Healthy Fruit, Vol. 26, No. 4, April 24, 2018
Jon Clements, Author (unless otherwise noted) and Editor
Current degree day accumulations
UMass Cold Spring Orchard,
Base 43 (NEWA)
Base 50 (NEWA)
Note that apple green tip should occur app. 101 DD (Base 43), although obviously there is a range. We are at half-inch green (23-April) in Belchertown.
Current bud stages
Current bud stages. April 23, 2018, UMass Cold Spring Orchard, Belchertown, MA
Honeycrisp Quarter-inch green
Regina sweet cherry
Green fruitworm 1st catch
50 to 148
Too early to do anything! You are not targeting the moths, but the worms when they hatch later.
Green fruitworm peak catch
96 to 231
Pear psylla adults active
31 to 99
Pear psylla oviposition continues
40 to 126
Oil, oil, oil. Adults continue to lay eggs. Keep early populations down to reduce future pressure!
Redbanded leafroller 1st catch
114 to 177
Spotted tentiform leafminer 1st catch
118 to 218
This first trap catch is very unreliable in predicting if you will have a problem, but moth flight is beginning; red sticky traps on tree trunks can also be used.
McIntosh green tip
Apply copper and/or oil
Mark you calendar, May fruit twilight meetings will be May 8 (in western MA) and May 10 (Foppema’s Farm, Sutton, MA). Details coming soon…
• 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?
A synopsis of spider mite biology, monitoring, and management using oils in the early growing season, with some notes on predatory mites.
In many cropping systems, like tree fruits, spider mites are secondary pests. They only become a management issue when pesticides are applied to control other pests. This is typically attributed to the non-target effects of many pesticides on spider mite natural enemies, especially predatory mites, which result in disruption of biological control. When mites do become a problem, then the European red mite is considered by many growers to be the most difficult pest to control.
A couple of growers reported problems with spider mites last year (in one case the outbreak occurred in Honeycrisp). This article provides a brief overview of the biology, monitoring and management (with a focus on oils) of the European red mite and the two-spotted spider mite. This information is presented in the table (see next page). Some of the information being presented was extracted from the New England Tree Fruit Management Guide.
Some notes on the application of oils against spider mites: Since tree architecture includes many cracks and crevices as well limbs and twigs that exponentially increase surface area, coverage to the point of drip is key. Mite eggs are most vulnerable just prior to hatching; therefore, true dormant sprays will not be as effective. The value of delayed-dormant oil application (at about half-inch green tissue) aimed at overwintering eggs of European red mite has been proven, based on research done by other Universities. Usually European red mite populations are prevented from building up through May and June because of the delayed-dormant oil spray, although by itself it does not provide season-long control. It does, however, help suppress European red mite populations long enough for predators to become established in the trees.
The pictures below can aid in the identification of overwintered eggs of the European red mite:
Identification tip: Masses of eggs may be laid together.
Identification tip: Masses of eggs may be laid together. Photo: Jack Kelly Clark.
Identification tip: Eggs are slightly flattened, red, and have a small stalk. The stalk is approximately the length of the diameter of the egg, arising from the top, and can be seen with a hand lens. Photo: Jack Kelly Clark.
Some notes on the predatory mite, Amblyseius fallacis: In sprayed orchards this predatory mite generally assumes prominence because it is more tolerant of organophosphate-based spray programs than are many of the other species in the family. Several studies have shown that it was the only predatory mite to remain common in sprayed orchards throughout the year.
Populations of predatory mites (e.g., Amblyseius fallacis) populations can be monitored at the same time growers are scouting for spider mites since they occupy the same habitat. Initial populations in the spring may be assessed by selecting 10 apple leaves from suckers beneath each of 10 randomly selected trees in a block. Examine the surface for Amblyseius moving across the leaf surface. They move faster than pest mites Research conducted in Michigan has yielded tentative thresholds for predicting success of biological control by Amblyseius:
Do you have any suggestions for articles on arthropod IPM? Please let me know!
Contact info: email@example.com; (413) 545-1031 (campus office); (808) 756-2019 (cell).
With a little warm weather and rain predicted for Tuesday evening and Wednesday, conditions are set for the first scab infection. NEWA and SkyBit simply say there will be an infection, while the more nuanced RIMpro forecasts a “moderate” scab infection for Massachusetts. Best to have some fungicide protection on going into the rain, unless you’ve put on copper in the last five days. At this point, mancozeb at 3 lb/A should be sufficient unless scab was an issue last year. If so, mancozeb combinations may be better: either captan, with the usual warning about no captan within 10 days of oil, or Syllit, Vangard or Scala are good options at this time.
Pruning newly planted apple trees -- while on a recent visit with a grower who was planting a bunch of new apple trees, I was being asked for pruning advice, and I had to remember I do have a few rules for pruning these trees. Let me see if I can put them in words:
Pear trees can be pruned similar to apples. Stone fruit are a whole other story! Let me know if you have questions or need advice after planting your trees. Good luck!
With this beautiful weather comes some great news: The bees are back! There are more than 4,000 native pollinators in the United States and it is estimated that ~200 of them live in the Northeast, pollinating our fruit (and other) crops. Many of them are ground nesters! So, when you see holes in the ground like this (below), don’t assume they are ants! These bees are a critical part of the success of our orchards as they are more effective pollinators than the average imported honey bee. They are generally not aggressive, you have to work pretty hard to get one of them to sting you.
Speaking of weather, don’t break out your swimsuits just yet. As Dan mentioned above, we have a decent infection event coming our way, beginning Wednesday morning. This infection event looks like it will last through Thursday’s grey wetness. (Infographic below.)
Bees aren’t the only interesting organisms making their way out of the winter doldrums! Field horsetail’s (Equisetum arvense) reproductive structures are poking up, sending spores out. (Pictured below.) The spores don’t contribute to its spread so much as the underground rhizomes do though, so, try to avoid disruptive cultivation of this plant to minimize its spread. Later in the season, you'll see their fern-like vegetative forms creeping around. These tend to grow in sandy soils, so, you may not have ever seen it inside of your orchard. For other weed management check out last week’s Healthy Fruit.
This week’s Hawkeye Pest Sighting actually comes from Jon! Can you see it? (Pictured below.) Tarnished plant bug is out and about after spending the winter in its adult form in weeds in and around your orchard. Since they are active, now is not the best time to be mowing or otherwise disturbing the weeds around the orchard as it will drive adults out of their current sites, straight into the buds that are finally opening. One more reason to get on top of weed management and stay on top of it!
No guest article this week...
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 1, 2018. In the meantime, feel free to contact any of the UMass Fruit Team if you have any fruit-related production questions.