Weed Control on Vine and Soft Fruits

Commission of the European Communities

• Verlag: CRC Press
• Jahr: 2021
• ISBN:
  9781000448382
• Auflage: 1
• Thema: Technology & Engineering
• Thema: Agronomy

This book demonstrates the common problems faced by fruit growers throughout the Community and shows the importance of weeds in fruit crops. It summarizes a list of the worst weeds in vine and soft fruits in each European Country.

Session 1
Weed control in vines

Chairman: C.N. Giannapolitis

New aspects of integrated methods of weed-management in Italian vineyards

A. Scienza

Istituto di Coltivazioni arboree, Università degli Studi, Milano, Italy

R. Miravalle

MOITAL, Milano, Italy

Summary

Due to new technical issues and adverse economic facts, Italian wine growers are paying more attention to weed control and soil management systems shifting from several tillage a year to less mechanical treatments, larger use of herbicides, grass-mulch or zero-tillage.

Trials carried out for several years have been followed to control the effetcs of different soil techniques on several parameters (yield, sugar, acidity, vigor).

An integrated system allowing spontaneous and selected weeds growing from harvest time to May followed by chemical weed control in Summer, may avoid weed competition and its negative effect on water and nutrition with less herbicides use, and without the negative impact on the soil structure caused by several mechanical treatments.

Introduction

In Italy 1 600 000 farmers manage 1 150 000 hectares of vineyards. This involves every climatic and pedological area, from sea-level to 1,300 metres above sea-level (Mount Etna, for example), with a thermal summation variation of between 1600°C and 5000°C and average rainfall ranging from 450/500 mm in the South to 1500 mm on the Eastern slopes of the Alps.

As far as the location of the growing area is concerned, 35% of vineyards is in the plains, 56% on the hills and 9% in the mountains. More than 400 cultivars are cultivated using about 32 root-stoks and more than 1000 different kinds of wine are produced, of which nearly 300 are ranked V.Q.P.R.D.

This leads to a wide and diversified range of planting systems (from 800 to 4000 vine-stocks per hectare), of farming and pruning techniques as well as, naturally, different aggressiveness by weeds and their specific control systems.

The most widely-used systems are the Espallier (440,000 ha.) especially in the North-West (Piemonte, Oltrepo’ Pavese and Toscana), the Bush-tree (230,000 ha.) and the Tendone (220,000 ha.) in the South, the Sylvoz and its varietions (120,000 ha.), the Trellis (80,000 ha.) and the Bellussi (60,000 ha.).

Economic aspects

With a gross production value of more than 3,000 billion lira, vine-growing accounts for 9.8% of farming income. Wine production amounts to 70/80 million hectolitres to which must be added 1,400,000 tonnes of table-grapes.

Changes in life-style have led to a dramatic drop in per-capita wine consuption (from 110 litres in 1955 to 81 in 1983); competition due to “alternative” beverages (beer and soft-drinks) as well as certain difficulty in entering the foreign markets have brought about a surplus in table wines.

On the other hand, since production is so parcelled out, no ad hoc response to an adverse market trend is possible. Furthermore, energy dependence coupled with a few production factors have influenced the cost-proceeds ratio by adversely affecting the vine-growers’ income.

There is, therefore, a general need for profitability to pick up again, which means a modernisation process in terms of mechanisation, phytosanitary defence and soil management. The problem of weed management in the vineyard is therefore tackled from an overall point of view, with particular attention being paid to agronomical aspects and by providing the vinegrowers with ad hoc economic solutions.

Soil Treatment

The different ecological areas have developed different soil-management techniques, but weed management is still carried out through several, repeated tillings (almost 80%). About 10% of vineyards are grassed over (all in the North) by resorting to an integrated system of mowing, tillings and weeding.

More than 20% of the wine-growing area is managed with herbicides which usually integrate with tillings and mowing (grass-mulch). To-day only 2% (a percentage which is rapidly increasing) of vineyards are managed in “no-tillage” by resorting to herbicides only.

The most widely-used mixed system is chemical control of weeds under the rows, whereas the inter-row is tilled or grassed over. Regional variations are marked, ranging from 5 to 50% of wine-growers.

The most important fact in the last few years – except for wider use of integrated system – is a qualitative one. The use of herbicides is less a stop-gap measure (in the past the use of desiccants was mostly intended to delay tillings than to replace them) and in situ, localized treatments agaist perennial species – however coupled with tillings – were confined to those vineyards which were most infested with weeds.

To-day the use of chemical herbicides is increasingly regarded as a soil-management method in line with a policy of “conservation-tillage” or “zero-tillage” so as to get economic, agronomical and technical gains.

UNSOLVED PROBLEMS

Traditional tillings

The need to develop some alternatives to traditional tillings stems from the inconveniences which this kind of tilling brings about, especially in clay soils which are fairly common in Italy.

Here, unsuitable tillings (with excess soil moisture) or use of unsuitable operating machines (milling machines or rotary hoes) cause the vineyards to suffer from so-called “compacting syndrome” as it is generally known (spring-time chlorosis, summer reddenings, vegetative and productive decay, sudden death of stocks); this can be ascribed to changes in the physical condition of the soil such as loss of porosity, compacting, anoxia, building up of harmful gases (ethylene, for example) in the soil, the tilling layer.

However, this is not the only hindrance: the operating machines find it difficult to enter and work in most hilly grounds, because of the steep slopes and the small size of plots where mechanisation is both difficult and costly.

Other problems linked to mechanical tillings which still await to be solved regard:

a) erosion hazards and stock wounds which pave the way to the onset of lignivore parasites;

b) the economic aspect in that vineyard-soil management through tillings is the dearest of all available techniques in Italy.

A major aspect – closely connected to the use of machines – must not be ruled out; this concerns the gradual but progressive ageing of farmers as a social class, leading to fewer skilled workers able to operate the machines being available. This social aspect changes the mechanisation process, putting more enphasis on machines which can either replace man or make his work much easier by dwindling down the number of more traditional jobs.

Weed cover

In a few areas sufficient rainfall in Spring and Summer enables forms of weed-cover – especially spontaneous ones – to be used.

Such practice involves several positive aspects such as improvement of soil texture and structure, of microbial life, of the soil bearing capacity, the proportion of organic matter and a reduction in soil erosion; however, it often causes a “water stress” in Summer and, at least in the first few years, it requires a greater amount of fertilizers than tilled soils do.

This is why in Italy, where emergency irrigation is not possible and there are small areas where Spring and Summer rainfall is higher than 700/800 mm – such practice is not advisable. There are, therefore, integrated solutions which enable weed-cover use to be extended to a wider environmental range.

Weeding

In order to overcome both technical and environmental problems relating to the previous systems and to reduce the economic burden, the use of weed-killing techniques has led to alternative solutions.

A few aspects, however, still await to be explained. Namely, it is a question of setting well-defined weeding patterns which enable the present problems, due to improper use, to be overcome.

The problems are temporary effectiveness, uncertain outcome, inversion flora, the danger of residue accumulation in the soil with possible adverse effects on vineyards. Barren no-tillage in soils with a high clay content has caused changes in the clay plates so as to lead to great laminar erosion. Furthermore, in this kind of ground the barren soil in Winter can cause the operating machines to slip; therefore, despite the fact that the soil bearing capacity has improved, this problem has not been solved yet.

Furtherm...