Lincoln University’s Professor Derrick Moot says farmers should be setting-up their lucerne stands in June and July if they want to graze them in September.
Lucerne should have been spelled in autumn to allow root reserves to build, but need to be grazed before spraying to remove leaf.
After grazing, ideally rain would wash away dirt from the surface area of the lucerne and weeds before spraying, to prevent the agrichemicals from being deactivated.
Similarly, frosts should be allowed to thaw before spraying.
The agrichemicals used will depend on the age of the stand, grazing pressures it has been subjected to and the weed profile.
However, a standard control option would be a mix of Paraquat and Atrazine. The Paraquat is a fast-acting contact herbicide, while the Atrazine provides residual control to help control weeds as they emerge in spring.
If weed infestations are particularly bad, a repeat spray maybe required in spring.
Without correct weed control, lucerne yields can be compromised by 20-40% and stand longevity reduced. With the correct management, lucerne stands should produce high quality feed for 10 years.
Derrick says after spraying, lucerne stands should not be grazed at all in winter, as grazing will impede spring production.
While there may appear to be a green pick, these are the growing points on the plants and removing these will stop the plant from producing green leaf in the early spring period.
He says the plants have nodes that respond to air temperatures.
In temperatures above 5 degrees Celsius, the plant will produce a green leaf which is held in compact form over winter. In spring these leaves elongate and this is what provides the high-quality spring feed that makes lucerne such a valuable forage crop.
Find out more
For more information about lucerne management in winter go to https://beeflambnz.com/search?term=lucerne+winter+managment