Organic Vineyard weed control is managed in several ways by modern vignerons. Mostly chemical means, using glyphosate, an organic salt, other chemical herbicide means, usually by spraying a fine mist onto all the plants under vine and by mechanical means, using ploughs that cut the soil or rotary action.
At Harris Organic vineyard the Spring under vine grapevine weed control has never included any chemical herbicide usage.
Every spring the Massey Ferguson MF135 diesel tractor was used to pull the “silly plough” along the rows to strip away the soil and growth under the vines. This aids to the health and fitness of the operator and to the communication skills of plough-man and driver. Now you can guess who drove the tractor and who did the yelling!
under vine weed, hat on, glasses focussed
Mechanical Weeding, not Chemical Weeding
There is a lot we can learn from the old ways in the Swan Valley region about grapevine weed control. At a recent European exhibition, there was not a single under-vine herbicide machine, they were all mechanical machines as many European vineyards are going organic.
Further, this gives some context to the recent decision from the French and Belgium Governments to ban the sale of glyphosate (the active constituent in Roundup). A large portion of European grape growers is opting for organic/biodynamic vineyards. The progress of the organic movement has allowed the advancement of chemical-free options.
Organic vignerons are turning to engineering companies which produce practical, versatile machines that combine a number of operations. These are all changeable to the base unit on the tractor.
Then the system uses an under vine blade, mulcher and a rotary hoe which are easily attached to the side-mounted unit. This gives the grapevine grower the ability to adapt to each vineyard situation which is crucial in Australian vineyards due to our varied weed species, vine age and differing soil types.
Here in this video is what we do now in our organic vineyard.
As glyphosate resistance is already a problem across the country, due to normal weeds becoming resistant to herbicides.
Then we should all be looking at ways we can manage our weed populations. Also, this can be done effectively, efficiently and in the most sustainable manner by ploughing. In the first instance giving the under vine area, a shallow ploughing removes the chemical-resistant weeds.
This leads on to the question, “When is glyphosate going to be banned in Australia”?
Is it possible to have a tractorless vineyard? Yes, I believe it is possible, however, the capital cost may be prohibitive, depending on how it is set up.
I can envisage a fox-proof fenced vineyard, that is filled with free-range chickens during the autumn, winter and spring. During the summer the chickens would need to be housed in a separate area away from the vines as free-range chickens eat grapes.
The free-range chickens will clean up and weed all the vineyard and reduce ground-dwelling vine pests as well as pest control.
Sheep may be an alternative too, but they will eat spring shoots.
I can see it may be a dual business between grape grower and free-range egg producer.
Pedro Ximenez is the name of a white Spanish grape variety. Some times it is called Pedro Ximenes or PX. It has been grown in Spain for centuries.
The first plants that came to Western Australia were taken by British settlers as cuttings from the Cape of Good Hope in South Africa in the early 1830s. The vines are vigorous on the rich alluvial soils of the Swan Valley with its Mediterranean climate. The vines produce large bunches of white grapes. To maximize the grape sugar levels the vines have to be meticulously maintained through the growing season. To make the rich and luscious liqueur wines that are renown worldwide the sugar level has to be extraordinarily high. This is achieved by letting the grapes ripen and shrivel as raisins on the vine in the autumn sunshine.
Growing Pedro Ximenez
Pedro Ximenez grows readily in the Swan Valley in Perth’s Western Australia. It is a white wine grape best known for the sweet sherries of Spain. Pedro Ximenez comes to the fore as a fortified wine either as a Sherry style or as a fortified single-variety wine known as Pedro Ximenez (PX).
In the Swan Valley, we make the greatest sweet dessert wines of the world. Once called sherry in Australia, and now called by its varietal name Pedro Ximenez, as the Europeans own the name, Sherry.
We have 300 Pedro Ximenez (PX) vines planted in our organic vineyard, situated at the top of the Swan Valley, 29 km from Perth, in Western Australia. Harris Organic Wines is the only certified organic vineyard and winery in Perth with 3 ha of land.
The vines cover an area of 20,000 square metres. The PX was planted in 2002 as part of our efforts to continue making our great fortified dessert wines. The clone of our Pedro Ximénez is unknown and here they are grown on their own roots and do well.
The vines are planted with 2.1 m spacing. The rows are 3.0m apart. The vines are trained to the wire at 900mm high and are rod pruned to 5 or 6 buds per rod. The vines are trained on VSP trellis to 1.8m above the ground.
We spray the vines during spring. The vines are sprayed with wettable sulphur after rain and Bordeaux mixture before any rain events.
We continually maintained the vines with summer pruning. After fruit set, the vines are leaf plucked on the southern side so that fruit thinning can be performed at veraison.
To reach the highest sugar levels the un-irrigated vines are only allowed to have one bunch of fruit per shoot. This leaves 6-8 bunches per vine and approximately two kilogrammes per vine at 25 Be’.
Pedro Ximenez is grown at an elevation of just 19m above sea level. Situated about 30km from the Indian Ocean, the vineyard is flat, as is the surrounding Swan Valley land. The Pedro Ximenez vines are planted east-west direction in soil that comprises a duplex sandy loam over clay. In January, the site experiences a mean maximum temperature of 33.2°C and a mean minimum temperature of 17°C. Further, the average annual rainfall over the last 10 years has been 650mm dominated by 140mm averages for June and July. The site doesn’t experience frosts while winds are predominantly south-west in the afternoon, with some easterly gales in spring and autumn.
Trellising and canopy management
The row and vine spacing of the Pedro Ximénez is 3m x 2.1, respectively, and is trellised to a five-wire Vertical Shoot Position (VSP). Sometimes we practise leaf plucking on the south side of the vines, shoot trimming around Christmas time, shoot thinning and shoot-positioning when putting the wires up in November and bunch thinning to carry the fruit through to 25 Baume.
Irrigation and soil management
The Pedro Ximenez vines are unirrigated. Between rows, we grow lupins, vetch and a mixture of wild radish, sour sobs and capeweed to increase soil carbon and nitrogen. Strip digging and ploughing the vine rows in spring produces a dry earth mulch. This helps to conserve soil moisture and help manage weed growth. Wood chip compost is spread out along the vine inter-rows to act as a fertiliser in autumn.
Pest and disease management
Pedro Ximenez is more susceptible to downy mildew than the other varieties grown here. Furthermore, to reduce its susceptibility, we prune the vines late in the season so that budburst is up to two weeks later than the other varieties. Budburst this year occurred on 10 October.
We spur-pruned the Pedro Ximénez to two-bud spurs as recommended by the Handbook of Horticulture and Viticulture of Western Australia. This book was first published by Adrien Despiessis in 1895. Due to my 1921 second edition of the handbook by the Western Australian Department of Agriculture started to fall apart, I undertook the task of reprinting this wonderful book on behalf of others as well as myself in 2007. We have the intent of producing a small amount of PX fruit at 25Be for a PX sherry liqueur. After 5 years of spur pruning, I have changed the pruning method to cane pruning. This reduces the amount of time required for hand thinning of the shoots during Spring.
Future methods of management
Changing from a four-wire to a five-wire trellis helped reduce hedging time, and increase the verticality of the shoots and changing from spurs to canes, to reduce shoot thinning handwork.
At version, all excess fruit is removed leaving only one bunch per shoot, i.e., about 12 bunches per vine. A typical analysis of our Pedro Ximénez at harvest: Sugar (Baumé) 25, Acidity (TA) very low with a pH of about 4.0.
We harvest less than a tonne of Pedro Ximénez per year at this sugar level.
Average phenological timing:
Budburst early October
Fruit set December
Veraison late January
We harvest usually about the 1st April but sometimes this can stretch out to May due the weather.
Pedro Ximénez fermentation is carried out on its skins for a few degrees Baume’ before pressing. The fermented juice is returned to the tank, prior to fortification. Once fortified with certified organic neutral brandy spirit the wine is racked and allowed to settle for a few weeks before racking to barriques. Ours is an organic fortified version, fortified with certified organic brandy from the only organic distillery in Australia. We mature our PX for many years in our underground cellar. The award-winning Pedro Ximénez sherry is packaged in 375ml bottles.
The biggest challenge in producing Pedro Ximenez
None really, it’s a matter of learning more about the variety and the terroir as the vines become more mature. Although PX does require a lot of hand-work, particularly fruit thinning to improve flavour and ripeness, it is well worth the effort.
Advice to other growers
For best results, the more handwork the better. Love your vineyard and the vines will perform for you.
Duncan Harris, the owner of Harris Organic Wines, has written about his organic wines, events and titbits for your information and education. This is a blog site to the main site of Harris Organic Wines and Organic Vodka websites because this is a word press site and the other is html. Enjoy.
Harris Organic has an online wine shop, so if you are unable to get to the Perth Swan Valley you may order online.
Our cellar door is in the Swan Valley, Western Australia. We are able to ship wine anywhere in the world and have heavily discounted freight to most capital cities in Australia. And on case sales, we have discounted postage costs on the interstate and overseas deliveries.
Feel free to ask a question by emailing our winemaker Duncan at any time. We even have an organic wine club. Members can receive the latest vintages, old and rare wines and reserved wines for members only.