Bioscience/5.
Molecular biology
Candidate
of Agriculture Beyshova I.S.
Postgraduate
student of natural sciences Dausheva K.M.
Kostanay State University named after A.Baytursynov, Republic of Kazakhstan
Distribution and harmfulness of septoria crops
On the territory of the Republic of Kazakhstan , as in many other
countries , septoria refers to a particularly dangerous disease of cereals .
The disease is caused by fungi Septoria tritici and Septoria nodorum. The
defeat leaves the upper tiers of wheat plants fungi of the genus Septoria cause
significant loss of productivity. Weather and climatic conditions of Kazakhstan
favor the development and dissemination septoria , reducing the profitability
of grain production . According to the Decree of the Republic of Kazakhstan
dated December 10, 2002 ¹ 1295 " On approval of lists of quarantine
objects and dangerous pests " ( with amendments of 23 . 11. 2005) , the
"List of particularly dangerous pests and diseases of plants" was
included Septoria of cereals .
Annual losses due to pests and diseases of agricultural crops, according
to the United Nations Food and Agriculture Organization (FAO), approximately
20-25% of the potential of the global harvest of food crops. Therefore, the
role of plant protection in increasing the production and conservation of
agricultural products is huge.
According to reports, Septoria in cereals distributed in more than 50
countries.
Wheat septoria epiphytoty periodically observed in Western and Eastern
Europe, the U.S., Australia, Central and South America, the Middle East
(Shipton et al., 1971) Thus, in Germany, as one of the most famous and
deleterious diseases of these crops, it cause yield losses of 25-30%, and under
favorable conditions pathogen - up to 46% (Obat, 1987; Ceynowa, 1992; Mielke,
Meiln-Vogeler, 1992; Mielke, 1994). In the UK, septoria leaf has long been a
prevailing pathogen of wheat as on epiphytic years crop losses here reach 65%(Broennimann et al, 1972; E..Baker, 1978; Polley, Thomas,
1991). In France, there was a decrease harvest by 10% for the weak
development of septoria and 25% - with a strong (Anon, 1989). In the United
States during epiphytoties individual varieties of wheat lost to 30-60 % of the
grain . In some states, the disease has caused a loss to farmers of $ 3 million
annually (Onogur, 1977 ; Watkins etal., 1979 ; Eyal et al., 1983). Literature
data testifies that septoria in wheat ubiquitous meets in Eastern Europe
(Jaczewska, 1995 ; Zamorski, Nowicki, 1997 ; Cosic, 1997). In addition, they
are common in neighboring countries , in particular in Ukraine, Belarus, the
Baltic States , Moldova, Georgia, Armenia, Kazakhstan, the Central Asian
republics.
Septoria manifested in the form of
plants and patchiness affects aerial organs cultures in all phases of
vegetations.
On shoots you can see the first signs
of Septoria, although in this period the disease unobtrusive.
Septoria occurs mainly on coleoptiles
resteny as brown hair, stains and mounds the size of a pinhead. On brownish
tissue visible to the naked eye dark fruiting bodies - pycnidia (Babodoost,
Hebert, 1984).
On seedlings of leaves Septoria growing
in the form of brown spots of irregular shape, which under favorable conditions
are formed pycnidia . Individual spots coalesce , causing the entire sheet or a
large part of his withers . With the defeat of adult plants on leaf blades and
sheaths first appear dark spots later brightening with pycnidia on dead tissue
. Pycnidia are often arranged in rows , as they move inside the cavities
(Wiese, 1977). Symptoms of the disease are well defined to earing , and in a
dry year still later ( Chigirev , Vasetskaya , 1989).
On the stem the disease manifests
itself in the form of diffuse white spots; pycnidia formed on the stem rarely.
Spots on the nodes are small, brownish, gradually discolored, with pycnidia in
the central part. In severe cases nodes sunken and darkened, dotted with
pycnidia (Wiese, 1977).
On the ears affected Septoria, visible
brownish-purple spots that, increasing, occupy most of the glumes and attach
the ears characteristic mottled appearance. Affected areas become lighter, and
they are the pycnidia. The disease can capture and stem blight, and grain,
which in severe cases have a brown spot on the dorsal bud (Rapilly et at.,
1973), become frail and wrinkled (Cook, Jones, 1970 Peresypkin Kovalenko, 1977
a).
The above are the most common symptoms
of Septoria, but in the field of disease diagnosis often difficult. Symptoms of
lesions can vary greatly depending on the variety, plant age, and environmental
conditions. Subject to change shape and color of the spots; during dry weather
on them for a long time are not formed pycnidia. Septoria especially difficult
to diagnose and identify the early stages, when there are no fruiting bodies
and the disease can be confused with the natural desiccation (E.Baker, 1978).
Atypical symptoms may coincide with Septoria symptoms caused by other fungi ,
in particular, of the genera Fusarium, Phoma, Pyrenophora, Ascochyta, Didimella
or, rarely, fungi of powdery mildews . Septoria on barley often confused with
gelmintosporioznymi patchiness ( Polozova , 1971; Kovalenko , 1966 ; Prestes,
Fernandes, 1985 : Scott, 1988 : Anon, 1989). Symptoms on the ears are often similar
to those of non-infectious nature spots . Sometimes visible symptoms of
completely absent (Bammon, 1976 : Buschbell, 1986). All of these can cause
serious errors, which lead to an underestimation of septoria , damage is
attributed to other diseases.
In this connection, the diagnosis of
the disease be carried out in vitro using microscopic analysis. If pycnidia on
leaves can not be found, their development can be stimulated by flotation
leaves benzimedazole to UV light (King et all., 1983). There are data on the
studies by light and scanning electron microscopy in asymptomatic presence on
plants (O'Relly, Downess, 1986).
Mechanisms of septoria deleterious
quite diverse. In pathogen infected leaves using cellulolytic enzymes exert
disconcerting effect on leaf parenchymatous tissue , destroying the cell walls
and cell protoplasts (Cordo, Marechal, 1987). Reducing the assimilation leaf
surface leads to the suppression of basic physiological functions of the plant:
decrease in the rate of photosynthesis in 4-9 times , breathing - by 5-17 % ,
resulting in chlorophyll content is reduced by 19,9-40,8 % ( Peresypkin
Kovalenko , 1978Verreet , 1985). Pathogen also prevents displacement of
nitrogen into reproductive organs of a plant (Verreet et al., 1988). Proven
ability of the fungus to form phycotoxins ( Kobielski , 2002).
Thus, septoria has considerable
economic importance, causing significant crop damage crops, both in our country
and abroad.
Literature:
1.Marland,
1948; Teterevnikova-Babayan, 1962; Markiavichus, 1978; Borzionova et al, 1989;
Mucha, 1990; Peresypkin Kovalenko, 1977a; Koishibaev 2002.