--> Principles of Weed Management Strategy
Weed Mangement Tactics
Weed Mangement System
Limitations to Weed Management


Weed management consists of developing a plan (weed management strategy) utilizing available tools, information and management skills (weed management tactics) integrated into a working weed-crop management system. This working management system is then modified with changing long and short term constraints and opportunities.

A weed-crop management system is a working plan of on-farm activities consisting of a collection of interdependent, interacting tactics.

A balanced weed management program includes several control tactics, including tillage, crop rotation, cultivation, cultural practices, and herbicides, thus promoting vigourous competition from the crop.

"An efficient weed management system integrates preventative measures, crop rotation, soil and water management practices, cultivations, and use of competitive crops, natural enemies, and herbicides when appropriate. Integrated systems of weed control must be compatible with management of other pests, other practices in to increase crop production, and with a quality environment."

An alternative way of thinking about weed management systems can be visualized in a model developed by Gregg Johnson at the University of Minnesota-Waseca that views the process of developing a weed management system as Optimum Resource Management:

Resources that need optimal management can be of several types:

-crop yield
-plant community
-physical resources like fertilizer and soil and others.

DATA is raw numbers, facts, or similar inputs.

INFORMATION is data put in some context or usable format: herbicide labels, weed maps of a field, etc.
In many simple weed management systems the temptation is irresistable at this stage of strategic planning to jump to ACTION. I have modified Gregg's original model by calling this premature leap the "Herbicide Shunt". You have information about some aspect of weed management, for instance the need to control cocklebur in a particular field, and some other information like a herbicide label, and the decision is made to spray. Because this is premature action is so often very successful, important planning and management planning is short-circuited by this approach.

KNOWLEDGE is information that has been placed in some framework, some organizational structure of larger view of that information. In our cocklebur example above this might be the recognition of long-term implications of herbicide information on soil carryover, seed bank changes, economic or environmental drawbacks or implications for other long-term aspects of the cropping system.

WISDOM is the most valuable and difficult to achieve aspect of weed management or resource optimization planning. Knowledge is filtered through the sieve of management skills, experience, limitations, risks involved, and even aspects of a growers personality and irrational beliefs. The final product is wisdom, for better or worse.

ACTION is doing, your actual weed management system.

Weed Mangement Strategy: Develop a Plan

Strategy in weed management is the development of a plan utilizing weed control expectations, information and management skills. Strategic planning involves making short-term (e.g. tillage, herbicide selection) and long term plans (e.g. seed bank deposits; crop rotations).


Management Skills
Goals & Expectations
Integrate Crop & Weed Management
Principles of Weed Management Strategy

Management Skills

The management skills of the individual grower include management of time, labor and information coupled with an individual growers experience, insight, training and intelligence.

LABOR is one of the least available, most expensive, resources for Iowa farmers. Most farmers hunger for ways to replace labor with information, equipment and management skills.

TIME is experienced differently when you are rushed than when you have less to do:

WEED CONTROL INFORMATION available to an individual grower forms the foundation of their weed management strategy. This information includes:

-Weed threshold information about prediction of crop losses and weed emergence
-Information stress (lack of; excess of)
-Farm and field information, especially weed mapping
-Institutional information sources including those from local coops, state extension services, agricultural chemical companies, libraries, etc.
-Informational tools such as weed control guides, weed threshold prediction software, WWW, books & bulletins, etc.
-Experience and information from other farmers

RISK MANAGEMENT is compromising the limitations and opportunies provided by management skills and information with the very real, complex and dangerous aspects of risk imposed by the scarce resources of time, labor, and farm finances.

Determine Your Goals & Expectations

What level of weed control is desired, expected, realistic, economic?:

What factors and forces should you consider that might modify these goals & expectations?

Will these goals and expectations change in the future?

Integrate Crop and Weed Management

One of the most difficult aspects of planning is compromising the several parts of crop production with each other. Simple systems are easy and inefficient (resource use, economically, environmentally). The best managers develop the ability to integrate all aspects of production with experience. Integration of management components may include:

Principles of Weed Management Strategy

Several important principles, or key concepts, should be included in any strategic planning. They include:

Weed Management Tactics

Weed Management Tactics: actions and plans used to achieve weed management goals.

Weed Management System

A weed management system is "doing" what has been planned. "Doing" is compromising plans with actual conditions. Management practices should be flexible and allow for adjustments to cope with changing conditions.

Recognize limitations and anticipate changing conditions, such as emerging seasonal weather conditions (e.g. rain, no rain, hail).

Compromise expectations with changing reality:

-in real-time as emerging conditions change
-modify long term planning

Limitations & Constraints to Weed Management

The plans made for weed management always are restricted in some ways, if not many ways. The plans that are allowed by these limitations and constraints is the weed management system that gets used. Some of these limitations include:


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