Recently, potato crop in eastern Uttar Pradesh has been seen with new symptoms similar to brown spot disease reported from other parts of the globe. The involvement of the A. alternate with the disease was confirmed (data

A total of thirty isolates of A.alternata were evaluated for their characteristics at four different temperatures viz., 15, 20, 25and 30 o C on potato dextrose agar medium (PDA).The data recorded on colony diameter and rate of growth after incubation at various temperature was found significantly different. Results revealed that most of the isolate had maximum growth at 30°C followed by 25°C. Minimum growth for most of the isolates was recorded in 15°C followed by 20°C. Rate of growth at different temperatures for most of the isolates of A.alternata was also found significantly maximum at 30°C followed by 25°C except few isolates like Pindra, Chirrayyakot, Jamalpur (JJ), Keshavpur, Bhikharipur, Raibarely and Nalanda where growth rate at 25°C was higher than 30°C.

It is now an established fact that strains of Trichoderma and Pseudomonas are most capable among all the potent biological control agents against phytopathogenic microorganisms recorded till now. They are effective against pathogenic microbes by the virtue of their capacity to produce some antagonistic chemicals (antibiosis), competition for food and nutrition, direct killing (parasitisation) etc. One such study was conducted to know the interaction between Trichoderma spp. against Rhizoctonia solani causing sheath blight disease in rice. Nine isolates of Trichoderma were tested for its parasitisation ability under dual culture shown and it was found that 77.03-100 per cent inhibition of Rhizoctonia after 72 hours of inoculation. Also, the effect of inhibiting volatiles was seen by inverted plate technique. It was found that none of the nine isolate of Trichoderma significantly reduced the growth of R. solani by producing volatiles and inhibition percent was found only 3.88-5.60 per cent. Three isolates of Pseudomonas florescens inhibited the growth of the test fungus by only 30.36-34.81per cent, which is very less when compared to fungal biocontrol agent Trichoderma.