Mesh crop covers improve potato yield and inhibit tomato potato psyllid and blight: The roles of mesh pore size and ultraviolet radiation. (31st January 2019) - Merfield, Charles N.
Abstract : Crop losses caused by the tomato potato psyllid (TPP; Bactericera cockerelli ) and blight ( Alternaria solani ; Phytophthora infestans ) continue to be major concerns for potato ( Solanum tuberosum ) growers worldwide, and commercial crops often require frequent use of agrichemicals to maintain tuber yield and quality. Nevertheless, a paradigm shift is unfolding in crop protection where new tools, such as physical barriers and light‐modifying filters, are being used to develop chemical‐free approaches for pest and disease control. In this study, we examined the use of crop covers as a non‐chemical method for controlling TPP and reducing blight in field potatoes. Our study demonstrated that those plants grown under mesh covers exhibited reduced levels of blight, TPP and associated psyllid yellows. Additionally, potatoes grown under mesh covers exhibited increased yield (91.4 ± 6.9 SD t/ha) compared with both uncovered control plants (75.0 ± 11.8 t/ha) and plants grown using agrichemical pest control (84.5 ± 10.8 t/ha). The plants grown under mesh produced fewer smaller tubers, with increased average and maximum tuber size, so that marketable yield (tubers ≥60 g) was also increased (83.5 ± 7.5 t/ha), compared with that achieved for uncovered control plants (60.0 ± 8.3 t/ha) and plants grown using agrichemicals (69.6 ± 9.2 t/ha). A second field experiment suggested that the incidence of TPP foliage damage and the development of blight were lowest when the passage of ambient ultraviolet (UV) radiation through the crop cover was reduced. This hypothesis was supported by a third trial where potatoes grown outdoors in pots exhibited reduced TPP foliage damage and fewer resident TPP when grown under UV‐blocking plastic screens. The results of these experiments suggest that the use of mesh covers offers new opportunities to sustainably protect potato crops both by acting as a physical barrier and by modifying the wavelength of light incident on the crop. Abstract : Relationships between passage of UV‐A and UV‐B (relative to the uncovered control) with median tomato potato psyllid (TPP) damage score and blight severity score on potatoes grown under under cloches with different crop covers.