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UVM Fruit Blog

Scab infection April 19-22

Posted: April 19th, 2017 by fruit

By Terence Bradshaw

It doesn’t take too much fancy software to tell that we are in the middle of a pretty good apple scab infection period in most every orchard in Vermont. Ascospore maturity is estimated at 4-8% for today, and up to 14% in some orchards by the end of the weekend with showers and rain expected for the next four days. Orchards that were covered with copper or another full-rate before April 12 may still have protection, but if more than one inch of rain falls, reapplication during a break in the weather would be warranted. Addition of Vangard or Scala in that spray (in combination with at least a half-rate of EBDC or Captan) will help to manage any infections that slipped though if poor coverage and/or washoff is a concern.

However, in cooler orchards with less tissue showing (and potentially low inoculum from last year), a postinfection material may not be warranted. Use your judgement here and err on covering up if in doubt. This is a good time to put on some oil (2%, good full coverage) but not if using Captan or sulfur in the next or previous 7-10 days.

Organic growers: ignore my suggestion for adding a postinfection fungicide if that means using liquid lime sulfur at this time. The scab risk isn’t great enough to offset the negative impacts that LLS has on orchard ecology and tree health. Save that ‘big gun’ for later in the season. If you feel like you need some retroactive coverage, consider Oxidate or one of the potassium bicarbonate products. Either of those must be applied shortly (<24 hours) within the onset if infection.

I’m away through the weekend, so good luck on this. In between worrying about scab (which, in the big picture, isn’t a massive threat right now), start planting trees and getting other spring activities in order. You can expect to fertilize soon when the soil warms up a bit. And of course everyone is done with pruning and pushing brush, right?


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


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.

Pest management in apples this week

Posted: April 17th, 2017 by fruit

By Terence Bradshaw

Warm weather over the weekend advanced bud stages, pretty much everything in the Champlain and Connecticut Valleys are at green tip and some orchards are bordering on half-inch green. If you haven’t gotten copper out yet, now is the time, tomorrow (Tuesday 4/18)v looks like a good day wind-wise. We’re also out of any frost risk for the foreseeable future (but not necessarily done for the season so don’t plant out your tomatoes), so you can apply oil any time. At this point I would apply 2% (volume/volume) oil and soak it down real well with 100+, preferably 200 gallons of water per acre. After tight cluster, 1% oil should be used to avoid phytotoxicity.

As temperatures cool down this week, bud development will also slow. However, scab ascospores will continue to mature and by mid-week we can expect 5% or more of ascospores to be available for release during the expected rains and wetting events. This is another reason to cover your trees Tuesday prior to the rain. If you put on a full copper rate Friday or later, you are probably good for now, but if you had spotty coverage or have had substantial bud development, and therefore emergence of new susceptible tissue, since you sprayed, then another preventative fungicide may be called for.

Insect activity is generally pretty quiet now, but tarnished plant bug will start to move as days warm up. This would be a good week to get trapes up for this insect pest. We recommend four white sticky traps per block hung knee high in a visible location, often at the block edges. Traps should be checked at least weekly and treatment for TPB considered if over threshold. Thresholds are variable based on tolerance for cosmetic damage- for apples marketed wholesale, three bugs per trap before tight cluster or five before pink bud would warrant treatment; for retail and pick-your-own orchards, the recommended treatment threshold is five and eight bugs per trap, respectively, for those bud stages. TPOB and other insects managed at pink are usually treated with a synthetic pyrethroid material and that is still the recommendation. In order to conserve wild pollinators, we do not recommend use of neonicotinoid insecticides before petal fall.

1Tarnished plant bug trap (lower left) in tree. Right picture: TPB on trap.

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


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.

Green Tip in Champlain Valley

Posted: April 13th, 2017 by fruit

By Terence Bradshaw

April 13, 2017

Champlain Valley orchards in Chittenden and Addison counties have reached the green tip bud stage on ‘McIntosh’ as of yesterday, April 12, which indicates that the growing season has begun for many Vermont orchards. Keep an eye out in your own orchards and plan on using actual green tip date as the starting biofix for scab models in NEWA and any other system that you might use to predict apple scab ascospore maturity. Apple scab can affect any green tissue on the plant at this time of year, but remember that ascospores, the overwintering inoculum that cause scab infections, mature in a typical bell-shaped curve with greatest spore maturity beginning after about 200 degree days (base 32°F) have accumulated from green tip. As I said last week, 2016 was extremely dry and scab was low in most Vermont orchards, so a small percentage of spores from a relatively smaller overwintering crop mean relatively low risk. Leaf wetness is needed to cause scab infection, and showers are expected over the weekend but not an extended, drawn out wetting event. So overall, scab risk is relatively low, but if you have high inoculum (i.e. had scab last year) and get a decent wetting event, you’ll need coverage before or during the weekend.

Luckily, the answer to the “What should I do?” question is the same. At this point, even if you are still at silver tip in your orchard, it would be prudent to apply copper at a full rate to reduce fire blight (which was present in plenty of orchards, and likely wild hedgerow trees, last year) bacterial populations. This needs to go on prior to 1/2” green tip to prevent fruit russeting, which I have seen in certain years and which can immediately drop a perfectly good apple down to cider grade. This copper application will give you 5-7 days’ protection against apple scab. I would stick to the old standard copper materials like Champ, C-O-C-S, Cuprofix, Nucop, or Kocide and apply at the higher rates (in the 5-10 lbs per acre range usually, check your label). The new, low-rate coppers (e.g., Badge, Cueva) are better saved for summer use if you need them, as they don’t provide the value in terms of amount of copper ions per dollar that the older materials do.

Beginning next week we will start our orchard monitoring program by hanging tarnished plant bug and European apple sawfly traps in select orchards in the region. I’ll pull together some resources shortly for those who wish to ‘scout along’ with us in your own orchards. Until then, wrap up that pruning, push out the brush, and get the copper ready. Spring is 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


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.

Timely registration for summer 2017 Cold Climate Viticulture course

Posted: April 9th, 2017 by fruit

UVM students will be signing up for fall courses this week, and often sign up for summer courses as well at the same time. If you have any interest in taking my summer Cold Climate Viticulture course, signing up sooner rather than later is recommended. This is an ideal ‘crash course’ for anyone who is seriously considering winegrape production in Vermont or surrounding regions.

Tuesdays and Thursdays, 9:00 am – 3:45 PM

June 20 – July 13, 2017

University of Vermont Horticulture Research & Education Center
South Burlington, VT

Information and registration

Students will learn principles and practices of commercial cold-climate grape production, including: site selection and preparation; varietal selection; vine training; nutrient, water and pest management; harvest; and introductory winemaking considerations. Special emphasis will be placed on environmental and economic sustainability of the vineyard operation. The class will apply knowledge of integrated horticultural and pest management practices in a real vineyard setting. The class format will consist of a combination of classroom lectures, hands-on fieldwork, and visits to local commercial vineyards. Students are responsible for their own transportation to the UVM Horticulture Research and Education Center.

For more information contact Terence.Bradshaw

Respirator fit testing services in Vermont

Posted: April 6th, 2017 by fruit

By Terence Bradshaw

Remember, the EPA Worker Protection Standard changes that took effect January 1 of this past year include new requirements for medical clearance to use respirators and fit testing of respirators for farmers and employees. Below are possible fit testing service providers to check with to ensure compliance for this coming year. I’ll send around more information shortly after I get my attachment issues sorted out with this email list.

Occupation Health Services, Brattleboro


Occupational Health Partners, Rutland, Manchester, Middlebury


Evergreen Environmental Health and Safety, Barton


Northwestern Occupation Health, St. Albans


Champlain Medical Urgent Care, South Burlington


VT Air Testing Services


Occupational Medicine and Rehabilitation Therapy Center, Berlin


Southwestern Vermont Healthcare Bennington


Beginning of apple scab season, 2017

Posted: April 5th, 2017 by fruit

By Terence Bradshaw

April 5, 2017

NEWA Apple Scab and Phenology Models

We don’t need computers and models to tell us that by mid-April we ought to expect apple bud break to be around the corner, and with temperatures in the 70s forecast for Monday and Tuesday of next week, I expect many orchards to be at green tip by then. Of course this does have us looking to apple scab development models to get a sense of where we’ll be on that front next week, and more than one grower noticed in the past day or two that there is an anomaly in the NEWA apple scab model for many sites. There are two models on the scab page, one which is predicting your bud stage, and the other which predicts apple scab ascospore maturity. The latter model relies on McIntosh green tip as the biofix to start accumulating degree days, so if the model guesses wrong, then your accumulation may be incorrect.

However, remember that these are simplified models that are predicting complex biological phenomena. The development of apple tree phenology is dependent on more than just air temperature, and of course there are multiple methods of measuring degree days to further complicate things. So the model that guesses the green tip and other phenology stages for your site may not be correct, and you should always enter site-specific data for your orchard to increase the accuracy of the model. On the other hand, the predictive phenology model built into the apple scab model is a bit more conservative than the previously mentioned and more visible phenology model that populates the ‘green tip date’ box on the site. During a conference call yesterday with NEWA state coordinators and overall program coordinator Dan Olmstead and former coordinator/NEWA developer Julie Carroll, we learned that they intentionally set the ‘green tip predictor’ in the scab model a bit more conservative so as to not miss early ascospore development. The result is that the apple scab model can show accumulated degree days since green tip while the green tip predictor model says you are still xx days away from green tip.

The moral of the story is twofold. First, for any NEWA model that calls for a biofix you will get more accurate results if you enter an actual value for your orchard. Second, remember that these are models and therefore are well-educated guesses, and thus you should not assume 100% confirmation to actual biology in the orchard. They are good, and have become invaluable to all of our work, but sometimes common orchard sense (e.g., there’s no green tissue so there’s no scab risk to worry about) is still important.

What About the First Scab Sprays?

I’ll go out on a limb and say that in the major apple production areas we will have green tip next week. However, the long-term weather looks relatively mild, warm but not outrageous, so I expect bud phenology and ascospore development to move along at a moderate pace. If your orchard was clean last year, and I mean you know it was clean by assessing lesions in the fall using a PAD method, then you can likely skip the first scab spray, depending on when that is needed. Of course we need rain and extended leaf wetness to initiate an infection, so if it’s dry, you don’t need protection. After the next couple of days where the prognosticator in me says with 100% certainty that it will be rainy (but without green tissue on trees to be infected), I don’t know what the rain situation will be like next week.

However, we will be advancing from green tip toward 1/2” green, and that is the last window to apply copper which will be extremely important to do on any orchard that had fire blight last year. That copper spray will also give you 5-7 days’ protection against scab, so consider that your first spray against both of those diseases. Copper’s effect on fire blight is to reduce overwintering inoculum on wood, this assumes that you were thorough in pruning out infected wood, especially those big cankers that can form on limbs and trunks. After 1/2” green tip, you run the risk of causing fruit russet with copper application which can severely downgrade fruit marketability. If you are growing fruit for sale to cideries and know for certain that you will not be marketing for fresh fruit, you may be able to extend your copper spray window a bit, or consider using low rates of copper later in the growing season for management of apple scab or fire blight. However, there are generally better alternative products to use later in the season if you plan ahead, unless you are limited to organically-acceptable materials.

I would plan on applying copper to any orchard that had any amount of fire blight last year and which is showing green tissue or at least solid silver tip as soon as you have a suitable spray window. If possible, I would plan on applying copper to any orchard, period, that is between silver tip and half-inch green in the next 7-10 days. There is a pile of materials out there and for all intents and purposes for this delayed dormant spray any of them are effective as long as you are applying a good full rate of copper ions. The standard dry materials like Champ, C-O-C-S, Cuprofix, Kocide, etc. will give you the best bang for the buck here, and I would apply the full label rate for any of them and thoroughly spray the whole orchard. The only caveat I offer is if phenology advances rapidly before you can get out there and the trees are at 1/2” green tip, in that case, I would apply a low to middle rate. After 1/2” green tip, unless you don’t care about fruit finish, I would avoid copper.

Cleaning Up

The next week looks good for performing orchard sanitation to get things ready for spring- wrap up your pruning, push any brush out of the rows, flail mow leaves and fine brush, and consider applying a coarse urea spray (44 lb in 100 gal water applied per acre, directed at the leaf litter). The latter two practices can reduce overwintering scab inoculum and allow you, if you had low incidence of scab last year and were thorough in flail mowing or applying the urea, to skip a scab spray, maybe two, while ascospore development is low.

Looking Ahead

Whenever I want to show someone scale on fruit I am pretty sure I can easily find fruit with damage at any supermarket, and many of those fruit are from Vermont orchards. In recent years many orchards have been backing off from oil applications which really do a good job reducing overwintering scale, mites, and, to a lesser extent, some other insects such as codling moth and aphids. Oil application must be made at a dilute setting, generally 100 gallons of water or more per acre, so they take a while. They are most effective against mites just prior to them hatching, and therefore are best applied around tight cluster, so we’ll discuss again in a week or two. You can also use lower rates at that time, so the cost is a little better. But if your orchard is clean and you’re looking for things to do this coming week, feel free to apply a 2% oil in all blocks. Oil can be mixed with copper, but it should not be applied 48 hours before or after freezing weather, which is another reason why growers tend to opt for later applications.

Don’t Forget- The New England Tree Fruit Management Guide is now housed at: http://netreefruit.org.

The growing season looms…

Posted: April 3rd, 2017 by fruit

April 3, 2017

By Terence Bradshaw

My predecessor and longtime mentor Lorraine Berkett always told me to be ready for the growing season to start any time after April 1. After receiving another eight inches of snow at my house on April 1 this past weekend, I feel safe in saying that we still have a bit more time to go before bud break. That said, we do need to be ready, and these first few weeks of spring are important ones to get caught up on pruning, reviewing previous seasons’ activities, and laying out our plans for the coming year.

While I confess I haven’t done any bud dissections yet to assess winter injury to grapevines, after ten years of collecting that data I feel pretty confident in saying that the winter we are coming out of was not severe enough to cause widespread bud damage and that growers should prune as usual without adjusting for winter damage. While larger vineyards have been at it throughout the winter, pruning in many smaller vineyards that can be done in short time is often put off until as late as possible in order to potentially delay bud break and avoid working in the coldest of winter conditions. I also feel pretty confident that the major cold weather that could cause damage to buds, canes, and trunks is behind us, so if you haven’t done so, get pruning.

Late winter is a good time to review your previous season’s spray records and to identify any gaps that may have led to disease issues. Because the 2016 growing season was unusually dry, many vineyards did not have disease issues, even if spray schedules were a little ‘loose’, but growers should be prepared to maintain a full preventative disease management program in 2017. I recently revised two documents that Dr. Berkett had written on managing disease in cold-climate grapes: a table of relative disease susceptibility of cold-climate cultivars and an initial IPM strategy for cold climate winegrapes. Additionally, the 2017 New York and Pennsylvania Pest Management Guidelines for Grapes are now available and should be used in combination with specific pesticide labels to select pesticide materials for use in your IPM program.

One pesticide spray that is often considered by growers is a dormant application of lime sulfur (LS) which aids in inoculum reduction against many diseases, especially phomopsis and anthracnose. Growers who have had more than a passing amount of either of those diseases, as well as organic growers with more limited choice of materials during the growing season may consider applying this practice, but I make that recommendation with several caveats. While LS is an organically-approved pesticide, it is one of the most acutely toxic materials I have ever used, and demands special considerations for its use. It is also a restricted-used spray material, so unlicensed applicators may not purchase or apply it. LS (active ingredient calcium polysulfide) is very caustic; spray mixtures tend to have pH around 10-11, and that characteristic is what gives it its sanitizing effect as a biocide. Contact with skin or especially eyes must be avoided, and it is pretty noxious even through a respirator. This material demands respect. While those effects will dissipate in the field after sufficient washoff and degradation by rain and other elements, I would only plan on applying after pruning is finished so not to muck around in it after application. In fact, very thorough pruning out of all dead and diseased wood is an important cultural disease control practice, and if you have a lot of such wood left in the vineyard, spraying your way around pruning it out won’t help.

LS is typically labeled for application at “15-20 gallons per acre in sufficient water for coverage” (Miller Liquid Lime Sulfur). That is a very high amount of LS, and would be difficult to apply and very costly when applied to large acreages. The key is to fully soak all woody tissues in the vineyard. This may mean aiming all nozzles at the cordons, but that would leave the trunks uncovered. Alternatively, the sprayer could be operated to cover the whole zone from the fruiting wore down, which would waster a tremendous amount of spray. The best application may come from a careful handgun application, which will take a long time and should be done with full protective gear including heavy nitrile gloves, full face shield and respirator, and Tyvek or other chemical-resistant, disposable coveralls. It is hard to say how much you would apply per acre in a directed spray, since that would be much more efficient with less wasted spray than an airblast application. My suggestion would be to apply a 10% solution (1 gallon LS to 9 gallons water) by handgun to cordons and trunks in a very thorough soaking spray. If you need to use an airblast to cover more ground, I would concentrate my nozzles toward the cordons but leave one or two directed toward the trunks, that will waste spray between vines but will allow you to cover ground much quicker. Because of the reduction in efficiency, I would calibrate to apply ten gallons of LS per acre in at least fifty gallons of water.

Remember, this stuff is caustic, stinky, and degrades just about everything it touches. It’s also quite phytotoxic- application at these rates to vines after bud break will cause leaf damage if not outright defoliation. I have used a lot of LS during the growing season in organic apple production, and don’t recommend it there unless absolutely necessary. I do not have experience using it in-season (post-bud break) on grapes, so this recommended spray must be applied during the window between pruning and bud break. The spray, if left on tractors and in sprayer plumbing, will corrode hoses, gaskets, and even stainless steel. It must be thoroughly rinsed from sprayer systems and the rinsate applied back out in the vineyard, not dumped on the ground. Some growers have applied a film of vegetable oil via backpack prayer to tractors and sprayers before an LS application to prevent it from soaking into and corroding steel and other materials on equipment. It’s that bad, and I could show you sprayer hitches, mix screens, and ceramic nozzles that have been degraded by it.

With all that said, LS is extremely effective as a preventative practice to reduce disease inoculum, and I still recommend its use in vineyards where anthracnose and/or phomopsis have gotten a bit out of control. Just be careful out there and treat it with the same (and a little more) respect that you should retreat any pesticide.

Apple season will soon be underway

Posted: April 2nd, 2017 by fruit

By Terence Bradshaw

My predecessor and longtime mentor Lorraine Berkett always told me to be ready for the growing season to start any time after April 1. Despite that being wrong in 2010, it has generally been good advice to live by, and after receiving another eight inches of snow yesterday, April 1, I feel safe in saying that we still have a bit more time to go before green tip. That said, we do need to be ready, and these first few weeks of spring are important ones to get caught up on pruning, reviewing previous seasons’ activities, and laying out our plans for the coming year.

As I mentioned at the winter meeting in Middlebury last February, there will, again, be no new printed New England Tree Fruit Management Guide for 2017. We (myself and the other University and Extension Tree Fruit IPM professionals in New England) have been struggling to keep the guide up-to-date and relevant with minimal and often no funding for as long as I can remember, and have decided this year to venture into a new, online system. I say this is new, but it is actually the same UMASS-hosted platform that the New England Vegetable and Small Fruit Guide have been published on for many years. We are still working to get the content all migrated over (and the complete lack of an organic section right now is entirely my fault), but it is now functional to the point that we will all be referring to it when making IPM recommendations this season. The guide can be found at: http://netreefruit.org. Bookmark it and refer to it regularly, it is mobile-friendly and is where we will be posting more information as we get it formatted and changes in pesticide registrations occur.

Again, there is no printed guide for 2017. Please hold onto your old guides, most any of them from 2010 or so and later will suffice to provide general background information but as any pesticide information should be checked against the online guide, a label aggregator like https://home.agrian.com/ (see label lookup in the top bar menu) or http://www.cdms.net/Label-Database, and, ultimately, the pesticide label itself. If you need an older printed guide, feel free to contact me and I’ll see if we can dig one up. But please know that even though many pesticide registrations haven’t changed in recent years, many others have, and I won’t vouch for the accuracy of the tables or other information in an out-of-date printed guide.

This year I will be working with Eric Boire, consultant with CPS, and my technicians Jessica Foster and Sarah Kingsley-Richards, and UVM Plant Diagnostic Clinic Director Ann Hazelrigg to expand our scouting to some commercial orchards to better inform our email updates. The details on that program are still developing, and I’d like to thank Eric and the VT Tree Fruit Growers Association in advance for their support.

As usual, we will be relying on the NEWA system to deliver site-specific weather information and pest model output to help guide recommendations to growers. If you are interested in setting up a station on your farm, please contact me as soon as possible. Stations are about $2,000 but even relatively small orchards can benefit from reduced number of or better-timed spray applications.

Until next time, Happy Spring!


Effective Spraying & NEWA Workshop NEXT WEEK

Posted: March 23rd, 2017 by fruit

Effective Orchard Spraying and NEWA Workshop, Champlain Valley – 3/28

Tuesday 3/28, 8:00AM – 4:00PM

Miner Institute, 1034 Miner Farm Rd, Chazy, NY



Registration: Register online http://enych.cce.cornell.edu/event.php?id=680

Or contact Abby Henderson at aef225 or 518-746-2553

Deadline: TOMORROW Friday, March 24th

Effective Orchard Spraying – Morning with Dr. Andrew Landers

Understand how to improve your timeliness and therefore apply sprays when needed and not be forever chasing the calendar. Correct application at the correct time will allow you to make better use of your time and materials over the season.

Navigating NEWA – Afternoon with Dr. Art Agnello, Dr. Juliet Carroll, Dr. Jaume Lordan, and Dr. Kerik Cox

Learn the ins-and-outs of the NEWA system (Network for Environment and Weather Applications). Learn how to efficiently navigate the NEWA interface, including how to get weather data, access station specific pages, and effectively utilize models for insects, diseases, crop thinning, and irrigation.

Bring your Laptop or Smart Device!!

Anna Wallis

CCE Extension Associate – Fruit Specialist

Eastern NY Commercial Horticulture Program

6064 State Route 22 Suite 5

Plattsburgh, NY 12901

Cell: 518.410.6823

Fax: 518.561.0183


Cornell Cooperative Extension is an employer and educator recognized for valuing AA/EEO, Protected Veterans, and Individuals with Disabilities and provides equal program and employment opportunities.

Fire blight model upgrade in pace for 2017

Posted: March 22nd, 2017 by fruit

[Terence Bradshaw] See the note below regarding upgrades to the Fire Blight model in NEWA that will be implemented this year. Upgrades to the apple scab model will be coming as well.- TB

We are pleased to announce that an upgrade to the fire blight model on NEWA is now in place, available from http://newa.cornell.edu/index.php?page=apple-diseases.

Kerik, Keith Eggleston and I worked to put this together. It incorporates season long disease management messages, an infection potential (EIP) calculation, Cougarblight logic upgrades, wetness events color-coded and calendar sensitive changes to the risk predictions.

These improvements were based on suggestions and comments from the field, as well as upgrades to Cougarblight in Washington. We hope you will like the new fire blight tool and welcome any suggestions you have going forward.

We are also working on upgrades to the apple scab model. We’ll write a blog and Scaffolds newsletter article on all of these once they are both operational.

-Julie Carroll

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