Soils & Management
We have come out of a three-year period of using no roundup and no pre-emergent. (Chemicals that stop weeds from emerging)
This was for a couple of reasons; firstly, was that the roundup had stopped being an efficient way of killing the remaining weeds – we had resistance. Secondly we had used Roundup for a long time, we stopped using preos because they were expensive and being unable to hold the remaining weeds. So we effectively decided to use the money normally used for preos for a second seasonal knock down.
We have gone through the process of building a double sided undervine slasher. This has worked well, but the costs of doing this in the current environment preclude it as it is more expensive through the speed that we can do it at and because we are not killing the grass of weeds under-vine. So any advantages in chemical reduction were being lost on increased fuel usage through increased slashing passes as aesthetically it needs to be done more often, this also compromised our clear under-vine thinking.
We are currently trialling an organic weed killer, this in its early stages is proving to be pretty interesting, it is expensive and what we are working on now is a system to reduce the amount that we use .
“We have come out of a three-year period of using no roundup and no pre-emergent”
The grass undervine and couch is also competing with the increased irrigation needs of the vine, I think a clear undervine also allows better air flow and reduced humidity for botrytis control. We have used phalaris as our preferred cover crop, this over a number of years has proved to be beneficial in the reduction on vigour through water use throughout the growing season. In dry seasons it is capable of handling high levels of water stress, it is also about to wake up and use rain much quicker than other crops we have tried.
It produces quite an amount of straw that is then slashed and re-mulched into the soil. It has a vast and robust root system that can extend under the undervine region so helping to maintain soil structure, I think it is a good indicator of soils salinity in that when we have seen phalaris thin out and other weeds come in, it can be a sign of a salinity build up. It is also able to assist in trying to even blocks out. Where it is planted on shallow soils, it runs out of water early and usually dies. Where if the soil has higher soil moisture water holding capacity, it will mine water down to a more consistent level.
Thinking about soil fertility and soil moisture management, is all about planning for the worst and hoping for the best. Planning for the worst be, planting a resilient fibrous drought tolerant monoculture of phalaris that will respond in a wet season quickly, control vine vigour and allow access. Phalaris also allows good amounts of stalky material to be cut and increase soil carbon levels, without increasing nitrogen levels.
Under-vine management is about trying cost effectively to have a clear under-vine that allows humidity levels under the canopy to be low, has little cover for snails and other pests and reflects some light up under the canopy.