GRASS-GRUB CONTROL.

Pukekohe & Waiuku Times, Volume 9, Issue 592, 14 December 1920, Page 4

GRASS-GRUB CONTROL.

EXPERIENCE AT RUAKURA.

(A. W. Green, Manager, Ruakura Farm of Instruction).

A case indicating the efficiency of soil-trampling by heavy live-stock as a practical means of controlling .attacks of the grass grub (Odontria Zealandica), in certain circumstances, has occurred at Ruakura this year. In February last the wilting of large patches of grass pasture in one of the fields (No. 9) bespoke the active presence of the grub, and this was confirmed by examining the ground. Shortly afterwards a maize crop became available for feeding out to the dairy herd, and arrangements were made whereby this fodder was fed on the affected areas of the field. Th« lesult was a thorough trampling of the ground by the cows. Later on, during the winter, the same procedure was repeated with hay and mangolds. The grub-infested areas made a steady recovery from late autumn onwards', and by spring-time the grasses and clovers were growing almost normally on them. The process has been assisted by the germination of grass-seed from the hay when feeding and tramped into the ground by the cattle. The hay contained considerable quantities of clover seedheads, and as clover-seed passes through cattle unharmed the establishment of clovers on the infested patches followed. The concentration of cattle on these areas- gave a further benefit, for in consequence the land received a heavy dressing of animal manure. Subsequent to the stocking the land was chain-harrowed, thereby turning to profitable account the animal droppings. , , * The foregoing, however, does not comprise all the data. A control area, greatly increasing the value and interest of the demonstration, was automatically provided by a wirefenced enclosure surrounding the sel-dier-trainees' quarters, which are situated in the field in question. Large parts of this enclosure were affected by the grub, including ground conterminous with grubby patches in the open field. The ground inside the fence was planted here and there with shrubs, and, of course, could not be subjected to the trampling process. On these enclosed patches the grass was practically killed out and the ground became bare. •It may be mentioned that in this case the rye-grasses were the first to .suffer from the attack of the grub, while cocksfoot proved the most resistant. Among the clovers, alsike and white soon succumbed, while red clover retained its roothold longest. The trampling action of heavy cloven-footed beasts is great, especially with a herd moving about after fodder 1 ., This was borne out by fan examination of the soil of the treated patches, which revealed numbers of crushed grubs, those that escaped having no noticeable effect. Such trampling is undoubtedly far more effective than rolling, where the pressure is distributed over a much larger area. The method here outlined is 4"! 1 based on the results of one season'? experience, for in the autumn of 1915 several acres of grassland infested with grass-grub received similar treatment, with the exception that turnips and mangolds only were fed cut. Regrassing in this case was accomplished by the surface-sowing of grass and clover seeds and hanjowing. Another field (No. 18) was badly' infested with grass-grub during the autumn of 1918. Treatment on exactly the same lines as that given to field No. 9 and described in detail ii) this article destroyed the grubs and renovated the grass pasture. This is now one of the best pastures Jon Ruakura. It is not claimed that the control plan here described could be carried out everywhere, or where the attack of the grub is widespread over the whole of the pasture of a farm. Attack, however is very commonly confined to limited areas, and in such cases a simple adaptation of farm practice on the lines given will aiford good prospects of successfully controlling the pest, especially in dairying districts where both cattle and fodder crops are available. Few dairy faimers would wish to break up their best pastures in an endeavour to eradicate grass-giuD by cultivation, which means that for the sake of dealing with comparatively small patches the whole of the field has to oe ploughed up. Farmers may be advised to especially watch for the grub on the lighter classes of land. The experience at Ruakura has been that the grub will be usually found in light loam, or loam over a gravel subsoil, rather than in heavy land with a clay subsoil. In the Auckland district the land varies considerably, and even in a comparatively small field the two extremes may be found. Such was the case in all the fields already referred to in this article. Patches of lighter land varying from three to nine acres were affected, while the remaining areas of the nelds varying from twlve to twenty-one acres -vere unattacked.