Ukraine:  Limited Frost Damage on 2012/13 Winter Wheat

Cold weather prevailed in Ukraine during late January and early February, raising alarms about potential damage to winter crops. Weather data and satellite imagery indicate that Ukraine’s 2012/13 winter-wheat crop likely did not incur significant widespread damage as a result of the low temperatures because of the presence of adequate protective snow cover throughout most of the country. Current prospects for 2012/13 winter crops remain poor, however, due to severe and persistent fall dryness that hampered emergence and establishment in all regions of Ukraine.

The condition of Ukraine’s winter crops was poor in early December, before the crops entered dormancy and prior to the first significant snowfall. Satellite-derived vegetative indices indicate that crop conditions were worse than normal in almost every territory of Ukraine following three consecutive months of meager rainfall and below-normal surface moisture. (See December 14 USDA/FAS report.) According to an assessment report the Ministry of Agrarian Policy, only 23 percent of sown winter-grain area was in good condition at the beginning of February, compared to 56 percent in mid-January 2011. An estimated 43 percent was either in weak condition or had failed to emerge, compared to only 7 percent last year. The conditions described in February were virtually identical to the Ministry's January 5 assessment.

Regional average minimum temperatures (i.e., the average of multiple stations within several designated regions in Ukraine) repeatedly fell below minus 20 degrees Celsius in eastern Ukraine, north-central Ukraine, and western Ukraine between January 25 and February 13. Temperatures were higher in southern Ukraine. Although some individual weather stations in Ukraine reported record low temperatures for individual days during this period, the cold was generally less severe than for the same dates in 2005.

The impact of this season’s frigid weather on winter crops was limited by the presence of protective snow cover measuring roughly 6 to 8 centimeters (about 3 inches) in southern and eastern Ukraine, and 16 centimeters (over 6 inches) in north-central Ukraine. Snow depth was substantially below normal through the first half of January, but snow was in place prior to the arrival of the low temperatures on January 25. Winterkill-estimation models indicate that snow depth of only 5 centimeters can protect winter wheat from sustained minimum temperatures of minus 25 degrees Celsius. While localized damage to winter wheat is inevitable on fields devoid of snow cover, or in pockets marked by particularly low temperatures, significant widespread losses to 2012/13 winter wheat due to frost are unlikely. Winterkill thresholds are lower for winter rape and winter barley. Frost damage to these crops is much more likely, and their lower tolerance for cold weather, compared to winter wheat, is reflected in the winterkill rates.

The valuable contribution of Yuliya Dubinyuk, USDA/FAS agricultural specialist in Kyiv, is gratefully acknowledged. Initial USDA forecasts of 2012/13 global crop production will be released in May 2012. Current USDA area and production estimates for grains and other agricultural commodities are available on IPAD’s Agricultural Production page, or at PSD Online.