MORTALITY IN ROWANS

Press, Volume LXX, Issue 21245, 17 August 1934, Page 12

MORTALITY IN ROWANS

♦ UNIDENTIFIED DISEASE SUDDEN DEATH OF TREES IN CITY AVENUES The sudden death oi many rowan trees in the city's streets and gardens, mentioned in a report presented to the Christchurch City Council by the reserves committee, has mystified several botanical experts, who have endeavoured to assign a cause. Fireblight has been mentioned, but it has been stated after exhaustive tests that fireblight is not the cause. For two years investigations have been made periodically, but no satisfactory explanation of this strange mortality among the splendid rowans has been arrived at. The report made to the City Council said that the greatest number of deaths of trees planted in the city streets occurred among the rowans. No sooner did the rowan reach its full beauty than, for no apparent reason, odd trees died out. "Further, the rowan is a member of the genus Pyrus, and from observations seems to be susceptible to the various ills to which this genus is susceptible. During the last two years trees have died from every indication of the fireblight disease." ] This report was supplemented to ; a certain .extent by Mr M. J. Bar- ] nett, the Superintendent of Parks and Reserves, when speaking to a representative of "The Press" yesterday, Mr Barnett. emphasised a point made by other experts, that the rowan was in any case a short-lived free. But those which had died from the mystifying disease in recent years had not reached anything like full maturity, he said. There was no doubt that the dead trees were diseased. Two or three dozen died every year, and had to be replaced, this meaning that the continuity of the lines of trees in several of the city avenues was beI ing destroyed. The same thing was i occurring in private gardens. It was j not known whether the disease was I contagious, but in some cases two or | three trees growing in line were : found to be infected. The indica- ■ tions of the disease were certainly very similar to fireblight, ! "Not Fireblight" This report was submitted for I comment to Mr B. G. Goodwin, the I orchard instructor attached to the I Department of Agriculture at ' Christchurch. lie said that it had ■ been proved definitely that the I disease attacking the rowans was ' not fireblight. Specimens of the j affected trees had been taken from I the city and sent to Dr. G. H. CunI ningham. the mvcologist at the Plant Research Station at Palmerston ' North. Dr. Cunningham had been . unable to find any trace of the firej blight disease in the specimens. ; There were certainiy indications ■that the trees had died of fireblight. but under tests the specimens had ; shown no sign of the bacillus ■ peculiar to fireblight. I One of the most peculiar manifes- ■ tations of the trouble in the affected ! rowans was that after a tree had : been attacked, in some cases it was ' found that the sap receded from the brandies and bled out through the n.ots in to the soil. The first indication of the infection was the withering of the branch tips. Then in a few weeks the sap ran out so frceiv that the entire tree collapsed. Fireblight usually did not kill the ontiro tree in that fashion, said Mr Goodwin, but attacked a few brandies, although it *• as also sudden in its effect. Dry Summers A botanist suggested as a possible cause of the mortality among the rowans the three dry sum'mers which have been experienced. The extreme scarcitv of moisture had had its effect on'many trees, he said, and in many cases those which m ordinarv circumstances would have lived for another 10 or 20 years had died. He described the reported loss |of sap in the affected trees, if a - cause of death and not an effect. as a remarkable state of affairs. ■ The prevalence of the disease ap- ' oears to have inc.eased in recent : -'ears and is perturbing the owners I of ma'nv private gardens. The rowan lis a much-loved tree, popular all 'over the citv. and greatly admired i !>r its heav'v crop of bright red j i-er'-os Tree lovers are hopeful i i vl , ,|,,. <tran<,'e disease will not j mean the disappearance of some of I ;he fine rowan avenues which now I 'rraee'thc city.