RUST IN WHEAT.

Patea Mail, Volume IV, Issue 312, 13 April 1878, Page 4

RUST IN WHEAT.

(From the Canterbury Times.') Ajicsct ail the diseases to which the wheal crop is liable, there is perhaps norm move sweeping in its effects than that of re,! rust. It is a disease which attacks the crop at the eleventh hoar, and generally the most nourishing crops, dashing the farmer’s hopes to the ground just when they look the brightest, llust seems to exist wherever wheat is grown, oftentimes making its appearance in eouutrjes and localities where, the climatic conditions might bo thought least favourable to its production. Neither extreme heat, nor the sharpest frost serve as a protection against it. Wheat growers in South Australia, probably the warmest and driest climate in the world in which wheat is grown, and vmv«-t-growers In the coldest parts of Canterbury are both liable to suffer from the ravages of rust. The loss from this cause has been so serious in South Australia that last December the Committee of the Agricultural Society of that Colony issued circulars to farmers in various parts of the country, with the object of detaining information as totiio cause ana possible means of preventing rust in wheat. These efforts, however, (!o not appear to have drawn forth any fads of much importance that wore not known before. It has always been known that crops of a rank, soft growth are the most liable to be attacked. When the vegetable matter in the soil is in excess, and the mineral substances deficient, a rapid flaggy growth is induced, and the plants fall to take up a due proportion of silicious matter. The want of a proper quantity of silica renders the surface of the straw soft and porous, and so capable of absorbing moisture, whereas when the mineral substances have been assimilated by the plants in due proportion, the. surface of the straw is smooth and flinty, , and the straw is, as it were, provided wi th a covering which serves the dual purpose of protecting it from the bad eff.-ats of moisture, and lidding the crop linn cud n prig hi, and So allowing the free access of the atmosphere in damp weather. booth Australian farmers find that laud heavily manured by sheep is much given to rust, and that old la no. riict-ts laud which has been long in cuUivaucii. is least liable toil. -Both those M.e easily understood. In the one c.s :> repui giowur lojs taseu- puaco through t. ,j action or a siimahtiiug mcvuir. v.'Lti in dig other the humus has ocuu heal liy drawn upon, and the .mineral ingredients, which are not, as a

rule, so soon exhausted, still exist in a sufficient quantity. The crop in the latter instance, it is almost needless to observe, would be thin, and the straw small and stiff. Some of the kinds of wheat are more suoject to rust than others. South Australian reports show that the Tuscan, the red purple, the old red straw, and the common purple straw, suffered the least from rust during the last season, and that the Goldsmith variety was in most cases badly affected with the disease. Two of these varieties —at least, the Tuscan and the purple straw —are familiar to our farmers, but we doubt whether the experience of Canterbury farmers bears out the opinion of those in South Australia as to the purple straw wheat not being liable to rust. This variety of wheat was brought here from Adelaide some eight years ago, and during that time has undergone some modifications through the influence climate and a richer soil. Although the straw still retains much of the brittle nature which characterised it when first introduced here, the purple straw wheat has at different times been known to be severely-affected by rust. The opinions of South Australian farmers according to the reports, are somewhat conflicting as to whether early or late sown crops are most liable to be attacked. It is said by some that early sown crops ripen before the period at which the disease is most prevalent. This opinion would, we think, bo borne out by at least nine Canterbury farmers out of every ten. Late on in the harvest, as the days shorten, the sun loses much of its power, and the nights grow 'cold and dewy, so that the. outer coating of the straw being kept in a more continual state of dampness, falls an easy prey to the dis -ase. Tjie state of the atmosphere during the ripening season and the nature of the surface soil are probably the chief sources whence the rust springs, but there can be little doubt that the condition of the subsoil must be taken into consideration. Klippart, and American agricultural writer of more than ordinary ability, remarks that “ In regions where a gravelly subsoil is found the wheat crop seldom suffers from rust, but the wheat is frequently rusted upon gravelly soils which rest upon hard pan or impervious clays. Rust or mildew also most frequently attacks wheat on bottom lands, where considerable ' moisture prevails. In all our reading and observations, we have never heard nor seen a well underdrained field of wheat attacked by rust, and therefore infer that drainage acts as a preventative of this very undesirable phenomenon.” Our own experience also bears oat these remarks to a certain extent. We have known wheat to he very badly rusted when grown in a stony soil, resting on an impervious clay bottom, and have also seen rust in its most, destructive form, on strong clay land, lying very wet and sloppy during the winter. But on the other hand, we have known wheat crops to-be totally destroyed on dry open land, with a moderate growth of straw. On damp land, or on land with an impervious clay subsoil, underdraining would, as Klippart affirms, have a powerful tendency to lessen the danger from rust. Deep drainage tends to keep the subsoil free and open, by the percolation of water, and the roots of the plants thus gain free access to the mineral matter contained by the subsoil. This is an advantage when the upper soil is excessively rich in vegetable substances, for a check is placed on the too luxuriant growth of a straw, and the plants are allowed both time and means to assimilate the quantity of silica necessary to give the stalks both strength and hardness. Drainage also acts in another way as a preventative of rust. A drained soil is always wanner than an undrained one, so that the crops come earlier to maturity, and the danger incidental to a protracted period of ripening are avoided.