Lincoln University’s Professor Derrick Moot says farmers should be setting their lucerne stands now – in July – if they want to graze them in September.
He says winter is the time to be controlling weeds and recommends spraying with a mix of paraquat (Gramoxone) and Atrazine at the recommended rates in June or early July.
While the paraquat has a knock-down effect and works on contact, the Atrazine has residual activity which means it will stay in the soil and kill weed plants as they emerge in spring.
If weed infestations are particularly bad, a repeat spray maybe required in spring.
Simazine, which also has a residual effect, can be used on lighter soils or where there is not a lot of weed cover. Where catsear, dandelion, storksbill and cocksfoot are a problem, Terbuthylazine could be considered although it can affect the lucerne plants so should be used in early winter.
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.
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For more information, go to: https://beeflambnz.com/knowledge-hub/search?term=lucerne+management+winter