Best plastic for basil in high tunnels

By Blake Jackson

High tunnels, also known as hoophouses, are popular for extending the growing season and protecting crops. But did you know the type of plastic film covering you choose can significantly impact your plants?

Researchers at Penn State University explored how different plastic film options influence the growth and health of basil in high tunnels. They evaluated four types of polyethylene films with varying levels of light diffusion and ultraviolet (UV) transparency.

Their findings, published in Horticulturae, revealed that the amount of light transmitted, particularly in the photosynthetically active range (PAR), plays a major role. Films transmitting and diffusing 80% of sunlight in this range yielded the most basil biomass.

The study also showed that plastic film type affects the nutritional quality of basil. Different films impacted the plant's mineral content, chlorophyll, carotenoids, total phenolics, and antioxidant activity.

But perhaps the most exciting finding concerns disease resistance. The UV-transparent film that diffused light effectively limited downy mildew, a major foliage disease affecting basil yield and quality. This highlights the potential of such films to manage pests and pathogens in high tunnels.

"The choice of plastic film covering can significantly impact crop productivity, quality, and even pest and disease incidence," explains lead researcher Francesco Di Gioia. "Selecting the right film with appropriate UV transparency is crucial for high tunnel production."

Basil was chosen for this study due to its popularity and sensitivity to UV radiation. Basil plants adjust their physiology and metabolism in response to UV light, which can influence flavor, aroma, and pigmentation.

"UV-transparent films promote the accumulation of beneficial compounds like phenolics and anthocyanins, leading to improved basil flavor, aroma, and color," says Di Gioia.

The increasing frequency of severe rainstorms in the Northeast makes high tunnels even more valuable for growers. These structures can help mitigate climate risks and disease pressure.

"With more rain and emerging diseases, traditional methods like fungicides are becoming less effective," says Kathy Demchak, a research team member. "High tunnels offer a powerful solution, and their importance will likely continue to grow."

This research highlights the importance of tailoring high tunnel plastic film selection to specific crop needs and growing conditions. By choosing the right film, growers can optimize both the yield and quality of their crops while promoting plant health and managing disease.

Photo Credit: gettyimages-seventyfour