• A-Z
  • Directory
  • myUVM
  • Loading search...

UVM Fruit Blog

EAS, FB, CG…observations from this week.

Posted: June 10th, 2017 by fruit

By Terence Bradshaw

June 10, 2017

CPS crop consultant Eric Boire sent me this picture yesterday of what, on first glance, looks like a first generation codling moth larvae burrowed into an apple at about 10-12 mm growth stage:

Figure 1. European apple sawfly damage posing as codling moth injury.

We have seen this a lot in the UVM orchards, especially the organic section. What we are looking at is European apple sawfly (EAS) damage. You can see the characteristics squiggly scar right below the hole, but sometimes larvae aren’t content feeding on one apple and will exit one fruit and enter an adjoining one- all the more reason to thin your fruit down to singles per spur early. There isn’t a lot to do to manage them at this stage except hand-thin the affected fruitlets and remove them from the orchard to lower nest year’s population-we’ve done this with seemingly millions of these in the organic orchards at the Hort Farm. The maddening thing about seeing this damage now in a commercial orchard is that we have caught very few EAS in our traps all over the state, including in this orchard. Traps used for monitoring EAS are unbaited white sticky cards that are designed to mimic a large blossom.

Figure 2. EAS trap.

We have used a trap for decades at the UVM farm that have been quite effective, but this year, we started using a smaller, more inexpensive trap that has less surface area and less ‘sticky’ and seems to be missing these pests during aa time when monitoring would help deliver actionable recommendations for their management. Long, extended bloom periods like this year’s make EAS management more difficult as well.

Codling moth will do similar damage but always later in the season, usually when fruit are over 20 mm in size. CM larvae are just starting to hatch now in the Champlain and Connecticut Valleys, so a targeted application at them would be prudent, as I’ve mentioned in recent posts.

Another oddity that came to me was the presence of crown gall in some trees at a commercial orchard that prompted me to check some dying trees we have at the UVM orchard on the same rootstock from the same nursery:

Figure 3. Crown gall on apple.

Notice the warty growths on the roots. This tree was dead, and had little to no root growth since it was planted in 2016. The affected rootstock was Geneva 935; keep an eye out for declining trees on that (or any) rootstock. Crown gall is caused by a bacterium, Agrobacterium tumefaciens, which affects many types of plants. It is not uncommon, but generally becomes pathenogenic when plants are damaged, e.g., from cold (commonly seen in grape) or from nursery digging. The best defense is to use disease-free plants. A careful inspection of roots at planting time should be performed to make sure you’re not putting a dying tree in the ground to start with. A. tumefaciens is one of nature’s original agents for horizontal gene transfer, a natural GMO, if you will, as it inserts its own DNA into the host plant which responds by growing the galls or ‘tumors’ as shown in the picture. AAs an aside, early GM breeding used this characteristic of the bacterium to transfer genes to new plants, although more precise methods are typically used these days for that task. There is no chemical management for crown gall in apple, basically we need to plant clean trees and keep them healthy through good cultural practices. A good fact sheet on the disease is available at: http://ohioline.osu.edu/factsheet/plpath-fru-19

If you were affected by fire blight from the May 18-20 potential infection period, you should start to see blossom infections now- scout orchards carefully and be prepared to cut out as you see it. Prime targets will be trees that had the disease last year, and highly susceptible cultivars like Cortland, Paulared, Gala, Fuji, and Honeycrisp. Damage will be evident on fruit clusters, and should be accompanied by oozing or water-soaked vascular tissue below the affected area. Some damage that looks like FB can often be attributed to other damage to blossom clusters, often from feeding by various shoot boring lepidopteran larvae. In that case, there will be an abrupt ending where the damage stops and clean tissue starts, often accompanied by an entry hole and a tiny larvae in the shoot.

Figure 4. Possible fire blight on an organic fruit spur. UVM orchard, 6/9/2017.

Finally, I get reports that sometimes my pictures do not come through on email postings. If that’s the case, my posts are always copied to my UVM Fruit blog, http://blog.uvm.edu/fruit/.

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.

Grape tumid gall maker- curiosity and management

Posted: June 8th, 2017 by fruit

By Terence Bradshaw

June 8, 2017

One of the great things about growing grapes in Vermont is that, by and large (and compared to my other crop, apples), the pest management is relatively simple- four or so well-timed fungicides sprays, and an insecticide aimed at grape berry moth. There are other considerations for unique situations: wet years or susceptible cultivars that need an extra botrytis spray; Japanese beetle or phylloxera on young vines. And then there’s the potentially weird, and maybe damaging, like grape tumid gall maker (GTGM).

This insect is similar to phylloxera in that the larvae feeds on leaf tissue which responds by forming a protective gall around it. GTGM is different in that it also affects rachises and fruit, and when the galls become fully engorged, can look pretty dramatic.

Figure 1. Grape tumid gall on a fruit cluster in midsummer. UVM vineyard, 2009.

GTGM is an midge insect (small fly) that lays eggs on grapevines. Flies are ephemeral and only live a day or so; management should not be targeted at adults. Hatching larvae burrow into vine tissue and are thus protected from contact insecticides. In most vineyards, GTGM is considered a minor pest or even a curiosity as the galls can be quite drastic-looking. That said, I have been hearing reports of high levels of GTGM in vineyard this year, and some of these vineyards reported them last year under different management, so I suspect that certain vineyards have increasing and potentially problematic populations.

Figure 2. GTGM on Marquette, UVM vineyard, 2010..

Vineyards should be scouted before assuming you have a problem with this pest. There is no threshold established, as most growers tolerate low levels of damage. However, I have heard reports of 50% or more leaves affected in some vineyards, and I can’t imagine how that wouldn’t negatively affect vine productivity.

Figure 3. GTGM on inflorescence. UVM vineyard, 2011.

Sanitation is an important method of reducing GTGM populations and may be enough in low-pressure situations. Galls can be crushed if seen on leaves, or severely affected leaves removed and destroyed. In organic vineyards, as always, this should be the first line of defense since spray options are minimal. If the extent of damage is beyond physical removal, an application of Movento is the best (only) recommended option I can find. Movento is a systemic insecticide with a unique mode of action and is listed as posing low risk to wildlife, and as non-toxic to fish and birds. It is best used at first sign of galls, practically speaking, as scouting for hatching larvae (which hatch from microscopic eggs) is difficult under normal field conditions.

GTGM may be distinguished from phylloxera by the gall surface, which is smooth compared to phylloxera which is bumpy or warty. Movento is effective against phylloxera as well as GTGM and has a long residual control period, so may be a good material if either or both of those pests are common in your vineyard.

More information on GTGM may be found in this Cornell fact sheet: https://ecommons.cornell.edu/bitstream/handle/1813/43134/tumid-gallmaker-FS-NYSIPM.pdf?sequence=1&isAllowed=y

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.

Codling moth and other pest management in apples

Posted: June 6th, 2017 by fruit

By Terence Bradshaw

Codling moth (CM) management is just around the corner in many Vermont orchards. This is an increasing pest in the state- many orchards never had a problem until recently, and some still don’t. Adults begin flying around bloom, and our monitoring program is designed to catch the first flight to tie later management applications. Mated females lay eggs in the tree canopy and hatched larvae burrow into fruit causing significant damage in some orchards. It is the larvae that are generally targeted for control. Materials effective against larvae include many broad spectrum pesticides that may also have substantial non-target impacts on beneficial insects. If you need a late petal fall cover effective against plum curculio (PC) or European apple sawfly (EAS), then a broad-spectrum material may be needed. However, if targeting CM specifically, then a more specific material may be called for. As I mentioned last week, there are a number of materials that have high efficacy against CM and low non-target impacts, including granulosis virus, insect growth regulators like Intrepid and Rimon, and some more lep-specific materials like Delegate and Altacor. Applications should be made about 250 degree days (base 50°F) from first trap capture. In South Burlington, current DD since the first capture is 193 as of today, with 250 predicted by Sunday. So the next spray application should include a CM-specific material if they have been a problem in your orchard and you are located in a warmer area like the Champlain or Connecticut Valleys.

San Jose scale is another insect which is increasing in Vermont orchards. Crawlers emerge about 500 DD base 50 from March 1; that should occur mid-late next week in the warmer sites and a bit later in the cooler ones. Some scale-specific materials include Esteem, Movento, and some of the neonicotinoids like Assail and Admire Pro, which may have activity against other pests, especially Assail which is fairly effective against CM, PC, EAS, and a number of other insect pests.

Disease: I recommend one more fungicide cover until we can get a handle on what the scab situation is next week. Captan (sulfur if organic) is fine, adding a DMI, stroby, or SDHI will cover for rusts and/or powdery mildew.

Fertilizers: I haven’t discussed them much this season. Nitrogen applications should be wrapping up by the middle of the month. Calcium applications, both ground (gypsum or calcium nitrate in that last N application) and foliar, should start now. If needed, magnesium and potassium applications can also begin any time now. Consult your leaf analysis for determining these.

Thinning: most orchards should know the fruit set, thinning, and general crop load status by now. If you need additional thinning, the window will start to close after this weekend. Maxcel and other 6-BA thinners will finally start to work given the upcoming heat. Also, remember that the leaves are soft and trees will thin easily, so don’t overdo it.

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.

Vineyard management approaching bloom

Posted: June 6th, 2017 by fruit

By Terence Bradshaw

Grapes are at 10-12” growth in most Vermont vineyards, and combined with the wet, cool, rainy weather, are at prime susceptibility for phomopsis, black rot, and anthracnose. Fungicide coverage should be maintained on 7-10 day intervals during this extended rainy stretch; if it dries out as expected at the end of the week, spray intervals may be stretched to 10-14 days. Best material options are captan or mancozeb with or without a DMI (e.g., Rally, Tebstar), although I would recommend the DMI given how wet it’s been. Strobilurins (e.g. Flint, Sovran, Quadris) are also effective, but best saved for later when Downy mildew is a concern.

Inflorescence is well-developed, and we can see the potential for the 2017 crop now, so this is a good time to continue shoot thinning, removing the shoots with the weakest clusters if possible. This is also an important time to maintain good weed control, as the period of most rapid growth coincides with a need for moisture and nutrients. It won’t necessarily stay this wet for the whole summer, and if weeds aren’t managed early, the vineyard can become a jungle later in the summer. I do not recommend glyphosate herbicide at this point of the season, there is just too much chance for causing vine damage. Postemergent contact herbicides like glufosinate or paraquat (be extra cautious applying the latter) can be effective in knocking back annual and (to some degree) perennial weeds. Cultivation also works well if the proper equipment is used, but is likely difficult to perform on wet soils. The time period needed for good under-vine weed controls isn’t long; by July, the vines begin to slow growth and shift resources toward developing fruit so a little weed growth is okay by then. But for now and in the next week or so, think about getting those weeds under control.

Insects are a relatively minor concern for Vermont vineyards, with a few exceptions. We are seeing a bit of grape tumid gall in the UVM vineyard this year. This is an infrequent pest that causes visually striking but relatively insignificant damage to the vines, and management practices are not recommended against them. Grape berry moth is the next insect to note in vineyards, although it likely won’t be active for another couple of weeks. Traps are available from Gemplers or Great Lakes IPM to assess flight patterns in the vineyard. Generally, one application of a narrow-spectrum material effective against lepidopteran pests such as Intrepid, Delegate, or Altacor (see other options in the 2017 New York Pennsylvania Grape IPM Guidelines), applied 10-14 days after bloom followed by another application 10-14 days after that will generally manage that pest for the season. Better management may be performed by scouting clusters and applying one of those materials or a Bt product immediately upon the first signs of larval feeding. There is also a good grape berry moth degree day model in the NEWA system that may be of use in your vineyard.

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.

Registration for summer 2017 Cold Climate Viticulture course

Posted: May 31st, 2017 by fruit

This viticulture course is an opportunity for new and aspiring growers to receive a comprehensive knowledge base for establishing or maintaining a vineyard for anyone who is seriously considering winegrape production in Vermont or surrounding regions. The course is guaranteed to run based on present enrollment, but won’t be offered again until 2019.

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

Orchard management at fruit set

Posted: May 31st, 2017 by fruit

By Terence Bradshaw

By now virtually all orchards, including those in cooler regions, are at petal fall with only straggling bloom around on later cultivars. The cool weather has shut down concerns for continued blossom infections of fire blight. If infection did occur in your orchard during the May 18-20 warm spell (wouldn’t we love one of those again?), you should start seeing symptoms in your orchard around the middle of next week.

Figure 1. Blossom blight symptoms, 2016

Figure 2. Shoot blight symptoms, 2016

Orchards should have received a full-orchard petal fall insecticide by now or next spray. While things have been relatively quiet on the insect from this spring, a number of pests, including plum curculio (PC), European apple sawfly (EAS), and (maybe) codling moth (CM) are ready to pounce now. We have found fresh EAS and PC damaged un unsprayed or organically-managed trees at the UVM farm. If you are finding fresh damage on fruitlets in your orchard, consider application of a material that will cover both of those pests, and maybe CM too. This usually means a neonicotinoid like Assail or Actara; indoxacarb (Avaunt); or a pyrethroid, although the latter will be especially hard on predators and other beneficial insects. for organic growers, a pyrethrum application will help knock down PC that are already in the orchard but will have no residual efficacy- kaolin clay (Surround) sprays should be maintained until PC oviposition activity is complete. If you have already made you full-orchard application, then any subsequent sprays should be targeted at borders (PC, EAS) or at specific pests based on monitoring.

Figure 3. This PC damage is probably about a week old, notice the corking over and lack of sap exudate.

Codling moth are now flying in most Vermont orchards. Unless pheromone traps are checked daily, it is difficult to catch their exact first flight date, but based on captures in area orchards, I am using the following dates for sites around the state:

Brookfield: 5/23

Cornwall: 5/18

E Montpelier: n/a

Essex: 5/23

S Burlington: 5/17

S Hero: n/a

Shelburne: 5/18

Shoreham: 5/18

I would love a good catch date for some sites in southern Vermont if someone is trapping and could send them to me.

Those dates are important, because they represent the biofix that you would enter into NEWA for tracking degree day development to time CM-specific treatments. For most spray materials, timing should be targeted at about 250 degree days (base 43°F) from first catch. There is some room on either end of this, and that can account for differences between actual first flight and first catch in a trap, as well as to line up with good application weather on the other end. Based on the above assumed catch dates, most sites in the Champlain Valley have accumulated about 125 dd, and with the cool weather, we are accumulating 7-15 per day. Therefore, a targeted CM application should wait until next week anyway, we’ll follow up on that later. Specifically targeting CM sprays is a great IPM tactic for reducing impacts to non-target species, because selective materials that affect primarily lepidopteran pests (e.g., Altacor, Delegate, Intrepid) may be used at that time. However, Bt (Dipel, etc.) is relatively ineffective against CM when used as a targeted spray, its use against other lepidopteran pests is recommended but only provides supplemental management of this pest. Other ‘lep’ pests that are active include redbanded leafroller (larvae active) and obliquebanded leafroller (OBLR) (adults now flying). Your petal fall spray should have managed these for now, but if inspections of clusters are turning up larvae, a Bt spray may be warranted. For any material that has bee toxicity (e.g. most all except Bt, kaolin, or the lepidopteran-specific materials like Intrepid or Altacor), be sure to mow flowering plants in the groundcover prior to application.

For disease management, I recommend keeping at least one more fungicide on until you can scout for potential lesions from this last week’s rains. Despite NEWA’s proclamation that all overwintering apple scab inoculum was expended a week or more ago, I don’t trust it and feel it is too conservative in predicting the end of primary scab season. Scouting for detection of apple scab lesions (or lack thereof) to determine the end of scab management season should take place a couple of weeks from now to allow any infections to show.

While we’re in that weird period between the end of ascospore release and waiting for evidence of primary scab infection to show, we can still manage a couple of other diseases in the orchard. I am expecting cedar apple rust (CAR) to be particularly problematic this year, and powdery mildew (PM) infections can still occur on susceptible cultivars. We are nearing the end of the season for mancozeb fungicides- an application tomorrow gives an earliest harvestable date of August 18 to allow for residues to degrade- but those materials have excellent efficacy against CAR and none against PM (worst on Paulared and Cortland, among common cultivars grown in VT). Captan, the ‘standard’ fungicide used against scab, fruit rots, and cosmetic summer diseases, also has no effect on either CAR or PM. The SDHI (Fontelis, Luna, etc.), strobilurin (Sovran, Flint), and DMI (Rally, Procure, etc.) are all effective against those secondary diseases, even when the local apple scab population is resistant to them. This would be a good window to consider their use. For organic growers, I am not recommending much beyond sulfur, maybe lime sulfur if you need to provide some thinning. However, if fruit finish is not a concern, some work I did in the past two seasons indicates that low-dose copper (I used Cueva, but Badge or another material labeled for summer use should work) had some efficacy against CAR (we had no PM in the trial) but did cause some fruit russeting.

Figure 4. Cedar apple rust gall on cedar sent to me by my cousin in North Hero. These ‘telial horns’ are spreading spores that will infect apple now.

Thinning- it’s still tricky this year with this cool, wet weather. Remember that thinner activity is based on promoting a short-term carbohydrate deficiency in the tree, when too many developing fruitlets are calling for the limited sugars the tree is producing. Cloudy weather reduces net photosynthesis (increasing thinning); cool weather reduces respiration (reducing thinning). Cool weather also prevents hormonal 6-BA (Maxcel, Exilis) thinners from working best. For orchards that received a thinning spray last week, you should see activity from that now- fruits that will abscise have already stopped growing. For orchards that have not thinned yet, do it asap.

General recommendations are difficult to make; where fruit remained clustered up and a previous thinners was applied, OI would consider a low rate of NAA with or without carbaryl; where no thinners have been applied yet, carbaryl + a moderate (4 oz Fruitone N / 100 gallons tree row volume) should be used. For hard to thin cultivars with heavy set (Fuji, Liberty, Gala, Macoun), a higher rate of NAA or carbaryl + 6-B,A (the latter especially on Fuji and Empire) is called for. Fruit set and thinning activity should be checked every day or two at this point, where growers are using precision thinning methods and measuring fruit to gauge thinning activity, measurements every three days should suffice.

As I said last week, good luck- unfortunately this challenging spring hasn’t gotten any easier yet, but I think good weather (and the insects it brings) is just around the corner.

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.

Vineyard management: Diseases and shoot thinning

Posted: May 26th, 2017 by fruit

By Terence Bradshaw

The growing season continues to be cool and wet, and grapevines at the UVM Horticulture Research & Education Center are showing about four to five inches of shoot growth. We are beginning to enter a critical time for disease management. Growers should consider applying a protective fungicide soon that has activity against phomopsis in particular, although anthracnose and, to a lesser degree, black rot may be active, especially in high inoculum vineyards. Organic growers should absolutely begin application of something at this stage in combination with keeping up sanitation of all dead or infected wood , rachises, and other grapevine debris- sulfur, one of the bicarbonate materials (e.g., Armicarb, Kaligreen, etc.), or a biofungicide like Serenade, Sonata, Regalia, or Double Nickel may be used, although there is little good efficacy data on that last class of materials.

I mentioned sanitation- now is a good time to get out and clean up the ‘nubs’ left at the ends of spurs after pruning that will die out and serve as reservoirs for phomopsis and other diseases. While you’re at it, this is an especially good time to thin shoots. Cold hardy grapes trained to a high-wire trellis and in good health can support about six shoots per foot of canopy; select the best developing shoots and break off the others now while they are easily breakable with your fingers. Maria Smith and Dr. Michela Centinari at Penn State recently wrote a good summary of shoot thinning available here. I suggest reading it on the deck this holiday weekend with a nice glass of wine, and getting out in the vineyard next week to set this year’s crop on the right track.

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.

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.

Contact Us ©2010 The University of Vermont – Burlington, VT 05405 – (802) 656-3131
Skip to toolbar