Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu
Prediction for 2010
Georgetown: 101.7 = Severe – Avg. monthly temp (Dec, Jan, Feb) = 33.9 °F
Newark: 97.5 = Intermediate – Avg. monthly temp = 32.5 °F
Control Strategies
For processing and fresh market growers this means that if you are planting susceptible or moderately susceptible hybrids that flea beetle control is very important. A number of strategies are available including seed treatments, granular insecticides at planting and/or foliar applied insecticides after emergence. For foliar applied insecticides treat susceptible cultivars at spike stage when 5% of the plants are infested. See the 2010 Delaware Commercial Vegetable Production Recommendations for control suggestions.
Average monthly temperatures in °F at Georgetown, DE. REC. 2000-2010
| 2009-2010 | 2008-2009 | 2007-2008 | 2006-2007 | 2005-2006 | 2004-2005 | 2003-2004 | 2002-2003 | 2001-2002 | 2000-2001 | |
| December | 37.9 | 41.8 | 39.7 | 43.5 | 36.2 | 38.9 | 38.6 | 36.7 | 43.2 | 31.2 |
| January | 32.7 | 31.0 | 36.8 | 39.7 | 43.0 | 34.9 | 29.5 | 28.9 | 40.0 | 33.8 |
| February | 31.1 | 39.2 | 39.9 | 30.1 | 37.4 | 36.7 | 35.2 | 33.8 | 39.9 | 38.8 |
| INDEX | 101 .7 | 112.0 | 116.4 | 113.3 | 116.6 | 110.5 | 103.3 | 99.4 | 123.1 | 103.8 |
Average monthly temperatures in °F at Newark, DE Experiment Station. 2000-2010.
| 2009-2010 | 2008-2009 | 2007-2008 | 2006-2007 | 2005-2006 | 2004-2005 | 2003-2004 | 2002-2003 | 2001-2002 | 2000-2001 | |
| December | 34.9 | 37.1 | 37.5 | 42.5 | 34.0 | 35.5 | 34.0 | 33.5 | 43.3 | 31.1 |
| January | 31.6 | 28.0 | 35.5 | 37.3 | 39.5 | 31.0 | 26.4 | 27.1 | 39.6 | 31.5 |
| February | 31.0 | 35.8 | 36.5 | 27.8 | 34.5 | 34.2 | 33.1 | 29.5 | 40.1 | 38.4 |
| INDEX | 97. 5 | 100.9 | 109.5 | 107.6 | 108.0 | 100.7 | 93.5 | 90.1 | 123.0 | 101.0 |
Severity Index: < 90, usually absent; 90-100, intermediate; >100, usually severe.
The index is used to predict overwintering flea beetle populations that vector the Stewart’s wilt bacterium, Pantoea stewartii.
Note: Weather records from University of Delaware Carvel REC, Georgetown, DE and University of Delaware Ag Experiment Station Farm, Newark, DE. Data records found online at http://www.deos.udel.edu/