Finds Water The Answer

Press, Volume CVII, Issue 31440, 5 August 1967, Page 10

Finds Water The Answer

Mr G. B. Henderson, of Lyndhurst in MidCanterbury, is convinced that irrigation is an effective counter to the porina caterpillar.

He has some most revealing colour slides (unfortunately not sufficiently bold and contrasting to be reproduced in black and white) which show thousands of gulls on one of his paddocks which was being watered at the end of February after a white clover seed crop had been taken off it Such areas closed for seed crops are recognised as being most favourable for porina and it is assumed that the inundation forces the porina up to the surface and the birds do the rest After such treatment Mr Henderson said that when the water drained off, the surface of the ground was like a pin cushion with holes.

Because he places such importance on watering as a means of controlling porina, Mr Henderson went round all of his paddocks and gave them a watering before the

irrigation water went off last April. He says that his whole water charge for the season, £B2, would be a cheap insurance against porina damage. Without Irrigation he believes that his country could be as badly devastated with porina as anywhere. There are plenty of porina about He has evidence of that in lucerne which is not irrigated. The porina are most active here. There is further evidence of them in a paddock which was watered but includes an area that missed the water. The pasture here has been wiped out This is concrete evidence of the value of watering. Mr Henderson believes that water should be applied to an area harvested for small seeds as soon as possible thereafter to stimulate recovery of growth and to exercise porina control. But he says that irrigation could, in fact create conditions favourable to porina. The upsurge of porina in the last two seasons appeared to be associated with the growthy conditions in the stimmer. The Irrigation farmer could induce these conditions by watering any Bummer so that irrigation had to be used in association with heavy grazing or else the irrigation farmer could get into trouble.

Had there been a downpour of four or five inches of rain in April and May Mr Henderson thinks that this might have had a similar effect to his Irrigation and porina would not have been as bad as it has been this season.

Mr Henderson has not spent any extra money on insecticides for pasture pest control. He applies D.D.T. soon after sowing down and with this one treatment he has had pastures still going strong after 10 years. He now has a trial to see how he gets on with no D.D.T. treatment at all.

Although he is living in country with a grass grub history, he says that grass grub has not been a problem on his country. So it seemed that the water must be doing something here too.