Ambrosia Beetle Decline of Apricot and Plum in Michigan Bill Shane SW Michigan Research and Extension Center Benton Harbor, MI Michigan State University shane@msu.edu
Purpose of Talk Share my experiences with this pest Connect with others in the Great Lake Fruit Workers group having expertise in this area Alert others to be on the lookout
In July 2011 visited a commercial stone fruit grower to help with dying plum and apricot trees. Samples were collected in 2011 from 1 to 3 year old plum and apricot trees showing decline symptoms in a SW Michigan commercial orchard. In 2012 additional samples were collected at the same site and two other plum / apricot plantings with similar symptoms
A stem-boring beetle was consistently associated with the declining trees. The beetle was identified as the Black stem borer (Xylosandrus germanus (Coleoptera: Cuculionidae), confirmation provided by Howard Russell, diagnostician at Michigan State University Diagnostic Services. Adult beetle size 2 mm long
July 2011 Toothpick like frass extending from entry hole on plum
Apricot, SW Station 2012 Photo credit: Bill Shane
Toothpaste like ooze from entry hole of apricot Ambrosia Beetle - Shane
Blood colored ooze from entry hole of apricot, cambium tissue was red/brown Ambrosia Beetle - Shane
The foam associated with the disease is due to the occurrence of the fermentative bacteria found within the vascular system known as Zymomonas. Foamy canker of almond
Larvae and pupae of black stem borer beetles Photo credit: Daniel Adam, Office National des Forêts
Black Stem Borer Beetle (Xylosandrus germanus) Introduced into the US from Japan in about 1932 First reported in Michigan in 1980 Reported across the US and in Canada. Reported hosts include: beech, birch, holly, honeylocust, elm, linden, maple, oak, planetree, sweetgum, tulip tree, willow, chestnut, apple, ash, black cherry, black walnut, cedar, dogwood, grape, pear, pecan, pine, plum, poplar, plum, apricot, rhododendron, boxwood, fig, hazelnut, hornbeam. Database & graphics: http://www.barkbeetles.info
Common name Black stem borer Granulate ambrosia beetle Scientific name Xylosandrus germanus Xylosandrus crassiusculus General distribution Mid eastern states to Canada & Pacific northwest Generally in southern but is found in Michigan
Female adults overwinter in galleries or in leaf litter near the base of trees. Research in Tennessee showed that ambrosia beetle attacks began about the time of bud swell. Females bore a tunnel with a brood chamber and one or more branches into the sapwood and sometimes the heartwood. They excavate tunnels in the wood, introduce a fungus and produce a brood. Adults and larvae feed on a symbiotic fungus ( ambrosia ) grown on wood tissue, not on the wood itself. X. germanus averaged 55 days from first tree attack to emergence of the progeny (as adults). Females are the only sex to fly and leave the brood galleries. Males are flightless and remain inside. There may be up to 100 larvae per gallery and usually two generations per year in northern U.S.
Monitoring Flight Activity of Ambrosia Beetles in Ornamental Nurseries with Ethanol-Baited Traps: Influence of Trap Height on Captures Michael Reding, et al. USDA, Wooster, OH 44691 Insecticides providing protection against entry include pyrethroids (permethrin, bifenthrin)
B.C. Weber and J.E. McPherson, Life History of the Ambrosia Beetle Xylosandrus germanus (Coleoptera: Scolytidae). Ann. Entomol. Soc. Am. 76: 455-462 (1983) Ambrosia Beetle - Shane
Summary The black stem borer is causing problems in young (1-3 leaf) apricots and peaches in SW Michigan. This insect has a very wide host range The black stem borer prefers small diameter stems (less than 1 inch in diameter), So far, infestations in SW fruit orchards have been seen in sandy sites. Primary time of adult movement and entry into hosts is during early spring from approximately bud break to 45 days later. The window for protection of newly planted trees will probably be over this primary flight period of the overwintering adults in the spring.