PETAL BLIGHT - A very serious, but thankfully uncommon disease. Brown spots rapidly join together to eventually destroy the head. Remove and burn all the affected crop.
APHIDS - Both black fly and greenfly can attack developing heads. Spray with permethrin or heptenophos at the first sign of attack.
SLUGS - A serious menace to many gardeners. Sprinkle slug pellets down around young plants, especially in wet weather.