Long-term protection from weeds in the vineyard

Davor Popović, M.Sc.Agr.

In the intensive cultivation of vines the role of weed control is very important. It is estimated that weeds in Croatian vineyard farming cause an average decrease of 8% in wine grape yields. The root system of vines pervades the land and draws water and minerals from it, and so do the weeds in the vicinity. Therefore, in order to maintain regular yield and quality, the soil under the vines must be free of weeds.

Generally speaking, in arid (drier) climate conditions we inhibit weeds using herbicides and tillage. In the north-western parts of Croatia the prevailing way of soil care is inter-row mowing (mulching) of grass, and we preserve the soil beneath the rows using herbicides. Also, it is important to know that in new plantations (1 to 4 years old) the use of herbicides is avoided, because the stems are still green and that could cause negative effects of herbicides on the vine.

In modern vine plantations it is unthinkable to cultivate vineyards without the use of herbicides. Earthing up of plantations is done in new vineyards up to 4 years of age, after which it is allowed to start using herbicides. When using herbicides, it is very important to be careful and avoid drift of the agent to the green parts of the plant, in order to avoid the damage of herbicidal effect.

Herbicides that inhibit the growth of weeds are usually applied after fertilization and top dressing, in the spring period. It is recommended to spray the weeds when they reach 15 to 20 cm in height, by early May at the latest, in order to keep as much moisture in the soil as possible, and at the same time use the dried weeds as a cover against undesirable drying of the soil in the warm days to come.

Until recently, the prevailing opinion was that one-time use of any herbicide could not solve the problem of weeds throughout the year. It was necessary to know the weed flora well and choose the best method of control. But with the emergence of the new active substance flumioxazine, there have been new discoveries and that opinion has changed. Using a combination of herbicides TOTAL 480 SL and PLEDGE 50 WP once a year, one can get herbicidal protection in the vineyard throughout the growing season. This kind of combination ensures that the soil in the vineyard is free of weeds until the beginning of autumn, when the growth of new weeds has no effect on the vineyard yield. TOTAL 480 SL affects the green plant mass and causes it to dry, while PLEDGE 50 WP affects the new broad-leaved and part of narrow-leaved weeds, which sprout from the root, rhizomes and seeds. After a one-year treatment with a combination of TOTAL 480 SL and PLEDGE 50 WP a herbicidal «film» on the soil surface is created, which prevents the growth of weeds. The active substance in TOTAL 480 SL is glyphosate, while the active substance in PLEDGE 50 WP is flumioxazine, characterized by not being washed out by water from the surface, and is therefore quite acceptable in karst terrain.

The aforementioned combination of herbicides is recommended for weed control in two ways: in strips (within rows) and throughout. The recommended dosage for:

- for the treatment of the entire surface: 0.70 kg/ha Pledge 50 WP and 4 l/ha Total 480 SL
- for the treatment in 70 cm strips: 0.25 kg/ha Pledge 50 WP and 1.5 l/ha Total 480 SL

The use of herbicides only once a year has positive effects in the end. Reduced human labor, less use of mechanization, reduced amount of herbicides and reduced trampling of the soil results with financial savings in the end, which puts a smile back on the face of every vine grower.