The Massachusetts Fruit Growers Association held its annual summer meeting and farm tour at the University of Massachusetts Cold Springs Orchard in Belchertown, MA. Around 80 fruit growers and Extension personnel from Massachusetts and Rhode Island attended to learn about current research in grapes, brambles, stone fruit and pome fruit.
The educational part of the tour started at the grape research plots. Sonia Schloemann, UMASS Extension Small Fruit Specialist, and Elsa Petit, an expert in evolutionary genomics of fungal diseases, discussed their grape trials assessing the value of shoot and cluster thinning on grape quality. Students thin the shoots at three densities in the spring and then thin the clusters to two to three clusters/shoot in the summer. The intent is to increase sun and spray coverage to the cluster and determine the degree to which disease, sugar, and acidity is impacted. Additional concerns include assessing the varieties themselves for suitability (i.e. cold tolerance) in New England.
Duane Greene, Professor of Pomology at UMASS, gave a discussion on emerging thinning options for apples. For the past five or six years he has been investigating the effectiveness of the endogenous hormone ACC (1-aminocyclopropane-1-carboxylic acid) on thinning. It has great commercial potential because it is effective on apples in the 18-20mm stage, a stage at which no approved thinners currently exist in the States. It would not be an option for organic growers and does cause some phytotoxicity. However, Greene notes the leaf and spur yellowing that occurs is “almost inconsequential” and has “no influence on fruit size.”
Another thinner that is on track for U.S. registration, and is already registered in Europe, is metamitron. A sugar beet herbicide that inhibits photosynthesis, the advantage is that the mode of action is well-known, allowing growers to choose appropriate conditions for use. It is effective on the 8-14mm stage.
The final thinning study Professor Greene discussed involved Amid-Thin. Experiments across the country are evaluating its effectiveness at bloom, petal fall, and both. Because it is a mild thinner, it will need to be used in combination with another product. It may prove a viable alternative to Carbaryl.
Jon Clements, UMASS Extension Educator, shared the protocol for precision thinning. Ten spurs on five trees of each of the monitored varieties were tagged. Every four to eight days, the fruitlets were measured. The data was entered into a spreadsheet, which was able to predict fruit set, assisting growers in deciding when and how to thin . . . and evaluating how effective their thinning practices are.
The tour moved from apples to peaches where Wes Autio explained the 2009 NC 140 peach rootstock trials. The trials are replicated throughout the Land Grant Universities, Mexico, Chile and Canada, providing a useful picture of rootstock performances in a variety of conditions. Fifteen rootstocks were included in this trial, including peach, plum, plum-peach, almond, and ornamental cherry. Most of the research is interested in disease resistance, but production is also a factor. Unfortunately, this final year of the trial had no fruit due to the now-infamous spring freeze.
Sonia Schloemann discussed the potential benefits of using a swing arm trellis (rotating cross arm trellis) on brambles, particularly blackberries. One goal with this system is to mitigate winter injury. In the spring, the plants are trained on a horizontal wire to maintain vigor and to prepare for laying down the system, bending the flexible primocanes rather than the canes. In the winter, the laterals are laid down and covered. They can also be covered during early/late cold snaps. Another benefit to the system is ease in harvest. If the system is down during fruit set and then raised, harvesting can be done from only one side of the trellis. Some growers, particularly the more diversified growers, find the time requirements of this trellis to be too onerous. Sonia recommended trying a small area to determine whether a swing arm trellis will work within a particular farm system.
After some reviews of various variety trials and two additional NC-140 plantings, the tour learned about pest management with Dan Cooley and Elizabeth Garofalo. They inoculated test trees with apple scab spores prior to rain events and compared actual spore activity to those presented by five modeling programs. The majority of programs proved to be good predictors of sporulation and useful indicators for when spray coverage should be maintained.
Participants then enjoyed a meal prepared by local caterer Brad Morris followed by a talk by Win Cowgill, Professor Emeritus, Rutgers University and owner/president of Win Enterprises International entitled “38 Years of Fruit Research and Extension.”