It cannot be perfect, but can we do better? Insecticide spray coverage in lettuce

Insecticide applications can vary in efficacy due to a number of factors. This can include factors related to the spray equipment, environmental conditions, and crop architecture. How well foliage is covered for foliar sprays and precisely where material is applied can be very important in determining how applications affect pest populations. In leafy greens, thrips and aphids are both challenging pests to manage. This may in part be due to the complex architecture of lettuce plants and how pests can live deep within the lettuce heads. We evaluated spray coverage in lettuce using a combination of water sensitive spray cards and fluorescent dye. Applications were made using tractor-mounted sprayers. We found that coverage was at times variable and that location on the plant was very influential. While coverage is a known challenge in vegetables, this work helps identify coverage issues, which could help growers anticipate when applications may not achieve the desired efficacy and elucidate opportunities for improvement.