CROP PROTECTION Plant Pathology – North Zone
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F - 1 - CROP PROTECTION Plant Pathology – North Zone Path.1 Epidemiological studies on cotton diseases Path.1 (a): Observations on the occurrence of various diseases Cotton scientists from Regional station, Faridkot conducted survey at regular intervals of farmers field and research farms in cotton growing districts of Punjab. Cotton leaf curl disease (CLCuD), Bacterial Blight (BB) and Fungal Foliar leaf spots (FFLS) were the diseases observed in different districts. The PDI of CLCuD varied from 3.5 to 59.2 %, 29.1 to 53% ; 12 % to 40 % on varieties/hybrids like RS 921, RST-9, F 846, F 505, F 1861 , F 2383, F 2228, US 51 BG II , RCH 776 BG II, Bioseed 6588 BG II and RCH 773 Bt in different villages, research farms of Faridkot, Fazilka and Muktsar districts (Table 1). Bacterial blight was found in traces to 3.1% in Faridkot and traces to 2.1% in Fazilka and traces to 2% in Muktsar on hybrids like Bioseed 6588 BG II, RCH 773 BG II, RCH 776 BG II, US 51 and various entries of co-ordinated trials in different cotton growing areas. The fungal foliar leaf spots caused by Alternaria, Myrothecium and Cercospora, ranged from traces to 3.0%, Traces to 2.4% and Traces to 2.1% DI on RST-9, RS 921, F 846, HS 6, Bioseed 6588 BG II , RCH 773 BG II, RCH 776 BGII and US51 BGII and on different entries of research farms. (Table 1). Six major Blocks were covered in the district Bathinda i.e. Nathana, Talwandi, Sangat, Bathinda, Rampura and Maur by RRS, Bhatinda. During Kharif 2018, severity of the CLCuD was found to be less in the cotton fields of Bathinda district as compared to the previous years. During Kharif 2018, initial incidence of the CLCuD having the disease severity Grade I was noticed in the village Mehman Dwana in the Bathinda district on July 03,2018 in the Bt cotton hybrid RCH 776 BG II. The incidence of CLCuD having the disease severity of grade II-III was noticed in the timely sown (in May)Experimental trial and Grade V-VI in the late sown(in June). The CLCuD PDI ranged from 0-49.17in experimental trial. Incidence of root rot, having the per cent disease severity, ranged from 0- 5% were found in the isolated pockets at 7-8 locations of the cotton field of Bathinda district. An incidence of fungal foliar leaf spots was also noticed but its severity grade was found to be maximum upto 1. After heavy rains during the second fortnight of September, incidence of fungal foliar leaf spot was noticed approximately after 120 days of sowing. Incidence of Bacterial Blight was also noticed in traces at the farmer’s field with maximum grade upto 1. The most popular Bt cotton hybrid sown in Bathinda District was found to be RCH 773 BG II followed by RCH 776 BG II and US 51 BG II. In Talwandi and Maur block of Bathinda district, during the month of June 2018, few plots of the cotton field raised on beds were affected with the accumulation of salts on the raised beds and plants were completely dried. (Table 2 ). The data on disease intensity of leaf curl virus was recorded during Kharif 2018 by surveying the cotton growing areas of Sriganganagar and adjoining areas of Hanumangarh districts of Rajasthan state. Out of four tehsils surveyed in Sriganganagar district, in Sriganganagar tehsil, disease intensity of leaf curl virus was found to be highest i.e. 23.8 per cent. In Srikaranpur, Padampur and Sadulshahar tehsils the average disease intensity was 22.1, 10.7 and 9.5 per cent, respectively. In adjoining cotton areas of Hanumangarh district the average disease intensity was 12.1 per cent (Table 3). The survey was conducted to record the occurrence of different diseases in major cotton growing districts (Hisar, Bhiwani, Fatehabad, Sirsa and Jind) as well as in the non- ICAR-All India Coordinated Research Project on Cotton – Annual Report (2018-19) F - 2 - traditional areas of Haryana (Mahender Garh, Rewari, Palwal, Jhajar and Rohtak) from June to September, 2018. At HAU research farm cotton leaf curl virus disease ranged from 9.50 to 64.77 per cent. Whereas at farmer’s field the PDI was low as compared to the HAU research farm. The highest per cent disease index (PDI) 33.0 per cent in Nidani district Jind followed by 30.0 per cent in Nidana and Ikkas district Jind and Dhand district Fatehabad (18.3%), in Dhani Sobha district Hisar 28.2 per cent, Meham district Rohtak 18.0 per cent and Kharkari district Bhiwani 13.4 per cent. Whereas, in Mahendergarh, Palwal, Jhajar and Rewari districts PDI ranged from 8.0-13.0 per cent. Among the fungal diseases Myrothecium leaf spot (MLS) PDI varied from 1.0 to 7.0 per cent. Other diseases viz. Alternaria leaf spot (ALS) and Bacterial leaf blight varied from 0-5.2 per cent, Root rot varied from 0-5 per cent (Table 4). Path.1 (b): Disease progress in relation to weather factors. Cotton leaf curl viral disease (CLCuD) was first observed on all the varieties in the 26th SMW. Observations on the appearance and progress of CLCuD were taken at weekly interval starting from 25th to 44th meteorological week at Faridkot. It was found that CLCuD % increased up to 44st meteorological week in all the varieties sown. Max PDI attained in CLCuD was 59.30 in variety F 846 . The intensity of disease at intial stage was very less. The bacterial blight was started late in the season in 31st meteorological week with 0.1 % DI. The fungal foliar leaf spots caused by Alternaria, Myrothecium, and Cercospora ranged from 0.1 to 2.9; 0.1 to 2.7 and 0.1 to 2.7 disease index from 31st meteorological week in all the varieties. (Table 5). Susceptible variety RST-9 of cotton was sown on 25.5.2018 in 545 square meter area following recommended package of practices to record weekly progress of leaf curl disease at Sriganganagar. Leaf curl disease first appeared on 21st June after 26 days of sowing during 25th St. week and the incidence at the end of this week was 5.4 per cent. However in subsequent standard week’s leaf curl incidence in crop showed fast progressive increase reaching maximum level of 100.0 per cent on 27th July during 30th Standard week. Data presented in Table indicate that disease incidence was increased gradually up to 27th Std. Week (2 July – 8 July) with disease severity of 40.0 per cent. In subsequent 28th to 30th std. week disease progression was found very fast reaching to the level of 100.0 per cent. The overall precipitation from June to August (vegetative phase) during this year was 220.0 mm. The average weekly temperature during this period of June to August remained between 27.3 to 47.6 oC and maximum relative humidity ranged between 40.1 and 80.0 per cent (Table 6). CLCuD appeared on 5th June, 2018 in the 23rd standard meteorological week after 30 days of sowing and disease incidence was 0.7 which increased upto 95.3 per cent on 39th week and per cent disease index was 0.1 which increased up to 48.7 per cent at Hisar. PDI on 41st week (8.10.18-14.10.18) was maximum, during this period the average maximum and minimum temperature recorded were 32.50 and 17.90oC, whereas, morning and evening relative humidity was from 86 to 42.80 per cent with 6.80 bright sun hours having whitefly population 36.20 per three leaves . The per cent disease index increased upto 48.7 per cent in the second Week of October, 2018. (Table 7). The leaf curl virus disease initiated in 25th met week (18-24 June) and the incidence reached 100% by 34th week (20-26 Aug) at Sirsa. An increasing trend of whitefly incidence ICAR-All India Coordinated Research Project on Cotton – Annual Report (2018-19) F - 3 - from 1.3 per 3 leaves up to 16.4 whiteflies per 3 leaves was observed during the season. The maximum temperature ranged from 34.1 to 38.30C whereas minimum temperature was between 21.4 to 27.40C. Relative humidity morning and evening ranged between 65.0 – 83.7 and 48.0-66.9 % respectively. The total rainfall received during this period was 202.5 mm (Table8). Path.2(a). Screening of AICCIP breeding lines for disease reaction The breeding lines in various national and zonal trials were screened against important diseases in the area. In each screening trial susceptible checks for the diseases were maintained and their reaction is presented at the end of each table where data from different locations of a trial is pooled. The reaction of a particular entry is considered valid provided there is either susceptible or moderately susceptible reaction in the susceptible check. The results of National trials are given in Tables – 9 to 14. The results of zonal trials (north zone) are given in Tables 15 – to 18. Path.2 (b): Confirmation and maintenance of disease resistant lines. The data presented in Table revealed that out of nine entries tested under field conditions against cotton leaf curl disease (CLCuD) at Faridkot, four entries viz., F 2382, CSH3075, RHCHD1406 and LH2108 showed resistant reaction. Four entries namely , RS 2814, RS 2821, RS 2814, PAUBT-1 gave moderately resistant reaction except RST-9 gave moderately susceptible reaction.