Plants in a natural or protected environment are often found associated with biotic and abiotic causes. Biotic causes sometimes assume serious proportion under congenial condition of the prevailing environment affecting economically important horticultural and forest plant species. Ample information with regards to diseases and management aspect of cereals, fruits, vegetable crops are available but information pertaining to losses, etiology and management practices of most devastating pathogens of flower crops is lacking. The book refers to losses, etiology, epidemiology, screening of resistant germplasm sources and chemical control of Alternaria blight of the marigold species Tagetes spp. With expanding floriculture industry, the diseases of flower crops has increased manifold, the research work carried has emerged out as an effective plant protection strategy in the form of package of practice to be implemented in the field by the farmers, growers or entrepreneurs, students, researchers engaged in discipline of plant pathology to harness maximum benefit.