Monday, September 27, 2010

Sallow Mildew

Photograph of a sallow spray affected by Sallow Mildew Uncinula adunca var regularis on what would otherwise have been a suitable branch (female tree of the Salix caprea type with leaves of mid-green colour, medium thickness, and a matt surface. The galls are no problem; indeed, iris eggs seem to mimic them). In several hundred hours (don't ask...) of searching I have yet to find a larva on a branch bearing anything more than the odd spot of this mildew, despite the fact that the mildew is quite common at this time of year on the shady sallows iris favours. This is remarkable, as it suggests that the females select sallows that are not going to be affected before the mildew actually starts to appear (usually from late August). Clever girls indeed... .

I have nearly finished searching the trees searched last year in Wiltshire, and it looks as if the 2010 egg lay was about 1/3rd of that of 09. More anon.

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