Physical and Cultural Weed Control Working Group of - European ...

9 th EWRS Workshop on Physical and Cultural Weed Control 52
Samsun, Turkey, 28 – 30 March 2011
method of drying or exhaustion) and application of total herbicides. In this respect during the period
June – July a treatment with products with active ingredient glyphosate is performed (Roundup,
Nasa 360 SL, Glyphogan, Glyphodin, Glyphosate C, etc.). The most suitable phenophase for
treatment with these herbicides is the beginning of ear formation of cereal weeds, budding (C.
arvense) and full blossom (C. arvensis, Aristolochia clematitis L.). Basic cultivation is performed
one month after the treatment (Tonev, 2000; Tonev et al., 2007).
Currently two major systems for maintenance of the soil surface in fruit tree plantings in
Bulgaria are applied – black fallow and grassing (natural grassing, grass – mulch system) (Stamatov
et al., 1982; Petrov and Grigorov, 1981; Iliev et al., 1983; Zhivondov et al., 2008; Stoynev et al.,
1986). Black fallow is the major system for maintenance of the soil surface in orchards. It is
recommended for cultivation of young trees planted under relatively dry conditions for the country
when there are not any options for irrigation.
This system requires periodic shallow spring-summer cultivations (at a depth of 7 to 10 cm)
and autumn tillage in the inter-rows at a depth of 14 – 16 cm once every three years. The major
advantages of black fallow are: efficient mechanical control of weeds; soil cultivations break the
soil crust which enhances the water and soil regime of the soil; allows for plowing-in of organic and
mineral fertilizers (Stamatov et al., 1982).
However it has been established that along with its positive effects, black fallow also has a
number of disadvantages: the frequent passage of agricultural machines leads to soil compaction
and formation of grooves which retain water during heavy rains or irrigation; significant expenses
for fuel and lubricating materials; the use of disking machines causes fragmentation of the rhizomes
of perennial weeds favouring their reproduction; frequent passage of machines leads to dust
formation in the top soil layer, which has a negative impact on the soil structure; the soil becomes
less rich in organic substances (Stamatov, 1982; Taseva and Ilieva, 1992; Taseva, 1995; Todorov et
al., 1982; Simeonov et al., 1979).
While keeping black fallow, it is most appropriate to combine agrotechnical measures (soil
cultivation) and herbicide application in the rows of plantings. The first soil cultivation is performed
early in spring when soil humidity allows passage of machines. Immediately after this, soil
herbicides are applied. During the vegetation period, the number of mechanized soil cultivations is
determined by the degree of weed infestation. Cutters with diverter sections can be used for
destruction of weed vegetation in the rows (Stamatov, 1982; Taseva and Ilieva, 1992).
In line with the global trend for adoption of ecological approaches and protection of
biodiversity, fruit growing needs to conform to the requirements of Integrated Fruit Production
(IFP). According to the definition of the International Ogranization for Biological and Integrated
Control of Noxious Animals and Plants (IOBC), IFP is the economical production of high quality
fruit, giving priority to ecologically safer methods, minimising the undesirable side effects and use
of agrochemicals, to enhance the safeguards to the environment and human health (Cross and
Dicker, 1994; Rankova, 2006).
IFP is the major method for fruit production in Europe. One of its overarching aims is to ensure
high quality fruit which are economically viable, while maintaining biodiversity, preserving soil
fertility and protecting the health of farmers and end-consumers.
In the context of the requirements of IFP, grass systems for maintenance of the soil surface are
defined as an environmentally friendly approach, which preserves the biodiversity and the structure
of the soil (Zhivondov and Rankova, 2009).
Grass systems for cultivation of fruit trees (natural grasslands, cultivated grasslands, grassmulching
system) are suitable for use in humid regions and on irrigated areas. Permanent grass sod
is established in the inter-rows and the periodically mowed down grass mass is left at the site for
mulching and organic fertilization. The grass sod is most commonly established in the inter-rows,
while the rows are maintained free of weeds by mechanical cultivation (cutters with diverter
sections) or application of herbicides. Grass mixtures of the following species are recommended for
grassing of the inter-rows: