It was years in coming, but in November, a major buyer of American leaf finally told tobacco growers it will not purchase any tobacco that contains residues of the growth regulator maleic hydrazide (MH).

“In response to customer feedback and new customer requirements, Universal Leaf of North America has made the decision to not allow the use of maleic hydrazide on any tobacco contracted in 2011,” said George Scott, vice-president for leaf of the leaf dealer, in a Nov. 16 letter to the company’s contracting farmers. “We will be performing residue testing on tobacco grown in 2011, and if your tobacco is found to have any MH residue, your contract will be terminated.”

MH controls the growth of suckers in the leaf axils, so that the suckers don’t drain the plant’s resources from leaf growth. Combined with timely removal of the flowers at the top of the plants (called the tops), MH has allowed growers to consistently increase yields.

It’s not like all this was a sudden development: One set or another of tobacco buyers have been threatening to prohibit MH since W.K. “Bill” Collins first took a tobacco agronomist job with the state of North Carolina.

That was in 1956.

“This is a controversy that has been going on almost constantly for 50 years,” said Collins, who is now on the staff of North Carolina State University. “Many buyers around the world have looked at MH and said they didn’t want it in their products. Now one has taken the step.”

“No buyer or anyone else has ever been able to demonstrate any physiological reason to prevent its use. There is no — repeat no — negative health impact for humans from MH,” said Collins. But that hasn’t mattered to buyers, especially foreign ones, who wish to avoid the presence of any systemic chemical in their finished products.

As this story was written, only Universal Leaf had pushed the MH panic button, but if MH-free leaf turns out to be a competitive advantage for anyone, Collins thinks the others will soon have to follow suit.

“The bigger question now is whether companies that make this change will provide adequate compensation to the farmers,” he said.

Higher production costs

Compensation will be needed because a farmer who has to convert from a sucker control program that uses MH to one that doesn’t will definitely face higher production costs because of increased hand labor.

“If we have to replace MH, we will wind up replacing it with labor,” said Sandy Stewart, North Carolina Extension tobacco specialist. “When you treat with contacts, there are going to be suckers that are missed. As long as we can use MH, it allows us to clean up those suckers. If we have to control suckers without MH, more hand labor will be needed.”

In fact, the timing of labor needs is going to be an important consideration if you have to choose a different chemical to use in place of MH.

“We may be drifting more towards Virginia blends, particularly if manufacturers are restricted in the flavors we can use,” said Collins. “That might be a good omen for North Carolina flue-cured growers.” “This is a controversy that has been going on almost constantly for 50 years,” on tobacco

Stewart expects to see more use of flumetralin, a contact chemical with some systemic action. “Dropline applications are generally the most effective way to apply flumetralin,” said Stewart. “They allow for the most consistent application to each leaf axil. However, they require more labor.”

Successful sucker control without MH starts with proper application rates and timing of contacts, Stewart said. Poor control with contacts cannot be corrected by flumetralin.

When applied by dropline, flumetralin should be mixed the same as with mechanical applications, two quarts of flumetralin in 49.5 gallons of water or three quarts of flumetralin to 49.25 gallons of water. The flumetralin solutions should be applied alone to deliver one half to two thirds of a fluid ounce of solution per plant.

There almost certainly will be one fringe benefit if MH is ever banned completely in the U.S.: It would make our tobacco more attractive to buyers on the international market. For whatever reason, the world prefers its leaf MH-free, and our No. 1 competitor, Brazil, trades hard on the fact that it uses no MH in its tobacco production.

It should be noted that at least one company has for some time prohibited MH use among its farmers, with no negative effect. Santa Fe Natural Tobacco Co. contracts for tobacco grown under an organic program and also for tobacco grown under a no-residue program called PRC. The growers get a premium for leaving out MH and seem happy with the arrangement.