Notes 071 Mildew. 3^5 



Art. XVIII. Notes on Mildexu, from a Lecture on that Subject hy 

 Professor Lindley, delivered at the Horticultural Society's Meeting 

 Room, on April 24. By J. W. L. 



Dr. Lindley began by stating that he did not intend, on 

 the present occasion, to give a regular series of lectures, as 

 that plan required his hearers to attend the whole course, 

 which very few individuals had leisure to do. He therefore 

 now proposed to take a different subject for every lecture, 

 and to make each complete in itself. His first subject was 

 mildew. 



Every horticulturist has heard of mildew; and, though it is 

 often confounded with blight, honey-dew, &c., the destruc- 

 tive fungi which constitute the veal mildew, and the ravages 

 they occasion, are unfortunately but too familiar to every one 

 accustomed to either a garden or a field. Notwithstanding 

 this, even the most eminent horticulturists know comparatively 

 little either of the nature of this pest, or of its cure. One 

 most important error exists respecting it, and this is, the 

 belief, common among gardeners and agriculturists, that one 

 kind of mildew will infect several kinds of plants: but this 

 can never be the case; each tribe of plants has a mildew 

 peculiar to itself, which cannot, under any circumstances, 

 affect plants of a different kind. 



Mildew generally appears on the leaves or stems of plants 

 in the form of red, white, or black spots, as a number of 

 minute projections, as a frosty incrustation, or as a brownish 

 powder ; in every case spreading, more or less rapidly, ac- 

 cording to its kind, and in its progress withering the leaves, 

 destroying the fruit, and, finally, killing the plant. The 

 popular reasons assigned for this pest are various : it has 

 been ascribed to insects, fog, and even, in one agricultural 

 report, to the inflammation of the oxygen gas in the air 

 towards the end of summer, which scorched the leaves. 

 These opinions have, however, been all proved to be 

 erroneous. Mildew is nothing more than different kinds of 

 fungi, or parasites, attacking different kinds of plants, and 

 varying in appearance and species according to the nature of 

 the plants which they attack. It is the greatest enemy to the 

 agriculturist, but the gardener also suffers from it severely. 



The fungi, commonly called mildew, are divided into three 

 classes : — 1. Those which grow, or rather lie, on the surface 

 of leaves, and which perhaps do not derive any nutriment 

 from the plant ; 2. Those which are formed in the interior of 

 the stem or leaf, and protrude themselves from it when ripe ; 



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