This is an important book for the purpose of academics, scientists, students, extension workers and others those directly or indirectly involved in agriculture production. It contains very interesting research aspects to study on the diseases caused by Sclerotinia sclerotiorum, which having ability to cause diseases on <400 host plants(economical and non-economical both). It have special information on the S.sclerotiorum molecular and pathogenic variability proven by experiments on cross-infectivity particularly the weed-plants which harbour this pathogen and provide the refresh virulent inoculum to the other economical crops cultivating in the same agroecosystem. The authors have been presented his research work during a special discussion on Sclerotinia Initiative Project session conducted by International Sclerotinia Working Group in International Congress on Plant Pathology (2008), at Torino, Italy. We are very hopeful this book will be helpful to all the person directly or indirectly concerned the research in discipline of Plant Pathology, Biotechnology, Agronomy, Horticulture and other related sciences.