Healthy Fruit, Vol. 26, No. 6, May 8, 2018
Jon Clements, Author (unless otherwise noted) and Editor
Current degree day accumulations
UMass Cold Spring Orchard,
Base 43 BE (NEWA)
Base 50 BE (NEWA)
Current bud stages
Current bud stages. May 7, 2018, UMass Cold Spring Orchard, Belchertown, MA
1st king bloom
Rainier sweet cherry
Black stem borer 1st catch
249 to 374
Traps could be made and hung
European red mite egg hatch
231 to 337
Last chance for oil application
Green fruitworm catch subsides
269 to 447
Jump on that petal fall insecticide if GFW is a problem in your orchard
Lesser appleworm first catch
276 to 564
Does anyone know if this pest is a problem in MA orchards, or is it taken care of with petal fall sprays?
Obliquebanded leafroller larvae active
158 to 314
Time to start scouting foliage, however, now is not the optimum time to treat or worry about, unless you plan to use Dipel or another B.t.
Oriental fruit moth 1st flight peak
333 to 536
Pheromone traps should be hung to establish biofix; petal fall spray likely to resolve
Redbanded leafroller 1st flight peak
230 to 378
Spotted tentiform leafminer 1st flight peak
269 to 407
Not a problem at this stage, but traps might give you an indication if it is going to be a later problem
Later this week...
Tuesday, May 8 -- Fruit Twilight Meeting, Apex Orchards, Shelburne, MA at 5:30 PM on May 8, 2018. Tim Smith will be our host. We will meet at his new sales room at 225 Peckville Road. Light dinner will be served. Bloom time disease and insect management, fruit thinning will be topics of discussion. Two pesticide recertification credits. Pre-registration is not required but $20 meeting fee for individuals getting pesticide credits will be collected at the door.
Thursday, May 10 -- Fruit Twilight Meeting, Foppema's Hilltop Orchard, 9 McClellan Road, Wilkinsonville (Sutton), MA at 5:30 PM on Thursday, May 10, 2018. In cooperation with Rhode Island Fruit Growers' Association. Ken and Evan Foppema will be our hosts. Light dinner will be served. Bloom time disease and insect management, fruit thinning will be topics of discussion. Two pesticide recertification credits. Pre-registration is not required but $20 meeting fee for individuals getting pesticide credits will be collected at the door.
Fruit twilight meetings this week, see above. Should be good! Please pay attention to the address were we will be meeting! Apple fruit thinning will be a major topic of discussion. Not quite in bloom, but things looking really good, In fact, I am not sure I have ever seen so much wild pollinator/bee activity in blooming cherries before, it’s truly astounding. You have to see it to believe it. Oh, wait a minute, here it is: https://youtu.be/oBIXGKG9wOU
Significant apple scab infection period this past Sunday, hope you were covered with fungicide or went on today with some kickback fungicide. Another BIG one coming this weekend, remember, it always rains around Mother’s Day, you can count on that, and you have all week to get covered up. Fire blight past risk likely minimal, but I know some strep went on open bloom. Risk level will ramp up this week, it’s already been warmer today than predicted, and risk will likely be very high when bloom is ongoing. Be prepared, watch the forecast and models. Remember, fire blight needs heat, open bloom, and moisture (rain or heavy dew). Make sure you follow the label directions for whatever make/kind/formulation of antibiotic you use, because they differ somewhat! Isn’t it amazing what information you can find on the label!
Jaime Pinero reports plum curculio have already moved into the UMass orchard, and migration will be ongoing during bloom. Expect a banner year -- and I don’t mean that in a good way!! -- for insect activity. We caught the first Oriental fruit moth in pheromone traps at the UMass Orchard, although I have not declared a first sustained trap catch yet. Mating disruption for OFM should go up ASAP if you are doing that.
When it comes to apple fruit thinning, use the nibble approach but be patient -- hormone thinning applications during cool weather are next to useless, wait for a period of warmer, cloudy weather, you will get much better results. Carbaryl being the only exception to that guidance. Also consider that my friend Phil Schwallier of Michigan has performed many chemical thinning experiments over the years, and he says he has consistently got the best thinning results (aka more thinning) when fruits are centered around 10 mm in diameter. Not petal fall. Not 5 mm. Not 7 mm. Yes 8 to 12 mm. Not 15 mm. OK? The other big factor for thinning success is to apply chemical thinner(s) when the trees are under a carbohydrate deficit, but I already said this -- when it is cloudy and warm, NOT sunny and seasonal.
THIS JUST IN: Oriental fruit moth trap catch overnight at UMass Orchard.
What does it mean? According to NEWA, not much. But take it under advisement. !!! AND NO INSECTICIDES DURING BLOOM !!!
• The New England Extension tree fruit specialists -- which include myself and Dan Cooley at UMass, Mary Concklin at UConn, Heather Faubert at URI, Terry Bradshaw at UVM, George Hamilton and Alan Eaton at UNH, and Glen Koehler and Renae Moran at UMaine -- have officially launched an online edition of the New England Tree Fruit Management Guide. Note that is it easy to print any of the sections, if you want to have old-school reference, for example, to hang on your spray shed wall. Also, it is quite mobile-friendly so make a home screen shortcut to here: http://netreefruit.org. Finally, if you really, really want a printed version, and especially if you have Amazon Prime, search ‘New England Tree Fruit Management Guide’ on amazon.com. Your comments/feedback on this work in progress would be appreciated. How do you get your spray/pesticide information these days?
It’s plum curculio showtime!
At the UMass Cold Spring Orchard, plum curculios (PCs) became active on May 2nd (McIntosh trees were at tight cluster). This was determined by means of odor-baited Tangletrap-coated panel and black pyramid traps (see picture on the right). One PC adult was captured on that day.
Over the subsequent days of relatively warm weather (May 3-5), 17 more PCs were captured by three traps, for an average of 1.9 PCs per trap, per day. On May 6th, 9 PCs were captured in three traps, for an average of 3 PCs per trap, per day. So, PC numbers are gradually increasing.
The onset of PC immigration closely matches the average (2000-2004 data) DD accumulation of 228 DD (base 43°F) reported in a research article published by Piñero and Prokopy (2006). In 2018, the first PC showed up at 220 DD (base 43°F). Really close to the average! The graph below provides, for 2000-2004 and 2018, the cumulative DD per day, per year. DD were calculated starting on January 1st, but are presented starting on March 1st. Colored circles indicate the date at which the first PC was captured by traps. Note the closeness in terms of cumulative DD days.
According to the NEWA PC model, Belchertown is approximately 116 DD from petal fall - the critical period for protection against PC. Note that NEWA uses base 50°F for its calculations.
Based on the weather forecast for the next 10 days in Belchertown, the highest temperature for the 10-day period will be around 77°F (on May 16th). This means that PCs will continue to colonize orchards but likely this will happen at a slower rate. This makes me think that a petal fall spray against PC that is delayed by a couple of days could be a possibility, to ensure that as many PCs as possible are killed. We want to minimize the chances that some PCs move into the orchard interior after the petal fall spray residue becomes ineffective.
Do you have any suggestions for articles on arthropod IPM? Please let me know!
Contact info: firstname.lastname@example.org; (413) 545-1031 (campus office); (808) 756-2019 (cell).
Not a Time to Snooze
Warm weather has moved fruit tree development rapidly, and along with it, disease pressure. As trees bloom, it is the highest risk period for apple scab and fire blight, and brown rot blossom blight. Now is the time to watch the disease and weather forecasts, and take action. Being protected is better than trying to clean up after an infection, so look ahead.
The apple scab models are all showing a lot of inoculum available, but for the next four or five days, no weather that will cause infection. The weekend brought an intense infection. Infected leaves should start showing symptoms in about 10 to 14 days.
Fire blight depends on open blossoms. With bloom, and warmer weather than last year, there has been and will continue to be risk of fire blight through bloom whenever there is wetting. Remember that includes a heavy dew or short shower. Be ready to apply streptomycin as needed.
Brown rot also needs some wetting to infect. There are a lot of fungicides available for brown rot on peaches and other stone fruit. Keep in mind that some are limited to early season use, during bloom, and that it’s important to rotate fungicides to maintain their effectiveness. Don’t keep pounding with one or two materials all season long! And take the time to get rid of those old peach mummies in trees – they’re a major inoculum source.
Most action focusing on disease and soon insect, management. But:
Thinning Options (Duane Greene)
Warm weather arrived last week to rapid development of bloom. The stage of bloom may vary from pink to full bloom and in some cases petal fall. Regardless of the bloom stage, this is a very important time to start chemical thinning of apples. The weather forecast for the coming week appea generally favorable for thinning. I urge all to take advantage of this opportunity. This could be one of the best opportunities to thin that you will have this year. Suggested thinner rates should be modified depending on how difficult it is to thin the variety in question.
Bloom is a good time to start thinning. The earlier you start to adjust crop load the more influence you will have on return bloom. At this time you have at least two good options and two that are less popular.
There are a number of options available at petal fall. If you did not apply a bloom spray make certain that you do apply one at PF. In some instances application at both times may be appropriate.
The threat of rain is always present during chemical thinning season. If rain does occur after a thinner application has been made the question that is frequently asked is how much activity was lost? A rule-of-thumb that I use in circumstances such as this is “If the spray had an opportunity to completely dry then at least 80% of the potential thinning activity can be expected compared with a tree that did not receive the rain”.
Pear psylla are in a small lull for now. Eggs will begin hatching soon, scouting for early instar nymphs will aid you in making an effective insecticide application if warranted. Recall the “hardshell” stage is far more difficult to control, you are targeting young nymphs. Continue to keep your eyes peeled for adults in flight, oil is a viable egg laying deterrent all summer long (temperature dependent, of course).
Target psylla nymph stage, early instar (pictured above, note this nymph is not from this year and is only intended as an ID reference).
Winter moth update from Heather Faubert:
Eggs have all hatched! As usual, Heather has done a great job letting us know what is happening on this front. Click on the link for Heather’s report which contains some exceptionally helpful pictures this week!
Gypsy moth are hatching, at least in Belchertown, where two ballooned their way down from the tops of the trees onto me. Not my favorite type of hitchhiker. But, they are still quite small and highly susceptible to Dipel or any other Bacillus thuringiensis material. Protecting young trees (and small fruits) from this voracious leaf and bud muncher is important, especially with the dry forecast we are looking at.
Gypsy moth aren’t the only lepidopteran larvae rearing their ugly heads. Oblique banded leafroller (larvae pictured above) are beginning to chew on leaves. Adult flight will begin after this overwintering larval population has pupated. This will occur somewhere around 887 DD base 43℉.
Apple scab and fire blight forecast looks pretty tame for the rest of the week (phew!). There’s about a 30% chance, according to NOAA, that we will see some rain over the weekend, but, we all know that this far out that’s as reliable as… Well, I can’t think of a comparison fit for print, so, fill in the blank as you see fit.
As far as apple scab goes this season, you’ll have to admit, I have shown remarkable restraint in the amount of spore information I have included, so, I feel like I can get away with just this one… Each of the red arrows indicates an ungerminated apple scab ascospore. The red circle shows three that have germinated, literally overnight.
Kerik Cox, Plant Pathology and Plant-Microbe Biology & Juliet Carroll, NYS IPM Program, New York State Agriculture Experiment Station at Geneva
Reprinted from Scaffolds Fruit Journal, Vol. 27, No. 7, May 7, 2018
The number and magnitude of fire blight outbreaks in NY was a little lighter than the previous years, but some growers still experienced losses due to fire blight. There were only two critical risk periods for blossom blight and these occurred around the 1st and 18th of May. In western NY, the risk period around the 1st of the May was of less concern given the cool weather at that time, but temperatures were warmer in eastern NY, increasing risks. While the period around the 18th of May represented "extreme risk for blossom blight", many sites were at or beyond petal fall, reducing the overall risk for some locations with early flowering cultivars.
In 2017, we received many fire blight samples for antibiotic resistance testing from the western NY and the Lake Champlain regions. Fortunately, no resistance to any antibiotics was observed in any of the samples. Shoot blight was the predominant type of sample received, and no places even reported blossom blight. It's important to note that low or even unnoticeable levels of blossom blight could have still been the source of the late season shoot blight outbreaks in 2017. As bloom is upon us in 2018, it will be important to keep track of the fire blight history in apple blocks, and, where fire blight history and scion / rootstock susceptibility warrant, to protect apples during high risk weather conditions during petal fall and shoot elongation.
Currently, only orchards in the Hudson Valley have reached bloom with the sudden warm weather. Unfortunately, these experienced a period of high to extreme risk over the weekend with the first open flowers. Orchards in western NY may only begin to reach king bloom this week and may only be at low to moderate risk of infection when the weather warms on Thursday. Orchards in the Lake Champlain region are unlikely to reach king bloom this week. While there is risk of infection on Wednesday/Thursday with the high temperatures and rain, the risk should be somewhat tempered by the low numbers of open flowers. While regional extension specialists in the Hudson Valley are rightfully concerned about the risk of blossom blight infection over the weekend, the situation seems less dire in the other production regions of the state.
The warm in the middle of the week could boost inoculum levels, but several days in the mid-60s toward the end of the week will slow bacterial reproduction and reduce risk. However, the risk of fire blight may increase following week as temperatures are forecast to be in the 70s. In this regard, it will be important to watch forecasts, check the models, and follow extension specialists' alerts.
As you consider model outputs from NEWA or other forecasting models, here are some things to consider before making applications of antibiotics or other costly materials for blossom blight:
Status of antibiotic resistance in 2018
Despite extensive screening, streptomycin resistance has not been detected in NY for the last four years. If we keep practicing resistance management by rotating bactericides and antibiotics with limited use of streptomycin application after bloom, we may never experience outbreaks of streptomycin resistance as we had in 2011 to 2013. However, sending blossom blight or trauma blight samples for screening, when they occur after streptomycin applications, is the best approach for assessing the occurrence of streptomycin resistance in your operation.
Even in the absence of streptomycin resistance, fire blight can still be difficult to control if weather favors the pathogen. Moreover, the shoot blight phase of the disease can still present a considerable problem following an apparent success in blossom blight management. In this regard, we have continued to refine and update our guidelines for managing fire blight in NY with an emphasis on young plantings. The guidelines are broken up into three sections: general guidelines for season-long management, additional guidelines for new plantings, and guidelines for on-farm nursery production. Tables of fire blight susceptibility for popular cultivars and rootstocks are linked from the NEWA model page for fire blight.
General guidelines for season-long management.
Additional guidelines for new plantings (1-2 years)
Guidelines for on-farm nursery production
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
The next Healthy Fruit will be published on or about May 15, 2018. In the meantime, feel free to contact any of the UMass Fruit Team if you have any fruit-related production questions.