Potato sprouting in storage is almost always undesirable not only because of changes in tuber physical condition such as shrivelling but also changes in carbohydrate composition. Sprouting tubers often contain high levels of reducing sugars which lead to undesirable browning of processed products. Sprouting typically leads to excess moisture and heat in storage aggravating decay problems.

Sprouting is especially troublesome in "organic" production systems because most if not all labelled materials are considered uccaceptable by consumers. Processors of organic potatoes are typically limited to the first two or three months after harvest. Research is currently underway to develop "organic" sprout inhibitors. Likewise, potato breeders everywhere are attempting to develop "cold processing" varieties which can be stored at low temperatures to restrict decay and sprouting.

Sprout growth in storage depends on a number of factors including:
 

• storage temperature -- warm temperatures promote sprouting;
• cultivar -- late-maturing varieties typically have longer dormancy (sprout-free) periods;
• growing, storage, and handling conditions -- stress in the field or injury during harvest and handling can physiologically age tubers and thereby lead to earlier sprouting.

 

Sprouts can usually be chemically controlled in the field with maleic hydrazide or in storage with chlorpropham. Be certain to obtain and use a current label.

Maleic Hydrazide

Label recommendations change from day to day. The following rates may no longer be applicable. Always follow current label directions. Labels can be obtained from the manufacturer or via websites such as CDMS--Agrichemical Database or C&P Press Greenbook.
 

Royal MH-30XTRA; 1-11/3 gals/acre.

Royal MH-30SG; 5 lbs/acre

Super sprout Stop; 1 - 11/3 gals/acre

Super Stop 60WS; 2 - 2 2/3 packets/acre
 

Apply any of the preceding during late season to healty, growing, non-stressed vines. Apply when most of the tubers of Russet Burbank are 4-6 oz and round white varieties are 1 3/4 - 2" in diameter. Apply at least 2 weeeks before application of vine killers. If rain occurs within 24 hours of application, the material will be less effective. Do not apply MH at temperatures above 85F.

Chlorpropham

Label recommendations change from day to day. The following rates may no longer be applicable. Always follow current label directions. Labels can be obtained from the manufacturer or via websites such as CDMS--Agrichemical Database or C&P Press Greenbook.
 

Sprout NIP 7A; Custom applied during storage. May be applied as an aerosol after cuts and exposed tissues have healed over. Control is best when the material is applied shortly after tubers have healed and before sprouting has begun.

Sprout NIP; w gal/2800 cwt, pre shipping. Applied as an emulsifiable concentrate when potatoes are removed from storage for packing. Dilute 1 gal. of SPROUT NIP in 35 gals. of water and agitate to a uniform 1% emulsion. Apply 1 quart of the 1% emulsion to 2000 lbs of potatoes through spray nozzles at the drying table.
 

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