Grazing management could be key to fighting the shady solanums

AG ADVICE - October 2021

Phil Cranney - Senior Land Services Officer, Pastures

With another big season on the way, the biggest long-term issues, other than soil health, are lurking beneath the cover of the lush annual grass growth.

The farmers that have been fighting the dreaded silverleaf nightshade east of Cowra can attest to that fact. They often spend most of the summer spot spraying silverleaf nightshade (Solanum elaeagnifolium) regrowth and seedlings to ensure they do not go to seed.

The same goes for the farmers in the upper-Belubula River, around Mandurama and Panuara, that have been struggling to find permanent solution to the sticky nightshade (Solanum sisymbriifolium) weed issue dominating un-arable undulating (once productive) pasture country.

We need to attack these solanums with more than just the herbicides that we apply. These perennial weeds need an integrated approach to control.

Concentrating your livestock grazing in the high-risk areas could significantly reduce the time spent chasing new growth from these solanums. High risk areas will vary from to farm according to farm topography, labour availability, enterprise types and your own spraying equipment.

However, in general, these are the common characteristics of high-risk areas that should be targeted for grazing from late August till early December:

  • Steep areas only accessible on foot
  • Creeks and rivers, especially for sticky nightshade
  • Timbered areas not suitable for broadacre spraying

Obviously, grazing silverleaf nightshade paddocks in November will need to be monitored regularly for fruit maturity to ensure sheep are not helping spread the seed. Click for the NSW DPI Best Practice Management Manual.

Spending the time to get the grazing duration and intensity (numbers/Ha) right in September and October for these high-risk paddocks will pay dividends. Ensure that at post-grazing biomass or when you start spot spraying that paddock, is less than 2 tonne Dry Matter/Ha. This simple grazing management strategy will help save you hours looking for seedlings and suckers.

The next step for a truly integrated weed control strategy, is getting a tropical grass in these areas to help compete with the early growth habit of these summer perennial weeds.

More to come in next month's edition of Ag Advice.

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