Ongoing research into organic apple production being conducted through the OrganicA Project is bearing fruit.
On Jan. 24, Dr. Lorraine Berkett, University of Vermont, presented the multi-state, multidisciplinary project’s latest findings on organic production of Ginger Gold, Honeycrisp, Zestar!, Macoun and Liberty apples during a webinar sponsored by Extension and eOrganic.
There are very few certified organic orchards in New England, Berkett noted, largely due to disease pressure that growers of Macintosh apples, long the most popular variety in the area, must deal with. However, a surge of consumer interest in new cultivars prompted a fresh look at the potential opportunities and challenges of organic apple production in the area.
With major funding from USDA Organic Research & Extension Initiative, the OrganicA Project (A is for apple) kicked off in 2006 as a resource for organic apple producers, principally those with 4-10 acres of trees intended for local sales such as co-ops, farm stands and farmers markets.
The project is spearheaded by a team of horticultural experts from the University of Vermont, University of Maine and University of Arkansas and has many involved growers. Berkett serves as coordinator and Terence Bradshaw, also featured on the webinar, as orchard manager.
Berkett explained that research efforts are focused on two orchards planted in 2006 at University of Vermont’s “Hort Farm.” They each contain the same five species of varieties identified as promising by growers.
The goal, Berkett noted, is to answer whether organic apple production is profitable and sustainable with the knowledge and tools presently available. To that end, extensive data has been collected, including detailed cultivar performance on each orchard.
Orchard #1 was planted with young trees. Honeycrisp is on M26 rootstock, while the remaining four are on Bud 9 rootstock. The orchard consists of 240 trees in eight rows with 5x15-foot spacing.
A few of the trees died during the orchard establishment years of 2006-09.
“We had a problem with our weed cultivator, which could easily take out a tree,” Berkett said, noting the culprit has since been replaced.
Orchard #1 has had challenges, including poor growth of the trees.
Berkett’s list of suspects included the site’s extremely sandy nature, which may have led to moisture shortage stresses and competition from weeds before the present mulch strip was established. A high mite population is also present.
Orchard #2 consists of 190 of the same five varieties top-grafted onto the existing orchard of 18-year-old semi-dwarf McIntosh or Liberty trees on M26 rootstock.
Both orchards were certified organic in 2008 and harvest began in 2009.
Each cropping year since has offered very different weather, including a very wet spring in 2009, frost during blossoming in 2010, and the wettest spring on record in 2011, followed by a summer drought.
Tree performance was measured by the girth 30 cm above the graft union at the end of each growing season, height, spread and shoot growth. Honeycrisp grew larger than any other variety, while Liberty was the shortest.
In bloom ratings based on numbers, Ginger Gold was the best in 2009 and Honeycrisp came in last, a pattern that Honeycrisp tended to repeat. Zestar! was the cultivar most affected by lack of hand-thinning.
In 2011, Ginger Gold and Honeycrisp had higher yields than their orchard mates, Berkett said, and preharvest drop was relatively high for Liberty. Yield efficiency figures over the three harvest years put Ginger Gold as the most consistent top performer.
In Orchard #2, tree survival was a critical factor.
Nearly 40 percent of Macoun and Zestar! trees are not growing very well, Berkett reported, compared to 95 percent of Ginger Gold and Honeycrisp growing well. While the grafted cultivar mattered, the cultivar base did not, with no difference observed between McIntosh and Liberty stumps.
Apple scab is considered a major disease and a major factor in regional apple production, Berkett noted. Data gathered from Orchard #1 suggests Liberty has resistance to apple scab and Honeycrisp has some resistance, while Ginger Gold had higher incidence of apple scab than the others.
Rust diseases have emerged as a problem in both orchards. In Orchard #1, Honeycrisp and Ginger Gold ranked highest in number of lesions. Sulfur did not manage the situation, Berkett noted.
Fruit or fungal rot is also a problem. Although rates were variable across the years and the cultivars, they appeared higher in Orchard #2 than in Orchard #1, a fact Berkett suspects is due to the higher canopy density and more dead wood.
As researchers documented a rise in the number of coddling moths over the three years, they began looking around.
“With experience, we have become more aware of the surrounding ecosystem,” Berkett remarked.
Ornamental crabtrees and junipers nearby were found laden with undesirable insects and innoculum, and were removed.
On the insect front, counts made in August showed numbers of European red mites were statistically high on all cultivars. Future research plans include reducing the number of fungicide sprays to find the threshold between effective control and tree damage, Berkett said.
Plum curculio, a major pest, showed no preference for variety and, although there was damage, Berkett said it did not appear to have a big effect on grading.
Tarnished plant bug damaged fruit in Orchard #1 in 2010, hitting Ginger Gold at significantly higher levels than Liberty, but having little effect on grading.
Apple maggot fly damage was low in all three years, although Honeycrisp and Ginger Gold seemed to be the preferred targets in Orchard #1. It was worth noting that fruit trees treated with kelp extract had significantly less damage than non-treated controls, Berkett said, suggesting the olfactory effect may have deterred the pest.
In Orchard #2 in 2009, she added, white apple leafhopper obviously preferred Ginger Gold apples to Macoun.
It is a concern that populations of coddling moth are high and increasing, both in the university’s organic and non-organic orchards, Berkett said. Evidence of internal Lepidoptera damage was highest in 2010, likely because researchers stopped managing for coddling moth too early, she observed.
On the positive side, biological controls by beneficials, including lavish populations of lady bug beetles, is occurring and the orchards have produced beautiful fruit. However, challenges remain, Berkett said.
Looking ahead, research will focus on the non-target impacts of scab management using sulfur and lime sulfur, and management of rust, fruit rots and codling moths.
Another facet of the research will be the new high-density orchard planted with scab resistant varieties. The orchard filled with Crimson Crisp, Crimson Gold, Crimson Topas, Williams Pride, Winecrisp, Quering and Galarina trees on M26 rootstock in 4x15-foot spacing should allow researchers to drastically reduce sulfur treatments, Berkett said.
For more information on organic production, visit www.extension.org/organic_production.
For more information on the OrganicA Project, including a practical guide to organic apple production, visit www.uvm.edu/organica.