Solan: Scientists of the Dr YS Parmar University of Horticulture and Forestry, Nauni, have achieved a rare feat by developing high- yielding hybrids of white button mushroom through crossing. The newly developed hybrid-4 is a cross between U3 and A-15 and it has recorded an outstanding average yield of 26.10 kg per 100 kg compost against 22.50 kg recorded in U3 and 14.02 kg in A-15 parents during the cropping period of 60 days on short method of compost.