On the Rust or Mildew. 69 



tfrcle, and the use of Dutch ashes, impregnated with saline matter as 

 a manure, tend greatly to that exemption from rust, by which wheat 

 in Flanders is distinguished. Potatoes, when the crop i$ large, have 

 sometimes had the same effect. A field was sown with wheat, part- 

 ly after summer fallow, partly after clover ley, and partly after pota- 

 toes; the two former portions were found rusted, whereas the part 

 where the potatoes had been sown, produced grain, plump and equal, 

 and only deficient about one-tenth of the usual quantity. Wheat, after 

 a thin crop of potatoes, is, however, often rusted in this country; but 

 in Flanders, where the wheat is never materially injured by rust, po- 

 tatoes are considered, in its highest cultivated district, (the Pays de 

 Waes), as the best preparation for that crop. If too much dung oc- 

 casion the propagation of fungi, which there is reason to believe is 

 the case, smothering crops, by exhausting and diminishing the strength 

 of dung, may take away that tendency. 



9. Mr Clack, the respectable Hector of Milton in Devonshire, 

 whose communication on the subject of rust is one of the most valua- 

 ble hitherto published, strongly recommends the cutting down all 

 those plants which retain the fungi, in their various stages, even dur- 

 ing the severest frosts of winter, and which, on the return of a little 

 mild or humid weather in spring, are thought to contribute to affect, 

 with an astonishing rapidity, the earliest leaves and shoots of those 

 vegetables, which are congenial to their propagation. These fungi 

 flourish with such an extraordinary luxuriance, that in the course of a 

 week or two, they seem to arrive at maturity, and disseminate their 

 baneful effects throughout thousands of acres, on which depend the 

 profit of the husbandman, and a large proportion of the sustenance of 

 the community *. 



Among the common plants, the colts-foot, the corn marigold, and 

 the common couch, are said to he so favourable to the growth of 

 these fungi, that no field can be free from rust, in which they are to 

 be met with. Every exertion ought therefore to be made, for their 

 total extirpation. 



Some evergreens seem to retain these fungi, during the coldest 

 seasons, as the box, when planted in low and damp situations, and 

 above all, the bramble-bush, which ought to be cut down as close as 

 possible, in hedges and coppices, at least once or twice a year. The 

 abele, or silver poplar, and willows, ought likewise to be kept under, 

 as some of the chief causes of rust in their neighbourhood. 



Several trees also, retain old fungi during winter, on their barks, as 

 the black alder, the common willow, the hazel, the birch, and some- 

 times oak coppice. The barberry retains this source of mischief, in 

 any fissure or cleft in the bark occasioned by injury, exhibiting nu- 

 merous black pustules. These should be cut out. The contradic- 

 tory accounts regarding the effects of the barberry-bush, in occasion- 

 ing rust, may thus be explained. Where the skin is smooth and en- 

 tire, the barberry does little or no mischief; where there are fissures 



Devon Report, p. 45G. 



9 



