CONTROL OF BLACKBERRY.

Stratford Evening Post, Volume XXXV, Issue 9, 9 January 1913, Page 7

CONTROL OF BLACKBERRY.

A POSSIBLE REMEDY. Settlers in Taranaki who have for years sought to keep the blackberry in check, will read with pleasure an article published by Mr. A. H. Cockayne, Government Biologist. Up till quite recently, says Mr. Cockayne, tiie blackberry was singularly free from the attacks of any natural enemy that might be of value in its control. For a number of years past several parasitic fungi—notably orange

rust (Caeoina nitens) —have been noted as occurring sporadically, but in no cases have their efforts justified the opinion that any of them would prove efficacious as control agents. During the past two years, however, a hitherto rare native moth (Carposina adreptella), belonging to*"the Tortrix group, has been found attacking the young shoots of the blackberry. The immense number in which this moth has been present, and the really effective work that it has already accomplished, indicate that it may prove an exceedingly valuable agent in controlling the spread of the blackberry. At first sight its mode of attack might lead one to think that its action would have but little permanent benefit. The eggs of the moth are laid in the leaf basis of the young shoot, or ii, tho bud itf|,'lf. The larvae, after hatching rapidly, penetrate the soft tissue, and bore through the pith for a distance of, perhaps, two inches. This is followed by the complete death of the terminal shoot. The blackberry

spreads extensively by means of pendant branches which, when they reach tho ground, root, and give rise lo new plants. If a blackberry plant has the terminal portions of those branches destroyed before they reach the ground the power to spread vegetatively is entirely eliminated, and the plant remains small in size, and will not be able to coalesce with its neighbours and form a dense, close thicket. This is exactly what is occurring whenever the carposina has attacked the plants, and, moreover, affected plants appear to be losing their power of producing flowers and fruit to anything like the same extent as unaffected ones. Mr. Cockayne believes that tho carposina also attacks the young flower buds before they expand, but this is a point that has not yet been investigated. The extraordinary part in the work of the carposina, and one hard to believe, is that this moth should for so many years occupy such an unimportant position in our fauna, and that within the space of two seasons it should become one of the commonest insects. The number of the larvae present on a single large blackberry bush is almost inconceivable, and Mr, Cockayne has seen whole areas of this weed with nearly every terminal bud eaten out and destroyed. The distribution of the moth is very widespread and in every district the biologist examined the effects of its work have been most noticeable. If it continues to extend it will completely prevent the blackberry from spreading vegetatively. Present indications point to its causing a great diminution in the amount of seed produced.