Jon Clements
Extension Tree Fruit Specialist
University of Massachusetts Amherst
clements@umext.umass.edu
Last week (February 10-11, 2004) I attended the first-ever Empire State Fruit and Vegetable Expo in Rochester, NY. Sponsored by the NYS Vegetable Growers Association, the Empire State Potato Growers, the NYS Horticultural Society and the NYS Berry Growers and Cornell Cooperative Extension, the Expo included excellent education sessions on apples, stone fruit, berries, and vegetables. In addition, there was a trade show with over 100 exhibitors.
I thought I would pass on some brief comments about the Expo's education sessions I attended as most were by Cornell Cooperative Extension specialists on topics of relevance to tree fruit production here in Massachusetts. If you want more details or copies of the talks, let me know.
Stone fruit diseases -- Bill Turecheck gave a rundown on stone fruit (peaches and cherries) diseases (with an emphasis on brown rot) and 2004 fungicide options. Among the protectant fungicides he recommends Captan and Bravo, the latter being the best choice when brown rot pressure is high and for cherries and plums because it also controls black knot. The SI fungicides Elite, Indar, and Orbit are all effectively control brown rot at bloom, however, they should be rotated with other fungicides for effective resistance management. He reminded the audience that although Abound is labeled and effective on stone fruit, it's use anywhere near apple orchards is strongly discouraged because it is extremely phytotoxic to some apple varieties, including McIntosh. Pristine is a new fungicide that appears to perform better than Orbit, but it is not registered (yet) in New York. Finally, he says "with the wide variety of fungicide options, brown rot can many times be controlled with one spray at bloom, but be sure to read the label carefully for rates and timing restrictions."
Peach thinning -- Jim Schupp of Cornell's Hudson Valley Lab said that bloom thinning of peaches shows real promise to reduce -- but not entirely eliminate -- the practice of hand thinning. Ammonium thiosulfate (ATS) has worked well in Massachusetts (research of Duane Greene) and is recommended there he reports. Schupp's latest research with Wilthin and several other bloom thinners has worked to varying degrees, however, phytotoxicity has been an issue. More research is needed to nail down some protocols for consistent (if that's possible!) chemical thinning of peach in New York and New England.
Mating disruption -- Art Agnello elaborated on current research to control oriental fruit moth and peach borers using mating disruption. For oriental fruit moth, mating disruption was effective deep within the orchard, however, where pressure was high from adjacent non-disrupted plantings (including apples) border sprays may be necessary to fully control this pest. For borers, the news is even better, as they (both peach-tree borer and lesser peach-tree borer) are easily disrupted by pheromones. In fact he says, "mating disruption is now the preferred tactic in our Cornell IPM guidelines."
Sweet cherry shelf life -- O. Padilla-Zakour portrayed research using modified atmosphere packaging (MAP) to extend the shelf-life of sweet cherries. The technology reduces oxygen while increasing CO2 (similar to CA storage of apples) in semi-permeable membrane bags during refrigerated storage of sweet cherries. Because they have notoriously short storage and shelf life, MAP may be the key to significantly extending the marketing season (up to one month per harvest) as more sweet cherries are being planted in New York, But, variety seems to make a big difference in how cherries perform in MAP, and she says more research is necessary before MAP technology will be truly useful to NY growers.
Sweet cherry systems and crack reduction -- Steve Hoying addressed these topics as related: the readily available and dwarfing Gisela rootstocks present an opportunity to use rain covers to prevent cracking. (Rain covers are already widely used in European sweet cherry production.) But first, the production goals for a modern cherry orchard -- precocious production, larger fruit size, high per-acre yields, and tree survivability -- must be addressed. A sweet cherry planting systems trial at Geneva was planted in 1999 to address these needs, and the Zahn 'vertical-axis' system with G.5 and G.6 rootstocks has performed the best (in terms of per-acre yield) after five years of data collection. To prevent cracking, Hoying discussed rain covers and calcium applications. Quite simply, covers are effective yet expensive. Calcium sprays -- either by airblast or automated over-the-row sprinklers -- can work, but, like covers, are far from perfect.
Watching and predicting weather -- A grower panel discussed their experience with weather prediction and stations. The Internet has become a primary source of forecasts, however, on-site weather stations are useful when paired with a personal computer and software that makes it easy to calculate degree-days and run predictive models for scab and fireblight. Weather stations from Davis (www.davisnet.com) and Spectrum Technologies (www.specmeters.com) were discussed.
Making 'scents' of insect trapping -- Wendell Roelof gave a brief history of how species-specific pheromones -- including redbanded leafroller, codling moth, and apple maggot -- were first identified at the Geneva experiment station. Such pheromones now form the basis of trap-monitoring in a modern IPM program, and Roelof and his crew were leaders in this field. In fact, they are still on the cutting edge -- he also gave an example of how a new technique that isolates biologically active attractants/antagonists in host plants, such as apple vs. hawthorn, may be used to reduce apple maggots in commercial apple orchards.
Sprayer testing -- Always colorful 'Brit' Andrew Landers described how mandatory sprayer testing is now underway in 14 European countries, and how the EUREPGAP checklist for 2004 now recommends sprayer testing by an independent agency. Clearly, he feels growers should be testing their sprayers annually to: increase application efficiency by improving technical condition of sprayers; reduce pesticide application costs; decrease environmental pollution; and improve knowledge of application technology and sprayer management. Landers has all the gadgets to perform the testing, so New York growers were invited to volunteer to have their sprayers tested.
1-MCP and future planting decisions -- Interestingly, Chris Watkins did not really answer the question posed by the title of his talk! Why? Watkins insisted that there are still significant unanswered questions about use of 1-MCP (SmartFresh) on popular NY/New England varieties such as McIntosh and Cortland. The exception may be Empire, on which 1-MCP has performed consistently well. He says stay tuned -- no doubt SmartFresh will have an impact on future planting decisions, but the writing is not on the wall was the take-home-message of his talk.
Orchard support systems -- Steve Hoying was back to share some experiences in New York with orchard support systems. His first point was that any support system should be designed to last 20 years. Second, that economics ought to play a role in choice of construction materials. For example, bamboo may be substituted for conduit at considerable savings in a single-wire system, which he prefers. And finally, little things count -- like a simple increase in staple gauge results in a significant increase in holding power. Hoying and Terence Robinson have developed specific recommendations for a single- or double-wire, vertical-axis support system that is worthwhile looking into if you need a system for a new orchard.
TracApple recordkeeping system -- Julie Carroll updated the audience on TracApple 2004, an Excel-based computer application that allows input of pesticide and fertilizer applications and makes it easy to produce use reports, including central posting for WPS, processors (Motts, Birds Eye, Beechnut, Knouse, generic) and EUREPGAP. The Excel spreadsheet has a built-in chemical table that reduces the amount of manual input using drop-down menus. Although TracApple is tailored for NY growers, it's applicable to out-of-state growers too. It costs $20 for the 2004 version. I'd recommend it for someone looking for a computer pesticide recordkeeping application. For more information, see http://www.nysipm.cornell.edu/trac/trac_apple.html.
Internal lep control in 2003 -- Entomologist Harvey Reissig reviewed their 2003 research on insecticide resistance and mating disruption of codling moth and oriental fruit moth. Both have been prevalent in recent growing seasons in New York orchards and have contributed to unacceptable amounts of 'wormy' fruit at harvest. In particular, oriental fruit moth appears to be on the upswing, and insecticides have been ineffective at times, either a result of resistance or poor timing. In 2003, these pests were adequately controlled, but usually at the cost of numerous applications of broad-spectrum, harsh insecticides. Mating disruption shows promise, however, not without some insecticide applications, and the details of spray timing in combination with mating disruption are yet to be resolved.
How much nitrogen does Gala need? -- Lailiang Cheng gave a research update on a nitrogen fertilization experiment with Gala. As you know, small fruit size of Gala is an issue, and the thought is that insufficient nitrogen may contribute (among other factors) to size dysfunction. In fact, Cheng's research confirms this hypothesis, that Gala does indeed need more nitrogen than soft varieties such as McIntosh, Cortland, and Jonagold to achieve good fruit size and yield. He addressed the issues of how much -- 30-100 lbs. N per acre, depending on soil O.M., 2.2-2.4% in leaf tissue -- and optimum timing, which he claims is budbreak to bloom.
Causes of phytotoxicity in fruit trees -- Dave Rosenberger of Cornell's Hudson Valley Lab addressed the subject of common causes of phytotoxicity in tree fruit. His experience suggests that pesticides are a common culprit, usually "when applied at the wrong rate, timing, crop, or part of the crop." Plant conditioning plays a role too when the cuticle is thin during periods of damp, cloudy weather. Rosenberger also says to beware of tank mixes, particularly when including products with fungicides or insecticides that are formulated to enhance uptake, such as oil, some foliar nutrients, adjuvants, and some plant growth regulators. Herbicides and nutrient sprays (zinc, calcium) were also identified as precursors of phytotoxicity.
EUREPGAP certification process -- Invited speaker David Speller, a consultant from England, discussed the EUREPGAP certification process -- a standard now used all over the world, and which many European retailers now require -- to a crowded room. EUREPGAP is really synonymous with Good Agricultural Practices, which key areas include food safety, environmental protection, occupation health and safety, and (where applicable) animal welfare. New York fruit growers are very interested in EUREPGAP because some ship fruit to European markets, and because a proposed set of Integrated Fruit Production guidelines for New York growers are based on the the EUREPGAP protocol. For more information about Eurepgap see http://www.eurep.org.
Cropload affects on Honeycrisp fruit quality -- Terence Robinson presented results of some recent research on this topic. As you may know, Honeycrisp is prone to biennial bearing and widely varying crop loads from year-to-year. Excessive crop loads have been linked to poor fruit size, reduced flowering the following year, poor tree growth, and lackluster fruit quality. Too light a crop load and the fruit are just too large and per acre yields are reduced. Robinson's research suggests an annual crop load of 4-5 fruits/cm2 of trunk area to be a target that will give optimum fruit size and quality. This will require "precise chemical thinning followed by accurate hand thinning." He also states per-acre yields of 600-700 bushels/acre will be "about it" with this variety at the suggested crop load.
Apogee for fireblight management on young trees -- Jay Norelli, USDA Research Scientist from Kearneysville presented some interesting research on fireblight prevention on young trees using Apogee. Because young tree shoot growth is important to fill in-row spacing rapidly, it at first seems contradictory to use Apogee on young trees he started off. But, when susceptible cultivars such as Gala and GingerGold enter their 3rd-6th leaf explained Norelli, they are most susceptible to fireblight. Therefore, he proposes a fireblight management strategy on young trees is to apply one or two shots of Apogee to susceptible varieties in the 4th to 6th leaf when shoot growth is most rapid (usually early in the season) and there is a concurrent high risk of shoot infection. But, he cautions "in young orchards the use of Apogee should only be considered when the risk of shoot infection clearly outweighs the negative effects of growth suppression."
Managing resistance of apple scab -- Wolfram Koeller, word-famous expert on resistance of apple to fungicides presented evidence that unless used very carefully, we can expect resistance to continue to develop to both old, where it has not already developed, and new fungicides. He is interested in the role of dose in resistance development and management, and for now, he suggests growers adopt the following tactics to minimize the resistance risk: be conservative with rates (i.e., use full rate); avoid post-infection use of SI fungicides; do not use fungicides where resistance has already developed (he estimates 25% of New York orchards already have some resistance to commonly used protectant and post-infection fungicides); and diversify chemistries, i.e. rotate fungicides.
Thinning apples with the new 6-BA -- Jim Schupp was back to update the audience with his research using the newly labeled thinner MaxCel. In 2003 MaxCel had an EUP in New York, and the rest of the country. Unlike Accel, which it essentially replaces, MaxCel has initially proven to be a potent thinner both in research trials and EUP orchards. "The GA was removed from Accel, and the per/acre rate was increased to make MaxCel," Schupp says "so now we finally have a truly effective BA thinning product." He notes it may be wishful thinking that the EUP status of MaxCel in New York will be elevated to a full label in time for the 2004 growing season, however, for apple growers outside of New York it's on-track for 2004 and we should have it here for sure in 2005.