Petal fall

By Terence Bradshaw

I know that some orchards are still in bloom, so the thinning and insect management portions of this message may not pertain. Hopefully everyone with any hint of risk for fire blight has treated sometime during this heat spell. Cooler weather this weekend and rapidly dropping blossoms will decrease risk, but until then, the pump is primed. Everyone also needs to keep an eye out for blossom blight symptoms, and for the shoot blight that will follow. Growers can apply Apogee (4.5-9 ounces per 100 gallons dilute**) any time now to reduce shoot blight incidence. Apogee treatments will reduce shoot elongation and thicken cell walls for about 2-4 weeks post-application, so retreatment may be necessary every 1-4 weeks until terminal bud set.

All set on FB? Okay, we have some big fish to fry this week. Let’s cover them one by one.

  1. This will all be said in light of the heat that we’re experiencing in the next couple of days. If you can avoid spraying anything (streptomycin excepted) when the weather is >85°, that’s a good thing. Then again, don’t ignore the very real threat of the following pests that need to be protected against. I have an inkling that many of us will be up pretty late/ early tonight/tomorrow morning to get things covered while dodging the heat.
  2. We are all headed for a pretty big apple scab infection period starting tomorrow Thursday 5/28 or Friday. Make sure you are covered going into it, I would not count on any material’s kick-back activity to handle this kind of scab load. As I’ve mentioned before, some materials (captan, sulfur) can cause leaf burning when applied ahead of hot weather. But, given what looks like an extended wetting period and an ample load of mature ascospores, I’d take the chance of a little leaf burn over a major scab outbreak. If you want to put on a lower rate now and follow up Sunday or so with a kick-back material (SDHI, strobilurin, or DMI, see here for more discussion, also mixed with a protectant like mancozeb or captan). Everyone should plan on phasing out mancozeb soon, as it it toxic to beneficial predatory mites that do some great biological control or European red mite and two-spotted spider mite, and we’ll soon have to be thinking about its 77-day preharvest interval. Organic growers, I would apply sulfur before and after the rain event, and maybe consider lime sulfur (LS) for the second spray to provide some post-infection control. LS is caustic, nasty stuff, so use it wisely, wear all the appropriate gear, and wash everything down well as it is very corrosive to steel and other materials.
  3. If you’re at total petal fall, then it’s time to start thinking about insect pests, especially plum curculio (PC). PC love this heat and will be ready to oviposit on fruit as they reach 7-10 mm diameter. Organic growers should plan on getting a coating or Surround on trees asap, and maintaining that coverage for about 400 degree days (base 50°F) after petal fall (NEWA has a good model for this). This is a longer window of coverage than for non-organic orchard management (308 dd base 50°F), because Surround does not kill the insects and so must be maintained longer until the biological urge to oviposit has completely subsided. For non-organic orchards, effective materials include Imidan, Actara, Avaunt, Voliam, and Agri-Flex. Carbaryl, if used for thinning (see below), will have some efficacy, but probably shouldn’t be your primary material of choice given the weather that is very conducive to PC activity. Thinning rates of carbaryl are about half the insecticide rate, and I would plan on using just that lower rate as a thinner and use a separate material for my insect management. Any of these materials will help to manage the other petal fall insects, including European apple sawfly and the various lepidopterans (obliquebanded leafroller, Oriental fruit moth, codling moth, etc) that may be emerging at this time.
  4. Thinning. Okay, this is always a tricky one. First, anything applied in the next 40 hours will be highly active because of the heat, so I’d err on lower rates and a lighter touch. A second application may be needed after this weather breaks. Now, I haven’t been in orchards all across the state, but where I have seen bloom from Connecticut valley, Addison county, and our own orchard in South Burlington, it was good to downright heavy. Pollination and fertilization conditions have been just about perfect, so I’d expect trees to need a decent thinning this year. The New England Tree Fruit Management Guide has some good variety-by-variety recommendations, so I recommend starting there. A good, standard petal fall spray of 1 qt/acre of carbaryl and 8 oz/acre Fruitone N or L (I did the TRV adjustment for you) should do the trick for most orchards. For organic orchards, it’s time to start hand thinning. A lime sulfur spray used for scab can help to knock some fruit off, but it’s not labeled specifically for that use.

I think that covers it for now.

**This reference to amount per 100 gallons dilute refers to Tree Row Volume (TRV), which is a somewhat out-of-vogue method for adjusting spray rates to compensate for canopy volume. I describe it some here, but in simple terms, it calls for measuring the tree canopy volume and estimating the number of gallons of water to saturate the canopy to wetness (dilute gallons per acre, DGA). No one sprays at full dilute, that wastes time, money, and water. For a good rule of thumb, large, standard trees 20 feet tall planted at 30 feet x 40 feet spacing had (notice the past tense) about 420 DGA. A more typical ‘large’ semidwarf orchard on M.7 or similar with 12 foot tall trees planted at 12 ft x 18 ft would have 200 DGA. DGA decreases down to around 100 and stays there pretty consistently for tall spindle and similar high density, narrow-canopy systems. BUT, we often do not recommend reducing TRV below 150, maybe 120 if you have excellent coverage and an easily sprayed canopy. And this TRV is only used to determine the rate of material used per acre, not how much water you put in the tank. So. Let’s just say use 200 DGA for semidwarf trees, 150 for trellised trees. Back to the Apogee example, let’s use 8 ounces per 100 DGA for simplicity’s sake, that would be 16 ounces per acre to the big trees, 12 ounces to the smaller high density trees. Then figure out how much to put in the tank based on the amount of water you spray per acre, which is likely 50 (or less?) to 150 gallons.

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 and spraying this week

By Terence Bradshaw

What an amazing weekend it’s been, weather-wise. I still need to check bud stages, my cider varieties here at 1500’ elevation in central Vermont are still at around half-inch green, and so are not an indicator of what things look like around the state in more typical orchards. However, I imagine many varieties are approaching petal fall, and growers may be itching to put on an insecticide of thinning spray.

The weather for the next three days (Tuesday-Thursday I mean) calls for pretty extreme heat, by May standards, anyway. Given that likely spray materials now include potentially phytotoxic fungicides (captan, sulfur) and insecticides (carbaryl), and that thinners will be very active if applied in this heat, I urge caution. I also don’t like to apply anything in temps of 85° or hotter.

I’ll look over bud stages in the next day or so and check the weather for later this week. Chances look decent for our first apple scab infection period in a while on Friday, and it could be a doozie. Combine that with need to thin and manage post-bloom insects, and we could be in for a complicated spray week.

If you spray anything now, I’d only consider streptomycin on highly susceptible varieties in orchards with recent fire blight infection. In that case, a coat of fungicide (not captan or sulfur because of phytotoxicity issues) may not be a bad idea. But in most cases, I’d lean towards no treatments and plan on an evening / night / crack-of-dawn-when-it’s-cooler treatment window later in the week.

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 & streptomycin questions

By Terence Bradshaw

I’ve received a few questions about the fire blight alert:

  1. If you are in an inland/upland site and no bloom or fresh pruning wounds, this alert does not apply. However, I bet most apples in the state, aside from some late cider varieties, will be in bloom before this disease alert is done.
  2. Strep can be applied within 24 hours before or after an infection / wetting event. So you could wait to see if there is dew, but need to know that there’s no dew if you decide to hold off. Dr. David Rosenberger from Cornell has also been discussing the possibility that high humidity may be enough to cause infections. Bottom line- I’d get out there sometime if you have any risk (susceptible blooming varieties, past history).
  3. A treated flower is a treated flower. So if you’re at full bloom and you’re going to treat anyway, treat any time.
  4. Rate: I was corrected on the rate of streptomycin that I’d recommended, which I’d passed on from another extension warning without reading the label. Harbour is the main (only?) brand of strep we use in the state, and it is labeled for 24-48 ounces per acre. The first application should include Regulaid or similar wetting agent, subsequent sprays, if applied, can and should omit the wetting agent to reduce phytotoxicity.
    The Harbour label is a bit confusing, as it makes some jumps from concentration to rate with an implied understanding of (and I’d say controversial application of) tree row volume. We’ll discuss TRV another time, not during an important disease event. Stick to the label rate, which is 24-48 ounces per acre.

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 alert

By Terence Bradshaw

I’ll keep this short and to the point. In spite of, or rather in keeping with, what I said the other day, fire blight risk is increasing in Vermont orchards. I’m seeing sustained warm, sunny, relatively windless, and dry conditions for the next 5-7 days, with increasing risk of rain as next week starts. The heat is driving the bacterial population to increase pretty rapidly. Warmth suitable for infection is present. Open blossoms are present. The question is whether ot not you a) have fire blight inoculum in or near your orchard and b) whether or not wou’ll get the necessary wetting to cause infection. For the first one, if you’ve ever had any fire blight in the past couple of years, assume that you have inoculum. The population is moving too rapidly to assume otherwise.

For the second, you may want to wait things out until just before a rain on Monday or Tuesday, but what if ypu miss a dew event? Sunday morning looks like there’s potential for some dew, and that’s enough.

Anyone in any stage of bloom, is to get a streptomycin (or pick your organic biocontrol of choice, but I can’t personally vouch for any at this time) spray on sometime between Friday and Sunday morning. Once a blossom is treated, it’s protected, so later is better to ensure you cover the maximum number of blossoms. But don’t wait so late that you miss a good spray window. Strep should be applied 16 oz per acre in sufficient water to get good wetting, amd I recommend Regulaid or another organosilicone wetting agent be included.

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.

Bloom, apple IPM

By Terence Bradshaw

Apple bloom has started in much of the state, and the weather looks about as good as it gets for pollination and fertilization. It’s been dry since last Friday, and, in most sites, that rain wasn’t even as much as expected. So, water if you can, trees in bloom and setting fruit have high energy requirements, and water is a key part of mineral nutrient transfer and photosynthesis. While I’m at it, this is a good time to get your fertilizers on. Nitrogen fertilizers should be applied between bloom and June 15, while your potassium and other fertilizers can go down between now and midsummer. It’s also not too late to put on foliar fertilizers, such as the prebloom nutrient cocktail recommended by Cornell University and New England apple experts. However, given the bloom, the dry weather, and minimal disease pressure resulting from that, I’d put the sprayer away for a while- with the caveat I’ll leave below..

It looks like dry weather will be the rule for a while, so apple scab just isn’t an issue. That means that, when we do get some wetting, an pretty good infection period could result, so keep an eye on things and plan to cover ahead of any rains, which look to be at least a week out. When the weather is dry, ascospore maturation goes into hibernation so we can’t assume the spores will all mature and release with the next rain and scab season will be done with in one event. Of course, use NEWA to help keep an eye on your scab and other disease issues.

The disease we really think about during bloom, and especially during a warm/hot bloom, is fire blight. This bacterial disease acts differently from scab and other fungal diseases in two key ways- first, it is essentially internal in the tree, and therefore can act systemically and therefore tends to stick around for a while. Next, its infective pathogen can ramp up its population rapidly under warm conditions. The cool spring so far has kept fire blight danger (measured as epiphytic infection potential, or EIP) down to a minimum. However, that EIP is expected to ramp up fast in the next week:

The fire blight model does assume that you a) have inoculum present, and b) that you have water to move it into blossoms which allow entry into the tree’s vascular system. You can adjust the latter condition a little in NEWA, and the former is a judgement call as far as making an application is concerned. I would have at least one application of streptomycin on-hand and be prepared to treat blooming trees, particularly if you have a wetting event. This could include heavy dew, especially if you have a day afterward that has high relative humidity. High-value, fire blight-prone varieties may warrant a prophylactic treatment going into the weekend, but that’s a tough call.

For organic growers, Actinovate, BlightBan A506, Bloomtime 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.

Once the EIP is sufficiently high (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 you’ll want strep or another material (really, if your orchard isn’t certified organic, strep is the only material to consider) on within a day. It will be hot Friday, 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.

But, make sure to look at the forecast at least twice a day. We not only are not predicting rain, but also, at least for the next few days, predicting dew, either. The NEWA fire blight model output (see above) includes predictions for rain and dew.

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 in the last two yearr or highly susceptible cultivars (Gala, Ginger Gold, Honeycrisp, Cortland, Paulared, etc), and of course blocks that are in bloom. Application well after any wetting event,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 (at all- don’t do it), and doing so is a) expensive, b) a waste, and, most importantly, c) the best way to develop antibiotic resistance in E. amylovera populations.

As for insects, there are management actions you can be doing now. Of course, no insecticides during bloom. But you should be checking pheromone-baited codling moth traps at least every other day and noting the date of first capture in order to set your biofix for the NEWA models we’ll use later. Now is a good time to get mating disruption ties for dogwood borer or codling moth up in the orchard.

Finally, keep a good eye on the bloom and on pollinator activity in the orchard. I suspect that this will be a year that we’ll need to really work on crop thinning, even though we’re in an ‘even year’ which, in the past decade or so, has meant smaller total crop overall. We’ll talk about thinning next time.

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.

SBA EIDL program re-opening for farmers; prebloom orchard activities

By Terence Bradshaw

Earlier today I sent a notice from Tom Berry at Senator Leahy’s office regarding availability of emergency funds to farmers affected financially by the COVID-19 pandemic. That was referencing a re-opening of the portal specifically for farms to apply for funds. If you are an ag business that was unable to take advantage of the SBA EIDL Loan/Advance Program, there is good news! The EIDL Advance/Loan portal will be re-opening shortly (today, May 4th). The re-opening of the portal is for agricultural businesses that were previously ineligible for the program. New non-agricultural business applications will not be accepted. The portal will be opened for a limited period, and it is recommended that you apply as soon as possible. The link to the portal will be: http://www.sba.gov/Disaster

Bud stage for most cultivars at the UVM Horticulture Research and Education Center is tight cluster. Cider cultivars are hanging back at half-inch green tip, and Zestar is ahead of everyone at early pink. This means that it’s time to really think about bloom activities. First, if you use rented beehives for pollination, make sure your hives are lined up. You’ve only got one shot to get those flowers converted into fruit, so make the most of it. Weather looks relatively cool in the days ahead, but I’m not seeing much in the line of hard freezes that concerns me. At this rate, boom is likely to hold off until next week, although that is very site-dependent. Upland and inland orchard still have a ways to go.

Any time now would be a good time to apply foliar zinc, boron, and nitrogen. Wes Autio from UMASS has published a good fact sheet on prebloom foliar nutrients here. Soil applied nitrogen and boron applications may also be applied at any time now.

Insect activity should be picking up in orchards soon. Many orchards choose to apply a pink insecticide prophylactically to manage tarnished plant bug and European apple sawfly, but those pests are best managed based on trap capture data. White sticky traps hung three per ten-acre block at knee height for TPB and head height for EAS may be monitored to assess whether populations are above economic action thresholds. Traps may be ordered from Great Lakes IPM or Gemplers and should be hung as soon as possible if they are not up yet. Thresholds for scouted insects may be found here. For TPB, five captured bugs per trap (eight for retail orchards with higher damage tolerance) is the economic threshold for an insecticide spray at pink. Cool weather this week is expected to keep activity low for the time being. EAS are typically managed at petal fall, and threshold for management is nine per trap averaged over all traps in the block for blocks that received a prebloom insecticide or five per trap for those where no spray was applied at that time.

Codling moth is an increasing pest in Vermont orchards and are best managed using degree day models to time insecticide sprays. CM are monitored using wing traps available from the sources listed above. Traps should be hung at pink and monitored daily to record the first moth capture. I posted a short explanation of the CM biofix to my YouTube channel today.

Some growers may be interested in using mating disruption (MD) against codling moth or dogwood borer this year. We have been deploying MD for several years on an experimental basis at UVM since we had significant damage a number of years ago in the organic orchards, and feel that it has been relatively successful. MD is expensive, however, works best in large contiguous blocks, and should be deployed orchard-wide to be most effective. Eric Boire at Nutrien ((802)759-2022) would be a good contact to explore this option further.

Do I have to remind you that we’re all heading into (or already in) the advanced /accelerated phase of apple scab ascospore maturity? Keep an eye on the weather, and protect ahead of rains. The New England Tree Fruit Management guide has good recommendations based on bud stage for managing this disease.

Fire blight? Still too cool to really be worried at this point. Keep an eye out for warm (>70°F) weather going into bloom and, as always, NEWA is your best bet for tracking disease potential.

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.

Oil application and expected rains Sunday-Monday

By Terence Bradshaw

It didn’t take long after I posted my last recommendations for someone to point out to me that it’s unlikely that apple scab ascospores can be released through two inches of snow. Point taken. This cool weather has put things into that slow, on-hold pattern a bit, but activity will pick up today and tomorrow as temperatures get into the 50s. In warmer southern Vermont predicted ascospore maturity is getting up around 10%, which is when we should be taking scab more seriously. In the Champlain Valley, where ascospore maturity is estimated around 5-7%, buds appear to be hovering around the half-inch green stage. Upland and inland, still at silver tip. Rains Sunday and Monday are expected to bring an infection period, so orchards with significant tissue exposed should be covered with a fungicide in the next two days.

Weather is looking good for oil application today and tomorrow, assuming that your site isn’t expecting freezing weather in the next couple of days. I am a proponent for putting oil on as late as possible, up to tight cluster or even pink. The rate should be adjusted down as buds open more: 2-3 gallons per 100 gallons water (straight % in tank, not adjusted for tree for volume or per acre) is good from dormant through green tip; 2 % GT-tight cluster; and 1% as you approach pink. Oil should be put on dilute- slow down and open up your nozzles if you can. For most orchards, 100 gallons of water per acre should be the minimum for applying oil. That means recalibrating your sprayer in many cases.

For growers with substantial bud development and concern about cold temperatures the past week, you may want to pinch some buds and look for browning in the developing ovaries…or not. There’s not much you’ll do about it now, anyway, but come bloom, it would be wise to observe flowers and be ready to adjust thinning if more than 20-30% damage is observed. I’m pretty hopeful that most sites have been fine, the critical temperature for 90% bud kill at tight cluster is 21°F, although some damage may be seen at 28. For half inch green, we can expect buds to be all right down as low as 23 or even colder. Trees at silver or green tip should be fine. Remember, if you suspect bud damage from cold temperatures, it is important to contact you crop insurance agent ASAP to get the claims process started.

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.

Orchard management- slow and low

By Terence Bradshaw

Here’s a real quick update. Bud stage in warmest Vermont orchard sites is around half-inch green (HIG). At that point, copper should not be applied unless you know the crop is going to cider, as copper applied at any effective rate for this time of year will russet the fruit finish. Frost is expected, again, the next few nights. At HIG, buds are hardy to around 20°F. I see no immediate issues in that regard. But, frost means that oil and/or captan should not be used in the orchard, at least until late next week. Early season scab fungicides of choice should be mancozeb or scala/vanguard. Sulfur, of course, is the main material for use in organic orchards.

In the Champlain Valley, we’re still closer to green tip for now. That means that copper is still a viable material, but be sure to not apply it after the first two “mouse ear” leaves emerge from the bud. See the bud stage link (above) for a visual. Otherwise, default to those listed above.

Buds are around silver tip or even dormant in upland and inland sites. Hold tight there, although you could get a prophylactic copper on for fire blight, but that won’t help much against scab.

BUT, this doesn’t suggest that anyone needs to spray. Modeled ascospore development is around 1-7%, more in southern areas. Potential for rain is pretty solid today and fairly spotty until midweek. You need rain and extended wetting to cause infection. Here’s my take: orchard at HIG or later should maintain coverage, especially if you have an orchard that takes substantial time to spray. Time it as close to rain as possible; if you were uncovered going into today’s rain, cover as soon as this rain is done with a protectant + Vangard or Scala for some kickback. If you were covered or are in one of the lower risk sites (decent scab control last year, green tip or earlier bud stage), hold off until we get a better idea of the chance for rain later in the week. Of course, use NEWA to keep an eye on scab development in your area.

Insect notes: if tarnished plant bug is a concern in your orchard (less so in pick your own than wholesale orchards), then get traps up soon. We use white sticky traps from Gemplers or Great Lakes IPM. Set three per block, knee-high, on a lower scaffold out in the drive row. Check weekly, giving enough time to apply prebloom insecticide if needed. Trap thresholds are listed in our monitoring guide located here. Print that out and out it on your wall in the shop.

If you’ve had mite or scale problems, think about your options for managing them in the next few weeks. Oil is a great first line of defense, but if you have high populations, especially of scale, you may need to consider adding a stronger material prebloom. Esteem is most recommended for scale, applied around HIG to tight cluster. If mites have been a problem, there are a number of materials available for prebloom use, you’d best check the New England Tree Fruit Management Guide for recommendations.

Be safe out there.

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.

Green tip has arrived in many Vermont orchards

By Terence Bradshaw

Yesterday, April 9, we ‘called’ green tip at the UVM Horticulture Farm, orchards. This signals that buds are beginning to open, and therefore green tissue is present that may be susceptible to apple scab infection. The apple scab ascospore maturity model, which predicts the presence of mature overwintering inoculum that could infect, given appropriate weather conditions, uses ‘McIntosh’ green tip as a biofix to start accumulating degree days. It is best to record your own green tip date, and if you are using NEWA to track infections, use the station that is closest to your farm (or buy your own station, and I can help you to connect it to the NEWA network).

Presently, the orchards in the warmest parts of the state (Bennington and Putney) are predicting 2-5% of ascospores mature; in Addison, Chittenden, and Grand Isle counties, it’s more like 1-2%. Inland and upland sites likely aren’t even at green tip yet, but will likely advance once the warm weather returns. What does this mean? In warmer areas, I would get copper on as soon as you can get in- remember, after the buds reach ½” green tissue, your window for high-rate copper is closed. Wind is looking pretty fierce on Monday (rainy too) and Tuesday, and both of those days look to be in the 50s-60s. So I’d try to get some copper on this weekend. Hold off on oil, as it’s looking like frost conditions Saturday night. For orchards that are closer to the very beginning of green tip and which have less chance of advancing beyond half-inch green on Monday and Tuesday, I would wait until Wednesday or so and apply copper (and oil if you can). For inland and upland sites with no bud break- hold off.

It’s important to recognize that early season infections when <5% of ascospores are mature typically won’t cause much if any scab, especially if your inoculum is low to begin with. Some orchards had terrible scab problems last year, and if you had any noticeable scab, assume that you’re high inoculum and need to take a more conservative strategy this year. But, if you had low scab (as in, none that you know of), and/or you perform orchard sanitation, you can relax a little bit in the early season. You still have time to flail mow leaves and / or apply urea to the orchard floor to reduce scab load for this year. However, copper is important not just as a (relatively weak) scab protectant, but also as a fire blight management tool, so I strongly urge growers to get copper on before the window closes if you’ve had any whiff of that disease in the recent past.

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

-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.

COVID-19 business resources, green tip approaching in VT orchards

By Terence Bradshaw

First, UVM Extension Farm Viability Program has posted a page of resources for farm businesses related to emergency loans, grants, and other updates from state agencies: http://blog.uvm.edu/farmvia/?p=1805. Of particular interest to the framing community is the Paycheck Protection Program which provides low-interest, forgiveable loans to small businesses to cover payroll, mortgage interest, rent, and utilities. The direct link to that program is: https://www.sba.gov/funding-programs/loans/coronavirus-relief-options/paycheck-protection-program-ppp.

In walking the orchards at the UVM Hort Farm yesterday, I saw a lot of swollen, delayed-dormant buds, but only none yet at silver tip. Given the warm weather expected next week, I would expect to see at least some cultivars reach green tip in the next seven days. If you have green tissue on your farm already, please send me a note to let me know. Thus begins the disease management season.

If you’re still pruning, you should wrap up what you can and get your brush pushed to make room for sprayer access. I am a believer in using copper at green tip for disease management. The timing of this spray is very important- too soon (no green tissue showing) and you risk ‘wasting’ some of the effectiveness of the material against apple scab when susceptible tissue isn’t present. Too late (beyond ½” green tip) and you risk fruit russeting, which can be quite severe. Given that, it’s better to err a bit on the early side, but you should have green tissue showing in the orchard before applying. Copper applied at green tip will give about seven days’ protection against apple scab.

Copper’s primary benefit is in reducing overwintering populations of fire blight bacteria. Even though we saqw minimal amounts of this disease last year, fire blight has become a regular disease to manage in Vermont, and a multi-pronged approach will be needed to keep it at bay. Copper should be applied to all trees in the orchard, not just susceptible varieties, and in as dilute a spray as possible. The specific copper material is less critical than the amount of metallic copper that is applied in the spray, and copper sulfate, copper hydroxide, copper oxychloride sulfate products all will be effective when used at label rates. A good primer on spring copper applications to pome fruit by Dr. David Rosenberger can be found in the March 28, 2011 issue of Scaffolds. Addition of one quart oil per 100 gallons can help improve penetration into bark crevasses where fire blight may reside. However, this could be a good time to apply a full oil spray to manage overwintering mites, and a 2% solution is recommended at this timing. Oil and copper products are compatible for tank mixing at this time of the year, but likelihood of phytotoxicity increases as more green tissue emerges. One benefit of applying oil in your first spray is that it allows more time for it to degrade or wash off before incompatible fungicides such as Captan and sulfur may be used as primary scab season ramps up. Avoid the oil if you’re within a few days (before or after the spray) of a frost to reduce chances of damage to tree tissues.

Now that the ground is clear and firming up, it also would be a good idea to perform spring orchard sanitation to reduce overwintering scab inoculum. Leaf shredding with a flail mower is an effective practice that also may be used to reduce small pruning wood to mulch, but the mower must be kept low in order to lift and grind leaves that harbor overwintering inoculum. Alternatively, there is still time to apply urea (40 lbs/100 gal water/acre) to leaf litter which aids in decomposition and breakdown of inoculum. Leaves should be wetted thoroughly and the majority of material directed into the tree row.

Good luck with the beginning of the season and please reach out if you need anything.

-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.