UAV-based early weed detection and precision spot spraying for pineapple fields

Overview

Densely planted pineapple fields (60,000-70,000 plants per hectare) present unique weed control challenges, particularly once the canopy reaches 75-100 cm in height. Early detection of weeds such as Guinea grass and Morning Glory is critical to implementing timely control. This solution uses unmanned aerial vehicles (UAVs) equipped with RGB and multiband cameras to detect early weed growth and integrate that capability into a precision agriculture service for pineapple growers. GPS-based localization of detected weeds enables targeted spot aerial spraying at all stages of crop development.

Technical specifications

• UAV-based imaging platform using RGB and multiband cameras to capture aerial imagery over pineapple fields
• Spectral reflectance analysis leverages the unique spectral signatures of Guinea grass and Morning Glory to distinguish weeds from pineapple plants
• Image processing software trained to identify small targets within a dense canopy, building on prior work that successfully detected pineapple flowers less than 3 cm across by recognizing leaf reflexing and red center development
• GPS localization of weed patches to enable programmed, targeted spot aerial spraying rather than broadcast application
• Flexible flight scheduling designed for two to four-week interval monitoring, aligned with crop growth stages
• Ground-truth validation through visual field monitoring to confirm the earliest stages at which weeds can be reliably identified

Technology readiness level

This technology is at an early-to-mid validation stage. Preliminary UAV work has demonstrated the ability to identify small-scale features (such as early pineapple flowering) within the canopy and to develop software that counts flowering plants from RGB images. The next phase, conducted in partnership with Dole Food Hawaii, will validate weed detection timing by postponing manual weed control in a selected field block and flying UAVs at two to four-week intervals while monitoring weed emergence from the ground. Dole Hawaii's year-round planting schedule provides fields at all stages of crop development for testing. Current readiness supports pilot-scale field validation rather than immediate commercial deployment.