10 September 1999

Crown rust risk in grassland

CROWN rust is an increasing concern in grassland this year because of recent hot, wet weather.

Poor grazing management has also increased disease risk, says BGS consultant Paul Bird.

"Not applying nitrogen in August may lead to poor-quality, slow-growing grass – ideal conditions for the fungus to develop."

Regular nitrogen applications lead to rapidly growing grass, which is less prone to crown rust.

But there are ways of controlling crown rust in grass, says Wilts-based grass seed specialist Mark Gillingham.

"When grass has a high population of crown rust lesions, animals will turn their noses up at it. This means the problem becomes worse as grass grows longer and so is more difficult to graze off."

Mr Bird says that when boots glow orange after walking through infected grassland, the advice is to get grass off the field by grazing as much as possible, then top it or take a silage cut and fertilise to ensure grass grows away well.

Mr Gillingham says cutting and removing the material by silaging can work. "But the economics of spraying with a fungicide to control crown rust in autumn are dubious because grass value is low.

For producers looking at grass mixes for new leys or re-seeds, ensure some varieties in the mix score well on the NIAB list for crown rust resistance, he adds. &#42