Posts Tagged ‘19:2’

Early Sweet Corn

Friday, April 1st, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist;

The first early fresh market sweet corn plantings have been planted. This March planted corn most often is planted under vented clear plastic covers to provide for extra heat accumulation. This allows for harvest in June, several weeks ahead of field plantings. Another option to improve earliness is to seed through plastic mulch. Special wavelength selective mulch (IRT) will allow for more soil heating that black plastic, however the difference is not always enough to warrant the extra cost. Planting on IRT or black plastic mulch often gains 1-2 weeks. Early bare ground plantings using shorter season varieties can often make the 4th of July market. These are most successful on sandy soils that warm up more quickly. Some growers have had success with early plantings grown on ridges to speed warming even more. Bicolor varieties are often used for these early plantings due to their better cold tolerance.

Processors in the region are switching more acreage to supersweet production. They are also interested in planting as early in April that will still allow for good stands. Seed companies developing processing supersweet varieties have made great strides in improving cold tolerance for these early plantings. Company fieldmen also spend time working with seed companies to identify the highest vigor seed lots for planting early. Growers also have an important role to play in the success of early processing sweet corn plantings. Early plantings will require shallower seed depths and planters need to be adjusted so that seed is placed uniformly at the proper depth and so that there is good soil to seed contact. Fields that warm up quickly should be selected for early plantings and should be worked well ahead of time. Remember that the wetter a soil is, the longer it will take to warm up. If at all possible, plant on a warming trend. Soil temperature around the seed should be >60°F during the day for best germination.

Winter Temperature Index for Predicting Stewart’s Wilt in Delaware Sweet Corn 2001-2011

Friday, April 1st, 2011

Bob Mulrooney, Extension Plant Pathologist;

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.

Prediction for 2011

Georgetown: 101.9 = Severe         Avg. monthly temp (Dec, Jan, Feb) = 34.0°F

Dover: 97.5 = Intermediate  Avg. monthly temp = 32.5°F

Newark: 94.7 = Intermediate  Avg. monthly temp = 31.6°F

Average monthly temperatures in oF at Georgetown, DE. REC. 2001-2011

2010-11 2009-10 2008- 09 2007-08 2006-07 2005-06 2004-05 2003- 04 2002-03 2001-02
December 31.3 37.9 41.8 39.7 43.5 36.2 38.9 38.6 36.7 43.2
January 31.0 32.7 31.0 36.8 39.7 43.0 34.9 29.5 28.9 40.0
February 39.6 31.1 39.2 39.9 30.1 37.4 36.7 35.2 33.8 39.9
INDEX 101.9 101 .7 112.0 116.4 113.3 116.6 110.5 103.3 99.4 123.1

Average monthly temperatures in oF at Newark, DE Experiment Station 2001-2011

2010-11 2009-10 2008- 09 2007-08 2006-07 2005-06 2004-05 2003- 04 2002-03 2001-02
December 30.8 34.9 37.1 37.5 42.5 34.0 35.5 34.0 33.5 43.3
January 28.7 31.6 28.0 35.5 37.3 39.5 31.0 26.4 27.1 39.6
February 35.2 31.0 35.8 36.5 27.8 34.5 34.2 33.1 29.5 40.1
INDEX 94.7 97. 5 100.9 109.5 107.6 108.0 100.7 93.5 90.1 123.0

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 2011 Delaware Commercial Vegetable Production Recommendations for control suggestions.

Note: Weather records from University of Delaware Carvel REC, Georgetown, DE, DE State Fire School, Dover, DE and University of Delaware Ag Experiment Station Farm, Newark, DE. Data records found online at

Sussex Soil Health and Vegetable Production Workshop

Friday, March 11th, 2011

Thursday, April 7, 2011     4:00 – 7:00 pm
University of Delaware
Carvel Research and Education Center Farm
(meet at Picnic Grove)

Commercial vegetable growers, market gardeners, crop advisors, and others interested are invited to attend a workshop dedicated to soil health and vegetable crops. With tight rotations, land limitations, and intensive cultivation, soil health is a major concern with vegetable production.

This workshop will focus on incorporating soil health principles into vegetable production as part of an integrated crop and pest management program. Participants will spend most of the workshop doing hands-on soil quality and soil health evaluations in the field (visual, chemical, physical, and biological). We will also discuss best rotations for vegetables, using soil improving cover crops and green manures, using composts and organic amendments, and biofumigant crops in vegetable rotations.

Each participant will be encouraged to develop a soil health maintenance or improvement plan for their vegetable production.

Dr. Gordon Johnson, UD Extension Fruit and Vegetable Specialist, will be conducting this workshop.

To register, contact Karen Adams at (302) 856-7303 or email If you need additional information, or if you require special needs assistance for this meeting, please contact Cory Whaley, Agriculture Agent,, or (302) 856-7303.

Produce Food Safety Training Sessions for Small Scale Growers: Good agricultural Practices and Good Handling Practices

Friday, March 11th, 2011

Small scale growers who did not attend voluntary produce food safety (GAP/GHP) training sessions in 2009 or 2010 are encouraged to do so in 2011.  This training program is offered by the University of Delaware Cooperative Extension, and the training certificate is issued by the Delaware Department of Agriculture.  Trainings are also sponsored by the Fruit and Vegetable Growers Association of Delaware.

Smaller growers that do not market wholesale are encouraged to become trained and learn about best ways to keep produce safe from food-borne pathogens.

Please Note: Training sessions for wholesale growers were held in Kent and Sussex counties in early March.

KENT COUNTY – Kent County Extension Office, Dover (UD Paradee Building), 69 Transportation Circle, Dover, DE 19901.  Call (302) 730-4000 to register.  Contact Phillip Sylvester for more information.

Small growers (limited or no wholesale) – 3 hour training, April 4, 2011, 6-9 pm.

SUSSEX COUNTY – University of Delaware, Carvel Research and Education Center, 16483 County Seat Highway, Georgetown, DE 19947.  Call (302) 856-7303 to register.  Contact Tracy Wootten or Cory Whaley for more information.

Small Growers (limited or no wholesale) – 3 hour training, April 14, 2011, 6-9 pm.

NEW CASTLE COUNTY – New Castle County Extension Office, 461 Wyoming Road
Newark, DE , 19716, Phone (302) 831-2506 to register.  Contact Maria Pippidis for more information.

Small Growers (limited or no wholesale) – 3 hour training, April 26, 2011, 6-9 pm.