Since plants are protected against rain, the tunnels minimise the chance for the appearance of two strawberry illnesses known as botrytis and anthracnose. Botrytis tends to occur in cold and humid conditions, but anthracnose happens in hot and humid weather.
According to Lewers, strawberry growers also use high tunnels, but these can be problematic because humidity condenses more in them, which can increase the chances for botrytis and powdery mildew, which is another strawberry illness. In lower tunnels, humidity remains the same as that of ambient conditions.
The strawberry high season in Maryland usually takes place from mid-May to mid-June, but with the system used by Lewers, the production starts earlier in the spring and continues until the autumn. During several months, the performance under these tunnels can be the same as that of crops in California.
There are no patents on the plants used by Lewers. They are available freely without the need for any special license.