Ukraine: Frost Damage to Winter Wheat in Eastern Region

A combination of low temperatures and shallow, patchy snow cover likely resulted in frost damage to 2006/07 winter wheat in eastern Ukraine between January 17 and January 19. Weather data indicate that damage was limited to three territories (oblasts) in far eastern Ukraine: Kharkiv, Donetsk, and Luhansk. These oblasts together account for about 20 percent of Ukraine's winter wheat area. The frost threat was more extensive in the Southern and Volga Districts of European Russia, where up to 40 percent of the winter wheat was subject to potentially damaging conditions.

The Ukraine winter grain crop was already in poor condition prior to the January cold snap. Excessive fall dryness delayed planting and hampered establishment of Ukraine's 2006/07 winter crops (see October 20 article). The dryness also contributed to a significant year-to-year reduction in planted area. According to the State Statistical Committee, sown winter grain area fell to 6.06 million hectares (against 7.46 million for 2005/06), including 5.14 (6.32) million wheat, 0.54 (0.48) million barley, and 0.38 (0.66) million rye. Farmers also planted 0.42 million hectares of winter rape, nearly tripling last year's area. A gradual decline in temperatures from late November through mid-December provided favorable conditions for winter crops to advance through the hardening process and achieve full dormancy, which increases the crops' frost resistance. Nevertheless, Ministry of Agricultural officials reported in late December that nearly 30 percent of the country's winter crops, while fully dormant, were in a weakened state due to the unfavorable establishment conditions. The poor condition of the crops reduced their ability to withstand the cold weather that arrived on January 17. Furthermore, the thin snow cover provided little protective insulation, especially for crops in eastern Ukraine. (See temperature maps for January 17, 18, and 19 and snow cover map for January 18.) Fully hardened winter wheat typically is capable of withstanding temperatures of approximately -18 degrees Celsius at the tillering-node depth (about 3 centimeters, or slightly over 1 inch). For crops that underwent insufficient hardening, or were in an otherwise weakened state, the critical temperature would be three to five degrees higher.

Despite the cold weather, meager snow cover, and relatively poor condition of the winter crops, most of Ukraine's winter wheat likely escaped significant frost damage. Assuming a damage-threshold temperature of -15 degrees, which is typical for a crop with slightly reduced cold tolerance following unfavorable establishment conditions, weather data indicate that frost damage to wheat occurred only in Luhansk and Kharkiv oblasts in extreme eastern Ukraine. Using a more cautious threshold temperature of -12 degrees, for wheat with significantly reduced cold tolerance, weather data indicate that the region of potential damage expands only slightly, to include Donetsk oblast as well. According to the State Statistical Committee, winter wheat for 2006/07 was planted on 372,000 hectares in Kharkiv (7 percent of the Ukraine total), 354,000 hectares in Donetsk (7 percent), and 236,000 hectares in Luhansk (5 percent).

In Russia, meanwhile, a significant portion of the country's 2006/07 winter wheat was subject to potential frost damage. (See January 25 article.) Weather data indicate that shallow snow cover provided inadequate protection from bitterly cold weather in parts of the country's prime winter wheat region. Winter wheat typically accounts for 35 to 40 percent of total Russian wheat area, and 50 to 60 percent of production. Rostov and Volgograd oblasts, which together account for about 25 percent of Russia's winter wheat, were likely the most severely affected territories. The data also indicate damage in parts of Saratov, Voronezh, and Belgorod oblasts. Krasnodar and Stavropol, two of the country's most important winter wheat territories, escaped significant damage to wheat although damage to less-resistant winter barley was likely.

A second wave of cold weather moved across Ukraine and European Russia during the last week of January, but the drop in temperatures was preceded by substantial snow that insulated winter crops and prevented significant damage.

Note that total winterkill in both Ukraine and Russia will not be limited to the January frost damage but will also reflect the losses attributable to the severe fall dryness, plus additional losses -- if any -- from subsequent weather events. Estimates from various Ukrainian commodity analysts informally peg winter crop losses to date at 20 to 30 percent, which is higher than average winterkill levels but not unreasonably high under the circumstances.

Official USDA area and production estimates for grains and other agricultural commodities are available at PSD Online. Initial estimates for 2006/07 will be released on May 12, 2006.