CHARACTERIZATION OF SORGHUM TURCICUM LEAF BLIGHT PATHOGEN AND ITS MANAGEMENT
Loading...
Date
2019
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR
Abstract
In the present research on “Characterization of sorghum turcicum leaf blight pathogen and its management”, survey was undertaken to assess the turcicum leaf blight (TLB) severity in major sorghum growing mandals of Guntur and Prakasam districts. PDI of 30.12% in Prakasam and 27.22% in Guntur district was recorded.
The cultural variability of E. turcicum isolates on PDA was assessed at 8 DAI. Initally mycelium was white and later turned to greenish black (2.5/10Y). The soluble pigment production varied from dark bluish to bluish black. Among all the isolates, Prakasam isolates KTP (8.96 cm) and ELC (8.94 cm) were significantly rapid in their radial growth with growth rate varying between 0.47 mm h-1 to 0.21 mm h-1. Sporulation varied from 0.02 x104 spores/ mm2 (SMG) to 0.35 x 104 spores/ mm2 (IRP). The mean conidial size of E. turcicum isolates ranged from 56.13-72.39 x 15.0015.83 μm and septa varied from 5.67 to 6.71. Conidiophore size ranged from 140.38 to 183.38 x 6.32 to 7.02 μm.
The incubation period of the isolates varied between 24 h (SMG) to 37.33 h (IRP) with least lesion size in DVT (1.68 cm) at 20 DAI. Maximum PDI of 28.64% was recorded with the SMG isolate
Molecular variability was analysed using a total of 25 RAPD arbitrary primers for 12 fungal isolates. A total of 84 bands were obtained that showed 100% polymorphism. The PIC (Polymorphic Information Content) values varied from 0.10 to 0.46. The highest PIC value was recorded with OPA-03 primer, followed by OPH-18 (0.41). The similarity coefficient varied between 0.45 and 1.00. The lowest similarity 0.45 was noticed between KMR and BPT while the highest similarity was noticed
xv
between the isolates of RJP and EDM of 0.93. The dendrogram obtained had two clusters or groups irrespective of the isolates obtained from the geographical distribution. Among the Guntur district isolates, from Bapatla mandal BPT and DVT isolates had 54 per cent dissimilarity and Muppalla isolates IRP and BVM had 68% similarity indicating the existence of different isolates. However, Rajupalem isolates were noticed with 92% similarity (RJP and RDG) and limited variation indicates absence of variation among the isolates.
Similarity of 87% existed between isolates especially EDM (Prakasam district, Komarolu isolate) and RDG (Guntur district, Rajupalem isolate) though geographically far apart.
Under in vitro conditions henna @15% concentration was found to inhibit the radial growth of pathogen significantly (2.64 cm) and could significantly inhibit sporulation to maximum extent (0.007 x104 spores/ mm2). Panchagavya @ 10% was found significantly effective among the cow based natural products with complete inhibition of mycelial growth and sporulation.
Combined treatment of Trichoderma (ST+ FS) + Panchagavya @15% (ST+FS) treatment was found most effective in controlling the disease even two weeks after second spray (64DAS) with the lowest PDI (18.89%) and with minimum area under disease progress curve of 474.26 as against unsprayed check (760.49).
Treatment 5 - Trichoderma (ST+ FS) + Panchagavya @15% (ST+FS) was found with highest number of grains per panicle 502.40 with highest test weight of 3.44 g, yield of 2388 kg ha-1. However, the benefit cost ratio (BCR) of the different treatments varied from 0.70 to 1.56 with the highest BC ratio being recorded with fungicidal spray of 0.25% mancozeb (1.56). However, among non chemical treatments best B: C ratio was obtained in T4 (Trichoderma (ST+ FS) + Henna @ 15% FS) with 1.48 followed by T 5 with a BC ratio of 1.40 treatments which represents a potential alternative to fungicide treatments.
Description
D5901
Keywords
null