Introduction to IPM Scouting
When employing Integrated Pest Management (IPM), farmers often grapple with 3 key questions:
- To Treat or Not? The decision to deploy pest control measures is not taken lightly.
- When to Treat? Timing is crucial and depends on understanding pest thresholds and their lifecycle.
- Choice of Agent or Technology: The selection hinges on multiple factors including the product's efficacy, pest or plant lifecycle, cost implications, and the target market preferences, whether organic or conventional.
The Essence of Scouting
Scouting stands as the cornerstone of any successful IPM strategy, emphasizing the early detection of pest issues. This proactive approach aims to accurately gauge insect populations to inform management decisions, thereby minimizing unnecessary pesticide use. Given the uneven distribution of insects across fields, direct observation is essential.
The following tools are useful during scouting: knife, pruning shears, hand lens, notebook, sampling bags, sticky traps, and pheromone traps.
Data collection and recording methods.
- Scouting Form: on the scouting form, indicate space for location, date, time of day, crop and variety, and growth stage (younger plants may be more vulnerable than older plants).
- A hand lens, specifically a 10x or 15x magnifier for inspecting plant material.
- A knife for cutting into stems or root tissue (disinfect the knife with rubbing alcohol between plants).
- Containers for samples and a permanent marker to label bags with location information.
- A notebook with record-keeping sheets. Plastic sheet protectors can be used.
- A digital camera for documentation.
- Monitoring cards to monitor the winged stage of flying insects.
- A bucket to examine roots.
Different crops, pests, and diseases require different Scouting Methods
- Sweep Net Approach - Used to scout for insects, such as leaf hoppers, on robust crops that won't be damaged by sweeping through them. Using a sweep net enables you to monitor for tiny insects you would otherwise miss through visual observation. They perform best on slow-growing plants that can withstand the sweeping of the net.
- The Visual Observation Method is a useful method for keeping an eye on exposed eating insects, including aphids, cucumber beetles, leaf miners, and plant diseases that impact the leaves and fruits. To gather a representative sample, choose plants at random across the crop, frequently strolling in a Zig-zag or W-pattern. Examine the top and bottom leaves. Gently turn a leaf over and count the items within any potential fruit or blooms, as well as the growth point, which is where the stem touches the earth. Use hand lenses to observe for small insects, such as young whiteflies, thrips, and mites
- Trapping Method: Sticky traps, light, and pheromones are used to monitor and manage insect infestations. The pheromones in pheromone traps are specific to certain pests. The sex pheromone that is particular to the insects you wish to keep an eye on is released via a bait enclosed in the trap. A bucket pheromone trap or a Hartsack pheromone trap can be used, depending on the bug. It is best to position sticky traps at crop canopy height.
- Determining the Damage Method: In certain cases, identifying an issue with an insect infestation can be done without actually seeing it. The key to managing these insects is understanding their eating habits and the harm they can cause: mining, sucking, rasping, and chewing insects.
Scouting Techniques to Manage Pest and Disease Population
During each scouting session, select 20 random locations within the field, and at each location, examine 1-5 plants, ensuring they are evenly distributed across the field. While it's important to pay attention to potential trouble spots, such as wet areas or field edges, ensure that your focus is not solely on these regions. Inspect both the upper and lower leaves of plants in each selected area. Record the presence of any diseases, detailing the extent of leaf damage observed. It is crucial to scout each cultivar individually, or make a note of which ones are more affected by specific issues.
For insect scouting, closely examine the cracks and crevices of plants, including leaves, flowers, and fruits, to identify and count all insect pests. Perform this detailed count on 5 plants in 10 distinct locations spread across the field to get a comprehensive overview of the pest population. After completing your counts, tally the total number of each pest found and divide this figure by 50 to determine the average number of pests per plant. For a more detailed analysis, further divide this number by the average number of leaves per plant to calculate the density of pests per leaf.
Determining Threshold Levels
Developing a pest's threshold level is a complex process, requiring extensive research. The action threshold level represents the critical point where the cost of pest damage surpasses the cost of control measures. This threshold underscores the importance of timely intervention to prevent economic loss.
Some smart decisions if you want to apply a material
- Examine the past performance of the pesticides used throughout the season.
- During the growth season, identify pests
- When in bloom, take pollinators into account. Choose insecticides that are extremely low-toxicity to them. Stay away from broad-spectrum pesticides.
- Assess the pre-harvest interval (PHI) insecticide application. As you approach the harvesting phase of the crop cycle, continue to use a product with a low pre-harvest interval (PHI), such as 0–3 days. In the ideal scenario, early in the crop cycle—when pesticide application is necessary during the crop's growth stage—long-acting insecticides (PHI) should be employed.
- Consider the resistance development of the product, how many times can you apply that product in a season? Read and follow the instructions on the pesticide label. Rotate or alternate your available product to avoid pests developing resistance against your product.
- Recognise the codes indicating the method of action of pesticides. Incorporate the codes for the modes of action into your IPM programs. When using pesticides that have the same mechanism of action, you run the risk of pests becoming resistant to them over time. Always switch out content with various action modes.
To make informed decisions about pesticide application, consider the following smart strategies:
- Examine Past Performance: Review the effectiveness of pesticides used throughout the season to guide current choices.
- Identify Pests During Growth Season: Timely identification of pests is crucial for effective management.
- Consider Pollinators:
- During bloom, prioritize the safety of pollinators by selecting insecticides that are low in toxicity to them.
- Avoid using broad-spectrum pesticides that harm beneficial insects. - Assess Pre-Harvest Interval (PHI):
- Opt for products with a short PHI (0–3 days) as you near harvest to ensure crop safety.
- Early in the crop cycle, use long-acting insecticides to protect the crop as it grows, balancing the need for pest control with harvest timing. - Manage Resistance:
- Be mindful of the resistance development potential of the product. Consider how many times a product can be applied in a season without risking pest resistance.
- Read and follow pesticide label instructions carefully.
- Rotate or alternate products to prevent pests from developing resistance. - Understand Modes of Action:
- Recognize the codes indicating pesticides' modes of action.
- Integrate these codes into your Integrated Pest Management (IPM) programs to make more informed choices.
- Avoid repeated use of pesticides with the same mechanism of action to reduce the risk of pest resistance.
- Always alternate products with different modes of action to maintain effectiveness.
Locating Insects & Pests
During a pest survey, it's crucial to meticulously inspect specific areas where insects and pests are likely to hide. Focus your examination on the following:
- The interior of flowers
- The underside of leaves
- The axils (the angles between the upper side of a leaf or stem and the supporting stem or branch)
- Young foliage
To effectively detect pests within flowers, employ a unique technique: position your lips close to the bloom and gently exhale. The carbon dioxide from your breath stimulates the pests' movement, making them more visible and easier to identify. This method enhances your ability to spot pests that might otherwise remain hidden.
Locating Diseases
When scouting for diseases in your field, it's critical to focus on areas that are more susceptible to disease outbreaks. These include regions near drainage zones, which often have consistently moist soil, and low-lying areas where water tends to accumulate and stand. Such conditions are conducive to the development and spread of plant diseases.
It's important to understand that the majority of plant diseases are most effectively managed when treated proactively, before visible symptoms emerge. This is because plant diseases can spread rapidly through a field, unlike insect infestations which may progress more slowly. Early detection and treatment are key to preventing widespread disease outbreaks.
Avoiding Pests and Biosecurity
The most effective strategy for managing insects and viruses on your farm involves preventing their introduction or spread. Since many insect pests are attracted to light blue and yellow, it's advisable to avoid wearing these colours during field activities. Additionally, to prevent the transmission of viruses and pests to other areas of the field, conduct scouting activities in regions known to have high populations of these pests towards the end of your session, rather than at the beginning. This approach minimizes the risk of spreading pests or diseases across your farm.
In conclusion, embracing Integrated Pest Management (IPM) is a strategic and environmentally responsible approach to agricultural pest and disease control. By focusing on early detection through diligent scouting, employing targeted treatments, and understanding the lifecycle and resistance patterns of pests, farmers can significantly reduce their reliance on chemical pesticides. Implementing the practices outlined in this guide not only promotes healthier crops and yields but also safeguards our ecosystem. As we continue to navigate the challenges of sustainable agriculture, adopting IPM strategies becomes not just a choice, but a necessity for the future of farming.
Contact a Demeter Agronomist today on +233 24 529 7047
