Cargill and Dow Chemical are teaming up to make a biodegradable plastic from renewable resources such as corn or wheat instead of from petroleum. The companies say their joint venture, branded NatureWorks, is ready to go into full-scale commercial production, putting the companies at the front of a race among agriculture and chemical firms to find cost-effective ways to make a durable plastic from common plants. The new plastic, dubbed polylactide, is said to be versatile and strong enough to compete with other plastics used for clothing, carpets, food containers, and plastic window envelopes. Cargill and Dow plan to construct a manufacturing plant in Nebraska that will produce 300 million pounds a year of the new plastic, and they say they have lined up enough customers to sell out its first year of production.