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Rhizoctonia infestation (?)

aymanesh at hotmail.com aymanesh at hotmail.com
Thu Dec 16 21:11:23 EST 2004

hello susan
here is infestation methods i used and it works
. Pathogenicity tests:
All the isolated fungi were tested for its pathogenicity against sugar
beet seedlings under laboratory and/or greenhouse in pre-infested soil
or eight weeks-old sugar beet plants.
5.1. Laboratory test:
The tested isolates were cultured on 20 ml of ¼ X Czapek-Dox agar
medium in 250 ml polypropylene tissue culture magnate (Sigma) as shown
in Fig (2). Equal disks (5mm in diameter) taken from 7 days-old tested
cultures were inoculated in the magnate center, incubated for 7 days at
25C. Sugar beet seeds variety Sofi, were socked for 24 hours in
running tap water, and then surface sterilized with 1% NaOCl for 2-3
minutes. The medium surface was covered with 50 cm moisten autoclaved
mixture of peatmoss:sand:clay (1:1:1).Ten of the sterilized seeds were
sown on the surface of the soil mixture. Then covered with 50 cm of the
previously mentioned moisten autoclaved mixture. Three replicates were
used for each tested isolate in complete randomized design, and
incubated in growth chamber at 27C for two weeks with 12 hours day
and night intervals (fluorescent day light was 3000 lux). Number of
pre-,post-emergence damping-off and standing plants were recorded.
5.2. Greenhouse tests:
5.2.1. Rhizoctonia pathogenicity test: In pre-infested soil:
Pathogenicity of the isolated Rhizoctonia solani against sugar beet,
mono-germ variety Sofi, was tested by using inoculum layer technique
described by Schmittenner and Hilty 1962 using sugar beet mono-germ
variety Sofi. The used soil mixture was consisted of field soil, sand
and peatmoss (3:1:1.v/v/v) moistened and autoclaved for one hour at
121C. Plastic pots (12 cm in diameter) were lined with paper
toweling, gently packed with 250 cm3 of the soil mixture. Seven
days-old culture grown on WA in 9-cm Petri dish was added as a whole
then covered with 50 cm3 of soil mixture. Twenty-five sterilized sugar
beet seeds (by dipping them in 70% ethanol for 30 seconds, placed in 1%
NaOCl for 2-3 minutes, and then  rinsed twice with sterile distilled
water and dried under a hood) were placed equidistantly on the soil
surface, then covered with 50 cm3 of soil mixture and gently pressed.
The control treatment was un-colonized WA. A randomized complete block
design was used with three replicates for each tested isolate. The pots
were kept under greenhouse conditions at 27C ± 5. Number of
pre-,post-emergence damping-off and standing plants were recorded 3
weeks after planting.

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