190 Journal of Biological Control, 26 (2): 190-193, 2012 Research Note Compatibility of Pseudomonas fluorescens with agricultural chemicals M. SURENDRAN*, G. S. KANNAN 1 , KAMALA NAYAR 2 and S. LEENAKUMARY Rice Research Station, Moncompu 688 503, Thekkekara P.O., Alleppey District, Kerala, India. 1 Department of Plant Protection, Faculty of Agriculture and Animal Husbandry, Gandhigram Rural University, Gandhigram - 624 302, Dindigul, Tamil Nadu, India. 2 Instructional Farm, College of Agriculture, Vellayani 695 522, Kerala, India. *Corresponding author E-mail: surenpath@yahoo.co.in Kuttanad, the rice bowl of Kerala, is an unique agricultural tract with the paddy fields lying 0.6 to 2.0 m below the mean sea level. Rice production in this tract has been laborious and expensive. Kuttanad being endemic to major pests and diseases of rice, is recognized as a “hot spot” for screening and evaluation of a number of commercial pesticides. Integrated management of pests, diseases and weeds has been prevalent in the area for over sixty years. Pseudomonas spp. are effective root colonizers and biocontrol agents by producing antifungal metabolites including antibiotics, hydrogen cyanide and siderophores (O’Sullivan and O’Gara, 1992). In recent years, emphasis has been laid on the combined use of biocontrol agents along with chemical pesticides for effectively managing the pests, diseases and weeds. In the present study, the in vitro compatibility of P. fluorescens (PF 43) with the recommended dosage major groups of insecticides, fungicides and herbicides was explored. A study on compatibility of effective strain of P. fluorescens (PF 43) with fungicides, insecticides and herbicides were conducted during 2011 under laboratory conditions using poison food technique. The doses of each pesticide was fixed as per recommendation of package of practices, Kerala Agricultural University. The standard recommended doses (g/ml lit –1 ) of 15 fungicides, 9 insecticides and 10 weedicides were used ABSTRACT: The compatibility of Pseudomonas fluorescens with 15 fungicides, 9 insecticides and 10 weedicides was tested under laboratory condition. All insecticides, herbicides and 12 fungicides except saaf, kocide (copper hydroxide) and zineb were found to be compatible with P. fluorescens. The study indicated that most of the fungicides, insecticides and weedicides can be mixed with P. fluorescens for use in agriculture. KEY WORDS: Pseudomonas fluorescens, insecticides, weedicides, fungicides, compatibility (Article chronicle: Received: 21-11-2011 Revised: 4-6-2012 Accepted: 8-6-2012) for the compatibility study of P. fluorescens with three replications. The chemicals were mixed with melted King’s B medium separately and poured in sterilized petri dishes. Forty eight hour old P. fluorescens culture was streaked in the centre of each plate and kept under room temperature. A control without chemicals was maintained for comparison. Observations were recorded after 48 hours of incubation by measuring the growth of P. fluorescens in the treated plates. Results of the fungicide compatibility study (Table 1) showed that P. fluorescens PF 43 culture was compatible with 12 fungicides at the commercially recommended doses, except three fungicides namely carbendazim, copper hydrochloride and zineb where the growth of Pseudomonas was completely arrested (Plate 1). Previous studies by Leha and Venkataraman (2001) also have shown that carbendazim was compatible with P. fluorescens. Kishore et al. (2005) found that a combination of P. aeruginosa GSE 18 and chlorothalonil (500 ìg ml –1 ) reduced the severity of late leaf spot in groundnut comparable to chlorothalonil (2000 ìg ml –1 ) alone. All the 9 insecticides tested were compatible with P. fluorescens under laboratory condition (Table 2). Mathew (2003) studied the compatibility of P. fluorescens with nine pesticides and found that mancozeb,