Agriculture Reference
In-Depth Information
on pure sugar yield. Control measures in leaf spot suppression includes cultural practices,
seeding of tolerant hybrids and the use of fungicides. Preventive cropping practices include
sowing of healthy and fungicide treated seeds, proper crop rotation and timely soil
preparation, as well as timely organised fertilisation and weed control. A quality nutrition
directly affects the sugar beet's health.
Application of tolerant hybrids has become a rule in Croatia. By breeding were obtained
tolerant hybrids against this pathogen, on the other side, this tolerance did not influence the
yield reduction, as it was the case with the first obtained tolerant hybrids to fungus
C. beticola
Sacc. Application of fungicides is necessary for sensitive and tolerant sugar beet hybrids
aswell (Kristek et al., 2006, 2008). The efficiency of the treatment depends on the application
time, number of applications and the choice of fungicide - cantact or sistemic. Furthermore, it
is extremely important to choose the right active substance of fungicide, which means do not
use twice the same active substance, or combine two or more active substances in order to
avoid the development of resistance.
As regards the development of genetic tolerance, it is important to note that breeders tried
to increase the genetic potential of hybrids, in the first place, and hybrids for most important
quantity and quality properties, thereafter they tried to increase their resistance to most
important diseases (
Rhizomania, C. beticola, R. solani
). Breeding for resistance to
C. beticola
and other diseases at all is very complicated because it is a relation between sugar beet, as a
host plant, and the pathogen. Difficulties come from the fact that both organisms have their
own heratibility and variability. Resistance to pathogenic fungus
C. beticola
is a very
complex trait. Smith and Gaskill (1970) reported that the resistance to this fungus is
controlled with 4-5 pairs of genes. In breeding it is often not possible to unite resistance with
maximum root yield and root quality. As root yield and root quality have priority we still can
not talk about totally tolerant sugar beet hybrids. So Kristek et al. (2006), testing the
resistance of 26 sugar beet hybrids owned by the most significant plant breeding houses in
Europe, concluded that the used hybrids do not show sufficient tolerance to fungus
C.
beticola
and that in sugar beet production the application of fungicides can not be excluded.
The aim of this study was to determine root yield and root quality of sugar beet under
different climate and soil conditions in dependence of fungicide efficiency and the tolerance
to fungus
Cercospora beticola
Sacc. of the studied hybrids.
M
ATERIALS AND
M
ETHODS
The research was conducted during the field experiments set up in eastern Croatia in the
period from 2010 to 2012.
The experiment involved 8 different hybrids (Table 1) and 3 ways to suppress the
pathogenic fungus
Cercospora beticola
Sacc. via fungicides (1-3 treatments). Considering the
technical side of performing experiments, i.e., the use sowing machines and sprayers, the
experiment was set up in a split-block scheme with 4 replications. Hybrids used in the
experiment were declared as tolerant to
C. beticola
and remain the property of companies
selling seed in Croatia. Only one, slightly older hybrid Belinda is declared sensitive to this
disease.
