Pear Rust Gymnosporangium sabinae
Following the articles in the Worcestershire Record numbers 21 and 22, I was interested to read Harry Green and James Wade’s article on page 18 of Worcestershire Record Number 34, in which they requested pictures of pear rust lesions on pear fruit. The evidence is attached! (01, 02 & 03).
Having seen pear rust on pear foliage in numerous private gardens, commercial dessert and perry pear orchards, and on hedgerow pear trees in the west of England and in Wales, I can confirm lesions on the fruit are extremely rare. The single fruit in the photographs of the variety Doyenne du Comice is the only time I have seen it, and yes it was in my garden in Ashton-under-Hill in 2011! Regarding galls on the alternative host, Juniperus spp., these are much more difficult to find and are probably far less widespread than those on pears, probably because there are far more pear trees than junipers.
Although the pear rust spores produced on pear foliage cannot re-infect pears, the disease can establish on the pear wood as a cancerous perennial growth. With some other diseases the normal air-borne transmission can sometimes be by-passed by a systemic infection developing within the plant and manifesting itself on the new foliage each year. I wonder if this may be happening with pear rust?
Green, H. 2007. Pear leaf gall caused by the rust fungus Gymnosporangium sabinae. Worcestershire Record. 21:49
Green, H. 2007. Pear leaf gall caused by the rust fungus Gymnosporangium sabinae. Worcestershire Record. 22:33
Green, H. & Wade, J. 2013. Pear leaf gall Gymnosporangium sabinae on juniper. Worcestershire Record. 34:18
Umpelby, R. 2007. Pear Rust. Worcestershire Record. 22:34.
Pictures 04 & 05 show Pear Leaf Gall on a leaf of Worcester Black Pear renowned for its long-keeping, rock-hard fruit and of course as an emblem of Worcestershire County (the tree) and Cricket Club (three black pears).
01.Pear rust on Comice fruit. Roger Umpelby
02.Pear rust on Comice fruit. Roger Umpelby
03.Pear rust on Comice fruit. Roger Umpelby
04. Pear leaf gall on Worcester Black Pear. Harry Green
05. Pear leaf gall on Worcester Black Pear. Harry Green