<div>Background: Phytophthora blight (PB), caused by Phytophthora cajani is a prominent disease in the low laying areas combined with intermittent rainfall. Induction of zoospores and sporangia of P. cajani in culture plate is troublesome and also limited information is available on the protocol for sporulation of sporangia and zoospores in the laboratory, The study developed and validated the protocol for induction of sporangia and zoospore of P. cajani.&nbsp; 
 
Methods: The Protocol using 5-7 days old culture, diluted tomato extract broth and other culture conditions like the temperature of 30oC, alternate 12 hours of fluorescent light (2000 Lx) and dark can induce abundant sporangia and zoospores in vitro. 
 
Result: The study developed and validated the new protocol for uniform and profuse induction of sporangia and zoospores of P. cajani. Diplanetism mechanism of Phytophthora spp. was recorded with P. cajani the findings are the first of its kind. Additionally, the study revealed the concentration of 1x10-5 zoospores/ml is optimum to develop the infection in plants with the shortest incubation period of 24 hours.</div>

<div>Laboratory Protocol for Induction of Sporulation in Phytophthora cajani causing Phytophthora Blight in Pigeonpea</div>

<div>Background: Phytophthora cajani causing the Phytophthora blight (PB) disease of pigeonpea. The disease will rampant during excessive rainfall coupled with hot and humid weather during the cropping season. The present study on micro and macro morphological characteristics can contribute to the identification and specification of biology of Phytophthora spp. There are no detailed studies concerning the characterization of the P. cajani are available with this backdrop the present investigation was taken.&nbsp; 
 
Methods: Phytophthora cajani was isolated on V-8 PARP medium, whereas stimulation of zoospores and sporangia was done using the diluted tomato juice broth. Micro and macro morphological characteristics of P. cajani were studied using micrometry and Olympus CX41 phase-contrast microscope. &nbsp; 
 
Result: The pathogen was homothallic with amphigynous antheridium and oogonium and able to produce oospore in vitro. Sporangium was nonpapillate, noncaducous, oviod-obpyriform shape. Further, the macro morphological characteristics like mycelial radial growth and colony type were studied. The colony characteristics were dull white, flat and rosette pattern. Other culture characteristics like optimum temperature and RH were mostly consistent with those reported former.</div>

Laboratory Protocol for Induction of Sporulation in Phytophthora cajani causing Phytophthora Blight in Pigeonpea

Illustration of Key Morphological Characteristics of Phytophthora cajani-Pathogen of Phytophthora Blight of Pigeonpea