MONOCULTURE ISSUES A CASE STUDY OF ELM YELLOWS ON THE PENN STATE UNIVERSITY MAIN CAMPUS.
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Transcript of MONOCULTURE ISSUES A CASE STUDY OF ELM YELLOWS ON THE PENN STATE UNIVERSITY MAIN CAMPUS.
MONOCULTURE MONOCULTURE ISSUESISSUES
A CASE STUDY OF ELM A CASE STUDY OF ELM YELLOWS ON THE PENN YELLOWS ON THE PENN STATE UNIVERSITY MAIN STATE UNIVERSITY MAIN CAMPUSCAMPUS
Elm Yellows
Previously known as Elm Phloem Necrosis The disease is caused by a phytoplasm Vectored by White-banded elm leafhopper
Elm Yellows Phytoplasm
Causes a systemic infection of the phloem sieve cells
Inoculation occurs in the small twigs and is translocated throughout the elm tree into the root system
Kills fine rootlets
Susceptible to Elm YellowsSusceptible to Elm Yellows(5 North American Elms)(5 North American Elms)
American / White Elm (American / White Elm (Ulmus americanaUlmus americana)) Slippery / Red Elm (Slippery / Red Elm (U. rubraU. rubra) ) Winged Elm (Winged Elm (U. alataU. alata)) September Elm (September Elm (U. serotinaU. serotina)) Cedar Elm (Cedar Elm (U. crassifoliaU. crassifolia)) Chinese Elm (Chinese Elm (U. parvifolia)U. parvifolia)
European and Asian elms growing in affected areas may escape disease(but are susceptible when inoculated artificially….possibly a feeding preference for the vector)
Dutch elm disease resistant American elms are not resistant to elm yellows
Elm Yellows Characteristics
Spectacular regional flare-ups Trees that show symptoms in late August
may survive the winter, but will die the following summer
Infected trees will never recover – there is no known cure
Symptoms
Rapid yellowing of foliage in mid-July to mid-Sept (with bright yellow leaves)
Downward bending of the leaf petioles – “Petiole Wilt”
Highly susceptible elms decline and die quickly, often within a few weeks; death usually occurs in the same year as the infection (3 - 10 mo. incubation period)
RemediesRemedies
Be aware of the disease/pest Be aware of the disease/pest potential of your area.potential of your area.
Communicate with your peers.Communicate with your peers. Hope for the best, prepare for the Hope for the best, prepare for the
worst.worst. Act decisively.Act decisively.
Diversify species selection within Diversify species selection within your urban forest. Begin this NOW, your urban forest. Begin this NOW, don’t wait until it becomes the issue.don’t wait until it becomes the issue.
Prepare government officials before Prepare government officials before situation becomes epidemic.situation becomes epidemic.
Seek out funding alternatives.Seek out funding alternatives. Be ready to act.Be ready to act.
Do you know this guy?Do you know this guy?EAB is on the move and threatens all native Ash treesEAB is on the move and threatens all native Ash trees
How about this one?How about this one?Gypsy moth caterpillars can completely defoliate a forest Gypsy moth caterpillars can completely defoliate a forest within days. Affected areas have full time program within days. Affected areas have full time program coordinators to combat this pest.coordinators to combat this pest.