The three potatoes on the left were treated with SmartBlock whereas the three on the right were not treated with a sprout inhibitor.
The three potatoes on the left were treated with SmartBlock whereas the three on the right were not treated with a sprout inhibitor.

SAN ANTONIO — With not yet a full season under their belts, applicators are continuing to learn about the nuances of a new chemical that literally burns the eyes off of sprouted storage potatoes.

So far, they say they’ve been encouraged with the performance of SmartBlock, a sprout-control chemical registered by the Environmental Protection Agency in February.

The product from Newport Beach, Calif.-based Amvac Chemical Corp. is designed as an alternative to CIPC, a commonly used sprout inhibitor, said Tony Zatylny, marketing director.

SmartBlock contains a naturally occurring molecule already found in many foods, including yogurt and mushrooms, he said. Because of this, it’s exempt from U.S. tolerances, and the company is considering organic listing.

CIPC, on the other hand, is a carbamate, and the EPA has limited the total amount of carbamates used on food crops. CIPC also faces challenges in some export markets that have no or reduced tolerances for the product.

Unlike CIPC, which is applied beforehand to prevent sprouting, SmartBlock is applied once the potatoes break dormancy and begin to sprout. Depending on temperature and other environmental conditions within the potato storage shed, it can provide two to three months of sprout control, Zatylny said.

Much like CIPC, SmartBlock is applied by custom application companies that specialize in treating potatoes in storage, he said.

Amvac is working with three companies nationwide: Agri-Stor Co., Twin Falls, Idaho; Nelson’s Vegetable Storage Systems Inc., Plainfield, Wis.; and GRB Technologies Inc., Mitchell, Ontario.

Under the arrangement, the applicators are working to fine-tune application techniques and will share their new-found knowledge among each other.

Nathan Oberg of Agri-Stor said he approaches each storage shed differently and looks at a variety of factors, such as potato temperature, variety, moisture, time frame and end use before writing an application prescription.

“It’s been very interesting for us to learn how to apply SmartBlock alone and SmartBlock with CIPC,” he said. “We’ve seen positive results, but the product is definitely different in terms of rate structures and how we apply it compared to other products on the market.”

Oberg said some Idaho grower-shippers are looking at SmartBlock alone and as part of a combination. After the end of the storage season, they’ll compare the results and determine each treatment’s return on invest for their individual operations.

So far, Oberg said he’s been impressed with the results of SmartBlock, although he hasn’t been through one complete storage season yet.

“What we’ve seen is there are no issues with defects or black spot on potatoes,” he said. “It burns these buds or peepers. It’s not going to cause any damage below the skin.”

Oberg said he also has been able to try the product under a worst-case scenario in a shed were sprouts were 6-12 inches high around the outside of the pile.

The potatoes, which originally were destined for cattle feed because of what Oberg described as a “forest” of sprouts, were cleaned up enough to go to processing, he said.