Fruit and vegetable growers (field crops, orchards): the wind call, at your height

As a grower or farm manager, you make daily decisions during the season about spraying, netting, and harvest. These decisions are often dictated by boom-height wind conditions. A wrong call on wind can lead to spray drift onto sensitive neighbouring crops or properties, potentially causing damage and financial penalties. Conversely, delaying essential operations due to perceived high winds can result in missed spray windows, repeat applications, or crop loss.

Your farm's operational limits for wind speed are set by product labels, Sustainable Use Directive (SUD) rules, and customer assurance schemes. You need to know not just the wind speed, but also the direction, especially when working near other orchards or residential areas. This requires a precise understanding of wind at your working height.

Each day, you assess the wind to determine if conditions are suitable for your planned tasks. This involves checking the forecast, often several times, and making a judgment call based on your experience and the specific requirements of the job. The consequences of misjudging wind conditions can be significant, affecting both your bottom line and your relationships with neighbours.

For field crop and orchard operations, the critical wind measurement is at boom height, typically around 2 metres above the ground. Standard weather forecasts often provide wind speeds at 10 metres, which can be significantly different from what you experience at your working height. The Wind Agent interpolates wind speeds to your specified working height, showing you the conditions where your equipment operates.

Wind conditions are not constant; they fluctuate between mean speeds and gusts. For tasks like spraying, the mean wind speed is important for drift management, but gusts can also pose a risk, particularly for netting or tunnel operations. The instrument shows both the mean wind speed and the gust speed, allowing you to consider both factors when making your decision.

Your operational limit for wind speed, whether it is 6 km/h or 19 km/h, is set by your own documents and the specific product you are applying. The instrument allows you to input this limit, so you can directly compare the forecast wind conditions against your threshold at your working height. This helps you to make informed decisions based on the actual wind conditions relevant to your work.

The instrument provides P(above your limit) by the hour, which is the fraction of ensemble members that forecast wind speeds exceeding your specified limit at your working height. This percentage gives you insight into the likelihood of exceeding your operational threshold. For example, if 20 per cent of the ensemble members show wind above your limit, you might proceed with caution, closely monitoring conditions.

If the odds rise to 50 per cent, it indicates a significant chance of exceeding your limit. At this point, you might consider delaying the operation, preparing alternative plans, or conducting a site-specific check before proceeding. When the odds reach 80 per cent or higher, it suggests a high probability that conditions will be unsuitable, prompting you to postpone the work.

The Agreement Spine shows where weather models concur and where they diverge. When the models agree, the forecast is generally more reliable. If there is significant disagreement, it highlights increased uncertainty, and you may need to exercise greater caution or seek additional information. This helps you to understand the confidence level behind the forecast and adjust your decision-making accordingly.

This example illustrates how you might use the instrument for a spray operation, with your limit set at 11.8 mph at 2 metres:

• 6:00 AM: You check the morning brief. The forecast for 10:00 AM shows a mean wind speed of 9 mph, with gusts up to 13 mph. The P(above your limit) is 20 per cent, and the Agreement Spine shows good model consensus.
• 8:00 AM: As you prepare, you check again. The wind at 2 metres is forecast at 10 mph, gusts 14 mph. P(above your limit) has risen to 35 per cent for 10:00 AM, with some model divergence appearing.
• 9:30 AM: Before starting, you review the forecast one last time. The 10:00 AM wind is now forecast at 11 mph, gusts 15 mph. P(above your limit) is 60 per cent. You decide to delay spraying until after lunch, as the odds of exceeding your limit are too high.
• 12:30 PM: You check the forecast for the afternoon. Wind speeds are predicted to drop to 7 mph, gusts 10 mph, from 2:00 PM onwards. P(above your limit) is 10 per cent, and models show strong agreement. You decide to proceed with spraying at 2:00 PM.
• 2:00 PM: You begin spraying, monitoring actual conditions on site, confirming the forecast. The instrument's record page will log your decision and the conditions.

Your operational limit for wind speed is a critical factor in determining when it is appropriate to carry out tasks such as spraying, netting, or harvest. This limit is not arbitrary; it is typically defined in your product labels, Sustainable Use Directive (SUD) guidelines, or the requirements of your customer assurance schemes. For example, some product labels may specify a maximum wind speed of 6 km/h, while others might allow up to 19 km/h.

When you set up the instrument, you can input your specific wind speed limit directly from your own documents. The instrument is preset to 2 metres, as this is the typical boom height for many operations. This ensures that all forecasts and odds calculations are directly relevant to your actual working conditions and your specific constraints.

By accurately inputting your limit, you ensure that the P(above your limit) calculation is precise for your operations. This removes guesswork and provides a clear, data-driven basis for your decisions, helping you to adhere to regulatory and assurance requirements. It is important to regularly review and update this limit if your operational parameters or product requirements change.

Maintaining a dated record of wind forecasts, observed conditions, and your operational decisions is essential for fruit and vegetable growers. This record serves as proof of due diligence, particularly when dealing with retailer auditors or in the event of a query regarding spray drift onto neighbouring properties. The instrument provides a dated record page that captures what was forecast, what was observed, the limit you used, and the call you made.

This historical data can be invaluable for several reasons:

• Audits: Retailer assurance schemes, such as those that may be requested by Bord Bia, often require detailed records of spray applications, including weather conditions. A clear, time-stamped log demonstrates your adherence to best practices.
• Dispute Resolution: In instances where spray drift is alleged, a comprehensive record can provide objective evidence of the wind conditions at the time of application, supporting your operational decisions.
• Operational Review: Analysing past forecasts against actual observations helps you to refine your decision-making process over time, improving the accuracy of your future operational plans.

This record is a practical tool for accountability and continuous improvement, offering tangible proof of your careful management of wind-sensitive operations.

Irish fruit and vegetable growers operate in a climate characterised by its Atlantic exposure, leading to variable and often strong winds. The main growing season, typically from April to October, coincides with periods where wind conditions can quickly change, impacting daily operations. This variability makes precise wind forecasting at your working height particularly valuable for planning and execution.

During the storm season, generally from October to March, while field operations might be reduced, understanding wind patterns remains crucial for protecting infrastructure like polytunnels and for planning any late-season or early-season tasks. Met Éireann provides national forecasts, but local conditions can vary significantly, emphasising the need for site-specific wind intelligence for your farm.

For growers, adherence to Sustainable Use Directive (SUD) rules and customer assurance schemes is paramount. These often require detailed records of environmental conditions, including wind, during critical operations like spraying. The ability to demonstrate careful consideration of wind speed and direction, particularly near sensitive areas, is a key aspect of good agricultural practice in Ireland. The instrument supports this by providing verifiable records of your wind-related decisions.