Tuber Talk, Potato Sprout Inhibitor Spud Smart Fall 2010

New Potato Sprout Inhibitor on the Horizon

Many scientists specializing in potato storage research have been trying to come up with novel sprout inhibitor solutions for a number of years, but actual commercialized products have been few and far between. As most potato growers know, chlorpropham (CIPC) remains the main treatment for the control of sprouting in storage. Notwithstanding the safety record of CIPC, the trend today is to reduce the use of synthetic pesticides in agriculture, thereby reducing chemical residues in the global food supply. As a result, CIPC is continually scrutinized by the United States Environmental Protection Agency.

California-based AMVA C Chemical Corporation is now in the final stages of commercializing a new sprout inhibitor with the trade name of SmartBlock, technically coded AMV- 1018 (3-decen-2-one). This new inhibitor is said to be a “green” biopesticide—a naturally-occurring molecule, approved as a direct food additive, which also has an environmentally friendly toxicity profile.

According to John Immaraju, manager of international product development at AMVA C and project manager for AMV-1018, global efforts are being made on various fronts by AMVAC to develop this new product line for controlling potato sprouting in storage.

The roots of the new technology can be traced back to work done at Washington State University by Lisa and Rick Knowles. Since 2000, they have been researching a group of novel sprout suppressants. The researchers discovered that certain unsaturated and saturated alpha-beta aldehydes and ketones have unique sprout control properties, and they have subsequently filed a patent in this regard. AMVAC, in 2005, licensed exclusive patents from Washington State University and has completed initial proof-of-concept trials, conducting a number of trials with AMV-1018 to test its efficacy and use as a potato sprout inhibitor in storage that simulates commercial  conditions. The trials were completed in several countries around the world on various key potato varieties.

“SmartBlock represents a totally new approach to sprout control in potatoes and our field trials thus far have been very successful in the United States, Canada, Japan and several European countries,” says Immaraju. The mode of action of AMV-1018 acts only on the exposed rapidly-growing meristematic tissues—or sprouts—in the case of stored potatoes, he says. It acts by destroying the internal cell structure and the sprouts exhibit a “burned out” appearance.

According to Immaraju, potato storage managers should make the first application of AMV-1018 as a thermal fog, when potatoes show signs of breaking dormancy. A 75 per cent “peeping” of sprouts is considered the preferred window for application. Recirculation of the product in the storage facility should be maintained for 24 hours.

“Generally, the apical bud, and some axillary buds, of potato tubers will be the first to be ‘burned off’ by SmartBlock,” says Immaraju. “The second application should then be made when the remaining axillary buds start to ‘peep’ as well. We have found in trials that residual sprout control can be achieved for two to three months depending on the variety and storage temperature. Sprouts up to 2.5 cm can be destroyed [and the dormancy restored].”

Trials completed at Arvalis, the French technical institute for cereals and forage, during the past season have been very successful. According to Immaraju, excellent sprout control was observed with AMV-1018 at 86 grams/metric tonne and 115 grams/metric tonne. Three applications provided at least seven months of sprout control. Although AMV-1018 has a distinct odour, no effect on tuber quality was observed as far as phytotoxicity, fry color and taste were concerned. Additional testing will be done in France in 2010–11.“

Excellent efficacy was also observed with SmartBlock applications in a trial conducted in Dethlingen, Germany, during the 2009–10 season, when two applications of either 86 grams/metric tonne or 115 grams/metric tonne SmartBlock provided residual sprout control from November through to the end of May,” says Immaraju. “Five key varieties with different dormancy characteristics responded equally well during the trials, with no effect on tuber taste, texture or fryquality. Additional testing will be done in 2010–2011.”

According to Immaraju, solo applications of AMV-1018 are an effective way to manage tuber sprouting, but the product can also be used in combination with CIPC. AMV-1018 can be considered a good “follow up” partner for CIPC. Storage managers can use CIPC at low rates early in the season, and follow up later in the season with AMV-1018 on an as-needed basis. A combination program could include:

Early application(s) of a low rate or full rate CIPC followed by AMV-1018 towards the end of the storage season to reduce CIPC residue concerns

One to two CIPC (low rate) plus AMV-1018 combination (simultaneous application) treatments

AMV-1018 has proven to be effective for “burning off” sprouts on tubers coming out of ethylene storages. In this regard, it can assist in restoring tuber dormancy. AMV-1018 can also be used for preventing sprouts or “rescuing” sprouted tubers on processing potatoes that are being reconditioned. According to Immaraju, fresh market potatoes have a longer shelf life when treated with the inhibitor. AMVAC is also developing EC formulations for direct-spraying of fresh market potatoes coming out of storage destined for supermarket shelves.

Immaraju says AMVA C has applied for registration of AMV-1018 in the United States and Canada, and launch of the product is expected early next year. “Organic” classification will be pursued in the United States. A separate registration package is expected to be submitted in the European Union sometime early next year.

By Lukie Pieterse