THE UBIQUITOUS BLACKBERRY

Dominion, Volume 6, Issue 1584, 30 October 1912, Page 8

THE ÜBIQUITOUS BLACKBERRY

. CONTROL BY A'N INSECT. :. Farmers whose lands have become overrun - with. the . (lcutji-detying blackberry-, will'bo jiarliculai-ly interested in an article, published' by llr. A. H. Cockayne, Uoycriiiiient: iiio.Cjist, which, article fives a ray ot hppo.to tuote who have lor years ueen battling to k«p the pest in cne'clc. ■ Up till quite recently,, says Mr. (Jock? .nyiic,. the blacKUerry' was, singularly, ii-ee .l'roui" tho attacKs of any natural enemy that might lie ot value in it's control. I'W'.a number of years [mst several parasitic' luiiK'i, notably orange-rust (Caconia mtens), have been noted as occurring sporadically, but in no cases have their erfects justiiieu 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 numbers in which this moth has been present, and the' really effective work that it has already-accomplished, indicate that it may prove air exceedingly valuable agent ill controlling tho 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 tho moth are laid in the leaf-bases oi tho young shoot or in. the bud itself. 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 shoots Tho blackberry spreads extensively by means or pendent branches which, when they roach the ground, root aiul give rise to new plants. If a, blackberry-piant has the terminal 1 portions of-these'branches destroyed before they reach the ground the power- to spread vegetatively is entirely eliminated, mid 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 wherever "Carposina" has attacked tho 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. Jlr. Cockayne believes that "Carposina" also attacks tho young Hower-buds before they expand, but this is a point that has not been yet investigated. The- extraordinary part in the work of "Carposina,"'and one hard to believe, is that this moth should for so many years occupy such an unimportnnt position in our fauna, and that within the spaco of two seasons it should become ono of our'commonest insects. The number of the larvae present on a single largo blackberry bush is almost inconceivable, i and Mr. Cockayne has seen whole areas of this weed with nearly every terminal Imd eaten out and destroyed. Tho '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 there is not the least doubt, he adds, that it will completely prevent the blackberry from spreading vegetatively. Present indications point to its causing a great diminution in'the amount of seed produced.