Winter care key to lucerne’s spring potential

Published date24 May 2023
Publication titleCentral Rural Life
It is important to spell lucerne during autumn as this allows depleted root reserves to be replenished

Once frosts have stopped growth, typically in May or June, the stands should be grazed hard by a large mob of sheep to remove all green leaf.

Ideally, once grazed, a rainfall will remove all dirt from the surface area of the lucerne plant and weeds before herbicides are applied. Dirt can deactivate agrichemicals.

The stands should be sprayed 14 days after grazing. Agrichemical selection depends on the age of the stand, what grazing pressure it has been subjected to, and the weed profile.

Standard weed control options may include paraquat, atrazine, simazine and terbuthylazine, but seek advice from an agronomist or spray contractor.

As it is the node accumulation of the stem that sets up the lucerne plant to reach its potential in spring, a late spray or early grazing can significantly delay spring production and impact on yield.

In spring, the crop can be rotationally grazed with ewes and lambs from when it is around 20cm high (1500kg of dry matter per hectare).

Lucerne winter weed control options

Graze out the stand to remove lucerne leaf and if a frost is present, delay application until the frost has thawed. Once grazed, a rain is preferred to remove all dirt from the surface leaf area of the lucerne and weeds to prevent the agrichemical from being deactivated.

Standard control options

Paraquat (e.g. Gramoxone)

A fast-acting contact herbicide which desiccates all green plant tissue but is deactivated with soil contact.

Paraquat forms the backbone of all winter spray programmes over established lucerne in a tank mix combination with a suitable triazine. Full leaf coverage is essential. Lower water rates normally show up as a spotting effect on the leaves, as the chemical only...

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