UVM Fruit Blog

Organic options for disease management in Vermont vineyards

May 15, 2015

I have received several requests for information on organic disease management in Vermont vineyards. I must say from the beginning that organically-certified options for managing some diseases are very limited. For some diseases, primarily powdery mildew and to some degree downy mildew, organic options are available to manage the disease fairly well. However, for phomopsis, anthracnose, and especially black rot, you will face an uphill battle. This does not mean it cannot be done, but expect significant frustration.

The first line of defense for organic disease management is strict vineyard sanitation. This entails removal of all diseased and dead wood during pruning and removal of spur stubs (blind or dead wood on spurs beyond the point where shoots emerge in spring) after bud break. It is too late in this season to apply now, but a dormant application of liquid lime sulfur may reduce inoculum for some diseases, however this material is unpleasant to apply (to put it mildly), as it is extremely caustic to applicators and equipment and requires much care in its use. During the growing season, removal of diseased berries and clusters must be completed on a regular (i.e. weekly) basis. Application of biological or (more effectively) mineral-based copper and/or sulfur fungicides will be required in most vineyards on a regular 7-10 day schedule, season-long, to reduce disease incidence on fruit and foliage. The most effective materials are copper-based products, which do not degrade and will accumulate in the soil.

Coming from a background in apple production, where disease management typically requires 8-12 applications of synthetic fungicides for disease management, I have been encouraged by the reduced spray schedule of as few as four sprays of conventional/non-organic materials that may manage disease in grapes. However, organic disease management will require many more applications in the vineyard to produce reasonable results. Growers who pursue this strategy should refer to the 2014 Cornell Production Guide for Organic Grapes, and prepare to be vigilant in vineyard sanitation and application of mineral and/or biologically-derived products whose efficacy is questionable.

Early season disease management in Vermont vineyards

May 13, 2015

by Terence Bradshaw

With bud burst in cooler sites and grape shoots ranging from 1-3″ in the Champlain Valley is the time begin thinking about disease management. I’ll put it simply: the next four fungicide applications, combined with good vineyard sanitation, will ‘set the stage’ for your vineyard in 2015 as far as diseases are concerned.

Disease Management at the 3-5 Inch Shoot Growth Stage – The following was written by Dr. Wayne Wilcox of Cornell University and appeared in the article “Grape Disease Control, 2013”: [Note: Ph = Phomopsis; PM=
powdery mildew; BR= black rot; DM= downy mildew]

“3 – to 5-INCH SHOOT GROWTH. A critical time to control Ph rachis infections if it’s raining or likely to be soon, especially in blocks with any history of the disease. Early is better than late if it looks like some rain is setting in. Late is much better than nothing if those are the only two options , i.e., you’re past this stage, haven’t gotten anything on, and wonder whether it’s too late . This spray can provide significant benefit against fruit infections as well, since many of them originate from movement into the berries from infected rachises and berry stems. Also an important time to control basal shoot infections, since this is where the fungus will establish itself for the future if infected tissue is retained in canes, spurs, or pruning stubs.

Now is the time to start thinking about control of PM on vinifera varieties if temperatures remain above 50 °F for long stretches of the day… This spray is much more likely to be important in vineyards that had significant PM last year (we’re talking late season foliar disease more than fruit infections here) than in those that were “clean ” into the fall; however, it may be beneficial even in relatively clean blocks of highly susceptible cultivars, which tend to be relatively valuable as well… If already spraying for Ph, most growers of highly susceptible (and valuable) varieties include something for PM while they’re at it. I would too.

In NY, spending extra money for BR control is almost never justified this early unless you’re trying to clean up a severe problem block AND weather is wet and reasonably warm. In general, the farther south you go, the more important early sprays can become. Still too early for DM.

Disease Management options for the 3-5 Inch Shoot Growth stage are listed on pages 55-58 of the printed version of the 2015 New York and Pennsylvania Pest Management Guidelines for Grapes.

Unless you have had issues with anthracnose or extensive black rot on your vineyard, an application of a protectant fungicide such as mancozeb or captan should be sufficient at this time.

Terence Bradshaw, UVM Tree Fruit and Viticulture Specialist

IMPORTANT: Conservation Compliance and Crop Insurance Subsidies

Further clarification on the Conservation compliance requirement for receipt of crop insurance subsidies (referenced in my 5/12/2015 message), from Bob Parsons at UVM Extension:

“Producers with crop insurance must have Form 1026 on file with their FSA office by 1026 to qualify for subsidized crop insurance rates. The form certifies they are in compliance with conservation requirements for highly erodible land and wetlands. This form must also be in the same name that the crop insurance policy is in. For example, if the crop insurance policy is in Dad’s name but the Form 1026 lists Dad and son, its not identical. Needs to be identical. If you don’t have crop insurance in 2015 but think you may consider crop insurance for 2016, you need to have Form 1026 on file in the FSA office to qualify for subsidized crop insurance rates.”

-Terry

conserve_compli_insure.pdf
FiveStep_Compliance_FactSheet.pdf

IMPORTANT: Conservation Compliance and Crop Insurance Subsidies

I received this message from Adrienne Wojciechowski in Patrick Leahy’s office via Steve Justis regarding new requirements for filing a conservation compliance form with USDA in order to receive crop insurance subsidies. This form is due on June 1! I am not well-versed on this provision, so please contact your Farm Service Agency office ASAP to make sure you do not slip through the cracks.

-Terry

conserve_compli_insure.pdf
FiveStep_Compliance_FactSheet.pdf

Scab, pink insect management, fire blight, what else?

May 7, 2015

by Terence Bradshaw

This is an important week for orchard activities, as you likely know. I’ll try to be brief but thorough:

Apple scab: Depending on whether or not you had green tissue showing on April 23 or (more likely) April 27-28, you may not have even seen an apple scab infection period in your orchard yet. We have had some false alarms as far as predicted wetting events, but things have overall been pretty dry. The chance of rain showers is there on Saturday May 9 and increasing daily through Tuesday, but no widespread soaker is expected, although localized showers may trigger an infection period in your orchard. Ascospore maturity is healthy, although in some orchards which have received no rain for seven or more days, development in the NEWA model has stalled, so the next wetting event will potentially trigger a significant infection period.

Spray conditions are good today Thursday May 6 and tomorrow May 7, with increased winds expected later Saturday and especially Sunday (check the conditions in your orchard prior to spraying, of course). Take home message- make sure you’re covered with a protective fungicide going into this rain event.

Pink-stage insecticides: Many orchards are at pink or approaching it now, and I expect first bloom in the Champlain Valley by Monday or Tuesday. If you have not already brought bees in, and tarnished plant bug or European apple sawfly are a problem in your orchard, an insecticide in the next spray may be prudent.

Fire blight: risk is still looking to be high for fire blight infection when blooms open in most orchards, and any wetting could trigger infection (including heavy dew or a spray application). Be ready to apply streptomycin within 24 hours of a wetting event, and reapplication will be necessary after a couple of days as new blossoms open and the material effectiveness wanes. Remember the conditions required for blossom blight infection: open bloom, wetting, sufficient bacterial population to infect (driven by weather in the past week or so, which has been warm), and warm weather during infection. Cooler weather in the middle of next week will likely reduce fire blight threat, but bloom and wet will likely occur before then.

General orchard activities: water if you can, especially newly planted trees. The potential showers in the next few days don;t look to be enough to give new trees what they need. Now is the time to apply nitrogen fertilizers, including prebloom foliar fertilizers (another thing to put in that pink spray).

Summer Orchard & Vineyard Management Course at UVM

Time is running out to fill this course with sufficient students to run it this summer, so if you’re interested in developing in-depth management knowledge of apple and grape crops in Vermont, now is the time to sign up!

Details and sign up information can be found at: http://www.uvm.edu/~summer/course-detail/?crn=60531. If you have questions about signup, please feel free to contact me.

The course runs Tuesdays and Thursdays from 9:00-3:00 from June 16 – July 9 at the UVM Horticulture Farm in South Burlington, VT. The course cost is $1,272, whether taken for academic credit or as non-credit. To put that into perspective, that amounts to 30 bushels of apples or one ton of grapes produced through knowledge gained in the course to pay it back.

In this course, students will develop an orchard/vineyard management plan as a final project. Past grower-students have implemented these plans on their farms to develop new plantings, attain financing, and plan business enterprises.
About PSS 195 BU3

Students will learn principles and practices of commercial orchard and vineyard crop production, including: site selection and preparation; cold hardiness development; varietal selection; tree and vine training and trellising systems; cold hardiness development; nutrient, water and pest management; harvest and postharvest considerations. Special emphasis will be placed on environmental and economic sustainability of fruit production systems. The course will cover both orchard and vineyard crops suitable for production in northern New England, and students will have opportunities to explore specific crops in greater depth if they so wish. At each course meeting, we will apply knowledge of integrated horticultural and pest management practices in a real farm setting.

“Super knowledgeable, and super on top of his game. Terry’s class is one of a kind and an invaluable resource for anybody interested in apples or grapes! It really is an incredible class and the real world application is off the charts.” – 2014 Sustainable Orchard & Vineyard Management student

2015_PSS195_fruit_syllabusDRAFT.pdf

More on Fire Blight

May 5, 2015

by Terence Bradshaw

We have run the Maryblyt model for the UVM Hort Farm in South Burlington and, as I had predicted this morning, conditions for infection will occur this weekend if blossoms are open. We may not have flowers showing by this weekend, but growers are advised to be diligent in preventing infection.

This week’s edition of Scaffolds from the Cornell Fruit team has a very good, thorough set of recommendations for managing the disease: http://www.scaffolds.entomology.cornell.edu/2015/SCAFFOLDS%205-4-15.pdf

Good luck with it. As an aside, any comments on blossom stages at your site in Vermont would be helkpful to me in the next couple of weeks.

-Terry

Fire Blight risk looks high

May 5, 2015

by Terence Bradshaw

With the string of warm days that we have been experiencing this week leading into bloom, as well as the amount of fire blight that was around in 2014, I expect that we may be in for a tough year with this disease. I have not yet run the MaryBlyt program for Vermont orchard weather stations, but if you were to trick NEWA by recording yesterday as having bloom in the orchard (most orchards in the Champlain and Connecticut Valleys are at tight cluster), predicted fire blight risk is ‘High’ by Thursday and ‘Extreme’ by Friday and through the weekend. Remember, for blossom infection you need open blossoms (or other wounds, I would avoid pruning right now), heat accumulation significant for bacteria to multiply into an infective population, warm weather during infection, and wetting events. Heavy dew or spray applications may be enough to trigger infection.

First line of defense (after you pruned out all infected wood during the winter) was the copper spray that should have been applied at green tip. In most orchards it is too late to apply copper, except for the highest elevation sites. Do not spray fixed coppers after half-inch green bud stage.

The next step will be to have some streptomycin on-hand to apply within 24 hours of a rain event during bloom (remember, we need open blossoms for infection to occur). Now would be a good time to order your supply.

There is too much to the fire blight disease to discuss in this one notice, please review the pertinent section in the New England Tree Fruit Management Guide if you need a refresher.

We will run Maryblyt later today and I will send updates as the situation plays out.

Apple scab management

April 30, 2015

by Terence Bradshaw

Cool weather has kept bud development in orchards behind ‘normal’, and I’m hearing reports ranging from late dormant in high elevation inland orchards through early half-inch green in the warmer valleys. Bud development will be moving fast with expected warm temperatures through Tuesday, when rain showers are expected to arrive. Ascospore maturation is increasing fast as well, and a significant infection period can be expected if wetting hours are sufficient. Because buds are developing so quickly, protective fungicide coverage should be applied as close to Tuesday as possible the ensure that material is on emerged tissue going into the infection period. Most orchards have applied little if any fungicide this season, so coverage will good spray coverage is critical since any ‘base coat’ of material is limited. Saturday through Monday look to have good weather (i.e. low wind speeds) for spray application. The point is, if you are among the majority of orchardists with green tissue showing, you should be applying a fungicide this weekend. With the dry weather and adequate warning going into this event, protective fungicides (EBDCs, Captan or sulfur (for organic growers)) should be adequate. Remember, do not use Captan or sulfur if oil was applied within the past 7 days.

Green tip through tight cluster is a good time to apply nitrogen fertilizers in the orchard. Applications are best informed by foliar nutrient analyses which should have been conducted last summer. Many orchards on heavy soils with high organic matter content may not need any nitrogen applications in most years. Another concern is that overapplication of nitrogen may increase susceptibility of trees to fire blight infection. A conservative rate of nitrogen to apply in most orchards is 30 of actual nitrogen per acre. Recommended fertilizer materials can be found in the 2015 New England Tree Fruit Management Guide.

Orchard activities week of April 27

I go away for a week and nothing happens in the orchard. Not quite, but with the cool weather, trees have been advancing slowly. We reached green tip on McIntosh on Friday, April 24 at the UVM Hort Farm in South Burlington. This signals the real start of pest management season for us. Other, warmer sites likely had green tip earlier and I have heard a few reports of half-inch green showing.

Last week’s rains likely occurred before emergence of green tissue susceptible to apple scab, but rain today and tomorrow cause enough wetting for an infection period. Estimated ascospore maturity based on degree day modelling is relatively low right now at 2-3%, but actual maturity may be higher. If you sprayed copper in the last week, you should be okay, but if not, and significant wetting occurs, application of a fungicide with kick-back activity may be important, especially if you had high levels of scab last year which would provide ample inoculum for infection this spring. Strobilurin and DMI fungicides may be effective if resistance is not an issue in your orchard, but they would be better used later in the season when their activity against other diseases that aren’t yet a threat such as cedar apple rust and powdery mildew are active. The anilinopyrimidine (AP) fungicides Scala and Vangard would be better choices now because they are effective at cool temperatures (<50 F) and have little to no activity against fruit scab which limits their at later times. Kick-back fungicides should be combined with at least a half-rate of a protectant material (EBDCs or Captan, but no Captan within 10 days of an oil application) to reduce development of resistance in the local apple scab population.

White rectangle traps may be hung at three traps per ten acre block any time for monitoring tarnished plant bugs in the orchard. A cumulative capture of three bugs per trap for wholesale orchards or five per trap for retail orchards by tight cluster may indicate a need to treat before bloom.

Weather continues to look good for tree planting this week.

-Terry