Jon Clements, Editor
Current degree day accumulations
| UMass Cold Spring Orchard, Belchertown, MA |
2-June, 2014 |
| Base 43 (SkyBit) | 691 |
| Base 50 (NEWA) | 417 |
| Coming events | Degree days (Base 43) |
| Codling moth 1st flight peak | 561-991 |
| Lesser apple worm 1st flight peak | 349-761 |
| European red mite summer eggs hatch | 737-923 |
| San Jose scale 1st flight peak | 554-742 |
| Obliquebanded leafroller pupae present | 601-821 |
| Obliquebanded leafroller 1st trap catch | 812-986 |
| Redbanded leafroller 1st flight subsides | 592-898 |
| Spotted tentiform leafminer 1st flight subsides | 668-950 |
| Black cherry fruit fly 1st catch | 702-934 |
Key insect life cycle and management dates
Note: for 2014, we have four Massachusetts orchard locations subscribed to AR: Belchertown, Groton, Phillipston, and Sutton. The website for looking at AgRadar for these locations is: http://extension.umaine.edu/ipm/programs/apple/pestcasts/
Codling moth (CM) -- 1st generation, first sustained trap catch biofix date: May 20, Tuesday. Codling moth development as of June 3: 1st adult emergence at 24% and 1st generation egg hatch at 0%. In most orchards, insecticide targetted against plum curculio and apple maggot prevent codling moth damage. If targetted codling moth control is needed, key management dates are shown here: 1st generation 3% CM egg hatch: June 10, Tuesday = target date for first spray where multiple sprays needed to control 1st generation CM. 1st gerneration 20% CM egg hatch: June 18, Wednesday = target date where one spray needed to control 1st genearation CM.
Lesser Apple Worm (LAW) -- 1st LAW flight begins around: May 16, Friday; Peak trap catch: May 26. 2nd LAW fligth begins around: July 14, Monday.
Obliquebanded leafroller (OBLR) -- 1st generation OBLR flight begins around: June 12, Thursday.
Oriental fruit moth (OFM) -- 1st generation OFM fligth starts: May 9, Friday; 1st generation 55% egg hatch and first treatment date, if needed: June 2, Monday.
Plum curculio (PC) -- Increase risk of PC damage as McIntosh and similar cultivars increase fruit size: May 26, Monday; Earliest safe date for last PC insecticide spray: June 2, Monday.
San Jose scale (SJS) -- First adult SJS caught on trap: May 25, Sunday; 1st generation SJS crawlers appear: June 22, Sunday.
Spotted tentiform leafminer (STLM) -- 1st STLM flight, peak trap catch: May 16, Friday. 1st generation sapfeeding mines start showing: May 24, Saturday. Optimum sample date is around Monday, May 26, when a larger portion of the mines are visible.
9-July, 2014. Annual Summer Meeting of the Massachusetts Fruit Growers' Association. 10 AM to 3 PM, UMass Cold Spring Orchard, Belchertown, MA. Details TBA.
Jon Clements
Today or tomorrow will be your last good days for chemically thinning apples. Do it now to get the job done. I will go out on a limb and suggest there will still be too many apples unless you pursue a moderately aggressive thinning approach. Don't worry that some trees have few fruit, if others need thinnning, just do the whole block. The NEWA Apple Carobohydrate Thinning model (for Belchertown) says to apply a Standard chemical thinning rate today, and then Increase chemical thinner rate by 30% beginning tomorrow. (See below.) AgRadar suggests "Increased senstivity" for chemical thinners applied today or the next several days, which is in a bit of disagreement with the AC model. I also have access to a SkyBit thinning product and it shows Active Hours (= good thinning application timing) between the hours of 11 AM and 5 PM both today and tomorrow (Tuesday and Wednesday). The next good Active Hours SkyBit shows is on the afternoons of June 7 and 8. (But the forecast could change. Remember: Fruitone at 3-4 oz. per acre (7.5-10 ppm) should give moderately aggressive thinning; Carbaryl at 1 qt. (1 lb.) per acre should result in moderate thinning; 6-BA (Maxcel and others) at 50-100 ppm will result in modes thinning (more if it is hot); and combinations of any of the above will result in the most aggressive thinning (be more careful).
It's getting dry and young trees planted this year should definitely be getting a near-constant drink of water when it is not raining. Get the irrigation up and running! Young trees need more frequent watering with smaller amounts of water than big trees.
Jon Clements
See Upcoming Pest Events and AgRadar above for current pest status.
Also see Guest Article below.
Dan Cooley
Apple scab - many more lesions started appearing on non-sprayed trees over the past weekend. By this coming weekend, Jun 7-8, most of the primary infections that occurred should start to show lesions. The time for most secondary lesions to show up will be about another week after that. All ascospores have been released by this point, so there is no chance for new primary infections. However if a few infections have occurred and went unnoticed, they may cause secondary infections that show up by Jun 15. Now is a good time to look around for scab lesions. For covers, a protectant program of captan, an EBDC, or should be adequate unless there is active scab visible in the orchard at this time.
Chemical Thinning
Duane Greene
Over the past several days trees have been exposed to some stress, perhaps the first significant stress since bloom. After application it requires about 7 days for a thinner to respond to the extent that you can start to see signs of fruit growth slowing. It is often difficult to establish if and how well a thinner worked initially unless you measure fruit. Assessment visually may require 3 or 4 more days. You should be out looking, measuring and assessing set. This is a very important week.
Thinners applied this past weekend should work well. The weather forecast for the next two or three days are less favorable with cooler temperatures and the threat of rain. Weather for the weekend does favor thinning. From now on it will be more difficult to achieve good thinning, especially if fruit size is much above 15 mm. While this may not be your last thinning opportunity, you are rapidly running out of time. The thinning window of opportunity is closing. The use of NAA at larger fruit sizes comes with the risk of reduced fruit size or thinning with obtaining the benefit of increased fruit size. MaxCel combined with carbaryl is a viable option at these larger fruit sizes, especially if the temperature is warm following application.
Some may be sitting on the fence about the decision to thin more since there is variable set in many orchards and blocks. If fruit are clustered and most in the cluster of similar size it is appropriate to thin. If fruit have stopped growing additional thinners are unlikely to affect the result since they are destined to drop anyway. After this week, if fruit growth is above 20 mm in size it will be much more difficult to thin and the available options are limited.
The following remarks about Calcium, Boron, Zinc, Nitrogen, and Potassium were presented by Dr. Cheng at the WNY thinning meetings last week (and summarized by M. Sazo). They appeared in the CCE Eastern NY Commercial Horticulture Program Morning Message, June 3, 2014.
Calcium: For Honeycrisp trees with a reduced crop, fruit Ca level will most likely be lower because: (1) vigorous shoot growth outcompetes with fruit for Ca, making less Ca available for fruit; (2) bigger fruit dilutes its Ca concentration; and (3) the high K resulting from a low cropload further lowers fruit Ca concentration. So, these fruit will be more susceptible to bitterpit and other Ca-related physiological disorders this year, especially for bitterpit-susceptible cultivars, such as Honeycrisp, Cortland, Jonagold, Mutsu and Northern Spy. For these cultivars, implementing a rigorous foliar Ca spray program is critical for minimizing bitterpit development and other physiological disorders. We have been recommending the following Ca spray program: 4 cover sprays of 1 to 2 lbs of calcium chloride (78% CaCl2) or its equivalent per 100 gallons (dilute basis) at 14-day intervals, beginning 7 to 10 days after petal fall, followed by 2 additional sprays of 3 to 4 lbs of calcium chloride (78% CaCl2) per 100 gallons at four and two weeks prior to harvest. It’s important to keep in mind that complete coverage of fruit is essential and more frequent spray is more important than exact timing of spray.
Boron (ground, foliar) and Zinc (only foliar): Both boron and zinc are important for fruit growth and development. In a good year like this, fruit growth requires more B and Zn. In addition to soil application, foliar spray of Solubor is a very effective way to supply B to fruit. For Zn, foliar spray is the only economical way of providing this element to apple trees. We recommend applying Zinc chelate at the label rate and Solubor at 1lb per 100 gallons at petal fall and the first or second cover to promote early fruit growth. Zinc chelate and Solubor can be tank-mixed with urea. However, Solubor should not be tank-mixed with any pesticides contained in water-soluble plastic packages because it inhibits the dissolution of the plastic. Also, Solubor should not be tank-mixed with oil. Because Solubor also increases spray water pH, pH of the tank mix should be tested and adjusted with a suitable acidifying agent if Solubor us used with pH sensitive pesticides.
Nitrogen (ground and foliar): The highest demand for nitrogen is from petal fall to the end of shoot growth. During this period, both rapid shoot growth and fruit cell division require substantial amount of nitrogen. The total annual requirement by high density Gala trees is about 50 lbs. actual nitrogen per acre, 70% of which occurs from bloom to the end of shoot growth. Foliar N application at petal fall and early cover sprays is a good way to supply nitrogen to the young fruitlets and spur leaves. Dr. Cheng recommends using foliar urea application at petal fall, first cover, and second cover at a rate of 5 lb. urea per 100 gallons on blocks that have marginal N status last year (urea can’t be mixed with oil).
Potassium: Did you know that apple trees have a constant demand for K from bloom to fruit harvest? K has the highest concentration in fruit and more than two thirds of the total tree K requirement is found in fruit. Dr. Cheng’s research has shown that 80 to 85 lbs of K is removed at a fruit yield of 1500 bushels/acre, which is about 100 lbs of potash (K20) bushels/acre.
Art Agnello, Entomology, New York State Agricultural Experiment Station, Geneva, NY
re-printed from Scaffolds Fruit Journal, Vol. 23 No. 11., June 2, 2014. http://www.scaffolds.entomology.cornell.edu/
In NY, there are two species of sesiid (clearwing) moths that attack peaches — the peachtree borer (PTB), Synanthedon exitiosa, and the lesser peachtree borer (LPTB), S. pictipes. The adult borers are striking clear-winged moths with yellow and steel-blue body markings. The adults of these insects have from one to four yellow-orange stripes across the abdomen, depending upon species and sex. The PTB enters the tree near soil level and does not require the presence of wounds or breaks in the bark for entry, but the LPTB nearly always enters
the tree at a pruning scar, canker, mechanical injury, or winter-injured area. The LPTB additionally attacks cherries, causing the same type of injury in the upper trunk and scaffold branches of these trees. Both species pass the winter as borers inside the tree, and in the spring emerge as moths that lay eggs on or in the trunk during the summer. The LPTB moth emerges first, normally in late May, (we caught our first of this season in Geneva on May 27), and the PTB doesn't show up normally until mid-June; both stay active (laying eggs) through August. When the borer stages hatch, the PTB tends to crawl down the tree to soil level and burrow in there, but the LPTB will move to the nearest injured area, which may be on the lower trunk or just as easily up in the scaffold limbs. LPTB completes its development in one year, but some PTB larvae take two years to develop, so any control measure a grower would elect will require repeating for at least 2–3 years.
Injury is caused by larval feeding on the cambium and inner bark of the trunk close to the soil level (PTB) or on the upper trunk and lower scaffold branches (LPTB). Occasionally, larger roots are also attacked by PTB. Areas attacked often have masses of gum, mixed with frass, exuding from the bark. All ages of trees are injured. Young trees are at times completely girdled and subsequently die. Older trees are often so severely injured that their vitality is lowered and they are rendered especially susceptible to attack by other insects or by diseases. Although both species may be found in infested trees, younger plantings and those not afflicted by extensive cankers or other bark splits are attacked primarily by PTB.
Chemical control is difficult, owing to the concealed habit of the larvae. Preplant dipping of roots and crowns of peach tree seedlings before planting using Lorsban has given complete control of the peachtree borer for the 1st growing season and has reduced borers during the 2nd season. For in-season control, growers have traditionally relied on one or more coarse insecticide sprays (e.g., Asana, Lorsban, Proaxis, Warrior) of the trunks and lower scaffold branches to deter egg laying and kill newly established larvae. Because this is a labor-intensive measure that often fails to completely control these pests, many growers choose not to elect treatment, or else do an incomplete job, with the intention of getting what they can out of a planting until infestations combine with other peach production factors to warrant tree removal. However, there is a good alternative in the form of pheromone mating disruption (MD) tools for the control of these perennial pests.
Isomate-PTB Dual (Pacific Biocontrol/CBC America, EPA Reg. No: 53575-34) is the twist-tie pheromone dispenser labeled for use against both of these species in all NYS stone fruits. They are placed in the trees at a rate of 150–250 ties/A at or before the first flight, with the higher rate (250/A) recommended when pest pressure is high. This product has replaced the Isomate-LPTB and Isomate- PTB formulations. We have conducted trials on the efficacy of Isomate-LPTB with and without the addition of directed trunk sprays in peaches, and after 2 years we saw that the pheromone dispensers completely suppressed trap catches of both PTB and LPTB for both seasons, compared with relatively heavy flights noted in the non-disrupted comparison blocks, showing that pheromone treatment was highly successful in disrupting the chemical communication of males and females of these two species.
These trials provided sufficient evidence that mating disruption alone is able to provide adequate protection from borer infestations in commercial orchards, giving growers an effective non-chemical alternative to trunk sprays for managing this pest complex in their stone fruit plantings. Growers interested in this approach should be placing the pheromone ties during these next 1–2 weeks, before the LPTB flight gets solidly under way statewide.
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UMass Fruit Advisor: http://umassfruit.com
Scaffolds Fruit Journal: http://www.nysaes.cornell.edu/ent/scafolds/
Network for Environment and Weather Applications (NEWA): http://newa.cornell.edu
Dr. David Rosenberger's Plant Pathology at the Hudson Valley Lab (including his 2014 Blog)
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The next Healthy Fruit will be published on Tuesday, June 10 or thereabouts, 2014. As always feel free to get in touch with any member of the UMass Fruit Team (http://extension.umass.edu/fruitadvisor/team-members) if you have questions or comments.