A TEXTILE “PLANT ARMOR” has been designed that forces insects to navigate a maze-like path if they try to reach a plant. This design was effective at blocking insects from reaching cabbage plants in multiple experiments, compared with an alternative crop cover.

Based on their findings, researchers said that it’s possible to use this  technology to protect against insects. They’ve shown that a mechanical barrier will protect against tobacco thrips and possibly other insects, allowing the plant to grow and thrive underneath.

Previously, plant covers have been designed to exclude insects based on size alone – like a window screen – researchers said. But that strategy can be problematic for trying to keep out insects as small as tobacco thrips.

To exclude insects that are really small using traditional textile cover designs, the size of the openings would have to be so small that it would also prevent water, air and moisture from penetrating. To that end, the researchers designed a three-layer, 3D cover knitted using clear yarn in the outermost and innermost layers. The yarn, which can be made from recycled plastic, still allows sunlight to pass through but restricts insects from reaching plants. A knitted inner layer is sandwiched perpendicular to the two surrounding layers, creating a maze-like structure within the Plant Armor.

With the design, the insect has to figure out how to get through the maze to get to the plant on the other side. The insect has a certain amount of time to find food or it will die. That time is relatively short for a young insect.

In the first of three experiments, researchers found it took significantly longer for insects to penetrate the Plant Armor. They placed a cabbage leaf and 10 tobacco thrips inside a Petri dish, separated by the Plant Armor or another crop cover. It took approximately three hours for five of the thrips to make it through the Plant Armor, while it took only 12 minutes for them to cross a commercially available, single-layer crop cover. In the same experiment with young, unfed caterpillars, their design was nearly 90% effective at preventing unfed young caterpillars from crossing the Plant Armor in 12 hours.

When researchers tested how well they could protect potted cabbage plants inside a cage with unfed caterpillars, uncovered plants were infested and almost completely eaten, while plants covered and sealed with Plant Armor were not. They did not find a single caterpillar on the covered plants after 10 days.

Their last experiment was a three-month, outdoor field trial testing how well the Plant Armor worked when they used it like a greenhouse cover. The researchers found plants covered with Plant Armor were larger on average; the weight of cabbages under the Plant Armor was almost three times larger than the control. Researchers think their crop cover could be a good alternative for high-value crops like grapes. In future research, they also want to explore whether the cover could be used to help protect plants in extreme conditions – and as the climate changes. By Manny Palomar, PhD (EV Mail November 21-27, 2022 issue)