Tomato disease in Australia

by David
(Perth, Australia)

Nearly all my tomato plants are showing signs of disease and I was at a loss as to why. Last year was the first year that I grew tomatoes in Perth Australia and all the crop was just great so this year I have planted around 29 plants. Not all of them have leave disease but I've lost and replaced about 5 to date. I was thinking it may be due to the cooler weather we have been getting. I have started spraying the plants with a fungicide spray in the hope that this will stop the rot.

Can anyone offer me some advice please.

Ps My plants were infested with caterpillars so I sprayed the plants to rid them.