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UVM Fruit Blog

Petal fall apple recommendations for Vermont orchards

Posted: May 23rd, 2017 by fruit

By Terence Bradshaw

Below are some notes I’ve taken, including my own thoughts and observations, from today’s Champlain Valley Petal Fall meeting hosted by Cornell Cooperative Extension. Thanks to Extension Associate Anna Wallis, plant pathologist Dr. Srdjan Acimovic, entomologist Peter Jentsch, plant physioloigist Dr. Poliana Francescatto, and consultant Jim Eaves for contributing to these observations and assessments of the apple crop as we shift from bloom to managing fruit.

Disease management

Pennsylvania fruit pathologist Kari Peters was reporting detection of mature scab ascospores in her state in February, which was earlier than normally expected. The Dr. Acimovic assessed leaves collected in the Champlain Valley of New York through spore towers since late March, after the blizzard snows melted. Ascospores were mature early in April. However, comparing actual spore release data with the RIMPRO model and comparing to estimated ascospore in NEWA models indicates that NEWA is likely overestimating the infection potential for early season (pre-bloom) apple scab. Despite NEWA suggesting that scab ascospores are expended for the season, actial spore releases and RIMPRO suggest 30% of ascospores are left to be expended in the North Country this season. Combined with the five infection periods which have already occurred in most orchards leading into and though bloom, this is expected to be a significant apple scab year. Growers should maintain fungicide protection going into rain/wetting events, apply a broad-spectrum kickback material such as a Strobilurin, DMI, or SDHI the next couple of sprays, and monitor orchards closely for signs of disease for the next couple of weeks.

Fire blight was a significant event in Champlain Valley and other locations in 2016, which has increased potential for inoculum buildup in area orchards leading into 2017. While much of the spring has been cool this year, hot weather leading into bloom last week coupled with high blossom density and high inoculum suggests that growers should keep an eye out for fire blight infections this year. May 18-21 was a period of obvious high infection potential. Cool weather since then has reduced inoculum pressure and further application of streptomycin is not recommended at this point unless future model guidance suggests otherwise. Only where late bloom is occurring on highly susceptible cultivars where fire blight was present last year (cider varieties, maybe Gala or Fuji in cooler sites) should another strep spray be considered.

Some growers use post-infection copper to reduce spread of fire blight infection. Tis should be done with extreme caution since copper materials can severely russet fruit. Only materials labeled for post-bloom use should be used, and they should be applied under rapid drying conditions and in as little water per acre possible (30-50 gallons per acre).

Infection from last year have been observed in rootstocks, sometimes through suckers and especially on M9 and M26. Affected trees may not have died last year but could have looked weak and succumbed over the winter. Other potential factors implicated in recently observed tree death that may be noticed this spring and in recent years include: winter damage, especially from the winters of 2013-14 and 2014-15; herbicide damage to tree trunks; drought stress; borer (dogwood, black stem, and roundheaded apple are a few borers of concern) infestation; and other causes, and many of those are likely interacting with each other in any given orchard. When growing young trees in challenging environments as we have had in the past decade or so, all best management practices should be applied to reduce tree stress: best site selection, good orchard nutrition, pest management, groundcover management, painting trunks, avoiding herbicide contact with trunks and foliage, avoiding overcropping.

Apogee, a plant growth regulator used to reduce vegetative shoot growth, is often recommended to reduce incidence of shoot blight which typically occurs a few weeks after bloom. Application should happen when new vegetative shots are 1-3 inches long (i.e., now) and again two weeks later. Apogee takes 10-14 days to act, but reduction in carbohydrate demand from shoots during that time increases the fruit’s proportion of carbohydrate partitioning from leaves. That means that use of full rates of Apogee may reduce the carbohydrate deficit in trees and make thinning more difficult to attain. Therefore, thinning and shoot fire blight management may be at odds at this time of year. It is recommended to use lower rates of Apogee, i.e. 1-2 ounces per acre rather than a full rate of four ounces, so that you may achieve good thinning and disease management together.

Insect management

Management of certain insects during the prebloom period, even if only with oil, or even with Lorsban or pyrethroids, can be easier because there is no foliage on the trees to block penetration of materials into the bark and tree canopy. Most materials, especially oil, that are applied for mites and San Jose scale (SJS) management require absolutely thorough coverage, which is difficult to attain with an airblast sprayer. Movento is a material effective against SJS that works a little better than others at this petal fall to first cover stage in case good early season management windows were missed for applying oil. This is also the window for applying a post-bloom miticide like those listed in the New England Tree Fruit Guide.

Dogwood borer is becoming an increasing problem in the region, especially on dwarf trees with high numbers of burr knots that are also stressed by drought and other factors. As we shift especially to high density orchards on dwarfing rootstocks, trees remain susceptible to borer damage for up to ten years (compared to the 3-5 years we used to think trees were particularly susceptible to borer damage). Black stem borer is another emerging pest in some orchards that provides another reason for maintaining clean weed control around tree trunks, painting trunks white to reduce stress from solar heating, and applying trunk-drench insecticides when appropriate.

Codling moth (CM) is an increasingly problematic pest in the Champlain Valley. CM have just begun flying in area orchards, and we will be reporting on best timing for management of hatching larvae.

For now, assuming you are at full petal fall and no bees (including wild ones) are in the orchard, insecticides should only be targeted at those pests that are above threshold (none that I’ve seen yet), or plum curculio which will be migrating into the orchard with the occasional warm weather we’re expecting. In many cases, insecticide application can wait until next week.

Thinning

Trees are stressed from many causes: 2016 drought; borers; weed control (lack thereof or collateral herbicide injury); cool, cloudy weather during leaf development this spring; and as a result, may overthin easily.

Thinning applications should be based on tree row volume. We haven’t discussed this much recently, Tree row volume is a calculation method which determines orchard canopy size and the theoretic al amount of water required to saturate that canopy with an airblast sprayer, generally ranging from 100-400 dilute gallons per acre (DGA). No one is planting 400 DGA trees any more, these are the big (20+ foot) old standard trees on wide spacings; most small/high density plantings are about 150 DGA; a typical mature M.26 orchard is about 250. Do not use more than 200 DGA as a basis for determining rates. Many materials will call for a rate based on xx/100 DGA. So if your material calls for 2 oz/100 DGA and you have a mature block of M7 trees, apply 4 oz per acre. No one sprays at the full dilute gallons per acre, so if you use 50 actual gallons of water on a 200 DGA block, you are concentrating your spray 4X. 100 gallons of water applied per acre is best for thinners, definitely don’t go lower than 50.

Some other notes to consider when applying thinners:

· Trees on large rootstocks thin easier, because there is more shading in the canopy.

· Leaves formed in low light like this spring will be more responsive to thinners.

· That said, cool temperatures in the next week will reduce activity of most thinners.

· Trees less than four years old will overthin easily.

· Options for each cultivar and more specifics on thinning are, again, in the Guide.

My thoughts:

Essentially all Vermont orchards should receive a petal fall thinner application this year, it’s our best chance to break the biennial bearing habit that many of our trees are in and to produce fruit of reasonable size and quality. Where you can (no bees, no accounts that disallow it), I would start with an application of carbaryl at 1 pint or 1 pound per acre, plus a moderate (5-7.5 ppm) rate of NAA. I would not use Maxcel or other 6-BA now, until temperatures warm up. One exception, and this comes with caveats that it’s not fully tested for effectiveness, is to replace carbaryl with 7.5 ppm NAA in a mix with Maxcel. However, I just learned of this today and have not evaluated it myself.

I will follow up in a few days after we see the weather and crop develop further. Keep good notes on what you have done and, if possible, try to skip a tree or two to compare against as you evaluate your thinning program. Remember that you’re trying to remove maybe 85% of the fruit from the tree, assuming strong bloom and good fruit set, not 50 nor 95%.

Organic growers: liquid lime sulfur applied (2% solution) in combination with 1% oil (watch for phytotoxicity) can help with thinning by stressing the trees while also giving some scab control. Otherwise, start hand thinning as early as possible to get the best results on increased fruit size and return bloom.

Where trade names or commercial products are used for identification,

no discrimination is intended and no endorsement is implied.

Always read the label before using any pesticide.

The label is the legal document for the product use.

Disregard any information in this message if it is in conflict with the

label.

The UVM Tree Fruit and Viticulture Program is supported by the

University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

Important clarification- 5/23 New York Petal Fall meeting, no tour

Posted: May 22nd, 2017 by fruit

By Terence Bradshaw

Sorry folks, I’ve advertised a tour that doesn’t exist. The Tuesday, May 23rd petal fall meeting will be held at 3:00 at Rulf’s Orchard in Peru, NY. There is no pre-meeting tour.

3PM: Thinning Meeting, Rulfs Orchard, 531 Bear Swamp Rd, Peru

Cornell Fruit Program Champlain Valley Petal Fall Meeting

Tuesday May 23, at 3PM

Rulfs Orchard

531 Bear Swamp Rd

Peru, NY 12972

Agenda:

Brief Introduction & Program Announcements – Wallis & Donahue, CCE ENYCHP

Fire Blight Survey – Liz Higgins, CCE ENYCHP

ENY Entomology Update – Peter Jentsch, HVRL

ENY Pathology Update – Dr. Srdjan Acimovic, HVRL

Thinning, Panel Discussion –

– Dr. Poliana Francescatto, Cornell NYSAES

– Jim Eve, Eve Farm Services LLC

– Dr. Greg Peck, Cornell University

– Dr. Terence Bradshaw, UVM

– Dan Donahue, CCE ENYCHP

– Anna Wallis, CCE ENYCHP

Where trade names or commercial products are used for identification,

no discrimination is intended and no endorsement is implied.

Always read the label before using any pesticide.

The label is the legal document for the product use.

Disregard any information in this message if it is in conflict with the

label.

The UVM Tree Fruit and Viticulture Program is supported by the

University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

Petal fall pre-discussion

Posted: May 21st, 2017 by fruit

By Terence Bradshaw

May 21, 2017

Most Champlain, Connecticut, and Taconic valley orchards are at petal fall or quickly approaching it, which means the management needs will ramp up quickly- insect and disease management; nutrient application, mowing/herbicide/cultivation; and, of course, thinning. I’ll be wrapping my head around thinning options in the next few days, but for now, virtually every orchard should receive a petal fall application of carbaryl or, if organic, lime sulfur to aid in thinning. Like every odd-numbered year since 2011, this looks like a heavy crop, and your best bet for a good crop next year is to take 80+% of it off now. This is not a year to be shy with thinners, but also recognize that foliage that developed during cool, cloudy weather, as well as trees that were drought-stressed last year, will respond more to thinners than non-stressed trees. On the other hand, sunny to partly cloudy, seasonably warm (not hot) weather like we’re expecting this week reduces the carbohydrate deficit in trees which is what drives thinning treatments, so we really can expect a fairly ‘normal’ thinning season overall.

That said, I will reserve specific recommendations until after Tuesday’s Petal Fall/Thinning meeting in New York, which all are invited to and which was discussed in a previous message. Wednesday looks like a decent spray day anyway, so I expect we’ll have a better handle on things by then.

I hope to see many of you in the Chazy/Peru (NY) area Tuesday,

Terry

Where trade names or commercial products are used for identification,

no discrimination is intended and no endorsement is implied.

Always read the label before using any pesticide.

The label is the legal document for the product use.

Disregard any information in this message if it is in conflict with the

label.

The UVM Tree Fruit and Viticulture Program is supported by the

University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

Disease management in Vermont grapes- the season begins

Posted: May 19th, 2017 by fruit

By Terence Bradshaw

Grapes are moving fast in Vermont vineyards, with most cultivars in the UVM vineyard at about 2” shoot growth. Shoot thinning now will give best results before the vines waste energy on growth that you won’t keep. We typically aim for 4-6 well-spaced shoots per foot of canopy, selecting for the most healthy/vigorous and those with appropriate orientation for our downward training system (high-wire cordon).

Figure 1 Before shoot thinning

Figure 2 After shoot thinning

This is a typical time to start thinking about a spray program to manage disease. The primary disease of concern at this point is phomopsis, as rachis infection at this point in the season is may cause significant fruit loss at harvest. Anthracnose may also be active at this point , given the warm/hot weather we recently had. Vineyards that have had recent problems with those diseases or organic growers using copper or other less-effective materials may consider treating this week; if you haven’t had major problems with those diseases, treatment can wait until the 5-8” growth stage as long as you are using a highly effective contact fungicide like mancozeb or captan.

As a reminder, a refreshed version of the Initial IPM Strategy for New Cold Climate Winegrape Growers is available at: http://www.uvm.edu/~fruit/grapes/gr_ipm/InitialIPMStrategyGrape2017.pdf

Organic growers are in for a bit more work. The standard fungicides, copper and sulfur, have only fair efficacy against this disease at best, and in a couple of weeks when black rot becomes the next disease of concern, those materials will have even less efficacy against that disease. The first line of defense in an organic vineyard is a strict sanitation program. This includes removing all mummies still in the canopy (not dropping on the ground, but actually removing them from the vineyard) as well as any obviously diseased wood. Phomopsis and anthracnose both overwinter largely on infected wood in the canopy, and removing this wood during dormant pruning or now is essential to reducing disease pressure. Stubs left at the ends of spurs should now be removed since you can see where this year’s shoot growth will resume (at the developing shoot)- these stubs will die and may become infected with phomopsis this season (or were last season) .

Figure 3 Removing stubs at end of retained spurs.

It is worth noting that both copper and sulfur (including lime sulfur) can cause phytotoxicity on certain cultivars. Dr. Patty McManus summarized her research on copper and sulfur sensitivity in cold-hardy grapes in the 2/8/16 Northern Grapes newsletter, and I’ll summarize it to say that Brianna should receive no copper; and Frontenac (all types), La Crescent, Leon Millot, Marechal Foch, Marquette, and St. Croix should receive no more than 2-3 copper sprays per season. Save those for later when black rot and downy mildew become bigger concerns. Sulfur sensitivity was observed on several cultivars, and its use (including lime sulfur) is discouraged on Foch, Millot, Brianna, and Louise Swenson; with limited (2-3) applications suggested on LaCrescent and St. Croix.

So, if you have removed all diseased wood and are ready to cover your vineyard for protection against phomopsis and anthracnose, the best choices is likely lime sulfur applied at two quarts per acre in sufficient water (25-30 gallons should do it) to wet the canopy. Lime sulfur is hot stuff: caustic, corrosive, and noxious. Use appropriate personal protective equipment and spray in cooler weather to reduce phytotoxicity. Powdered sulfur may also be a good choice, I would suggest 3-5 pounds per acre at this stage.

Where trade names or commercial products are used for identification,

no discrimination is intended and no endorsement is implied.

Always read the label before using any pesticide.

The label is the legal document for the product use.

Disregard any information in this message if it is in conflict with the

label.

The UVM Tree Fruit and Viticulture Program is supported by the

University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

Trauma blight

Posted: May 19th, 2017 by fruit

By Terence Bradshaw

May 19, 2017

An short, extremely intense line of thunderstorms passed through the state last night, accompanied with damaging high winds and, in some cases, hail. I was cutting trees out of our road soon after to make it passable, a neighbor lost 24 around his relatively small yard, many uprooted. That type of weather event can trigger trauma blight, where fire blight bacteria is moved to new abrasions and other wounds resulting from the storm damage.

Although the storm brought cooler temperatures, which will drop the bacterial inoculum levels in most orchards, that high inoculum of E. amylovera was around right before the storm. Many growers applied streptomycin in the past couple of days to protect against the infection that likely occurred to open blossoms as a result of last night’s wetting. Now I’m going to suggest, especially in high-risk blocks that had fire blight last year, getting out there again and putting on a second strep spray ASAP (as in, between now and tomorrow morning) to protect against trauma blight.

If you had hail or other damaging weather, make sure to contact your crop insurance agent within 72 hours.

Where trade names or commercial products are used for identification,

no discrimination is intended and no endorsement is implied.

Always read the label before using any pesticide.

The label is the legal document for the product use.

Disregard any information in this message if it is in conflict with the

label.

The UVM Tree Fruit and Viticulture Program is supported by the

University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

Cornell Champlain Valley Thinning Meeting Next Tuesday 5/23

Posted: May 18th, 2017 by fruit

By Terence Bradshaw

It’s hot today, it doesn’t take an expert to tell you that. Bees should be moving; orchards all over the state including in the inland, cooler regions are at least in king bloom. Hopefully you got a fire blight spray on if you’re at all concerned about that disease in your orchard. We found a short window of relatively calm weather this morning to treat the UVM orchards.

Next Tuesday, Anna Wallace and the rest of the Eastern New York Commercial Horticulture Program will host tours of orchards in the morning and a thinning meeting in the afternoon. I strongly recommend anyone who can make this meeting do so, there will be a lot to talk about and you’ll have the experts there to cover all of your questions, From Anna:

Hello everyone-

The Champlain Valley Petal Fall Meeting will be next week Tuesday 5/23 at 3PM.

Here is the approximate agenda for the morning orchard tour and the meeting agenda. I hope you will all be able to join us for the morning tour. If not, please be in touch and we will meet with you when you are able to join us. Addresses are approximate, so please be in contact with me if you’re arriving late. My Cell: 518-410-6823.

Morning Tour – approximate agenda

9-10AM: Chazy Orchards, 9486 U.S. 9, Chazy

10:30AM: Everett Orchards, 345 Pleasant St (22B), Peru

11:30AM: Forrence Orchards, 86 River Rd, Peru

12:30 Noon: Quick Lunch, TBD

1PM: Northern, 537 Union Rd, Peru

2PM: Hart (if time allows), 2327 Rt22, Keeseville

3PM: Thinning Meeting, Rulfs Orchard, 531 Bear Swamp Rd, Peru

Champlain Valley Petal Fall Meeting

Tuesday May 23, at 3PM

Rulfs Orchard

531 Bear Swamp Rd

Peru, NY 12972

Agenda:

Brief Introduction & Program Announcements – Wallis & Donahue, CCE ENYCHP

Fire Blight Survey – Liz Higgins, CCE ENYCHP

ENY Entomology Update – Peter Jentsch, HVRL

ENY Pathology Update – Dr. Srdjan Acimovic, HVRL

Thinning, Panel Discussion –

– Dr. Poliana Francescatto, Cornell NYSAES

– Jim Eve, Eve Farm Services LLC

– Dr. Greg Peck, Cornell University

– Dr. Terence Bradshaw, UVM

– Dan Donahue, CCE ENYCHP

– Anna Wallis, CCE ENYCHP

Again if you have any concerns or questions, please let me know.

Thank you again for assisting with this meeting!!

Anna

Also: I will be along for the whole tour and meeting, so if you have any questions about where we are at any time, feel free to call me during the day at: (802)922-2591. –Terry

Where trade names or commercial products are used for identification,

no discrimination is intended and no endorsement is implied.

Always read the label before using any pesticide.

The label is the legal document for the product use.

Disregard any information in this message if it is in conflict with the

label.

The UVM Tree Fruit and Viticulture Program is supported by the

University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

Fire blight risk for Thursday and Friday of this week

Posted: May 16th, 2017 by fruit

By Terence Bradshaw
May 16, 2017

Okay, we’ve been hinting around about it for weeks, and the risk for fire blight will be upon us later this week. Warm weather today, and hot weather Wednesday and Thursday will allow for substantial increase in populations of E. amylovera, the bacteria that causes fire blight. Once that population is sufficiently high (characterized as the EIP or epiphytic infection potential in NEWA, 100 is considered high enough to cause infection), you need three factors for infection to occur: open wounds (i.e. blossoms or fresh pruning cuts); mean temperature above 60°F; and wetting, even a spray or dew event can be enough to move bacteria into susceptible openings.

This risk is pretty much widespread across the state. The thing to remember is that protective measures, i.e. application of streptomycin in most orchards, or caustic materials/biological controls in organic orchards, must be applied to open wounds or blossoms within 24 hours before or after infection. So if we assume that an infection event occurs in a rain event Thursday afternoon, you’ll want strep or another material (really, if your orchard isn’t certified organic, strep is the only material to consider) on by mid-day Friday. It will be hot Thursday, so blossoms will be opening all day (or petals falling on cultivars that have finished bloom already) and potential for phytoxicity will be greater. The later you can go, the better to make sure you cover any blossoms that open, but don’t delay and miss it. It’s also going to be on the windy side, so there’s that.

Harbour is the strep material available to most growers. I would recommend applying at 1-2 pounds per acre based on tree canopy volume, if in doubt, err on the lower end. I also recommend including a wetting agent like Regulaid or LI-700. If possible, apply on its own, without other fungicides or insecticides (you are in bloom, so no insecticides anyway). You will get leaf yellowing from this application, expect it and the tree will soon grow out of it. One application Wednesday PM-Friday AM should cover you. Once any particular blossom is treated, it’s protected. Temperatures are expected to drop after Friday, which lowers risk, but if high risk continues through the weekend and you keep having blossoms open, then a second application Saturday-Monday (I have no good idea of what the weather will be five+ days from now) may be warranted.

Trees that are at full petal fall are not susceptible, but straggling late blooms can be infection sites. Ideally, the whole orchard would be treated. If you need to prioritize, go first for cultivars that had fire blight last year or highly susceptible cultivars (Gala, Ginger Gold, Honeycrisp, Cortland, Paulared, etc), and of course blocks that are in bloom. Application well after Thursday’s infection event, on Saturday or later, will not give protection against it. Also, despite the wording on the Harbour label, continued treatment every 10-14 days after bloom is not recommended, and doing so is a) expensive, b) a waste, and, most importantly, c) the best way to develop antibiotic resistance in E. amylovera populations.

For organic growers, Actinovate, BlightBan A506, Bloomtine Biological, Blossom Protect, Double Nickel, Regalia, and Serenade are labeled biological controls. I can’t vouch for any of their effectiveness, and I know that some growers apply copper or lime sulfur (warning- both are very phytotoxic) during bloom to manage the disease but again, no promises are offered from me there. If you can, I would suggest Serenade or one of the other biological materials if you have it on-hand and to watch carefully for symptoms which will require cutting out.

I’ll be following up on this as things develop. The key here is to treat for this week’s infection, then relax.

Terry

Where trade names or commercial products are used for identification,

no discrimination is intended and no endorsement is implied.

Always read the label before using any pesticide.

The label is the legal document for the product use.

Disregard any information in this message if it is in conflict with the

label.

The UVM Tree Fruit and Viticulture Program is supported by the

University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

May 14 Orchard thoughts

Posted: May 14th, 2017 by fruit

By Terence Bradshaw

May 14, 2017

Orchards in the Champlain and Connecticut valleys are in full bloom now, and it looks like a good one. After my worrying comments last week about poor weather for bee flight, one grower last Monday told me, “You’re worrying too much. It’ll happen.” And it looks like Thursday and Friday the bees were flying. Although I am not trapping for native pollinators this year, I did notice some small native bees in trees in Putney Thursday afternoon. I wasn’t at the UVM orchard Friday, but my technician told me the bees were moving well. Orchards in cooler upland and inland spots will likely be flowering later this week, which also looks like a period of decent (>60° and sunny)bee weather.

Since we are talking bees, we need to continue to keep them in mind as we begin to think about petal fall and insect pest management. We have found extremely low levels of the usual pink/petal fall insects, tarnished plant bug (TPB) and European apple sawfly (EAS), in orchards all across the state. Some growers predicted and I confirmed a suspicion of a protracted bloom and therefore applied prophylactic insecticides at pink. In terms of bee protection, that is a valid response as long as those who applied a broad-spectrum, non-neonicotinoid material at pink use that extra protection they applied to give a little more time for all petals to drop and to clear out other attractive blooms by mowing before applying the next insecticide. This is our most dangerous timing for potentially damaging bees, because we need to get in to protect the developing crop, but there is still potential for a lot of pollinator activity in the orchard. Remember, pollinators aren’t just the honeybees you bring in to the orchard, and as we have been developing softer, more pest-specific spray programs in recent years, we are encouraging pollinator conservation in the orchards (good), which increases the number of pollinators that could be impacted when we apply that important post-bloom insecticide (not good).

I have been advising growers who are either still at pink or approaching petal fall who have below-threshold populations of TPB and EAS but who have concerns about lepidopteran pests now to consider using only a Bt spray like DiPel. Green fruitworms and obliquebanded leafroller are active now and may be monitored by inspecting 100 blossom/fruitlet clusters and terminal tips in multiple sections of the block and looking for larvae (small green caterpillars). Bt is very effective against moth larvae but has no known effect against most other insect orders, including bees.

Speaking of moths, if you have not already done so, now is the time to hang codling moth (CM) traps in the orchard. These traps are baited with either a pheromone (most common) or fruit volatile (used where CM mating disruption is used) lure and is used primarily to set the biofix date for use in the CM development model in NEWA, so daily or at least 2-4 times per week inspection is needed until the first moths are caught. Trap counts may be collected for the rest of the season to gauge population size and flight patterns. I mentioned CM mating disruption. We have been using this tactic since 2011 after suffering 65-75% damage in our organic orchards at the UVM Hort Farm. This year we have started using a Trece product, Cidetrack CMDA Meso, which reduces the needed number of applicators per acre from up to 200 to 36. This greatly affect the ability of larger-acreage orchards to hang the dispensers. Eric at CPS can provide details on availability and pricing, but growers who wish to try them must be prepared to treat the whole orchard, and should get them up as soon as possible before CM start flying and mating. A good background on using mating disruption in orchards can be found here. It’s a little bit old so the products listed may not be available or registered for use in Vermont.

Fire blight continues to be a non-issue for now, but increasing temperatures forecast for next weekend may trigger an infection, I’ll keep you posted as things develop. Keep in mind that bacteria need open blossoms to cause blossom blight, so as your petals fall, so does your risk. Scab- it’s still active, and I assume everyone is protected for today’s rain. As we get into the late bloom/petal fall window, addition of a material to the usual protectant (mancozeb/captan/sulfur if organic) schedule may be prudent. Consider a strobilurin (IRAC class 11), SDHI (7), or, if the bees are all gone, DMI (3) fungicide in your next spray or two.

Thinning is going to be interesting this year. Every orchard I have seen will need thinning, and I am going to work up some thoughts on recommendations later this week.

Finally, I have been asked to pass on to the orchard community that Dave Boyer, from Boyer’s Orchard in Monkton passed away last week. His obituary can be found here.

Where trade names or commercial products are used for identification,

no discrimination is intended and no endorsement is implied.

Always read the label before using any pesticide.

The label is the legal document for the product use.

Disregard any information in this message if it is in conflict with the

label.

The UVM Tree Fruit and Viticulture Program is supported by the

University of Vermont Agriculture Experiment Station, a USDA NIFA E-IPM

Grant, and USDA Risk Management Agency Funds.

Pink bud in Vermont apple orchards, some thoughts on bloom and pest management

Posted: May 5th, 2017 by fruit

By Terence Bradshaw

May 5, 2017

Ugh. Vermont orchards are largely at tight cluster (inland, cooler sites and cider cultivars) to pink (most of the Champlain Valley, Honeycrisp of course is lagging) to early king bloom in a few spots and even a little full bloom in the warmest spots. Yesterday was a decent but not great ‘bee day’

for those with open flowers, but an extra 3-5 degrees would have moved their activity up a bit. My greatest concern going into the 2017 crop is this weather we’re facing as we go into bloom- gray, wet, and cool. Hopefully bud development will slow sufficiently so that by the time we get king or at least full bloom, we’ve got good bee weather. Pollen viability extends quite a bit in this weather, up to five days or more after a flower opens, so that’s a good sign as well. If you have the ability to get any extra bees in the orchard, consider doing so. And of course if you have any bees flying in the orchard, treat them right- no insecticides, especially neonics and any materials rated highly toxic to bees; lay off sterol inhibitor/DMI fungicides, at least until we learn more about their effects on pollinators; and mow competitive flowering weeds, if necessary, to funnel them to your apple blossoms. I wish I had a magic bullet that would improve pollination/fertilization/fruit set in a tough bee year, but there just isn’t any proven snake oil you can throw at the trees to compensate for this weather, so the best you can do is to promote and protect the pollinators (managed and wild) that we do have.

That said, this may be a year to consider supplemental pollen application. We have blown pollen at the UVM orchard as long as I have been around (over twenty years), and while it’s not a commonplace practice, it’s something I’ve done partly out of tradition (it was one of the first jobs I did when I started at the UVM orchard as an undergrad in May 1995) and partly to improve our overall pollination since we don’t bring in migratory bees (but we do have seven hives on the property). I was going to skip manual pollination this year, but this bad weather had me calling Firman Pollen to order some up to apply next week. I cannot point to a good peer-reviewed study that says it works in all conditions, but supplemental pollination has, anecdotally anyway, been successful for us. Application method is a little tricky and I don’t know if Firman has the leaf blower guns anymore, but it’s worth checking with them. They also have hive inserts that you add to bee hives to increase the amount of pollen that bees are carrying as they travel through the orchard.

Thursday’s weather provided an ideal spray day between rain events, and I assume everyone took the chance to get covered up. We maintained our spray coverage at the UVM orchards- scab sprays (mancozeb + Vangard) on the IPM and cider blocks, and insecticide (Aza-Direct and Dipel) in the Vf-gene scab resistant organic block where scab isn’t a problem but European apple sawfly and green fruit worn perennially are. Those two sentences covered most of what you need to be thinking about as far as pest management in the next week. Apple scab is the primary threat now, and I expect that when it’s all over, the models will call the period from April 30 through May 10 or so one long infection period. We are entering peak ascospore maturity right now, which means the guns are loaded and each wetting event will release more spores and infection will occur unless you’re protected. Keep covered with a protectant fungicide- mancozeb, captan if you haven’t applied oil recently, or sulfur if you’re organic (and same warning with oil). Five to seven days, max, between applications, and remember that an inch or two of rain removes the coverage you just put on. If you have another perfect, dry day like we has yesterday, add in a more broad-spectrum material with kickback activity (i.e. activity after an infection has occurred but before spores penetrate the leaf cuticle) that can broaden activity against rusts or powdery mildew. Remember the tables in the new spray guide to help guide your decisions. This is a good time to use your strobilurin or SDHI materials.

Notice that I just mentioned a disease concern, but didn’t bring up fire blight. Despite my warning last week to have some streptomycin on-hand for bloom this year, the onset of cool weather has almost completely shut down concern of blossom blight infection, for now anyway. Remember that in order to have a fire blight blossom infection, you need four conditions to occur: 1) open blooms through which bacteria can enter the plant; 2) wetting events during bloom to move bacteria into susceptible tissues; 3) sufficient heat (daily average over 60°F) during an infection event to permit bacterial reproduction in susceptible tissues; and 4) sufficient levels of bacteria present going into bloom. The cold weather has shut down bacterial population growth so the last condition isn’t a concern, and I don’t see any window in the next week anyway where mean temperatures will be over 60°F in any stretch of more than a few hours. Until I say otherwise, put fire blight out of mind, but remember that a warm/hot spell during bloom could turn the situation around quickly. In the meantime, this past week’s Scaffolds newsletter from the fruit team at Cornell has a great synopsis of the fire blight situation in the region.

Insect trap captures are very low across all monitored sites, nothing that I would treat anyway. That said, we are looking like we’re entering an extended bloom period, and that means that those pests waiting in the wings can start doing damage on early-blooming cultivars while you’re waiting for petals to drop on the later ones. Growers with low tolerance for cosmetic injury or history of European apple sawfly may consider a prophylactic pink spray, but I only say that because of the drawn-out bloom. Ideally, sprays will be based on quantifiable trap data, and in no orchard have we caught even remotely enough of either to warrant a pink spray.

In between sprays, this is still a great window to get your trees in the ground, apply herbicide, and fertilize orchards. We did all three this week at the UVM Hort Farm, or at least my technician Jess and chief engineer Andy did. I had one of those days yesterday when it took me as long to spray seven gallons of material (herbicide in the vineyard() with an electric backpack sprayer as it did Jess to spray 600 gallons of materials from three sprayers in multiple orchards. The lesson here is to make sure your equipment is ready to go the day before you need it. And maybe to not let the Professor play Farmer, but I’d say I still do all right at it when I prepare properly.

-TB

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Wine grape webinar

Posted: May 1st, 2017 by fruit

Dear Northern Grapes Project Webinar participants:

Announcing the May Webinar (last webinar of the season):

“Introducing Itasca – Minnesota’s new cold-hardy white wine grape”

Matthew Clark John and Jennifer Thull
University of Minnesota University of Minnesota

Tuesday, May 9th, 2017

12:00 Noon Eastern (11:00 am Central)

7:00 pm Eastern (6:00 pm Central)

With Matthew Clark, Jennifer Thull, and John Thull

The University of Minnesota has released its newest wine grape variety. Itasca is lower in acid, exhibits improved cold-hardiness, and should be suitable for making a dry-style white wine. The final Northern Grapes Webinar will discuss the characteristics of this new variety including tasting notes, growth habit, and juice chemistries. Matthew Clark is an assistant professor of grape breeding and enology at University of Minnesota. His research focuses on traditional and molecular plant breeding techniques to develop improved cold-hardy grape varieties for wine production. Jennifer Thull, gardener, and John Thull, research professional, work in grape breeding and enology at University of Minnesota.

If you have received this email from someone other than Alex Koeberle, you need to register via the link below:

https://cornell.qualtrics.com/jfe/form/SV_6rtPeOtaWTh3xuR

Registering for this Northern Grapes Webinar will place you on the mailing list, and you will receive announcements and connection instructions.

Registration will close at 12pm (Eastern) on Friday, May 5th

Registration is NOT required if you received this email directly from Alex Koeberle, as it means that you are a member of the Northern Grapes Webinar mailing list.

All members of the Northern Grapes Webinar mailing list will receive an email the Monday before the webinar containing the web address (URL) for both webinar sessions as well as connection instructions.

Feel free to email Alex Koeberle (alk239) with any questions, if you want to check your registration status, or if you’d like to be removed from the Northern Grapes Webinar mailing list. Please DO NOT respond to the Northern Grapes listserve.

The Northern Grapes Project is online and on Facebook! Previous recordings of the 2016-2017 Webinars are now available online. Please visit this link.

The Northern Grapes Project was funded by the USDA’s Specialty Crops Research Initiative Program of the National Institute for Food and Agriculture, Project #2011-51181-30850 and through the New York State Specialty Crops Block Program.

We thank the following organizations and businesses for their support of the Northern Grapes Webinar Series:

Grower Associations Sponsors

Iowa Wine Growers Association

Illinois Grape Growers and Vintners Association

North Dakota Grape and Wine Association

Eastern Winery Exhibition

Colorado Wine Industry Development Board

Michigan Wine Industry Council

Connecticut Vineyard and Winery Association

Wisconsin Grape Growers Association

South Dakota State University Grape Program

Southern Minnesota Wine Grower Alliance

South Dakota Winegrowers Association

Industry Gold Sponsors

Double A Vineyards

Agro K

Bevens Creek Vineyard & Nursery

Mariposa Fields Vineyard

Industry Silver Sponsors

Scott Labs

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