The carpels of pearl millet (Pennisetum typhoides) are infected bySclerospora graminicola. Vegetative mycelium present in the diseased mother plant infects the carpel through the stalk of the spikelet. This process may or may not cause hypertrophy. Zoospores infect the carpel through the stimga and style, without inducing hypertrophy. Infection process leading to the establishment of downy mildew mycelium in the carpellary tissue and its implications are discussed.