Monitoring and evaluation

Key learning outcomes

  • Understand the importance of knowing which weeds are on-farm, where they are and their density
  • Develop an understanding of Decision Support Tools, and when they might be useful


Knowing about the weeds you have in field is an important first step in being able to manage them. This can begin with simple scouting by the grower or an agronomist and recording the species and density, mapping of patches, or using camera technology to individually detect and map weed seedlings. This information can be used to inform a range of Decision Support Tools, which can influence decision making. This module will introduce the concepts of surveillance and decision making for weed control, and discuss the most recent developments in this area.

Training session

Monitoring and evaluation in weed management

This is a presentation developed by Philippe Delval, ACTA, France. The video is about nine minutes 30 seconds long. Additional notes, comments and links to additional content are given below the presentation.

Music by Olexy from Pixabay

Comments, notes and resources referenced in the video


Methods = There are observation protocols allowing precision of the data
Instruments = Models, grids, kits help to reasoning
Qualified advisors= through individual certification and continuing education
Scientifically sound threshold = Biological thresholds of pest = Density or level of infestation from which a decrease in yield or quality is statistically detectable
Threshold levels = Indicative risk threshold = Density or level of infestation above which the effect on the reduction in yield or quality is greater than the costs of the means of intervention. These thresholds are often indicated in alert bulletins in some countries

Warning tools must be supplemented by field observations


IWMTOOL one section of the tool is dedicated to describing monitoring

Monitoring and evaluation activities are cross cutting activities that take place throughout the growing season and during the entire crop rotation. The tools under this pillar help in making informed decisions on what tactics to choose, and to evaluate the success of previously applied strategies and tactics.

Knowing how to identify and recognize the different pests
Integrated protection must be based on a good identification of pests, on the one hand in order to assess the effectiveness of the preventative measures implemented and on the other hand to make the best choice as to the control measures to be applied, whether they are chemical or not.

Monitoring the arrival of pests by observing your plots
Even though the farmer and the advisor have many tools available to help with decision-making, field observation remains essential in many cases.
Monitoring the arrival of pests by setting up traps
Placing traps within fields is a practice that makes it possible to estimate the populations of pests present in the crop. Also called "monitoring", this technique is supplemented by the notion of threshold of harmfulness which makes it possible to take a decision or not to intervene.
Monitoring the arrival of pests by following their development in the territory
Farmers and advisers may have regional references on the evolution of pests at the national level or in their territory. It is a complementary tool to field observations as well as other resources made available.

    IWMPRAISE Inspiration Sheet: Several IS have been produced to described weeds or flora in different crops (for example, arable crops in France, olive orchards in Spain and vineyards in UK).

    Important weeds in olive orchards in northern and southern Spain 

    Major weeds found in vineyards of south-east England  

    A botanical overview of the most common spontaneous grass cover crop species in olive orchards 

    Blackgrass (Alopecurus myosuroides)  

    Ragweed (Ambrosia artemisiifolia

    Barren brome and other bromegrasses (Bromus sterilis and Bromus sp.) 

    Field & Great bindweeds (Convolvulus arvensis and C. sepium

    Hogweed (Heracleum sphondylium

    Common ragwort (Jacobaea vulgaris - Senecio jacobaea) 

    Rat’s-tail fescue (Vulpia myuros


    Establish a diagnosis for the health of a crop

    Like human health, plant health diagnosis leads to a recommendation that can be a single treatment or a set of prophylactic measures. Thus, the upstream phase, which is the diagnosis, is essential for a precise assessment of the risk represented by the cause of the conditions and for an appropriate management of this risk. It can also be applied after the recommendation to assess the impact of the control methods implemented.

    IWMTOOL : one factsheet is dedicating on describing scouting methods usable in IWM


    To complete this information, it is important to consider the evolution of pests


    Use agricultural drones to carry out a diagnosis

    Agricultural drones can be used to establish a crop diagnosis: collection of georeferenced data on the condition of crops.

    Use connected traps to assess pest populations

    Monitoring the development and evolution of pests and diseases is essential in integrated protection. Connected recording systems are a solution to have real-time indication of this development and to facilitate the use of monitoring methods which too often require assiduous monitoring.

    IWMGAME [arable & perennial crops] : one card is represented use of mapping with UAV. You can play it to decrease side effects of the use of chemical products.

    IWMTOOL : one factsheet is dedicating on describing all sensing technology usable in IWM


    Assessing risks = monitoring and assessing pests and their beneficials

    Deciding = establishing a diagnosis and planning using available tools


    Assessing risks

    Based on the indicative risk threshold to plan an intervention

    The “indicative risk threshold” is defined as being the threshold from which protective measures can be put in place by the grower. It is established by expertise at a given moment, for a territory and in a defined context. This threshold makes it possible to decide whether to take or not to take the decision to intervene in the crop. It will also make it possible to choose which type of intervention to carry out: biocontrol, biological, physical or chemical control.



    Establish a diagnosis using specific tools

    Early, accurate and rapid diagnosis is necessary for the management of plant pests and diseases. To facilitate this diagnosis, there are specific tools that can be used in the laboratory or in the field.

    Evaluate health risks using decision support tools

    These tools describe phytosanitary situations of the presence, development and prediction of pests and diseases and are accompanied by decision rules to guide the user towards the decision to intervene or not. They can be accompanied by advice tools which allow their use to be traced at field level.

    Decide on an intervention using reasoning aids

    The reasoning support tools describe phytosanitary situations of the presence, development and prediction of pests and diseases and are accompanied by decision rules to guide the user towards the decision to intervene or not. They can be accompanied by advice tools which allow their use to be traced at field level.

    IWMGAME [arable & perennial crops]: one card represents the use of DSS. You can play it to decrease side effects of the use of chemical products.


    Decision-making is based on five complementary tools: Of course, this must be supplemented with regular field observations which confirm the decision.

    Prior = risk knowledge tools

    In production = useful tools to know and assess the sanitary situation

    • Technical recommendations = Set of recommendations to limit the appearance and development of resistance
    • Major = Having a significant nuisance
    • Resistance problems = see module six
    • Hrac =
    • Natural = for Conservation Control
    • Introduced = For control by naturalization or large-scale releases
    • Reason for their use = Possibility, stage and conditions of use
    • Ppdb =
    • Ecoacs =
    Biological (or visual) nuisance threshold = level of attack from which damage / damage is observed on the plant

    Pest threshold (technical) = level of infestation from which a depressive action of weeds on the crop is detectable or even observable or measurable varies according to the quantitative and qualitative criteria of the harvested product

    Indicative risk threshold = level of infestation from which an intervention is of economic interest. the cost of the intervention becomes lower than the cost of the estimated damage is added the cost of interventions therefore difference depending on the methodit is important to take into account the natural regulatory organisms of the pest that can make the intervention unprofitable

    • Diagnosis and risk assessment = By simulating the appearance and development of pests and diseases
    • Reasoning tools = These tools are equipped with decision rules making it possible to propose an intervention or not

    IWMTOOL: one factsheet is dedicated to describing DSS tools used in IWM


    The IPM Decisions project will create an online platform that is easy to use for the monitoring and management of pests. This platform will give farmers and advisers access to a large range of existing Decision Support Systems for their regional conditions.

    • Summary = These bulletins are both a source of information on the presence of a pest (monitoring) of its development and its possible impact on crops (decision)
    • Region = It is advisable to consult the bulletins of other regions, creating a broader view and sometimes helping to anticipate the arrival of a pest
    • Thresholds = These thresholds are provided by pests and diseases and can thus indicate the pressure level of key pests and diseases
    • Regulatory messages = Bulletins are also vectors of regulatory information (reminder of texts adapted to the period, new texts)
    • Observations = By a network made up of field observers from different structures as well as farmers
    • Modeling = Using risk assessment and reasoning tools
    • Follow-ups = Allowing simulation of the pest cycle and thus to indicate its stage at a given moment
    • In France, the BSV = Bulletins de Santé des Végétaux (trad. Bulletins of Plant Health)