116 CULTURE OF FARM CROPS. 



the plots excite in one. From the moment the seeds appear 

 above ground the interest increases daily; and it will be 

 strange indeed if the experimenter does not find himself 

 making numerous and oft -repeated visits to the plots to 

 watch and record the progress of the plants which they 

 bear. We have little to say of the measures to be taken, 

 or which can be taken, to prevent the ravages of the rust 

 fungus (uredo rubigo and uredo linearis) and the mildew 

 fungus (puccinia graminis). The spores of these fungi do 

 not it is understood enter the plants which they infect 

 by the roots, but by the more minute pores in the stems 

 and leaves which botanists call stomata. The point is, 

 however, doubtful ; but as the " fungi at first make their 

 appearance in little cavities seated immediately beneath 

 these pores, it certainly looks very much as if the sporules 

 entered there. The stomata are naturally exhaling organs, 

 continually discharging, under the influence of light, a large 

 proportion of the water which they imbibe by the root. But 

 in moist weather the function is impeded, if in some cases 

 it J)e not actually reversed, when it would be easy for the 

 sporules to enter these invisible stomata with the moisture 

 imbibed by them." Excessive manuring, and especially 

 manuring directly for the wheat, is pretty well understood 

 to be the cause of mildew and rust ; and Mr. Knight states 

 distinctly that mildew is induced by foggy weather. Hence 

 the benefit of the practice followed by some of growing early 

 varieties so as to have the crops off the ground before the 

 autumnal fogs set in. It is also fairly established that 

 wheat grown in light soils is more liable to mildew than 

 wheat grown in heavy soils; and that spring wheats are 

 less liable to the attacks than winter wheat. " Amongst 

 the antidotes to mildew," says the Eev. E. Sidney, " I ven- 

 ture to name clean farming, amendment of the texture of 

 the soil, ventilation and letting in light, checking over- 

 luxuriance in the young plants, growing early varieties in 

 places subject to it, and avoiding putting on manure di- 

 rectly before wheat, and howing the wheat when young." 

 In a word, whatever tends to make the plants become sickly 



