TDA 140 Winners and Losers in 2010
Tree Damage Alert No 140
30th Sept 2010
Winners and Losers in 2010
A winter that was cold by recent standards followed by a spring that was high in the records for both temperature and dryness must have had an influence on trees?
Early and spring flowering trees and shrubs produced a magnificent display. Does this reflect the winter/spring weather or should the conditions in late summer and autumn 2009 be thanked? The result has been abundant fruit and seed production by many species.
The cold does not appear to have had a seriously adverse effect on any tree species. However, driving through England and southern Scotland revealed many Sycamores showing sparse foliage or even recent dieback. We have had an enquiry from East Anglia about Sycamore trees flushing and then shedding all their leaves. Similar incidents have not been reported from other areas and the cause has not been investigated.
Trees affected by the late spring frost (TDA 138) produced a new flush of growth and by early July appeared comparable with trees of the same species nearby that had not been affected by the frost. However, frost damaged trees have not produced any signs of a lammas flush. Where lammas shoots have developed the new leaves showed quite intense silvering and distortion associated with an attack of Oak Mildew (Erysiphe (Microsphaera) alphitoides).
There appeared a higher than usual incidence of Dutch elm disease particularly on the many sucker shoots of English elm (Ulmus procera). Does this reflect these regrowth shoots have achieved the minimum height at which the beetles use them for maturation feeding?
After significant dieback of Robinia pseudoacacia ‘Frisia’ in south east England
during 2008, and to a lesser extent in the Midlands in 2009 symptoms appear to be largely absent in 2010.
Symptoms of Horse chestnut leaf miner (Cameraria ohridella) appeared slowly, affected trees are now showing very extensive browning of leaves. Trees that produced a lammas flush have not been reported to be showing any symptoms of leaf miner damage on those second flush leaves suggesting that perhaps emerging adults had not mated and laid eggs. We would welcome reports and specimens of leaf mining on lammas leaves.
Trees, shrubs and hedges clothed with webbing in spring caused by caterpillars of Ermine moths (Yponomeuta species) have been locally common, and the effects more spectacular than for many years. While this is unsightly and leads to intensive, and sometimes extensive defoliation of the host plant(s) from our observations this damage has been largely subsumed by new growth.
Finally, Dandelions featured in at least one national tabloid newspaper because of the profusion of flowers? (TDA136). The usual succession of Dandelion flowers did not materialise even in lawns, that this year have not grown and so not needed repeat cutting, and areas of rough herbage alike. Has it been too hot and dry for the spring formed seed to germinate and old plants to thrive?
In some areas, by the end of July, Birch trees were showing browning leaf margins while others were totally browned and defoliated – symptoms of water stress? However, this early sign of the end of the growing season has been followed by a very gentle development of autumn colours.
Derek Patch Arboricultural Advisory and Information Service, Farnham.
This is one of an occasional series of Tree Damage Alerts produced for the benefit of the arboricultural profession and issued by the Arboricultural Advisory and Information Service.
AAIS Alice Holt Lodge Wrecclesham Farnham Surrey GU10 4LH
Call the Tree Helpline on: 09065 161147
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