DENVER — Washington marijuana business owners are urging regulators to require cultivators to test adult-use crops for pesticides, a move that has triggered alarm bells among smaller growers. Some cultivators hope such a move — already adopted in other states — would inspire confidence among consumers and bolster recreational marijuana sales. But smaller growers — already squeezed by falling prices — worry they wouldn’t be able to afford mandatory pesticide testing, which is estimated to cost up to $300 per test. The move also could force small farmers to cultivate fewer strains to keep costs down, although regulators so far have not signaled they will require the testing. “Fundamentally, requiring pesticide testing doesn’t bother me,” said Mark Greenshields, a cannabis grower in Seattle, “but technically, increasing the costs, that’s a problem.” Regulators already conduct random pesticide checks.