Dutch elm disease spread by beetles
By PAULA MYERS
This is the second of a series of three stories on the Dutch elm disease. Tomorrow's article will describe methods of control.
Once elm trees are infected by the Dutch elm disease, they are doomed—there is no cure.
The Dutch elm disease is one of several vascular wilt diseases attacking elms, all with similar symptoms.
The disease produces a wilting and yellowing or dying of foliage, usually followed immediately by defoliation and death of affected branches.
THE DISEASE USUALLY appears first on one or several branches and then spreads to other portions of the crown.
"By seeing where the most wilting occurs, it is possible to determine where the fungus has entered," said R. W. Lichtwardt, professor of botany. "If the whole tree is affected, then it has entered by the roots. If it is located in certain areas, then the fungus has come from separate branches."
Infected trees commonly die within a few weeks, but some die gradually, branch by branch, over a period of several years.
TREES WHICH ARE infected in the spring or early summer usually die quickly. Those that become diseased in late summer are much less seriously affected and may even recover, unless they are re-infected, according to a statement in a U.S. agricultural bulletin.
When the symptoms appear, pieces of suspected elms are cultured in the Snow Hall laboratories to determine of the Dutch elm disease fungus is present. The fungus also may be isolated from the beetles which spread the disease and the tunnel debris they leave. Presence of beetles in a dying tree is not proof of the disease.
Several culture plates are run for each tree. Chips of suspected trees are placed in the culture of potato dextrose agar. It takes five to seven days for the culture to reveal the fungus.
If symptoms occur in the branches it is necessary to take samples in various areas, especially in the dying areas, Lichtwardt said.
WHEN SAMPLES are cut from the suspected tree, "the fungus can be carried from one tree to another if the cutting and sampling instruments are not sterilized." Lichtwardt says.
The principal carrier of the Dutch elm disease in the United
States is the small European elm-
bark beetle.
The beetles do most of their feeding in the living elms nearest the place they emerged as adults. However, the insect has been found feeding in elm trees more than two miles from the nearest breeding place. Feeding injuries are most numerous in the twig crotches.
For Complete Automobile Insurance Gene Doane Agency 824 Mass. St.
HOW EXTENSIVELY these fungus-carrying beetles infect healthy elm trees depends on such factors as time of feeding and age of twigs they feed upon have an important bearing on any control program.
Spring and early summer feeding is more likely to result in serious effects of the disease than feeding before or after this time.
Not only can the Dutch elm disease be transmitted by the beetle, but it can advance from one affected tree to a healthy one by the roots. This is a great threat to the closely-spaced elms on Jayhawk Boulevard.
THE AGRICULTURAL information bulletin "The Dutch Elm Disease and Its Control." states:
"The only effective means of control for Dutch elm disease is the treatment of healthy trees to prevent them from becoming infected and the prompt destruction of all dead or dying elms, regardless of the actual cause of death."
Co-star
HOLLYWOOD—(UPI)—Joanna Moore will co-star with Dick Van Dyke and Edward G. Robinson in "Never A Dull Moment" for Disney.
Daily Kansan Thursday, May 4, 1967
PAT ARNOLD President of Corbin Hall
Ladybug makes living a whole new experience—in a sleeveless skimmer that's practically wrinkleproof! Visit the Coach House for further inspiration.
Father, daughter make defense movie
12th & Oread
ST. LOUIS — (UPI)—Detective Sgt. Jack Patty and his 13-year-old daughter, Linda, made a police movie together on self-defense. Police have circulated the film to women groups to show
how Linda can send her father into an overhead flip, legs flailing in the air.
Both Linda and her father are competent in judo. When the St. Louis County police department
sought volunteers for a film, Patty and his daughter agreed. In the movie, Linda demonstrates different methods which women may use to ward off would-be muggers or molesters.
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