January 2011: Chilling in Sweet Cherry
Alert: January 4, 2011: Current concerns for chilling adequacy in sweet cherry and questions about Rest Breaking Agents (RBAs)
from: Kitren Glozer Ph.D., Associate Project Scientist, Dept of Plant Sciences, UC Davis
NOAA’s outlook for January: http://www.cpc.ncep.noaa.gov/products/predictions/long_range/fxus07.html
THE SST (SEA SURFACE TEMPERATURE) ANOMALIES IN THE NINO 3.4
REGION ARE FORECAST TO AVERAGE SOMEWHERE BETWEEN -1 C AND -2 C THIS WINTER SEASON, SUGGESTING MODERATE TO STRONG LA NINA CONDITIONS FOR JANUARY 2011.
La Nina is the cold phase of the El Nino—La Nina cycle and it is expected to remain strong for at least January with lower than normal temperatures predicted, by 1-20C (each degree C = 1.80F). 1 Chill portion can accumulate every 26 hours given optimum low temperature. We are only slightly behind last year in most locations and I expect we will have enough chill for this year. Dormex applications can start at ~45 CP and Can 17 applications at ~48-50 CP.
The 3 month forecast (Jan-Feb-Mar) at NOAA indicates continued below average temperatures for this period. I would caution use of high rates of rest-breaking as the following period (see below) also indicates fairly cold weather and if we have a late freeze, as we did in 2005-2006 (and in 2009-10 in some areas of Linden), buds treated with RBAs will be advanced and more susceptible.
BY SPRING (MAR-MAY) 2011, THE AVERAGE OF THE STATISTICAL TOOLS, AND THE AVERAGE OF THE DYNAMICAL TOOLS, SUPPORT NINO 3.4 INDICES AROUND -1.0 C OR SLIGHTLY COLDER, AS DOES THE CPC SST CONSOLIDATION FORECAST. FINALLY, THERE IS THE ARCTIC OSCILLATION (AO) TO CONSIDER, WHICH UNFORTUNATELY CANNOT BE RELIABLY PREDICTED MORE THAN ABOUT 2 WEEKS IN ADVANCE. THE LATEST EXTENDED-RANGE GUIDANCE SUGGESTS THAT A FAIRLY STRONG, NEGATIVELY PHASED AO WILL CONTINUE AT LEAST THROUGH MID-JANUARY, AND LITTLE OVERALL CHANGE IN THE ATMOSPHERIC CIRCULATION.
Please see the attached files:
- Glozer, K. 2010.Dormancy, Chill Accumulation, Rest-Breaking and Freeze Damage: what are the risks?
The ‘best’ state of my knowledge and recommendations as of this time last year, reflecting the risks inherent in what I have described above.
- Glozer, K. and J. Grant: Use of the Dynamic Model and chill portions to time chemical rest-breaking treatments in ‘Bing’ Cherry
Information from 2005 (see Table 3 especially)