Agriculture: Floriculture and Ornamental Nurseries Pest Management Guidelines

Reflective Mulches

Reflective mulch delays or prevents certain flying insects from infesting plants because reflected ultraviolet light confuses insects' ability to locate their hosts. Reflective mulches have been effectively used to greatly reduce colonization of young crops by winged aphids, leafhoppers, thrips, and whiteflies. Although few floral crops have been studied, reflective mulches have been shown to be effective in various vegetable row crops against melon aphid, silverleaf whitefly, and western flower thrips. In field-grown crops especially sensitive to viruses or other insect-vectored pathogens, the added cost of reflective mulch may be justified because the mulch can be significantly more effective than insecticides in preventing pathogen infection. Insects that migrate onto a crop often have time to feed long enough to transmit viruses before being killed by pesticide residue on treated crops; reflective mulches can prevent such pests from alighting on the crop. Reflective mulches also conserve soil moisture and can improve crop growth beyond that provided by pest control, possibly due to warmer night soil temperatures, additional available soil moisture, more even soil moisture, and increased (reflected) light levels.

Reflective mulch is most effective during early growth when plants are small. As plants grow larger, reflective mulch becomes less effective and other management methods may be warranted. Reflective mulches cease to repel insects when the plant canopy covers more than about 60% of the soil surface. Note that working around reflective mulches can be annoying to workers and require protective eyewear.

Transplant through holes in the mulch or apply the mulch before seeded plants emerge from the soil by leaving a thin mulch-free strip of soil along the planting row. Reflective mesh is also available for application over the top of a crop; light-weight material is lifted as plants grow. Various materials, such as plastic (polyethylene or nylon) film, can be used. Silver or gray are the most effective colors for reflective mulch or mesh. White also works, but may not sufficiently suppress weed growth beneath it. Commercially available products include aluminum-metalized or silver embossed polyethylene. Aluminum foil is also effective, but it is expensive, delicate to handle, and not economically feasible on a large scale. Reflective material can also be sprayed onto planting beds.

Text Updated: 03/21