Black Stem Borer: Old Pest, But New Problem For New York Apple Growers [Slideshow]

The black stem borer (BSB) is not a new pest in the U.S. however, we first detected black stem borer in 2013 in six sites in the Lake Ontario fruit region of New York, and have identified at least eight more sites this year. These beetles have killed large numbers of apple trees in western New York.

The BSB was introduced from Eastern Asia and first detected in New York in 1932. It has since been detected in most parts of the U.S. It is a general wood boring insect, in the group called Ambrosia beetles, with a huge list of suitable hosts including American beech, maple, dogwood, black walnut, oak, magnolia, and several other ornamental and forest species. It was also documented in apple and sweet cherry in 1982.

How They Infest Trees
The tiny black beetles overwinter in galleries at the base of infested trees. The first beetles emerge from overwintering sites to infest new sites after two to three days with temperatures of at least 68°F. This means they can first become active in early-late April. One study cited the first activity within four days after first bloom on Norway maple, and full bloom on border Forsythia.

The second generation is expected to start in late July or early August based on literature from Ohio, but our traps continue to capture adult beetles in early July.

Only females fly and emerge in spring to colonize new hosts. The adult female drills a hole approximately 1 millimeter in diameter, and hollows out a channel into the heartwood of small trees. The female tunnels into the sapwood of a small tree (2 to 50 centimeters diameter) and starts to culture a fungal food source, Ambrosiella hartigii. She lays her eggs (tiny, 1 millimeter, white, football-shaped) in the chamber. She lines the chambers with the Ambrosia fungus for the larvae, (also white, with three instars) to feed on before they pupate to develop as an adult.

It is this fungus that the larvae will feed on in the brood chambers, not the tree. It takes about 30 days for development from egg to adult. The ratio of females to males is about 10 to 1. The females can lay 2 to 54 eggs, depending on the host, but they average about 18.

Although the biology of this insect is not fully understood, we believe it has two generations per year in New York. Late in the summer, the beetles will migrate to a hole lower in the trunk to overwinter where researchers have found as many as 100 in a chamber. The beetles go into diapause in the summer and will not be active again until the next spring.

What Growers Need To Know
So far orchards where BSB has been detected are tall spindle or super spindle plantings in areas of wet soil conditions, or where no irrigation is available. Although these borers have a reputation of attacking stressed trees that are giving off ethanol volatiles, they also have been reported to attack apparently healthy trees. In the spring the trees look like they are weaker than uninfested trees and with some flakey bark. However, some look perfectly healthy. Other infested trees ooze sap or have fire blight oozing from the entry holes.

If the weather is calm and dry, growers might be lucky enough to see the “toothpick” frass pushed out of the holes. Upon close inspection, growers might find small pin pricks (1 millimeter in diameter), and the tiny black beetle in the hole. Using loppers or a pruning saw, growers can cut 1/8 to 1/4 inch from the hole to see the galleries that extend perpendicular to the trunk of the tree and are hollowed out a bit vertically to accommodate the brood of eggs; additional channels may be cut into the pith of the tree.

Although several chemical and biological controls have been tested, researchers have not yet identified anything that will stop these beetles. With a very wet spring or fall and poor soil drainage, you might see more damage the following season. The fungus the beetles carry with them can kill the trees as well and does not seem to be dependent on any particular weather condition.

What To Do If You Detect BSB
If growers identify black stem borer in their high density orchards, the recommendation (in ornamental nursery situations) is to rogue the infested trees (taking the rootstock as well), and take them to a location where they can be burned immediately. The grower might start a trapping program using ethanol-baited traps, checking them weekly.

A second trapping method we might be able to use for trap cropping is to adopt the system used by USDA — 12-inch beech loglets (1 inch in diameter) soaked in 15% ethanol for three days and deployed outside of the orchards as super-attractive targets — to time insecticides for when the beetles emerge from the galleries to find a new place.

As we looked in orchards where this problem was extensive last year, many trees showed crisp, blistered bark. We marked the trees and expected them to collapse the next spring. But to our surprise, many of the trees were still healthy — green trees with no sign of collapse.

It seems if we can find an effective control tactic to prevent continuous infestation of the trees in your high density plantings, tree removal may become unnecessary.

Control Methods
The ornamental nursery industry, where this is a serious pest, relies on pyrethroids on a two-week schedule which would certainly be a challenge in apples with concerns over how it would impact mite control. The nursery industry has also tested neonicotinoids, anthranilic diamides (cyazypyr, acelepryn), and tolfenpyrad and has not found them to be effective in controlling BSB.

We have nothing registered specifically for control of this pest except for Syngenta’s Warrior II or Winfield Solution’s Grizzly Z, lambda-cyhalothrin, labeled for tree borer species, but we have no experience or efficacy data to make any recommendations at this time. It is also expected that chlorpyrifos trunk sprays for borers may be effective, but will not prevent higher points of entry which have been seen as high as 4 feet in the tree.

We — along with Kerik Cox — are working on this pest to better understand the biology and identify viable controls. We are also trying to document economic damage for this pest so this issue can get more attention for research.

Topics: , , ,

Leave a Reply

Apples & Pears Stories
KIKU space featured image
Apples & Pears
April 13, 2016
‘Kiku’ Apples Are Out Of This World — Literally
Apples from Washington State among the supplies sent to astronauts in the space station. Read More
Fly Creek Cider Mill
Apples & Pears
April 11, 2016
Orchard Picked As Stop For Presidential Primary Coverage Broadcast Site
Recently renovated Fly Creek Cider Mill & Orchard to host live NBC broadcasts on Thursday and Friday. Read More
Photo credit: USDA
Apples & Pears
April 9, 2016
Sliced Apples Recalled
Red apple slices sold separately and in lots with sliced vegetables could contain Listeria Monocytogenes. Read More
GP Sazo Temp Chart
Apples & Pears
April 7, 2016
Apple Growers Need To Be Cautious About Frost Treatment
Always follow the instructions on the product’s label. Read More
Photo credit: Wikimedia commons
Apples & Pears
April 6, 2016
Risk Of Apple Scab Is High Despite Cold Temperatures
Researchers say snow does not kill spores, but it does complicate spraying copper and other products. Read More
Ambrosia Apple for featured image
Apples & Pears
April 6, 2016
‘Ambrosia’ Apple Takes Tournament
Variety claimed the top spot in U.S. Apple Association’s first-ever “Apple Madness” tournament. Read More
‘Franklin’ cider apples hang on the original tree in Franklin, VT. (Photo credit: Bill Mayo)
Apples & Pears
March 30, 2016
Chance Seedling Nets New Bittersharp Apple
Vermont apple grower finds tree in orchard, discovers it has unique profile which makes it a good addition to sweet and hard cider blends. Read More
The Latest
Apples & Pears
April 28, 2016
Cracks In Your Orchard’s Infrastructure …
Modern blocks can increase your production, but if your training system is shoddy, you could see major losses. Read More
Apples & Pears
April 28, 2016
The Truth About Most Farmworkers [Opinio…
Just ask any grower who has placed a help wanted ad. Read More
Apples & Pears
April 26, 2016
Comment Period Extended For EU Imports O…
USDA APHIS is extending the comment period on the proposed rule that would amend the regulations to allow the importation Read More
Apples & Pears
April 13, 2016
‘Kiku’ Apples Are Out Of This World — Li…
Apples from Washington State among the supplies sent to astronauts in the space station. Read More
Apples & Pears
April 11, 2016
Orchard Picked As Stop For Presidential …
Recently renovated Fly Creek Cider Mill & Orchard to host live NBC broadcasts on Thursday and Friday. Read More
Apples & Pears
April 9, 2016
Sliced Apples Recalled
Red apple slices sold separately and in lots with sliced vegetables could contain Listeria Monocytogenes. Read More
Apples & Pears
April 7, 2016
Apple Growers Need To Be Cautious About …
Always follow the instructions on the product’s label. Read More
Apples & Pears
April 6, 2016
Risk Of Apple Scab Is High Despite Cold …
Researchers say snow does not kill spores, but it does complicate spraying copper and other products. Read More
Apples & Pears
April 6, 2016
‘Ambrosia’ Apple Takes Tournament
Variety claimed the top spot in U.S. Apple Association’s first-ever “Apple Madness” tournament. Read More
Apples & Pears
March 30, 2016
Chance Seedling Nets New Bittersharp App…
Vermont apple grower finds tree in orchard, discovers it has unique profile which makes it a good addition to sweet and hard cider blends. Read More
Apples & Pears
March 26, 2016
Millennials Drive Premium Apple Demand
Consumer trends are among the topics at the annual AgroFresh “Crunch Academy.” Read More
Apples & Pears
March 16, 2016
New York Apple Leaders Contribute To Foo…
New York Apple Association, Inc. contributes $55,000 to Center For Produce Safety. Read More
Apples & Pears
March 9, 2016
International Fruit Tree Association Ann…
Industry members recognized at annual conference banquet. Read More
Apples & Pears
March 9, 2016
Pears Certified Heart-Healthy
American Heart Association classifies pome fruit as a good choice for heart health. Read More
Apples & Pears
March 9, 2016
Apple Varieties Tip Off For First-Ever N…
U.S. Apple Association’s March “Apple Madness” bracket tournament encourages people to select their favorite apple variety, discover fresh health research. Read More
Apples & Pears
February 29, 2016
An International Release Is Good News Fo…
A new partnership between Midwest Apple Improvement Association and International Pome Fruit Alliance will get the ‘EverCrisp’ apple international exposure. Read More
Apples & Pears
February 24, 2016
Learn About The Hard Cider-Making Proces…
Workshop offered by Penn State University highlights production of hard cider beverage. Read More
Apples & Pears
February 23, 2016
Dock Slowdowns Last Year Cost Washington…
New report prepared for Washington Council on International Trade says late shipments, etc. hurt the state, including growers. Read More
[gravityform id="62" title="false" description="false"]