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Healthy Fruit 2013 Vol. 21:2

Apr 9, 2013


Volume 21, Number 2. April 9, 2013.
Current degree day accumulations
Current bud stages
Upcoming pest events
Upcoming meetings
The way I see it
2013 New England Tree Fruit Management Guide available
Guest article
Useful links
Current degree day accumulations
Location: UMass Cold Spring Orchard, Belchertown, MA
8-April, 2013
Base 43
Base 50
Current bud stages
Location: UMass Cold Spring Orchard, 8-April, 2013
Honeycrisp apple
McIntosh apple
silver tip
Rainier cherry
PF-14 Jersey peach
swollen bud
See pictures of current bud stages here:
Upcoming pest events
Coming events
Degree days (Base 43)
Green fruitworm flight peak
Pear psylla adults active
Pear psylla 1st oviposition
Redbanded leafroller 1st catch
Spotted tentiform leafminer 1st catch
McIntosh silver tip
McIntosh green tip
Upcoming meetings
APRIL 16 (Tuesday): UMass Fruit Team Twilight Meeting, Big Apple, 207 Arnold St., Wrentham. MA. 5:30 PM. 1 pesticide re-certification credit will be available. $20/25 meeting charge.
APRIL 17 (Wednesday): Harmonized Good Agricultural Practices (GAP) Training, 249 Lakeside Drive, Marlboro, MA.10 AM to 4 PM.
APRIL 17 (Wednesday): UMass Fruit Team Twilight Meeting, Outlook Farm,136 Main Rd., Westhampton, MA. 5:30 PM. 1 pesticide re-certification credit will be available. $20/25 meeting charge.
The way I see it
This WILL be your last Healthy Fruit unless you subscribe here:
Note that Healthy Fruit will only be available on-line beginning in 2013. You must have an e-mail address to receive Healthy Fruit. Subscribe here:
Otherwise, it's nice to have some warm weather, but that means things are going to "heat up" fast. Apple scab, pear psylla, and powdery mildew are all on the radar screen and referenced below. New tree planting should be done as soon as possible, there are many benefits to getting trees in the ground early, including better bud stage timing with the rest of the world, reduced fire blight risk, and longer growing season = more shoot growth = more fruit next year! Plant ASAP.
2013 New England Tree Fruit Management Guide available
The 2015-2016 New England Tree Fruit Management Guide is available here:
The cost is $50 payable by credit card. Copies of the Guide may be available to purchase with cash next week at the Twilight Meetings, however, there is a limited supply -- first come, first served.
See Guest Article on applying oil to help control mites, scale, psylla -- apply with discretion. Art Agnello does a real nice job of laying out the options with oil at this time and over the next week or two.
Winter moth -- starts hatching at app. 20 degree days base 50. (That is now.) Hatch stretches for a couple weeks depending on the temperature. For apples, the gold standard treatment is a pyrethroid (such as Warrior) plus DiPel timed at tight cluster to when the clusters start opening. This could be as early as next week depending on the weather.
Arthur Tuttle of UMass directly assessed apple scab ascopspore maturity yesterday using the roto-rod method -- there were no mature spores. But that will change on a daily basis. If you have green tip showing, you are at risk for getting a scab infection. Copper applied before an infection event (monitor on NEWA, will contol any early infection and is also a good (make that essential) component of fire blight management program. Use the higer rate of copper at this timing (for example, Kocide 3000 @ 4-7 lb per acre).
According to Mike Fargione (Tree Fruit Grower Alert Message, April 9, 2013): "If you miss an [apple scab] infection period this early, you could come in right away with mancozeb plus either Syllit, Vanguard or Scala ( ). You might instead gamble saying there aren’t enough mature scab spores ready at this time, and wait until the weekend to spray. Just remember how cheap a copper or mancozeb spray is compared to fighting scab all summer long.  I believe a preventative spray now makes sense. An early spray provides the protection needed if infections are possible and helps get some material on the trees and available to redistribute to coverage gaps of the next spray when you are definitely under the gun."
It's too early to start treatment for powdery mildew of apple, however, it shold be on your mind given the severity of it last year. Control begins about tight cluster. Dave Rosenberger wrote an excellen treatise in this week's Scaffolds Fruit Journal:
Soak tree roots in water for 24-48 hours before planting; this fully ‘hydrates’ the tree, very important given how dry the soil is now; water-in trees and/or apply irrigation ASAP.
Use Gallery/Prowl H2O or Surfaln for pre-emergent weed control in the tree rows of newly planted trees. Has good crop safety, and Gallery is very effective on broadleaf weed seedlings.
Guest article
By Art Agnello. Reprinted from Scaffolds Fruit Journal, Vol. 22, No. 3, April 8, 2013.
With this year's leisurely progress into the growing season so far, growers have an uncharacteristically adequate amount of time to consider the potential value of using horticultural mineral oil as an early season pest management tactic, which used to be a pretty much universal practice years ago, when mites and scales were more problematic and the options for dealing with them were less abundant. Those of us familiar with fruit insect and mite trends still believe it is worthwhile to consider the use of oil applications for early season mite and insect control in both apple and pear plantings, because of its effectiveness, relative affordability, and safety from a biological and pesticide resistance perspective. Taking advantage of the most favorable spraying conditions to maximize tree and block coverage can be a challenge in our area, but few pest management efforts have such potentially high returns when all factors are taken into account, and this year may offer more opportunities than are normally available.
Mite and scale population trends are typically not the same each year, and weather conditions are certainly among the most variable of factors in the pest scenario from one year to the next. Before you decide that it's too much trouble or cost to invest in a prebloom spray of oil, be sure you're aware of how much it could cost you (biologically as well as financially) if a rescue treatment for mites or scales ends up being necessary later in the season.
Probably first, chronologically, early oil applications are useful against pear psylla all throughout the swollen bud stage. Although it's capable of killing adults and nymphs that are directly contacted, oil is recommended mainly because the residue repels adult females looking to deposit their eggs, something that is already taking place across the state. The objective of using oil is to delay the timing of any needed insecticide spray until as late as possible before (or after) bloom. Oil rates depend on when you start: If your buds are at the dormant stage (most orchards are probably past this point), one spray of 3% oil, or two of 2% through green cluster are recommended; if you start at swollen bud, one spray at 2% or two at 1% up to white bud should be adequate for this purpose, especially if applied as soon as the psylla become active (which they have). This will also give some European red mite control at the same time.
The Book of Paul
The following advice developed from Paul Chapman's original research is essentially unchanged from what I print every spring, which shows the durability of not only the information, but also of a crop protectant that's still as good as it used to be:
A delayed-dormant spray of petroleum oil in apples from green tip through tight cluster can be a favored approach for early season mite control, both to conserve the efficacy of and to help slow the development of resistance to our contact miticides. Our standard advice has been to try for control of overwintered eggs using 2 gal/100 at the green tip through half-inch green stage, or 1 gal/100 at tight cluster; this assumes ideal spraying conditions and thorough coverage. Naturally, this is not always achieved in real life, mainly because of weather and coverage challenges, coupled with the difficulty of getting to a number of blocks during a fairly brief window. It is possible for mites to start hatching when the trees are at solid tight cluster, so the suffocating mode of action tends to be compromised if the nymphs are able to pick their way through the droplets, or else dodge them entirely. Let practicality determine how best to use the following guidelines.
First, to be sure that mites are in the egg stage, start on your blocks as soon as the weather and ground conditions permit, even if this means using a higher rate. Depending on how wet the winter months have been, local conditions will be the prime determinant of how easily you can get through the rows early on. Also, tend toward the high end of the dosage range, especially if there's been no frost during the 48-hour period before your intended spray, and no danger of one for 24–48 hours afterwards. For example, use 1.5 gal/100 if the buds linger somewhere between half-inch green and full tight cluster during your chosen spray period. Naturally, when warm temperatures start as early in the year as they have this season, cold snaps and overnight frosts are a wild card, so be aware of any imminent changes in weather patterns that could result in tissue damage in oil-treated trees.
Obviously, good coverage of the trees is critical if you're to take advantage of oil's potential efficacy; this in turn requires adequate spray volume delivered at an appropriate speed. Experience and research have shown that a 1X concentration (300 gal/A) in large trees is clearly preferable; however, if all other conditions are optimal (weather, speed, calibration), then 3X, or 100 gal/A, is the highest concentration that should be expected to give acceptable control at any given time. Growers like to concentrate more than this to save time and the hauling of extra water, but reducing coverage too much can compromise your efforts if you end up covering only a small fraction of the egg population with the residue.
Don't limit this mite control tactic just to apples and pears. Talks with stone fruit growers have reminded us that many cherry, peach and plum plantings can suffer equally serious European red mite infestations that weren't given the early season attention they might have needed. We don't have hard and fast threshold guidelines for these crops, but stone fruit plantings with a history of past ERM problems should be examined for presence of the red overwintered eggs, and if they're numerous enough to see without a hand lens, then a prebloom application of 2% oil would be a prudent tactic to help ward off this damage, particularly if your fungicide program at this time doesn't present any compatibility problems.
A Matter of Scale
San Jose scale is one of the historically important pests that has taken advantage of our changing insecticide programs during the last few years. The disappearance of products like Penncap-M and Lorsban from our list of summer spray materials has been at least partly responsible for the fact that SJS persists or has returned to pest status in a number of orchards. It's therefore worth pointing out that a 2% oil treatment at half-inch green will control the immature forms overwintering on the trees, and this is a preferred treatment if no other problem insects need to be controlled. Combining the oil with an insecticide generally has not been shown to be more effective than using the oil (or insecticide) alone, except possibly in the case of one alternative, Esteem, which has shown good efficacy when mixed with 2% oil at the pre-pink timing.
Finally, regarding the frequently voiced concern that oil may have a negative impact on the health of the trees, I would note that petroleum oil has been used for well over a century as a delayed-dormant treatment to control mites, scales, and even some aphids, with no ill effects on the health of the tree or the current season's crop. The primary cautions we advise when using oils at that time of year stem from their use a) in association with or too close in time to applications of sulfur-containing fungicides, or b) just before or too soon after sub-freezing temperatures; both of these practices risk the occurrence of phytotoxicity, as oil's penetrant activity is capable of damaging the bark, wood, or bud tissues in these situations. Applicatio of oil under any circumstances that do not allow for normal drying to occur can also result in some tissue damage. Also, oil sprays during pink bud can cause burning of the sepals or petals, which may or may not affect normal pollination and fruit set.
Useful links
UMass Fruit Advisor:
Network for Environment and Weather Applications (NEWA):
UMass Vegetable & Fruit IPM Network (on Facebook,
The next Healthy Fruit will be published on Tuesday, April 16 or thereabouts, 2013. As always feel free to get in touch with any member of the UMass Fruit Team ( if you have questions or comments.