Last year I noticed masses of orange-coloured blobs on two large juniper shrubs in my garden. The shrubs seemed to be unaffected. This year I noticed in May that several of the leaves of hawthorn in my garden hedge were displaying yellow spots. Many leaves have since turned brown and died. Some of the twigs have brown, shriveled leaves, but also healthy green leaves. The reverse of the yellow spotted leaves have short spiky dry growths (which may be the shriveled remains of the jelly growths of the juniper). The problem occurs to the hawthorn close to the offending juniper. I found your article, 'Rust Diseases of Hawthorn' by Thomas R. Martin et. al., on the internet and as a consequence have removed the juniper shrubs. My garden lies on the boundary of common land, which is covered by trees, primarily oak, ash, blackthorn and hawthorn, and is also bounded by field hedges containing hawthorn. Your article lists chemical treatments, which should be applied in the spring. It is now too late to apply these and the junipers have been removed. Should I spray surrounding hawthorn nevertheless? There are fewer juniper than hawthorn in the area so it would therefore be easier to spray the juniper. Would this be successful? For what distance can this rust infection spread? I have been trying, unsuccessfully, to locate supplies of those chemicals listed in your technical report. Could you tell me how, if necessary, to obtain them?
On the positive side, rust on hawthorns is rarely associated with tree death. The article you refer to was written by my colleague who is based is the U.S. The problem we face is that there are no conventional synthetic fungicides that have approval for rust control in the UK. However, you may wish to visit your local garden centre. There may be one or two garden centre products (Fungus Fighter, Systhane) that have applicability. If so, you will need to spray every 7 to 10 days for any form of control. The other key to rust control is promotion of tree vitality by mulching, irrigation, and fertilisation. Make an appointment today for a free evaluation.
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