DO not let blackgrass blind you to the threat from meadow- grass, warns a southern agronomist.
"With a lot of IPU going on late last autumn we have had some very high levels of meadowgrass in winter cereals this season," says Steve Cook of Hampshire Arable Systems.
"It is difficult to control once it has passed the three-leaf stage."
On many farms blackgrass is the number one target, but some of the newer graminicides for dealing with it are not as effective against meadowgrass as isoproturon or pendimethalin (as in Stomp), he notes. "Growers might be missing out on control."
Heavy infestations of both annual and rough-stalked meadow grass reduce cereal tillering and lock up nitrogen making it unavailable to crops. Yield losses of up to 15% and 33% respectively have been noted, says Mr Cook.
"In the past high rates of IPU, chlortoluron, and pendimethalin for blackgrass and wild oats will have given good control and may have masked a background population.
"In our area we have always been aware of the problem and generally have to consider meadowgrass on most fields. With Lexus we will usually add 2 litres/ha of Stomp, and Hawk often gets 1000g of IPU added for the meadow grass." *