Caring for new vines over the summer – Vineyard Magazine

Managing newly-planted vines well is vital for laying the foundations to develop strong, healthy and productive vines over the years to come.

One of the most important considerations in the first year is weed control, as small vines with minimal root systems are particularly sensitive to competition for light, water and nutrients.

Most growers will have started with a ‘blank canvas’ by using glyphosate prior to planting vines earlier in spring, however fresh weed flushes can soon reappear, especially in a season like 2024 when soils have remained moist and warm – ideal conditions for weed growth.

The most effective approach is generally to use a herbicide, such as carfentrazone-ethyl applied through a guarded sprayer, to maintain a weed-free strip beneath the vines. Alleyways can be sown with a grass or other cover crop mix to protect the soil and outcompete any weeds growing between the rows.

Mechanical weeders, such as rotary tillers, finger weeders or side hoes, do offer a chemical-free alternative to managing the undervine strip, but may be less suited to use around young vines given the increased risk of damaging small, shallow roots, or even uprooting new plants completely.

Organic mulches are another option, but it must be remembered that we want roots of new vines to grow down into the soil profile in search of nutrients, and adding mulches with a higher nutrient content (e.g. compost or grass cuttings from a side discharge mower) could encourage roots to remain closer to the surface, potentially reducing their future resilience.

In years when mildew risk is particularly high (both powdery or downy mildew), there is merit in protecting new vines with a copper/sulphur mix. Two applications may be necessary depending on risk; one in June to protect the first flush of growth after planting, followed by another in late July to protect any new leaves ahead of late summer storms. Chemical options offering curative mildew control are increasingly limited, so, as with any disease, it is always better to take a preventative approach.

A good quality phosphite, such as Phorce, can be a useful addition to help build root development, and research has shown phosphites can trigger a natural defence mechanism in vines and reduce downy mildew infection.

The seaweed extract-based fertiliser, Maxicrop, is another useful option, both for strengthening root growth, and helping to encourage healthy foliar growth at a time when roots are not yet fully developed. It may help to ‘soften’ the tank mix when applying copper/sulphur.

Similarly, the phlorotannins, polyamines, and other biological actives in the Kelpak liquid seaweed biostimulant have been shown to promote root initiation and development in young plants.

A key task during July and August is to select a strong shoot that can be trained to a stake to ultimately form the main trunk. Experience suggests that doing this in summer generally results in less scarring than with wiser shoot selection.

The typical approach is to select two strong shoots, one of which will eventually become the main trunk in year two or three, the second acting as a reserve option that will be removed at a later date. On very fertile, vigorous sites, some growers may let a third develop as a way of managing the increased vigour.

When selecting shoots, make sure they are growing from above the graft union, so they represent the fruiting variety rather than the rootstock.

After such a wet winter and spring, the need for irrigation may seem irrelevant this year, however we know how quickly conditions can change. While soils may still have sufficient moisture at depth, remember that the roots of new vines will be relatively shallow in the first year, so may benefit from some irrigation if conditions turn very hot and dry later in the summer. Allowing vines to become water stressed in year one will stunt their growth and could limit future potential.

One of the main drawbacks of maintaining bare soil in the undervine area is the increased risk of soil drying out and cracking, potentially exposing roots to dry air. Organic mulches can help in this respect, by retaining moisture, building water holding capacity, and reducing evaporation losses, although beware of the potential impact on nutrient availability and rooting mentioned previously.