Gordon Johnson, Extension Vegetable & Fruit Specialist;email@example.com
Produce buyers in the region have expressed an interest in buying more fresh greens demonstrating the potential for expanding fresh market production for local and regional distribution. In particular, there has been an increased consumption of kale. There are also increased opportunities for oriental greens for ethnic markets. In addition, there has been an interest by regional processors in sourcing ethnic greens from the Mid-Atlantic area. This would provide processors and growers a new specialty crops market opportunity in processed collard greens, mustard greens, turnip greens and kale for national distribution. Lettuce demand in the region has also increased
Research was conducted from 2010-2012 at the University of Delaware Carvel Research and Education Center near Georgetown, DE on spring, fall and overwintered production of kale, collards, mustard, turnip, and Asian greens. Research in 2012 included spring and fall lettuce trials. The following are summaries of the results from these trials.
Fall Planting Date, Population Density, And Variety Trials for Processing
Large scale, direct seeded fall trials were conducted on the University of Delaware Research Farm near Georgetown, DE in 2010 and 2011 on loamy sand soils. Planting dates were July 15, July 30, August 16, and August 30 in 2010 and August 1 and August 15 in 2011. In 2010 varieties tested included Seven Top turnip; Southern Giant Curled mustard, Champion collard, and Vates and Siberian kale. In 2011 varieties tested included Seven Top turnip; Tendergreen mustard; Champion collards; and Siberian kale. Low cost open pollinated varieties were tested because that is what the industry is using in other areas of the country.
Insect pressure from Harlequin bugs and Lepidoptera larvae was heavy in the July planting, causing losses even with insecticide sprays in 2010. In the 2010 trial, collards had the highest yields in the July planting. Mustard and turnip gave the highest yields from an early August planting date. Siberian Kale performed best from early and mid-August planting dates. Vates kale did not perform well in the fall of 2010 in the large plot trials. In 2011, Collard yields were lower than the other greens tested in large plot trials. Siberian kale, Tendergreen mustard, and Seven Top turnip performed well. In general, fall yields were lower than April-planted greens
A fall population trial was conducted in 2010. Plots were seeded with a precision planter (Monosem) at seeding rates to give target spacings of 1-2 inches, 2-4 inches, 4-5 inches and 5-6 inches between plants. Planting date was August 17. Varieties tested included Seven Top turnip; Southern Giant Curled mustard, Champion collard, and Vates and Siberian kale.
Champion collard had the highest yields with a 4.5 inch spacing between plants as did Vates Kale. Seven Top Turnip had the highest yields at 6 inches between plants. Southern giant curled mustard had the highest yields at 3 inches between plants. Results show that current recommended planting rates may be too high (giving a spacing of about 1 inch between plants). However, this needs to be balanced against cutting height as closer spacing produces more upright leaves.
Fresh Market Greens Variety Trials
Fresh market greens trials were conducted on the University of Delaware Research Farm near Georgetown, DE in 2011 and 2012 on loamy sand soils. Plots were one row wide rows with 30 inches between rows. Plots were seeded with a push planter at a seeding rate to give a target spacing of 3 inches between plants except or were transplanted at a spacing of 12 inches between plants. Fall planting dates were August 23 in 2011 and August 9 in 2012 for direct seeding and August 15 in 2012 for transplants (kale and collards only).
In Fall 2011, with the hybrid kales, Reflex was the most productive, with over double the yields of other varieties. However, the open pollinated Siberian was far more productive with over 21,000 lbs. compared to 8223 lbs/a for Reflex. If packaged greens are the market, Siberian would be the best choice. If fancy curled greens for garnish are desired then Reflex would be the best choice. Hi Crop collards out-yielded all other hybrid collards and had over 3 times the yield of the open pollinated Champion. With turnips, the highest yielding varieties were Southern Green and Alamo with 29,900 and 27,000 lbs/a respectively. This compared to 22,000 lbs/a for Seven Top. Mustard yields were highest with Savannah (28,400 lbs/a) but were not significantly different from Tendergreen (26,100 lbs/a).
Fall 2012 trials with fresh market greens showed that All Top and Southern Green turnips performed the best and Tendergreen and Savannah mustards have the highest yields. For Kale, Winterbor and Green Curled have the best yields for stripping leaves on green types and Red Russian has the highest yields for a red type. Collard yields were similar across varieties; however, Hi Crop Collard had the highest yields. Asian greens trials showed that Mizuna varieties had the highest yields along with Tokyo Bekana Chinese leaf cabbage and Vitamin Green mustard with over 20 ton per acre yields with harvests from August through December in unprotected field conditions.
For lettuce, only a few varieties maintained good flavor and did not bolt or had minimal bolting in all trials: Forlina, (Butterhead); Acropolis and Spartacus (Iceberg); Starfighter (Leaf); and Dov (Romaine). Several other varieties demonstrated some heat tolerance, resistance to bolting and reduced bitterness in either the late spring, or early or late fall trials: Harmony, Hungarina, and Skyphos (Butterhead); Excalibur and Keeper (Iceberg); New Red Fire (Leaf); Rubicon, Camino Verde, Rio Bravo and Musena (Romaine).
A full report on the lettuce trials (with photos of the varieties) is online at:http://extension.udel.edu/ag/files/2012/03/lettuce2012.pdf