DISEASE IN ROWAN TREES

Press, Volume LXX, Issue 21247, 20 August 1934, Page 9

DISEASE IN ROWAN TREES

TO TUB IDITOIt OF THE rCRS3. Sir,—ln "The Press" to-day is a report on flie Rowan trees about Christchurch, which Mr Cunningham and Mr Goodwin state is not tirebliglit. in sectional volume No. J, Ministry of Agriculture, is a photograph showing DieBack disease, caused by the lungus (Cytaspora Lencastoma or other species >. Many varieties of fruit trees in almost every part of the world are subject to a disease characterised ch icily by a dying back of the branches. This disease is caused by a lungus named Cylaspora. Plums, peaches, apricots, apples, and cherries • both wild and cultivated) have all been found to be attacked by various species of this fungus. The dying back, which may extend to the larg.; branches, and even cause the death of entire trees, is common to them all, but as the 'symptoms vary somewhat, a brief description of the disease as it occurs on the different kinds of trees is given below. With plums, young, vigorous-grow-ing trees suffer more often than older ones. The first sign of disease is a withering of the leaves, often of a single branch. At the same lime, areas of bark, which may be on the main shoot or on a side branch, collapse and turn brown and the shoot or branch attacked commences to die back. The dying bark does not as a rule confine itself to the younger branches, but extends downwards and gradually involves the largest branches and the trunk. It may then endanger the life of the tree. After a branch or main stem has been dead some time, the fungus produce."! its fruitifications, which can be recognised externally as pimples or minute pustular swellings in the bark. The fruit bodies themselves, which are fount! within these pustules, soon rupture the bark horizontally, and are seen on the surface as more or less elliptical, flattened bodies, white in colour, and perforated by one or more pores, which appear as black dots, minute spores, which readily spread. The disease is produced from pustules in great abundance. This is copied from notes by Dr. H. Wornall, South-East-ern College, Wye, Kent. About 12 or 14 years ago my 10 Coe's Golden Drop plums all took this disease. I did not know at that time what the disease was, nor could I find out in the Dominion. I cut fhe tips of the shoots down to good wood off nine of the trt»es\ One tree I left, to see what would happen. Well, I still have the nine, but the tenth one died right out, roots and all. The Rowan trees are affected with DieBack. Those trees should be watched and every • bit of diseased wood cut back to healthy wdod, and every scrap of the wood cut off should be gathered up and Dr. H, Wormald was the greatest authority on DieBack diseases, and he saw the only cure was to cut the diseased stuff off and burn it.—Yours, etc., GEORGE LEE. August 17, 1031.