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Epidemiology and Management of Fennel (Foeniculum vulgare) Blight Incited by Alternaria alternata (Fr.) Keissler

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Title Epidemiology and Management of Fennel (Foeniculum vulgare) Blight Incited by Alternaria alternata (Fr.) Keissler
 
Creator Meena, Suresh
 
Contributor BANSAL, R.K.
 
Subject Plant Pathology
 
Description Alternaria blight of fennel caused by Alternaria alternata (Fr.) Keissler
has emerged as an important constraint to the growers of fennel particularly in
Jodhpur, Sirohi, Pali, Tonk and Dausa districts of Rajasthan. Alternaria blight
appeared on leaves, stalks, peduncles and seeds as light brown to dark brown
lesions leading to blight & death of affected parts. Disease intensity varied from
61.00 to 83.00 per cent in five surveyed districts of Rajasthan. Maximum
disease intensity was recorded in Jodhpur (83.00 %) followed by Tonk
(69.66%), Dausa (66.00%), Sirohi (63.66%) and Pali (61.00%).
Isolation from infected plant materials yielded A. alternata. Significant
morphological, cultural and pathogenic variability were observed among fifteen
isolates of A. alternata collected from Sirohi, Pali, Jodhpur, Dausa and Tonk
districts of Rajasthan. Rate of disease progress was significant and positively
correlated with relative humidity, rainfall and negatively with temperature and
sunshine hours. Thus, the disease was greatly favoured by relative humidity
and rainfall.
Maximum disease intensity was recorded on 50 day-old-plants with 10
days old culture. Spore germination was favoured by 25 0C temperature and
100 per cent relative humidity.
Two sprays of mancozeb (0.25%) at 7 and 21 days inoculation was found
most effective in avoiding (48.15 %) the yield loss.
Late sown crop exhibited more disease development as compared to
early sown crop. The wider spacing of 70x40 cm, 60x30 cm and 50x40 cmbetween rows and caused significant reduction in disease intensity over
standard recommended spacing of 50x20 cm.
Among four bio-agents Trichoderma viride was observed to be most
effective in inhibiting mycelial growth and in reducing disease intensity. Among
five plant extracts garlic extract was observed most effective in both in vitro and
in vivo condations.
Among six fungicides tested, mancozeb + carbendazim gave maximum
inhibition of mycelial growth at 100 ppm concentration. In field test, two sprays
of mancozeb + carbendazim (0.2%) at 14 days interval from disease initiation,
was found most promasing in reducing the disease intensity & increasing seed
yield. The cost benefit ratio was highest (1.95) in mancozeb + carbendazim
treatment.
Out of thirty six germplasm lines screened under field conditions, only
RF-101 was observed to be resistant against Alternaria blight. Among four
systemic acquired resistant activators, salicylic acid (100 ppm) proved most
effective in inhibiting mycelial growth (in vitro) and increasing seed yield by
reducing disease intensity in field conditions.
 
Date 2016-11-12T11:11:01Z
2016-11-12T11:11:01Z
2016
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/85210
 
Relation TH2063;
 
Format application/pdf
 
Publisher SKNAU