"This affects many lines, including new-season veg crops, especially potatoes, onions and carrots, as well as many lettuce lines, but especially baby leaf, of which spinach and roquette are worst affected," he wrote on his blog.
"Spinach is showing signs of physical damage from the torrential downpours as well as yellowing due to nutrient leaching. Crops that have survived are yielding poorly and growth on next plantings is also slow, due to the rain, but also lower-than-average temperatures and overcast conditions."
But the weather has not so far impacted too heavily on English wine growers, UK Vineyards Association general-secretary Jo Cowderoy told Horticulture Week. "Flowering is just underway with the main varieties just starting now," she said. "The flower cluster numbers and size are generally good - often two per shoot - and vine growth is good and healthy at the moment. In fact, night temperatures have been okay, so vines are loving it."
But she pointed out: "Disease risk is higher, in particular downy mildew and Botrytis. This is also occurring across mainland Europe, which is ahead of the UK, but with similar wet weather. There have already been losses to downy mildew, which can be devastating at flowering. At least we have advance warning from our neighbours."
Cowderoy added: "If the poor weather continues over flowering, with a lower fruit set and reduced berry numbers, yields may be lower, but this can be favourable for quality and can also reduce Botrytis as the clusters are less compact."
Most of England south of the Humber experienced above-average rainfall in June, with some areas in the south and east in particular seeing double the monthly average. While temperatures have been around average, much of southern and eastern England struggled to pass 70 per cent of average sunshine levels, said the Met Office.