SMUT IN WHEAT.

Dunstan Times, Issue 1064, 15 September 1882, Page 4

SMUT IN WHEAT.

The crop of t his v or proinis s well, -mid at the present i-ime, w v ' -h is the '•most critical period of its growth, a -■ntudv of the habits of the plant, its 'Ynode of growli, and the n tore of the "diseases with wide • it has to oontmd >«i v be made with advantage. The most serious enemy of the wheat plant the present season is smut, a'-d hj • -attacks of the parasite may he rea ily •observed at present. "Now the wheat ■ around u i* in nil b'o >m, and those ■ days of fine, hot, sunny weather which have come in the nick of time will go : a long way towards effecting the salvation of the crop, for the polen dust ■ which emerges from the longitudinal -silts of the anther lobes as thev hang bv their delicate filaments outside the ‘■florets will not Vie drenched with rain, rand so get clogged with mois'ipe, but ' will be c -rried by the gentle winds on to the feathery styles of other florets, -and so effect the useful and essen ial ■o' jects of their existence—namely, ler'tUisation. The embryo of the next "year’s plant will then form in the ovu’e. as the result, of fertilisation, and the ovule its* If will commence to -run into seed, with the commencement -of which process the wheat plant’s dependence upon the soil virtually ceases, for henceforward the chemical pro- ■ cesses within the plant will be almost -exclusively confined to the transfer of the nutrient matters in the stem and leaves up to the young seeds, which in brief time should, under normal circumstances, develop into the plump and ripened “ berry,”-or grain. This is as it should be, but a walk amongst • our wheat just now leads to lesnlts ■ suggestive of amatenr ehimney-sweep-ing. particularly if inquisitive fingers • handte the cars pretty freely. To .-.peak "more plainly, the wheats this season appear io labour nndera heavier’attack • of smut than usual, and the very pre-'-va’ense of the evil, black dusty fungus ■rat. present raises in the mind the uncpleasaut reflection as to how extremely "dangerous and destructive this parasite might conceivably become. The sorry sight, of smutted ears of corn is too familiar to require description. Before writing we sprinkled a little wheat smut on a glass slide, added a ■ drop of water laid unon the mixture a thin cover glass, and examined the preparation under a very high power of the microscope. It revealed to us a number of minute cells, spherical in shape and brownish in colour—nothing more. The dust from smutted • ears of barley gave the same appear- -- ance, with *iio cells a trifle smaller, these little stinatures are the spores of the fungus, and they are so extremely small that it would take i-eany • eight millions of them to occupy one square inch of tnrface, so what they Mack in size is abundantly compensa ed for in numbers. Every one of these • graunels is a new c nitre of infection ; • each is capable of germinating, of • c irrying on its own growth at the exi pease of the elabo ated materials alrrendv piesent in plants which work, vas it were, for their own living, and eventually of producing myriads of ■such spores as itself originally came ifrom Without going into the details ot the life history of smut, in so far as the meritorious labours of eminent botanists have made us familiar therewith we may neverthele-s briefly sum -up-what is known. The snores are introduced wit hj the seed ; of this there ■ appears to he no reasonable doubt. 'Theyaieso excessively minute that •..dozens of them might exist, merely in the irregularities of surface ot a grai < •of wheat without detection. The seed ■may be, and usually is, pcifectly sound for these spores only adhere to it meichanically, having, in a'l probability. ■ dropped on to the ripening grain of a sound ear from an adjacent smutted ■ ear which has undergone utter destruction. When the grain germinates the spore germinates likewise; the • jour.g seedling sends its rootlets into the soil, and its stem into the air in search of food, while the snore, in pur suance of the same laudable object, sends its thread like tubes, known as the mveeliuns (from my his. a moul I), 'into the, young plant, and so tiny ■ grow on together, the wheat nourishing and harbouring the fungal pest •■which lives on its nutrient juices, and and which in the fu'ness of time will utterly destroy its host. As the wheat-plant grows higher and higher, so do ‘he mycelial tubes of the fungus • carry their virulent contents more and ■more intimately into the tissues of the -doomed cereal,and when vertical growth • of the latter is terminated by the deivelovemcnt of the ear, it is that the ' true character of the insidious pest betrays itself. It, has so sapped the vital energies of its victim that the ‘feebleness which hj, as it were, the harbinger of death, seems to warm the fungus that it, likewise, must prepare ribr a speedy' dissolution. When the devoted plant has given to its rapacious foe all that there was to give, then the fungus does something particu'arly characteristic of a fungus ; its own oppor unities for doing mischief are over, but it prepares a crop of spores, millions in number, everyone of which is capable of repentin ' what its parent has done before. These spores are prepared in the ear, and their formation involves the consumption of all nutrition iii the ear, till, by-and-ly, nothing but a thin layer of epidermis is left. This, too. is consumed, longitudinal fissures appear in it, and in a oW hours’ time the spores in all their ilaekriPKß aie exposed to view along &*e entire ear. Gradually the wind

scatters them, and a bare white axis on tlm tnj) of (he straw ia th ■ only indication left of what might have been. From the very nature Vf the case, smut is an inouraldo disea e. When once established it, is as impossible to nrevent the progress of smut as to stop the wind from blowing. But it it is preventible, and we ive inclined to think that it ia clue entirely to the precautions which have.fir years past, been observed ii.y c ireful farmers in their treatment of s*-ed before sowing that the disease is not far more prevalent. If smut spores exist, and tli y do exist, on seed corn, they can never he lemoved by mechanical agencies The only cure is that of extermination, of utter destruction, and chemical agencies can alone effect this for ns The operation of pick ing seed corn before sowing, is, therefore, quite rational. A solution of sulphate of copper, better known as blue-stone, or vitroil, has long been used for this purpose. The de'icate wall of the spores allows the liquid to percolat - through and poison the protoplasmic contents, result! g in the death of th latter. Another method is to wn-h the seed in a strong solution of than bei’s salts, and afterwards, before the seed ia dry, to apiinklf quicklime over it. A chemical re-action between the lim- and the sulphate of soda in the Glauber’s salts results in the formation of caustic soda, which is fatal to the germination of the spores. It is objected that too strong a solution of sulphate will injure the grain ms well as the spores, but only the weaker grains are likely to suffer, and this is hardly a disadvantage. So far as we know, this dressing of seed-corn has, all along I een the only obstacle to the greater devastation among cereal crops by smut, and the lesson pointed nut is clearly that the dressing should be thoroughly and carefully performed so that every individual grain may get well moistened It is an opera tion not to be left in the hands of the men, and it is of quite sufficient moment to merit the personal supervision of the farmer himself. In dressing corn for the destruction of smut spores, we, at the same time destroy the spores of bunt. This latter lias a history very similar to smut ; but it is, on the whole les- common, and appeal's later in the history of the crop. It does not rupture the epidermis, but fills up the interior of the grain, the substance of which it replaces by a blackish greasy mass of spores, with an odour st ongly suggestive of nutiid fish. It is a more serious enemy' than smut, for smut makes a e'ean jo > of its work, and leaves no injurious traces behind, whereas hunt, deteriorates a sample very considerably, inasmuch as many partially bunted grains may he present, and the odour causes the miller to refuse to have anything co do with it. Such bunted corn sooner or later finds its way into the feeding trough.— Nation.