This was the finding of a report by ADAS plant pathologist Dr Peter Gladders, who was commissioned by chemical company BASF to study the impact of increasing temperatures - experts predict a rise of 2 degsC by 2050 - and more variable rainfall.
Gladders looked at how these changes would influence disease incidence and severity in seven different crops - vegetable Brassicas, carrots, lettuce, onions, potatoes, strawberries and top fruit.
He studied individual diseases - identifying the optimum temperatures and wetness needs for each pathogen and so predicting where changes might occur - to find that Brassicas, carrots, lettuce and potatoes could be among the worst affected crops.
He said: "Vegetable Brassicas already suffer from a range of diseases and it appears that climate change may exacerbate most of these. For example, dark leaf spot (Alternaria), white blister (Albugo) and black rot (Xanthomonas) are all favoured by high temperatures and powdery mildew by drier summers.
"Heavy rainfall events and subsequent flooding would increase soil-borne diseases such as clubroot and Phytophthora root rot. We could even see new diseases emerging. Verticillium wilt and Fusarium wilts are favoured by higher soil temperatures and summer drought.
"On the bright side, we could see less downy mildew and less light leaf spot because spore production is inhibited by high summer temperatures. In carrots, many pathogens are favoured by high temperatures and high rainfall."
BASF field vegetable product manager Robert Storer added: "Growers will need to be prepared to use an effective and timely fungicide programme to protect against loss of both yield and quality.
"Starting to build protection around a robust broad-spectrum product provides the ideal platform for a fungicide programme - both now and as we move into a higher disease risk future."