SWD and Blueberry Varieties for Organic Production
Future Harvest - CASA
Above center: A male spotted wing drosophila (SWD) on blueberry; another likely SWD is in the background.
Q: We were really hit hard with SWD on our organic blueberries…everything harvested after mid-August was affected. We're planting more blueberry plants in 2014, and I need to order now. Are there varieties or other considerations I should make in terms of managing SWD?
A: Note that the timing and extent of SWD infestations will vary depending on location and spray programs. However, for all growers considering planting blueberries (and actually, this applies to any mid to late summer berry crop), it makes sense to utilize varieties that ripen before SWD numbers soar. This way you can hopefully avoid SWD issues for at least a portion of the harvest period.
We were interested in different people's thoughts on early and early-midseason varieties, so we had a little conversation via email.
Dr. Eric Hanson (Michigan State University) had these top picks: Early season: Earliblue (not good for frost pockets), Reka, Duke, and Patriot. Early-mid season: Draper, Huron, Bluecrop (in order of fruiting) and possibly Blue Ribbon, a new introduction from Fall Creek.
Kathy Demchak added these thoughts: When we grew Reka, it was productive, but the berry size was really tiny on 2 of our 4 plants and overall, berry size tended to be smaller. Maybe that was just its tendency to overcrop and we should have pruned differently. Birds also seemed to prefer Reka, maybe because the berries were bite-size for a bird, or maybe they just liked the flavor better. Mark Ehlenfeldt recommended it for our blueberry school last year.
I personally found Duke to be too lacking in flavor, but feel pretty good about Patriot and Bluecrop. You'd need at least one or two SWD sprays to make it through harvest on Bluecrop. When we incubated Bluecrop berries from our research plots starting during the second week of harvest in 2013 (note that this is without any sprays), we found 0 SWD per berry on July 18, then 0.08 per berry on July 24, increasing to 0.98 per berry on July 31. This backs up what the grower mentioned – that anything from mid-August on was pretty well infested. The date when heavy infestation is noticed will likely be earlier the further South you go.
So then we floated the question past Mark Ehlenfeldt, USDA-ARS blueberry breeder, who was a wealth of information, which follows:
Breeders are always hesitant to give an unequivocal answer, because we know there is no perfect variety, and a lot depends on the locale and the grower. That being said, here are some useful thoughts (hopefully) followed by the descriptions. Expanded versions of the info in italics below can be found in the Mid-Atlantic Berry Guide.
Duke. For more northern climates like ours, Duke has the most proven productivity record. Duke’s major down-side is its mild flavor. Duke’s flavor improves after a day or two in storage, but will never be a “wow” berry. Nonetheless, there are people who like the mild flavor of Duke and its crispness. Berry Guide comments: Duke is vigorous and blooms late, avoiding early frosts, but ripens relatively early. It starts producing quickly after planting. Harvest can be completed in two or three pickings. Duke is moderately resistant to anthracnose; has good resistance to mummy blight (primary shoot infection); and is moderately susceptible to mummy berry fruit infection. Stem blight problems have also been documented.
Draper. Draper is an offspring of Duke and is not as early ripening, but has better flavor. I haven’t seen any fully-mature fields of Draper in NJ, but the young ones look pretty good and will probably have good productivity. Some of our disease screening studies have suggested Draper is susceptible to mummy berry blight, but field performance may be better than the screening results which were done with high levels of inoculum Timing factors also come into play with blight infection, but I would still assume it’s less resistant than Duke. (As a side note, we’ve had very little mummy berry in NJ for about the last 5 years, although this spring there was a bit of a rebound with the cool wet weather). There are easy cultural practices for organic growers to control mummy berry, as long as there isn’t uncontrollable outside inoculum (i.e. wooded areas with mummy berry). Mid-Atlantic Berry Guide comments: Released in 2004 from the breeding program at Michigan State. Ripens slightly later than Duke, but with better flavor. Relatively susceptible to mummy berry blight.
Reka. I did mention Reka as a “best bet” as Kathy stated, and I stand by that recommendation. Reka does have a tendency to crop heavily and fruit size can be small as a result. Thus, it becomes a cultivar that needs to be managed more aggressively. Fruit area bit dark, and the flavor, to me, is just average, but it grows well in many places and has “average” to “better than average” disease resistances. Berry Guide comments: From New Zealand. Upright, very vigorous habit that has been very productive where grown. Berries are small and deep blue with a spicy flavor. Average resistance to anthracnose, relatively resistant to both phases of mummy berry.
Now for a few others:
Bluetta. I have occasionally seen really nice plots of Bluetta. The fruit was at a perfect stage of development and was firm, beautiful, and flavorful. It made me see why someone released it originally. Even now, I think it may be the earliest-ripening blueberry. Its downsides are included in the comments below. Mid-Atlantic Berry Guide comments: Bluetta - Bush is compact, low growing, and of medium vigor. Fruit is medium-sized, soft, and blue-black with fair flavor. Consistent production may be a problem. Moderately resistant to mummy berry disease; highly susceptible to anthracnose and red ringspot virus.
Hannah’s Choice. Hannah’s Choice is a variety with significant potential, and delicious fruit, but performs variably in different locales. A nice variety if it can be grown reliably. Mid-Atlantic Berry Guide comments: Fruit has superior firmness, sweetness, and flavor with peachy overtones. Large first-pick berries, with some size decrease in later picks. Relatively resistant to anthracnose; average resistance to both phases of mummy berry. Less productive in some areas than others.
Sweetheart. Sweetheart is an early variety, with perhaps the best flavor in early-season fruit, but needs to develop a large plant before yielding ability is fully apparent. Many people will probably judge this plant too early and dismiss it. Even after it “sizes-up” it will need good management to keep fruit size up. It’s too early to know if it performs equally well in all locales. Mid-Atlantic Berry Guide comments: A new productive variety with excellent flavor that holds up in storage. Can overcrop. Cross-pollinate and prune assertively to maintain fruit size. Not precocious like Duke.
Bluejay. Bluejay is early-ripening, and is one of our standards for mummy berry resistance. It’s another variety that would be excellent if one could get it to produce consistently. But we don’t see that consistency here in NJ.
Spartan. Some growers here in NJ grow modest amounts of Spartan as an early variety that tastes better than Duke. For me, it hasn’t grown very well, nor been very productive, probably due to soil issues, and it doesn't do very well on amended upland soils.
And finally …
Huron. We only have some small plants, so I haven’t been able to judge them very much. Below are a few notes from the plant patent (with my highlights and comments). The patent gives no indications as to disease resistance.
“It is exceptionally late flowering and was one of the few early to mid-season genotypes to survive a late frost in the mid-1990s. ‘Huron' also has excellent winter hardiness, as it has routinely been challenged with mid-winter temperatures below -20 C.”
“In the trials conducted in Michigan at Grand Junction, 'Huron' was consistently one of the top rated advanced selections. It had among the highest fruit load of any of the early to midseason cultivars and the best flavor. The average date of first harvest was 5d before 'Draper' and 6d after 'Duke'. The fruit of 'Huron' was slightly softer than 'Draper' and much firmer than 'Bluecrop'. 'Huron's' fruit were smaller than 'Draper', but larger than 'Duke' and 'Bluecrop'. Its fruit color was similar to 'Duke', but a little darker than 'Bluecrop' and 'Draper'. 'Huron' fruit had a storage life as long as 'Draper', which was several weeks longer than 'Duke' and 'Bluecrop'. 'Huron' had the second highest levels of soluble solids next to 'Draper' and the second lowest acidity next to 'Duke'.”
“Blueberry growers in Michigan and the cooler production regions across the USA, Europe, and Canada will find 'Huron' desirable as a new early northern highbush variety. However, some fruit pedicels of 'Huron' fruit remain attached in very hot weather. The fruit of 'Huron' also develops sugar slowly and if picked too early can be very tart. In addition, the fruit clusters of 'Huron' are relatively tight, which may reduce picking efficiency.”
Mark’s bottom line (mostly on consistency and productivity): Top picks (still): Duke, Draper, and Reka. Wild cards: Hannah’s Choice, Sweetheart, Huron, and Bluejay. Bottom picks (for me): Spartan and Bluetta