Differential spore production by Botrytis cinerea on agar medium and plant tissue under near-ultraviolet light-absorbing polyethylene film

Plastic films containing additives that alter their transmission of the light spectrum may be useful tools for the control of aerial plant pathogens of greenhouse crops. Several samples of polyethylene films containing additives that absorb near ultraviolet (nUV) light in the range 280 to 380 nm were compared for their ability to affect spore germination, mycelial growth, and sporulation of Botrytis cinerea on agar medium. One film was selected and further evaluated. The kinetics of spore production by the pathogen was similar on agar medium and on tomato stem tissue, and whether incubation took place under the nUV-absorbing film or under a control film. However, spore production on both types of substrates under the nUV film remained at less than 0.05% that of the control for several weeks after inoculation, demonstrating that the nUV film inhibited rather than delayed sporulation. A sharp reduction of spore production was also observed on other plant tissues. However, the efficiency of the nUV film appeared different for different plants, and it was lower on flowers and cotyledons than on stem tissue. Two of the five strains of B. cinerea tested on tomato stem tissue were less sensitive to sporulation inhibition by the nUV film. To clarify the potential of nUV films for the control of gray mold on greenhouse crops, the epidemiological significance of these results needs to be further examined in light of the abundance of such strains in the environment.