. The principles of agriculture; a text-book for schools and rural societies . Fig. 69. Work of the four-lined leaf-bug—a snckiag insert—on ctirrantfoliage. robbing it of nutriment and sometimes by breaking up its cellularstructure, and by obstructing the breathing-pores and interferingwith the movement of its fluids. 2936. Physiological troubles may be termed internal troublee,although the germs which cause some of them enter from the. SUBSEQCJENT CARE OF THE PLANT 175 outside. There is no external growth of a fungus, and rarely anywell defined small spots on the leaves. Fig. 72 shows the spo
. The principles of agriculture; a text-book for schools and rural societies . Fig. 69. Work of the four-lined leaf-bug—a snckiag insert—on ctirrantfoliage. robbing it of nutriment and sometimes by breaking up its cellularstructure, and by obstructing the breathing-pores and interferingwith the movement of its fluids. 2936. Physiological troubles may be termed internal troublee,although the germs which cause some of them enter from the. SUBSEQCJENT CARE OF THE PLANT 175 outside. There is no external growth of a fungus, and rarely anywell defined small spots on the leaves. Fig. 72 shows the spots ofa fungous disease ; if this leaf had been attacked by a bacterialor physiological disease, the entire leaf would probably haveshown signs of failing, for the food supply is usualh cut off inthe leaf-stalk or the main veins. In Fig. 72, however, each spotrepresents a distinct attack of the 73 is a type of physiologial trouble, theedge of the leaf dying from the cutting-ofl ofits food supply ; this dead border will widenuntil the leaf dies. 294a. Physicians treat some diseases byprophylaxis,—that is, by giving attention tomeans of sanitation and of preventing thespread of the disorder. Farmers must do thesame. Wire-worms are rarely troublesome Fig. 70. The short and quick rotations, particularly in sucking lIlS6Ct those in which sod is not a prominent fea-ture. Club-root of the cabbage i
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
