What was it all about?

This project sought to determine the productivity of strawberry plants growing under high plastic tunnels and protected from rainfall. Experiments to compare the productivity of plants growing under tunnels versus plants growing outdoors were conducted on the Sunshine Coast from 2012 to 2015.

Other experiments conducted in Florida assessed the effect of different chemicals for the control of powdery mildew, an important disease affecting strawberry plants growing under protected cropping.

In the first two years, the experiments showed that the marketable yields of strawberry plants growing under the tunnels were 24 to 38 per cent higher than the yields of plants growing outdoors. This was due to less rain damage and mould losses.

In the third year, supplementary overhead irrigation was given to the plants growing outdoors to provide a water application about twice that of the long-term average for the season at Palmwoods.

In the fourth year, no supplementary irrigation was given, and rainfall was about 80 per cent of that of the long-term average for Palmwoods. In these last two experiments, half the plants in each group received the standard sprays to control grey mould, while the other half received no sprays.

The relative marketable yields of the plants under the tunnels were more than 200 per cent of the yields of the plants outdoors in year three (overhead irrigation outdoors), but about 25 per cent lower than those outdoors in year four (no overhead irrigation outdoors). There were no differences in the incidence of grey mould in sprayed and unsprayed plots under the tunnels, suggesting that plants growing under tunnels may not need to be sprayed for this disease.

In the Florida experiments, treatments that included pyraclostrobin plus fluxapyroxad, or quinoxyfen applied alternately with cyflufenamid, dramatically reduced the incidence of powdery mildew on the fruit.

The researchers noted that further information needs to be collected to determine whether the responses recorded from commercial growers are similar to those recorded from this project.