Low dose plus burial trials…
ULTRA-LOW rates of post-emergence cereal herbicide can make some broad-leaved weeds more susceptible to mechanical weeding, and possibly also to winter frost.
A study at Long Ashton Research Station, jointly funded by MAFF and the Home-Grown Cereals Authority, shows the weed control effects of harrowing after weeds have been squirted with tiny amounts of herbicide are prolonged, so reducing the need for autumn herbicide.
Mecoprop P at 5% or 15% of the normal recommended rate and tribenuron-methyl at 5%, 15% and 25% were sprayed on cleavers, speedwell, and poppies at the 2-4 leaf stage. Seven days later they were buried to simulate harrowing.
"By squirting low doses of herbicide both root and shoot growth of weeds are reduced, so making them more susceptible to harrowing," said LARSs Wendy Cashmore.
"We are also looking at the effects of temperature to see if harrowing is best done in autumn or spring."
Results so far suggest the combined effect of low doses and burying works well against some weeds, but not all.