APHIS AND DIAMOND-BACK MOTH.

Dominion, Volume 4, Issue 1187, 24 July 1911, Page 8

APHIS AND DIAMOND-BACK MOTH.

SJPBAYING EXPERIMENTS. Tho parasites nphis and diamond-bncl; moth and the chects m spraying mips troubled oy them are dealt witn by Jir. I'l'iuirose jf'Connoll in an article in me July number ol' the "Journal oi Hie Uoparcment of Agriculture." Air. Al'Connell's remarks concern tho expeniuenvs luudo during the tinio he was at rho Akmmaiiaki Experiment l'arm. Tne swede crop at Moumajiaki suffered, from the pests iast season, and Jlr. M'Connell Bay's that he has no doubt that the long spell of dry weather had fhe effect of intensifying che attack of the parasites. Uiiuer tho direction of tno biologist various sprays were tested. The cost of the sprays ranged from 7s. Gd. per acre to- £1 2?. lid. Air. M'Conncll says: "In taking the cost per acre- into consideration, it must be remembered that if a water supply is uot within easy distance (ho cost will be considerably increased. In . the present . case a good supply of water was available in the affected- paddock. Tho speed at which a sprayer travels will also lessen or increase tho cost. If the horse walks at a quick pace the, cost will be comparatively small, as only a comparatively small quantity of the spray will be used, and the work will be moro or less effective in proportion. 1 find that spraying only once over, if slowly done, required about SO gallons of liquid nor acre." ~ 8 'Plin'Cnllnn-i'niv H, n rnnJ i H/in C 11 n.

tho following , , stating the conditions.under which the experiment was carried out, needs to be taken into consideration: ."When the work of spraying was undertaken the attack was well developed, both aphis and moth being present in enormous ■ numbers. Tho spraying, machine used was' attached to' an' ordinary farm' cart, tho pump requiring two to maintain the necessary pressure. From the first it was very apparent that complete success could not be expected, as itwa.s found impossible to lower tho nozzles sufficiently so that Hie spray.would reach tho under surface of the leaves. To make the latter possible, when spraying, from an .ordinary cart, the turnip rows would require to bo of a uniform width of 30in., so that the wheels would travel in the centre of tho row, the nozzles also occupying a similar position in each row. If the rows are irregular, or tho turnips sown broadcast, 'top' spraying only is possible, as tho turnips continually obstruct the nozzles and prevent them from bsing lowered sufficiently.' . Two days after spraying was carried out ho examined the turnip foliage carefully, and found that, with the exception of one, all the sprays had : killed or dispersed the parasites where the two had come into contact, but the lower surface of the leaves were, still, Ivithout exception, covered with live insects. The sprayings would probably have shown a better result had they been carried out at an earlier stage. Hβ was of opinion that the spraying of swedes would only be successful when done as a preventive. This would probably' require two sprayings, the cost of winch wpidd be very considerable—probably too niuch to be .practical. As far as could bo seen, the spraying in this instance had had no final result. A great percentage of the leaves in both a tho sprayed nnd tho unsprayed swedes had dropped otf, and in both cases new and clean foliage was appearing^;' Taking' the drought into consideration, the bulbs had grown well m spite of the parasites, "nnd," continues the article, "they are perfectly sound and quite oh average crop—in fact, the only passable crop of swedes I have seen this season. The success of the crop in spite of all the difficulties it had to encounter is no doubt due to the effects of green manurin" and thorough cultivation. I consider that if the soil is thoroughly cultivated and judiciously manured, so as to make the plant as vigorous as possible, an ordinary attack of aphis in an average season need not be much dreaded, except lhe attack ocevs when the plants are young. Certainly,the crop in question has come through the ordeal miieh better than I anticipated."