Novartis, the world's second-largest drug maker behind Glaxo Wellcome, said it agreed to buy Merck & Co.'s crop-protection unit for $910 million in a bid to boost its agribusiness sales. The Swiss company said the purchase includes the rights to Merck's agricultural pest-control unit and about $21 million in inventories, but not the business' manufacturing plants. The unit generated sales last year of $200 million. "It's a good move, for crop protection is one of the core areas of Novartis," said Peter Stenz, who manages $560 million in equities at Swissca Portfolio Management. Shares of Whitehouse Station, N.J.-based Merck, the United States' biggest drug company, declined 12.5 cents to close at $92.50 on the New York Stock Exchange.