SECC Agricultural Outlook
Date updated: August 30, 2010
Prepared by Clyde Fraisse
La Niña Conditions Return to the Pacific Ocean How can it affect your crops?
The El Niño-Southern Oscillation (ENSO) phenomenon is the biggest player in the game of year-to-year climate variability. El Niño and La Niña events tend to develop during April-June and tend to reach maximum strength during December-February. Typically they persist for 9 to 12 months. After a winter of moderate to strong El Niño conditions, ocean temperatures have cooled very quickly in the last 3 months and have now reached thresholds consistent with the La Niña phase (Sea surface temperatures more that 0.5 °C colder than normal). If we look back in our climate records, years in which there were similar quick transitions to a La Niña phase included 1964-65, 1973-74, 1988-89, and 1998-99.
La Niña conditions usually bring a warmer and drier winter and spring seasons (November through March) to Florida, central and lower Alabama and central and southern Georgia. La Niña events in 1999 and 2000 and in early 2006 were associated with an increase in forest fires across Florida and Georgia.
Hurricanes: La Niña is known to bring a more active hurricane season to the Atlantic basin, so we anticipate that the 2010 hurricane season will produce more storms than normal. The most recent NOAA forecast calls for an 85% chance of an above normal season with 14-23 named storms, 8-14 hurricanes, and 3-7 major hurricanes. Hurricane hazards come in many forms: storm surge, high winds, tornadoes, and flooding. Impacts on agriculture are mainly related to flooding including loss of livestock, water contamination, damage to crops, increased susceptibility of livestock to disease, and flooded farm machinery. This means it is important for you to have a plan that includes all of these hazards.
Winter Vegetables: Tomato and green peppers generally yield more during La Niña years than during Neutral or El Niño years. Dry weather associated with La Niña generally decreases fungal and bacterial diseases and help growers reduce the number of fungicide applications, however viruses caused by thrips (Tomato Spotted Wilt [TSW]) and white fly (Tomato Yellow Leaf Curl [TYLCV]) are problems. High nighttime temperatures (above 65°F) can be a problem for fruit setting. For more information on how to apply climate information for reducing tomato production risks check the following UF- Extension EDIS publication: http://edis.ifas.ufl.edu/ae269
Row Crops: La Niña impacts are less evident on annual summer crops since its strongest signal occurs during fall, winter and spring. Warm conditions associated with La Niña may help certain pests and diseases. Warm, dry winter may increase flower thrips abundance. Yellow mustard and wild pansy are ideal hosts for thrips, and a warm winter may provide ideal growing conditions for these and many other host plants. Warm conditions may also help soybean rust over-winter on kudzu in South Georgia and throughout the Panhandle of Florida. If conditions are dry during the spring it may be best to kill cover crops earlier in order to preserve more moisture in the soil.
Pasture: Success of winter pastures depends on rainfall. This is especially true when overseeding. In central and south peninsular Florida overseeding of cool-season annuals into a established grass sod often fails due to insufficient soil moisture. This practice is generally not recommended unless irrigation is available as dry conditions can be exacerbated during La Niña seasons. Related extension resources:
- UF Forages website: http://agronomy.ifas.ufl.edu/foragesofflorida/
- UGA Forages website: http://www.georgiaforages.com/
Temperate Fruits: Seasonal climate variability impacts deciduous fruit production mainly because of a decrease in the satisfaction of dormancy that occurs by the accumulation of chilling hours (temperature at or below 45°F) and changes in the accumulation of heat units that promote flowering and fruit development. The extent of the threat from freeze damage during flower and fruit development can also be affected as can the timing and severity of diseases and pests.
Winter annual broadleaf weeds may thrive under warm and dry conditions, and these weeds act as host plants for catfacing insects (sucking bugs) in peaches. High populations of cat-facing insects have been documented in peach orchards where winter annual broadleaf weeds are allowed to grow.
Forestry: Warm and dry conditions associated with La Niña events may prompt managers to consider re-scheduling planting of drought vulnerable seedlings, reinforce existing control efforts of southern pine beetle, and delay the harvest of pine straw to retain soil moisture. La Niña also brings the potential for a very active wildfire season. Average acreage burned during La Niña years is often more than double that of normal as seen in 1998 and 2001. For more information about using climate information in forestry management check the EDIS Extension publication: Using Seasonal Climate Forecasting to Plan Forest Plantation Establishment. http://edis.ifas.ufl.edu/ae282
For more information about the potential effects of La Niña events on Florida’s agricultural industry and on rainfall and temperature patterns in your county, visit AgroClimate at http://www.agroclimate.org reduce fungicide costs without a great risk of compromising their profits.
Contact:
Dr. Clyde Fraisse
University of Florida
Agricultural and Biological Engineering
352-392-1864 ext 271
cfraisse@ufl.edu