RUST AND MILDEW IS WREAT.

Ashburton Guardian, Volume V, Issue 1465, 25 January 1887, Page 3

RUST AND MILDEW IS WREAT.

The following remarks are ttken from Mr Oar rathers's paper m tho j mrnal of the Royal Agricultural feooiety cf ':"nghn'*:—

"The injury done to the wheat «by the rast and mildew arises from the fuogus appropriating to its own as* the elaborated juces of the wheat. Fungi are plants without tl ejuioes, coloring matter, or choropbyl which exist m oihpr plants, and they are consequently unable to separate the carbon from trie carbonic add gas of tho air — that is, to manufacture plant-food from the raw materials on which plants live They therefore depend on the already prepared food of the plants on which they are parasitic The fu no us m its ruttt>sage takes poseession of the growing plant, and weakens it so far as it appropriates the material which was intended to build "p the growing wheat Bnt, is the wheat at the time of the attack is very active m assimilating food, the rust rarely m j area to any serious e xtent the crop, uoleas m on exceptionally wet acneon, when the abundance cf moißtnre eecures the germination of successive orops of spores A f.w bright Gunny days arrest the progress of the fungus ; and vigorous plants overcome tho nttick without uny real injtuy When, however, the mildew appoarn at a iater Btage m the life of th 6 wheat, tho oonditior.B are entirely changed, The period of active assimilation of food is passed Tne plant has laid up stores cf fo d In various parts of its Btmcture ; .»nd the prooecees of flowering aud fruiting, which use up theee etores, are proceeding The altered starch is being conveyod from the c 'Us, where it was tempo arily located, to its final dosMnaMon m the seed The fungus arretti it iv Its progress, and convers it to ita own use. The whoat is not able to cope with the parasite, as m the earlier stago of its life when .the fungus vtfts present as rust. It cannot utart again the process of assimilating food, ard. consequently, the seed is more or loes imperfectly filled, m propnrtiqn to the time at which the fungui attacks the plant and the extent of the attack.

The story of the fungus suggests impor'ant considerations to the farmer. Firßt, it Is oet tain that the brown npores of the mildew, whioh remain attached tq the straw after harvest, are the means by whith the fungus retains its vitality through the winter. Converting the straw into manure doeß not destroy the spores but rather provides m the spring the conditions fitted for their germination. It may be recommending a eerioria destruction of property to suggest the burning < f mildewed straw, but fire is the only agent which will eff*tnally destroy the apr rep. Then it should b-) n* ed that even the brown winter spore pr; duced hy the mildew will be harmlpßß unlesa ihe sprr a formed at the tips r>f its branches m the spring rest on the leaf of the barberry. The farmer should not pernvt the barberry to have a place m his hedges, or fa plantations on his farm.

Farther, while rast may m itself be Injurious to theorop, it is more dangeroun, as the earlier stage of the mildew, and as the producer of crop after crop of eporef which p oluce mildew. The only checl^ to tbe rust is a bright pun and warm, dry atmosphere. From the history of the fungus it ia mauifeat that at no stage 1b it under our coi trol ; and though, we can take steps which may prevent, at different Btagb«, the unnecessary Increaee of the * pores, we mast be baffled m any attempt to prevent the appearance of the disease, whether m the rust or the niildew stage.