12-18-86 Agenda & Packet - Laserfiche WebLink

Home Browse Search

MEMO Tlx: Bruce K. Anderson , Director. Parks, Recreation and Forestry FROM: Rick Wriskey, City Forester DATE: December 31, 1985 RE: 1985 End of Year Forestry Summary DUTCH ELM AND OAK WILT DISEASES Slight increases in both Dutch elm and oak wilt diseases were seen in 1985. The total of dead or diseased elms removed was • 137. Of these, 46 or. 34 percent were "Chinese" or "Siberian" elms. Seventy-four ( 74 ) diseased red oaks were removed . This is up from last year' s 49 oaks. The annual rate of loss for elms was 1 . 54 compared to last year' s 1 . 36. This rate of loss, even though increased , remains a strong indicator of a strict sanitation program where any dangerous elm trees and wood are removed as soon as • possible. Loss rates of below 3 percent of the remaining elm population are generally considered acceptable by established • programs with controls. Twenty-two ( 22 ) woodpiles were found to contain viable elm wood (with intack bark) or diseased red oak wood . All were promptly removed by the respective owners. About 33. percent of these originated from trimmings left behind by N.S.P. crews. An appeal to N.S.P. to take such elm wood with them • after trimming will he made before the next trimming cycle. The same firm• was in full compliance of season oak trimming guidelines as of 1985 per a similar agreement. • OTHER TREE DISEASES Heading the list of other miscellaneous tree diseases of orna- mental and shade trees in Mounds View were ash anthracnose and apple scab on flowering crabapples. While it ' is much too early to tell what impact ash anthracnose will have, it could be said that there is a keen interest in it because of the numbers of green ash one finds in a suburb like Mounds View. 1986 should give us a clear indication of what might be in store for us with this disease. Anthracnose ( a fungus) , in general , favors cooler, moist conditions for establishment. The usual minor cases of oak and maple anthr.acnoses, fire- blight bacteria and cedar apple rust were seen in no greater than usual intensities. DAMAGING TREE INSECTS Populations of spring-active, leaf-chewing worms ( cankerworms and loopers) were at low levels again. This was the second • year of noticeable decline and the first time in five years where spot spraying of Bt on newly-planted trees was allowed . Such trees ( less than three years planted) usually were sprayed twice each spring.