Solanky, Kalyansinh UdesinhPatel, B. K.2018-06-212018-06-211992http://krishikosh.egranth.ac.in/handle/1/5810054785Chicory (Cichorium intybus L.), a unique cash crop of the monosequential cropping system, is being grown in Gujarat. In epiphytotic conditions, about 90 per cent leaf area was found to be covered by distinctive small, necrotic, circular, coalesced black spots (4.07 x 3.40 mm) with brown centre and the zonate, brown spot (6.36 x 4.90 mm) with dark brown margin and dirty white centre, were appeared simultaneously without stromata and found to be caused by Cercospora cichorii Davis (of C. apii group, IMI herbarium No. 353409) and Cercospora cichorii Davis (of typical genus, IMI herbarium No. 353410). Black spot produced bigger hyaline conidia (100.50 x 3.86 >im) with 2-11 septa than the pure isolate (45.90 x 3.78 pm) with 2-8 septa. Similarly, brown leaf spot also produced the bigger conidia (138.10 x 4.19 yim) with 3-14 septa than the pure isolate (58.40 x 3.81 um) with 2-11 septa. Both, black and brown leaf spot aerobic isolates lost the sporulation within 4 transfer on carrot leaf decoction agar medium. C. cichorii survived in the leaf debris, as saprophyte, without stromata and infected the same crop in subsequent season. Brown leaf spot (CL-2) isolate typically changed the substratum colour of Asthana and Hawker's medium into brown and differed from black, spot isolate (CL-1). Cercospora leaf spot disease increased the phenol and decreased the total chlorophyll, chlorophyll 'a' and 'b', amino acids and nitrogen content by 32.48, 54.15, 67.34, 61.16, 29.54 and 23.26 per cent respectively. None of the crop/plant was found to be infected by these host specific ' pathogens under natural conditions. Significantly the highest radial growth (65.66 mm) and dry mycelial weight (362.33 mg) was recorded on carrot leaf decoction agar and Richards solution on 15 and 20 day of incubation at 30°C temperature respectively. This fungus significantly grew best (58.33 mm) in diffused day light with one hour exposure to sunlight (morning 08.00 to 09.00 hrs). Brown leaf spot isolate grew best at 30°C temperature when pH adjusted to 6.00, without sporulation. On replacement of sucrose and potassium nitrate from the basal Richards" solution, starch, urea and ammonium dihydrogen orthophosphate individually gave significantly the highest dry mycelial weight by 459.00, 423.33 and 457.33 mg respectively, without sporulation. Naphthalene acetic acid (750 ppm) inhibited the fungal growth, but gibberellic acid, kinetin and 2,4-D increased the fungal growth with increase in concentrations Gibberellic acid (250 ppm) and 2,4-D (50 ppm) gave the maximum sporulation of this fungus - CL-2. Trace element Mg (2500 ppm) and a vitamin biotin (1 ppm) found to be essential for the better dry mycelial harvest, without sporulation. Sterols were found ineffective in sporulation and fungal growth. In iri vitro studies, Trichoderma spp. and Aspergillus spp. completely over grew the colony of Cercospora cichorii Davis. Pseudomonas sp. - A (GSFC), Bacillus sp. and a milk bacterium - Bifidobacterium adolescentis (HB1) showed significant reduction of fungal growth by 33.67, 23.15 and 29.67 per cent respectively. Under field conditions, Pseudomonas sp. - A (GSFC) gave the maximum reduction (29.55) in per cent disease intensity as compared to control, followed by a milk bacterium - Bifidobacterium adolescentis (HB1) (27.927%) and remained at par. Phytoextract of Pothos scandens L. @ 57% proved superior as the fungal inhibitor (65.357% inhibition) over rest of the phytoextract and botanical insecticides studied. Extract of Caesalpinia crista L., Nerium indicum Mill, and Vitex negundo L. increased the fungal growth, whereas phytoextract of Calotropis gigantea (L.) R.Br., Catharanthus roseus (L.) G.Don., Lawsonia infermis L., Nerium indicum Mill., Lantana camara L., Vitex negundo L. and a botanical insecticide repelin favoured the sporulation.enPLANT PATHOLOGY, AGRICULTUREA StudyThesis