Row covers reduce insect populations and damage, and improve early season crisphead lettuce production.

Rékika, D., Stewart, K.A., Boivin, G., and Jenni, S. (2009). "Row covers reduce insect populations and damage, and improve early season crisphead lettuce production.", International Journal of Vegetable Science, 15(1), pp. 71-82. doi : 10.1080/19315260802494468  Access to full text

Abstract

Insect damage on cripshead lettuce (Lactuca sativa L.) can reduce its marketability and cause significant crop losses. There is increasing interest in using alternative control strategies to replace or reduce pesticide use for this purpose. Crisphead lettuce cv. Ithaca grown under two densities 10 (ARC10) and 17 (ARC17) g/m2 of polypropylene applied as floating covers or low tunnels were compared with an uncovered control. Effects on tarnished plant bugs and aphids, air and soil temperature, and lettuce growth and development were recorded. Aphids and tarnished plant bug were almost completely excluded by covers. Once removed, insect population in the covered treatments increased but was 5.5 times less than in uncovered control. Covered plots had higher air and soil temperatures than uncovered plots. Air temperatures were higher under the floating covers than tunnels. ARC17 had higher soil temperatures than ARC10. Row covers promoted earlier growth and maturity. Head weights of lettuce covered with ARC17 were 1.4 times heavier than those of ARC10, which in turn were heavier than the control. Head weights were similar for floating covers and low tunnel treatments.

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