Jon Clements, Author (unless otherwise noted) and Editor
Current degree day accumulations
| UMass Cold Spring Orchard, Belchertown, MA |
29-June |
| Base 43 (SkyBit) | 1414 |
| Base 50 (NEWA) | 1,001 |
| Coming events | Degree days (Base 43) |
| Spotted tentiform leafminer 2nd flight peak | 1382-1794 |
| Apple maggot first catch | 1249-1669 |
| San Jose scale 1st flight subsides | 864-1238 |
| San Jose scale 1st gen. crawlers present | 1033-1215 |
| Oriental fruit moth 2nd flight peak | 1451-1969 |
| Lesser appleworm 1st flight subsides | 992-1528 |
Key insect life cycle and management dates
Note: for 2015, we have five Massachusetts orchard locations subscribed to AR: Belchertown, Groton, Phillipston, Stow and Sutton. The website for looking at AgRadar for these locations is: http://extension.umaine.edu/ipm/ag-radar-apple-sites/. What follows is for the Belchertown location.
Dogwood borer (DB) -- First dogwood borer egg hatch roughly: June 24. Peak hatch roughly: July 30.
Codling moth (CM) -- 1st generation, first sustained trap catch biofix date: May 16, Saturday. Codling moth development as of July 2: 1st adult emergence at 70% and 1st generation egg hatch at 16%. 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 20, Saturday = target date for first spray where multiple sprays needed to control 1st generation CM. 1st generation 20% CM egg hatch: July 4, Saturday = target date where one spray needed to control 1st generation CM.
Lesser appleworm (LAW) -- 2nd LAW flight begins around: July 10, Friday.
Obliquebanded leafroller (OBLR) -- 1st generation OBLR flight begins around: June 9, Tuesday. Early egg hatch and optimum date for initial application of B.t., Delegate. Proclaim, Intrepid, Rimon, Altacor, Belt, pyrethroid or other insecticde effective against OBLR (with follow-up applications as needed): June 23, Tuesday. Where waiting to sample late instar OBLR larvae to determine need for treatment
is an option, or to check on results from earlier sprays: Optimum sample date for late instar summer generation OBLR larvae: July 4, Saturday
If first OBLR late instar larvae sample is below threshold, date for confirmation follow-up:
July 7, Tuesday.
Oriental fruit moth (OFM) -- 1st generation OFM flight starts: May 5, Tuesday; 1st generation 55% egg hatch and first treatment date, if needed: May 26, Tuesday. 2nd generation OFM flight begins around: June 28, Sunday. 2nd generation - first treatment date, if needed: July 6, Monday. 2nd generation - second treatment date, if needed: July 18, Saturday.
Redbanded leafroller (RBLR) -- 2nd RBLR flight begins around June 29, Monday. Peak catch and approximate start of egg hatch: July 23.
Spotted tentiform leafminer (STLM) -- 2nd STLM flight begins around: June 15, Monday. Rough guess of when 2nd generation sap-feeding mines begin showing: July 5, Sunday. Optimum first sample date for 2nd generation STLM sap-feeding mines is July 12, Sunday.
21-July, 2015 (Tuesday) Massachusetts Fruit Growers' Association Summer Meeting, Red Apple Farm, 455 Highland Ave, Phillipston, M. 10 AM to 3 PM. More details coming week of July 5...
For more information and updates, see Upcoming Events or contact Jon Clements, 413-478-7219.
Fairly quiet, hand-thinning of peaches and apples should be on-going and treatment for summer diseases of apple, brown rot of stone fruit (as fruits ripen), lepidoptera pests (obliquebanded leafroller, codling moth) sprays (as necessary), young apple tree training (stipping of leaders), cherry harvest, mowing, calcium chloride sprays on apples, etc., etc. Did I say it is quiet? Try and take some time off for yourself this 4th of July weekend. And mark your calendar for the Mass. Fruit Growers' Assoc. Summer Meeting on July 21 at Red Apple Farm in Phillipston. More details and registration information next week...
Below are the two Insect alerts! I sent out previous. I also observed Japanese beetles on apple foliage today, so start to keep an eye on those buggers and treat as necessary. Oh yea, apple maggot fly traps should go up fairly soon. For more detail and deploying and monitoring AMF traps, see Alan Eaton's latest New Hampshire Integrated Pest Management Newsletter. JC
Insect alert! OBLR Jun 27 (5 days ago) "Obliquebanded leafroller (OBLR) adults have been caught in pheromone traps beginning app. 10 days ago setting the biofix for first trap capture. (See attached.) According to NEWA, and AgRadar (see attached), if OBLR is a problem in your apple orchard, an insecticide spray targeting OBLR should have been applied by now or very soon. This is typical timing for this pest, i.e. the last week in June. Insecticides rated as excellent include: SpinTor, Entrust, Proclaim, Delegate, Altacor, Belt, or Voliam Flexi. Good luck."
Insect alert! PLH Jun 27 (5 days ago) "Yesterday I found potato leafhopper (PLH) on terminal foliage of young apple trees in the lower Connecticut Valley, and they had already started to cause damage/stunting to the growing shoot tips. See attached. Immediate action is required, because if left unchecked, they will cause newly planted and young apple trees to stop growing. PLH may not be in all orchards yet, but keep on the lookout for them and treat young plantings immediately with insecticide. Rated as excellent for controlling PLH: Imidan, Lannate, Provado/Admire Pro, Actara, Assail, Calypso (if you have it), and Belay."
See Guest article below, and a reminder to use the NEWA website to help determine the need for summer fungicide sprays based on time from last spray and amount of rain.
Calcium sprays to improve apple fruit quality and storability should be ongoing with summer cover sprays or by themselves as necessary. Visit the Fact Sheet "Foliar Calcium Sprays for Apples" (on the recently updated UMass Fruit Advisor) for details.
CONTROLLING SUMMER DISEASES ON APPLES Dave Rosenberger (retired), Plant Pathology, Highland
Reprinted from Scaffolds Fruit Journal, Vol. 23, No. 14
Summer diseases on apples include the fungal surface blemishes known as sooty blotch and flyspeck (Fig. 1) and also the fungal fruit decays known as black rot, white rot, and bitter rot. More than 60 different fungi can cause sooty blotch and flyspeck (SBFS), but most of the SBFS in sprayed orchards is attributable to just a few of those species. Black rot and white rot are caused by Botryosphaeria obtusa and B. dothidea, respectively. Bitter rot is caused by one or more species of the fungal genus Colletotrichum. Strategies for timing sprays for SBFS have changed and evolved over the past 25 years. Those not interested in the history of proposed control measures for SBFS that are presented below should skip to the last section for current recommendations.
Development of SBFS models
Determining optimum timing for fungicides needed to control SBFS has been complicated by the long incubation period that separates infection from disease appearance on the fruit. In 1995, Brown and Sutton published results of field studies in North Carolina that showed that the incubation period for SBFS required 272 hours of accumulated leaf wetting, but they did not count wetting periods of less than three hours in duration. Work in Dan Cooley's lab at the University of Massachusetts showed that the fungus causing flyspeck began releasing ascospores sometime during bloom. At about the same time, observations in New York led me to believe that some fungicides (especially benomyl, which is no longer registered) could provide some post-infection activity against SBFS. Putting all of this information together, I proposed the following logic for determining when the first fungicides targeting SBFS might be needed during summer:
Why the old model no longer applies
Three major changes have occurred that make the old model obsolete. First, the North Carolina model indicating an incubation period of 272 hours of accumulated wetting was based on string recorders, as were the subsequent suggestions for when growers in the Northeast should begin their SBFS sprays. However, NEWA stations are equipped with electronic recorders that are somewhat less sensitive to wetting that the old string recorders. Our current best estimate for the SBFS incubation period using electronic sensors is 185 hr of wetting (i.e., 272 hr on a string recorder = 185 hr on electronic sensors in the NEWA network).
The second reason for changing the model involves the need for protection against black rot. We have found that omitting fungicides for extended periods in late June and July can result in establishment of quiescent black rot infections that then develop into fruit decays as fruit approach maturity. These quiescent infections are more problematic on early-maturing as compared to late-maturing cultivars.
The third reason for changing the model is that continued field trials and observations at the Hudson Valley Lab have revealed that fungicides almost certainly do NOT provide the degree of post-infection activity that we initially thought we were observing. We have found that fungicides can arrest fungal development of pre-existing infections, but they never provide complete eradication. Once fungicide residues are depleted, many of the pre-existing SBFS colonies resume growth. Thus, if fungicide applications are delayed beyond 185 hr-AWPF (using NEWA data), then some colonies may become established and persist through summer. Those SBFS colonies may never show up on fruit if fungicide protection is maintained right up through harvest. However, in many years, fungicide protection will lapse a week or two prior to harvest and incubating SBFS infections will then appear suddenly prior to harvest because they got a jump-start early in the season. If there are no fungicide protection gaps during summer, then the preharvest protection gap can be as much as 185 hr of accumulated wetting before SBFS will appear on fruit, but any protection gaps during summer must be subtracted from the 185-hr "grace period". A protection gap occurs anytime that the interval between summer sprays exceeds either 2 inches of accumulated rainfall or 21 days.
To illustrate, let's use conditions at the Hudson Valley Lab and data from the Highland NEWA station. I will use May 18 as the petal fall date for starting the SBFS model. (Be sure to set the petal fall date to match your own observations rather than using the default date that is entered at the top of the NEWA page for the SBFS model!) The NEWA model indicates that as of 22 June we have accumulated 170 hours of leaf wetness since petal fall. Let's assume that my last scab fungicide was applied on 2 June. Rainfall since 2 June totals 2.27 inches, so I know that my last scab fungicide is no longer providing any viable protection against SBFS. Rains predicted for later this week will probably push us over the 185 hr-AWPF threshold for the beginning of the SBFS spore influx from the orchard perimeter. To prevent establishment of any SBFS infections, I will want to apply my first SBFS fungicide sometime this week. However, the timing is not critical. If it is more convenient to delay my next fungicide until next week, that will still be OK so long as I remember that, if we get a lot of rain and a lot of hours of wetting later this week, I will end up using some of my total "grace period" which consists of 185 hr of wetting without fungicide protection between now and harvest.
Current recommendations for SBFS control
The NEWA model provides a reasonable estimate of when the SBFS risk period begins if the petal fall date is entered correctly at the top of the model. Timing of summer fungicides is not nearly so critical as timing for scab sprays, but I strongly recommend that growers avoid extended protection gaps after the NEWA model indicates that SBFS is active. Leaving trees unprotected after late June will increase the likelihood that black rot fruit decays and/or SBFS will appear shortly before harvest. Fungicide recommendations for SBFS have not changed much in recent years. I will provide a more detailed summary of apple fungicide options for summer in next week's issue of Scaffolds. However, a quick summary is provided below:
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Taking the week off...
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
New England Apple Decision Support System maps (experimental)
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The next Healthy Fruit will be published on Tuesday, July 7 or thereabouts, 2015. 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.