During a recent site inspection it was quite surprising how many plum and damson trees were looking very sickly so Jill decided to do a little bit of research.
She have discovered that many of our trees are suffering with rust fungus of one form or another. The pear trees have European Pear Rust (orange & brown spots on the leaves) and the plums have Plum Rust (small yellow spots on the top of the leaf with tiny brown spots on the underside), both spread rapidly by means of airborne spores. Although most information suggests that fruit is not affected this does not apply if the infestation is severe or if it takes hold early in the season. Fruit may be under developed and fail to ripen or totally inedible.
It is possible to treat with a chemical spray, although on a large tree this may not be practical. Myclobutanil (Systhane) in various forms such as Bio Systhane Fungus Fighter can be applied in July. However, good crop management is probably the best solution. Burn fallen leaves and fruit debris in autumn or take it off site for disposal elsewhere, this will reduce the number of spores laying dormant for the winter. Avoid over application of nitrogen fertilisers, this encourages soft growth which is more susceptible to the fungus. Maintain an open centre to fruit trees to allow good air circulation. As a general rule prune pip fruit trees in winter (apple and pear) and stone fruit in summer (plum and cherry).
Another common disease of fruit trees is Brown Rot; the skin of infected fruit will have a brown appearance with small raised light brown bumps. If fruit is left on the tree it will dry and shrivel completely. There is no chemical treatment available for brown rot. Infected fruit should be removed and destroyed as quickly as possible, do not leave rotting fruit on the ground.
It would seem if blight didn’t get your crops then rust or rot just might ….. Oh the delight of airborne fungus spores. There is much to do in autumn and winter, thank goodness the weeds stop growing for a while!