Scouting and monitoring for pests and diseases

23
Nov

Scouting and monitoring for pests and diseases

Scouting and monitoring are crucial steps in making informed decisions about pest and disease management, which can go beyond pest control and affect other important practices (e.g. identifying nutrient deficiencies, water issues etc.).

Proper scouting and monitoring must achieve the following goals:

  • Detect problems, pests and diseases, as early as possible, before the pest or disease are established and control becomes difficult.
  • Identify the pest correctly.
  • Rank the severity of the problem, e.g. low, moderate, severe, or numerical ranking.
  • Plan and implement a safe and effective treatment program
  • Asses treatment efficiency.

Knowing your crop, your farm and the area around the farm can help identify the problem.

  • Pests have preferences for certain crops – knowing which pests/diseases might attack your crop will help you focus on those pests and learn how to correctly identify them.
  • Pests and diseases usually have certain times of year where they are active, depending on weather conditions.
  • It is not only your field – pests from farms around you may affect your crop.
    For example, wind blowing in your direction can carry pests from a neighboring farm during harvest.

 

How often should you scout your field?

Regular and systematic monitoring is essential, otherwise you may have to deal with crisis situations and control becomes much more difficult.

When to start? It is recommended to start scouting immediately after the crop emerges.

Different pests and diseases may appear in different times along the growing season. Knowing the life cycle of each common pest or disease that might affect the crop, and when they may appear, helps to determine what to look for and when.

Pests have a predictable development pattern, based on heat accumulation. They require a specific amount of heat accumulation in order to reach a certain development stage. Therefore, pest infestations can be predicted using GDD (Growing Degree Days) data.

 

Scouting patterns

Growers usually develop their own scouting patterns, depending on their experience and knowledge of their crop, variability in the field and common problems.

Some common scouting patterns include U shape, Z shape or W shape.

 

Scouting tools, aids and techniques 

When scouting, it is recommended to use tools and techniques that can help detecting and identifying the pest. For example:

  • Use a magnifier glass
  • White paper sheet –Tapping flowers over a white sheet of paper may to detect thrips
  • Inspect both upper and lower side of the leaves, don’t leave out stems and stem bases

In greenhouses you can use dedicated tools:

Yellow sticky traps attract   adult whiteflies, leafminers, cabbage loopers.

  • Blue sticky traps attract thrips.
  • Electric insect killer catches butterflies, moths.

Other tools can that be used anywhere, include sweep nets and pheromone lures (for monitoring some species of moths).

In large open fields,  precision agriculture tools can be used, such as satellite imagery, GPS, drones etc. Today, remote-sensing technologies can help in detecting and identifying pests and diseases. The most commonly used index is NDVI (Normalized Difference Vegetation Index), which is used to detect changes in biomass. Near infra-red cameras are used in order to obtain this index. RGB cameras, which are standard cameras that capture images and videos, are also used for pest and disease detection.

 

Record keeping

Keeping records of the scouting findings is essential in order to evaluate the efficiency of the treatment and to predict problems in future seasons.

Records must include at a minimum:

  • Crops scouted
  • Date
  • Findings – identification of the pest, development stages, Severity of infestation
  • Treatment applied
  • Findings of follow up monitoring

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